Nanoparticles in Therapy and Diagnosis: A Comprehensive Review of Mechanisms, Applications, and Translational Challenges

Abstract

Background: Conventional therapeutic and diagnostic approaches, despite improving clinical outcomes, remain limited by poor bioavailability, inadequate targeting, suboptimal pharmacokinetics, and systemic toxicity, particularly in complex diseases. To overcome this, nanomedicine has emerged as a transformative strategy, employing engineered nanoparticles to enhance drug stability, controlled release, targeted delivery, and diagnostic performance, thereby enabling theranostic applications. This review evaluates major nanoparticle platforms in therapy and diagnosis, comparing their mechanisms, applications, and challenges while highlighting their potential to advance precision medicine and theranostic strategies. Method: For providing the context and evidence, relevant literatures were sourced from Google Scholar, PubMed, and ScienceDirect using targeted keywords including “drug delivery,” “diagnostics,” “nanoparticles,” “nanomedicine,” “nano drug delivery,” “nanotheranostics,” “targeted therapy,” “controlled drug release,” “solid lipid nanoparticles (SLNs),” “lipid nano carriers (LNCs),” and “inorganic nanoparticles.” Although no strict time limit was applied during the literature search, clinical trial data were collected and analyzed up to January 2026. Given that clinical trial registries are continuously updated, the included trials represent the status at the time of data retrieval. However, it is pertinent to note that the earliest relevant studies appeared in 1973. Conclusions: This review highlights nanoparticle fundamentals, major material classes, mechanisms of action, and applications in targeted therapy, imaging, and theranostics. It also addresses translational barriers related to safety, scalability, biological complexity, and regulatory compliance. Overcoming these challenges through standardized characterization and interdisciplinary collaboration is crucial for clinical adoption. Future efforts should focus on AI-driven design, computational tools, smart nanomedicines, and advanced biosensing technologies to integrate nanoparticle-enabled precision diagnostics and therapy into routine clinical practice.

1. Introduction

The contemporary pharmaceutical sciences and biomedical landscape have profoundly reshaped the prevention, diagnosis, and treatment of a wide range of diseases. Conventional drug therapies, including small-molecule drugs, biologics, and diagnostic agents, have substantially improved clinical outcomes and patient survival across multiple therapeutic areas [1]. Nevertheless, the increasing complexity of disease biology, particularly cancer, neurological disorders, infectious conditions, and cardiovascular diseases, has exposed the critical gaps between therapeutic intent and clinical reality. Despite their widespread clinical use, conventional drug delivery and diagnostic approaches are often constrained by factors such as low bioavailability, poor water solubility, limited tissue targeting, first-pass metabolism, food interactions, and degradation by gastric enzymes [1,2,3,4,5,6,7,8]. These factors culminate in a suboptimal pharmacokinetic profile and reduced therapeutic efficiency, thereby undermining effective drug concentration at the target site while minimizing systemic exposure [5,9,10]. A critical, consequential, and longstanding limitation of conventional therapeutic modalities is systemic and off-target toxicity, which may result in dose-limiting toxicity and a narrow therapeutic window [2,4]. This particularly poses a significant challenge in cancer chemotherapy, where anti-neoplastic agents exhibit non-specific cytotoxicity and lead to drug resistance [10]. Notably, premature release of drugs, poor stability, immunogenicity, and low drug-loading contents represent additional significant challenges associated with the conventional drug delivery system. These limitations underscore the need for innovative nanotechnological approaches that enable precise, on-demand, controlled, and sustained drug delivery while mitigating the risks inherent to conventional systems.

Nanomedicine is an interdisciplinary field that applies principles of nanotechnology to medical interventions, encompassing disease prevention, diagnosis, and therapy, and enabling integrated theranostic applications [11]. This field leverages engineered nanoparticles (NPs), such as solid lipid nanoparticles (SLNs), lipid nanocarriers (LNCs), liposomes, polymeric nanocarriers, nanostructured lipid carriers (NLCs), dendrimers, lipomers, and carbon-based nanomaterials to enhance drug stability, protect therapeutic agents from degradation and enable site-specific delivery while minimizing the toxic effects [1,11,12]. NP-based drug delivery systems overcome the limitations of conventional therapy by facilitating improved drug stability, solubility, and bioavailability, along with controlled and sustained release of therapeutic agents [13]. For instance, nintedanib-loaded iron chelated melanin nanoparticles have demonstrated controlled drug release over 36 days following zero-order kinetics, reduced cytotoxicity in BEAS-2B and A549 cells [14]. Moreover, it also showed enhanced MRI contrast, serving as a promising theranostic platform. Notably, incorporation of α-mangostin into nanomicellar systems increased its solubility by over four orders of magnitude [15]. In addition, polymeric NPs facilitated targeted delivery and significantly improved organ-specific biodistribution of α-mangostin. Moreover, NPs enable targeted and precise delivery of drugs to specific tissues or cells, such as tumor cells of prostate cancer [7], cervical cancer [16], pancreatic cancer [17], hepatocellular carcinoma [18], and urological cancers [19], by mechanisms such as enhanced permeability retention (EPR) effects or receptor-mediated endocytosis. In addition to this, NPs significantly enhance the imaging contrast in various diagnostic modalities, particularly MRI, enabling non-invasive visualization of disease progression [1,14,17,20]. Furthermore, multifunctional NPs such as aptamer-conjugated polymeric NPs provide ultrasensitive MRI contrast, simultaneously delivering drugs to the targeted tissue for conditions such as castration-resistant prostate cancer [20]. Collectively, these attributes enable NPs to simultaneously perform therapeutic and diagnostic functions, establishing them as a robust theranostic platform for a broad spectrum of clinical applications.

This review aims to systematically compare major classes of NPs with respect to their design principles, mechanisms of action, therapeutic and diagnostic applications, and associated translational challenges. By integrating insights from preclinical and clinical studies, the review also examines the opportunities and limitations of NPs-based systems for advancing precision medicine and theranostic strategies.

2. Methodology

For the synthesis of context and evidence, a comprehensive literature search was conducted across multiple scientific databases, including Google Scholar, PubMed, and ScienceDirect. The search strategy employed a combination of predefined and targeted keywords such as “drug delivery,” “diagnostics,” “nanoparticles,” “nanomedicine,” “nano drug delivery,” “nanotheranostics,” “targeted therapy,” “controlled drug delivery,” “solid lipid nanoparticles (SLNs),” “lipid nanocarriers (LNCs),” “organic nanoparticles,” and “inorganic nanoparticles.” Moreover, Boolean operators (AND, OR) and keyword combinations were used to refine search outputs and enhance relevance.

Study selection was performed using defined inclusion and exclusion criteria to ensure methodological rigor. Peer-reviewed literatures published in English that focused on the design, development, characterization, or application of nanoparticle-based systems in drug delivery and diagnostics were included. Furthermore, it is noteworthy that both preclinical (in vitro and in vivo) and clinical studies from clinicaltrials.gov were considered. However, a clear distinction was maintained during data extraction and synthesis to differentiate mechanistic insights from translation and clinical outcomes. Clinical trials were specifically identified through database filters and cross-referenced with trial registries, and data were included up to January 2026. Notably, studies lacking sufficient experimental detail, duplicate publications, non-peer-reviewed reports, and articles not directly relevant to nanomedicine applications were excluded. Additionally, greater emphasis was placed on recent studies to reflect current advancements, while seminal and foundational studies dating back to 1973 were included to provide historical context and trace the evolution of the field.

3. Fundamental Design Principles of Nanoparticles

The physicochemical attributes of NPs, encompassing size, shape, surface charge and chemistry, and colloidal stability, dictate their interaction with biological barriers, protein corona formation, cellular uptake mechanism, biodistribution, and clearance [21]. A thorough understanding of these principles is crucial in designing nanomedicine with optimal pharmacokinetic and pharmacodynamic behaviour [22]. This section of the review sheds light on core physicochemical design parameters intrinsic to NPs design, rather than providing disease-based optimization strategies, to provide broader coverage that can be applied across various NPs classes.

3.1. Size and Shape

The size and shape of NPs principally drive cellular uptake, biodistribution, cell accumulation, and clearance [23]. Notably, uptake mechanisms are broadly categorized into two pathways: passive and active [24]. However, the NPs often traverse the cell membrane (CM) via active transport [25]. This is because passive diffusion allows only small, uncharged molecules to pass [26]. The internalization process of NPs is primarily carried out by endocytosis, in which the NPs are initially engulfed into vesicles and then released intracellularly [27]. Key endocytic mechanisms include phagocytosis, caveolin-mediated endocytosis, clathrin-mediated endocytosis, clathrin/caveolae-independent endocytosis, and macro-pinocytosis. Notably, the NPs size and shape serve as crucial determinants of the endocytic mechanism [28,29]. Emerging evidence suggests that, in addition to phagocytosis and micropinocytosis, clathrin- and caveolae-mediated mechanisms exhibit size-dependent NPs endocytosis [30]. This hypothesis is supported by two critical facts: (1) a majority of phagocytosis relies on protein opsonization, and (2) macropinocytosis often undergoes non-specific cargo uptake, enabling concurrent uptake of NPs of various sizes simultaneously and usually through involvement of other uptake mechanisms [30].

Conversely, Clathrin- and Caveolae-mediated endocytosis are majorly dependent on NPs’ size [31]. The average size of clathrin-based vesicles is approximately 120 nm, which is comparatively greater than the average diameter of Caveolae-based vesicles (~60 nm). These vesicle sizes display substantial intraindividual variability among cells [30,32]. Despite this size variability, it is expected that the vesicle size differences may drive the uptake mechanism [30,32]. To illustrate, NPs ranging from 20–100 nm are commonly internalized by Caveolin-mediated endocytosis [33,34]. Following the engulfment of NPs, this process exploits lipid rafts to create specialized caveolin-containing vesicles, which bypass the lysosome-endosome pathway. Overcoming this pathway avoids degradation of the carrier contents, thereby precisely delivering the NPs to the cytoplasm or nucleus [35,36]. Notably, nanorods, graphene Quantum Dots (GQDs), and carbon nanotubes utilize this pathway for cellular uptake [36,37,38].

The Clathrin-mediated endocytosis (CME) represents a key mechanism for NPs uptake, as it is the most preferred route of uptake in non-specialized mammalian cells [39]. This process is characterized by the formation of clathrin-coated vesicles (CCVs), which invaginates, mature, and undergo scission, facilitating carrier internalization [40]. It is a receptor-mediated process that involves the initial attachment of the clathrin coat protein to cell membrane receptors, which is followed by the formation of CCVs [26,41]. The cellular internalization of nanospheres primarily occurs via CME [38]. Accumulating evidence from multiple studies indicates that NPs ranging between 30 and 50 nm exhibit superior interaction with CM receptors, thereby facilitating optimal cellular uptake and effective internalization via endocytic mechanisms [42,43,44,45,46,47,48,49,50,51,52].

In addition to size, the shape of NPs plays a significant role in the uptake pathway, particularly endocytosis. To illustrate, spherical or round NPs are easily endocytosed as compared to NPs having irregular shapes, such as tube or rod-shaped NPs [53]. This reduced endocytosis of nano-rods is primarily because of the failure of the cell to facilitate the necessary actin-based membrane kinetics required for endocytosis [54]. Notably, spherical NPs are often internalized by CME, while the uptake of complex shape NPs occurs through clathrin-independent mechanisms [55,56]. Mounting evidence highlights potential benefits of non-spherical shapes, such as nanotubes [57,58], nanorods [59,60], nanocages [61,62], and nanodiscs [63,64] in tumor penetration. These distinct geometries encompass more complex rotational and translational dynamics within systemic circulation, facilitating their migration toward the vessel wall and thereby enhancing their extravasation into cancer tissues. Following their entry into tumor interstitium, their morphology provides an added benefit of achieving deeper tumor penetration compared to their spherical counterparts [65].

Apart from cellular uptake, NPs shape influences its endosomal escape. For instance, nanostars have been shown to effectively enter the cells and escape endosomes, thereby enhancing the intracellular delivery of genetic material [41]. This endosomal escape is a crucial parameter for functional delivery, as these endosomes induce a series of events featuring low pH, elevated ionic strength, and the activation of proteolytic enzymes, resulting in NPs degradation [39]. Commonly, this escape can be achieved by employing responsive NPs, such as ionizable NPs, which ionizes under low pH environments, and escape the endosomes (Figure 1) [66,67].

Beyond cell internalization, NP size affects biodistribution, tumor permeability, and clearance [49]. For instance, NPs with small diameters easily cross capillary walls compared to larger NPs [25,68]. The NPs follow a size-dependent distribution pattern across organs, with the highest accumulation observed in the liver and spleen. This size-dependent biodistribution is primarily due to the presence of distinct filters or barriers within organs and surrounding fluid [69]. To demonstrate, administration of NPs sized 20 to 100 nm into the renal tissue showed no correlation between the particle size and its accumulation in peritubular capillaries. Nevertheless, upon administration of NPs having a 50 nm diameter, a strong correlation between particle size and particle accumulation was identified in the renal corpuscle cells [69]. Additionally, NPs having a diameter less than 10 nm are rapidly eliminated by the kidneys [49]. Nevertheless, this distribution pattern is often altered by chronic pathological conditions, such as cancer, leading to the development of larger intercellular gaps, enabling the passage of larger NPs from the blood vessels [70]. Moreover, NP size is inversely proportional to the vascular permeability, meaning that as the size increases, the permeability decreases [71].

3.2. Surface Charge, Chemistry, and Surface Modifications

The surface charge and chemistry of NPs critically influence their in vivo behavior [67]. Upon their entry into systemic circulation, NPs are exposed to circulating biomolecules, such as serum albumin, complement components, apolipoproteins, and immunoglobulins, forming a protein corona on the NPs surface, which severely affects its in vivo activity thereafter [72,73]. For instance, a corona containing opsonin accelerates the NPs clearance by immune cells [74]. Additionally, the presence of protein corona on the NPs surface diminishes its specific targeting capability [75]. Moreover, the corona induces the clearance and elimination of NPs by attaching the NPs to a phagocytic cell, particularly the mononuclear phagocytic system (MPS) or the reticuloendothelial system (RES) [76].

Notably, the positively charged NPs are rapidly cleared by the immune cells, which is followed by negatively charged NPs and uncharged NPs [25]. However, these cationic NPs exhibit enhanced cell internalization attributable to electrostatic attraction to the negatively charged CM [26]. In the tumor microenvironment, these cationic NPs have demonstrated greater tumor penetration. Additionally, it has achieved superior antitumor efficacy compared to its anionic or neutral counterparts [77,78]. Emerging evidence highlights that this electrostatic attraction may result in undesired effects. To demonstrate, NPs possessing stronger electrostatic affinity towards the CM can be captured by perivascular cells, limiting their diffusion and transport into tumor cells [79]. The cationic NPs often exhibits greater toxicity profile compared to anionic and uncharged NPs [26]. Intriguingly, accumulating evidence indicates a charge-dependent formation of protein corona on NPs’ surface [80]. Notably, cationic NPs are a major determinant of the protein corona composition. As a result, anionic or uncharged NPs are preferred options to attain optimal systemic circulation, as it minimizes nonspecific protein adsorption and opsonization, thereby reducing NPs clearance [76].

Given the significant disadvantages of protein corona formation, a majority of NPs incorporate surface coatings to improve their stealth, which is the ability to bypass immune system detection that enables NPs degradation and clearance [76]. Over the past decades, Poly(ethylene glycol) (PEG) as a stealth strategy has gained significant interest [67]. Notably, the PEGylation on the NPs surface enhances its circulation times by shielding it from circulating biomolecules. However, emerging evidence indicates the development of anti-PEG antibodies, which, in higher concentrations, can facilitate rapid clearance of PEGylated NPs [81,82]. Beyond PEGylation, another option for stealth includes platelet membrane cloaking, which reduces cell uptake and complement activation [83]. While this method bypasses macrophage-based immune issues associated with PEGylation, the NPs may still be recognized and cleared by other cells [84].

4. Platform Categories of Nanoparticles: A Functional Classification

4.1. Organic Nanoparticle Platforms

Organic NPs, composed primarily of lipids, proteins, and natural or synthetic polymers, represent a versatile class distinguished by their biocompatibility [85]. The most prominent examples of this class are lipid-based NPs, such as SLNs, NLCs, liposomes, dendrimers, and ferritin nanocages (shown in Figure 2) [86]. These NPs are typically non-toxic and biodegradable and, in some cases, e.g., liposomes and micelles, can have a hollow core. Lipid-based NPs, such as SLNs and NLCs, are functionally engineered and rationally designed drug delivery systems due to their ability to encapsulate both hydrophilic and lipophilic drugs. Moreover, these NPs enhance dissolution, improve drug stability, and absorption by avoiding proteolytic degradation and reducing the first-pass effect [7,87]. Owing to their small size, surface area and surface modifiability, lipid NPs potentiate the mucosal adhesion and targeted distribution [16,87,88]. Building on these advantages, NLCs, a second-generation modification of SLNs, further improve the loading capacity and drug stability while preventing drug leakage [89]. These lipid-based platforms confer notable advantages such as biodegradability, prolonged half-life, and reduced toxicity, making them promising for protein and peptide delivery over conventional therapeutic modalities [87,90]. However, the inherently limited membrane permeability, plasma stability, and short circulation half life of peptides and proteins pose significant translational challenges. Nonetheless, these limitations can be effectively mitigated through surface modification of lipid-based nanocarriers with polymers, ligands, surfactants, and fatty acids, thereby enabling controlled peptide release with enhanced penetration efficiency [87,88].

Polymeric NPs, including sub-15 nm ultrasmall NPs, constitute a versatile organic nanoplatform capable of protecting encapsulated payloads from chemical and enzymatic degradation [91,92]. In addition to improving cargo stability and solubility, these systems optimize local drug concentration at the target site [92]. This enables sustained and controlled drug release and reduces drug clearance, conferring broad therapeutic potential in cancer therapy, neurological disorders, and vaccine delivery. Notably, Lipid–polymer nanoparticles (LPNs) have emerged as a distinct class of hybrid carriers featuring a core-shell architecture, wherein the polymeric core ensures structural stability and the surrounding phospholipid shell enhances biocompatibility [93]. This hybrid design enhances drug encapsulation efficiency (EE) and attenuates initial burst release, thereby promoting sustained and localized drug delivery at the target site.

4.2. Inorganic Nanoparticle Platforms

Building on the biodegradability of organic nanoplatforms, inorganic variants prioritize stability and tunable electronic and optical properties. The typical examples for this class of nanoplatform are metal, silica, ceramic, and semiconductor NPs (Figure 2) [86]. Metal NPs can be monometallic, such as gold (Au), silver (Ag), and graphene-based NPs; or bimetallic, such as iron oxide and zinc oxide NPs. By virtue of their localized surface plasmon resonance (LSPR) behavior, these NPs possess advantages over organic counterparts, including a broad spectrum of mechanical, magnetic, and optical characteristics [94]. Moreover, the surface of inorganic NPs can be modified with ligands to improve targeting specificity, which is crucial for bio-imaging and targeted delivery, serving the theranostic potential. Notably, the core-shell design of these NPs enables the combination of multiple functional properties within a single nano system for targeted and controlled drug delivery [95]. In addition, a few metal NPs exhibit unique magnetic, thermal, and biological properties, making them increasingly essential nanomaterials for the development of nanodevices for numerous biomedical and pharmaceutical applications [86,96]. AuNPs are widely used for plasmonic photothermal therapy owing to their tunable optical response, which enables imaging and photothermal ablation [97,98].

Moreover, iron oxide NPs, particularly superparamagnetic iron oxide nanocrystals, play a pivotal role in magnetic field-guided targeting and magnetic resonance imaging (MRI). Notably, these nanocrystals are frequently encapsulated within silica matrices to generate multifunctional platforms for applications, such as drug delivery and cell-specific targeting [98,99]. In parallel, silica NPs have gained significant attention as an anti-cancer drug delivery vehicle [100] and have progressed into clinical evaluation for a range of applications, including diagnostics, oral drug delivery, and photothermal ablation therapy, collectively demonstrating favourable safety and efficacy profiles [101].

4.3. Hybrid and Bioinspired Nanoparticle Platforms

Biomimetic NPs, including cell-membrane-coated NPs (CMCNs), inherit specific biological functionalities such as homing tendencies, which enable improved drug delivery efficiency while maintaining biocompatibility and low toxicity [102,103]. They facilitate targeted drug delivery by camouflaging synthetic NPs, allowing them to evade the immune system’s recognition and clearance. This results in enhanced targeting efficiency and prolonged blood circulation time to specific pathologic tissues such as tumors or inflammatory sites [104,105,106]. For instance, a review of biomimetic strategies highlights that structures mimicking white blood cells (WBCs), red blood cells (RBCs), and cancer cells demonstrated prolonged circulation and enhanced drug delivery [104]. Moreover, CMCNs act as a protective carrier for delivering immunotherapeutics to minimize rapid clearance from the body, thereby ensuring sustained presence in the circulation. This, in turn, increases the retention time of NPs and their ability to target cancer sites, thereby improving the efficacy of chemotherapeutic agents [107]. However, the clinical translation of biomimetic nanocarriers is constrained by several key challenges, such as potential immunogenicity, manufacturing hurdles, and regulatory clearance, which are addressed in later sections of this manuscript.

Table 1. Applications, advanatges, and challenges of Biomimetic nanocarriers.

Nanocarrier Type	Membrane	Nanocarrier	Application	Advantages	Challenges	References
Cell Membrane-Coated Nanoparticles	WBCs, RBCs, cancer cells	Synthetic nanoparticles coated with cell membranes	Targeted drug delivery to tumors and inflammatory sites)	Immune evasion; prolonged circulation time; enhanced targeted delivery; high biocompatibility and low toxicity; mimic natural cell functions	Manufacturing scalability; potential immunogenicity; membrane heterogeneity; regulatory hurdles; limitations of single-cell membrane coatings for complex pathological microenvironments	[104,107]
Platelet Membrane-Coated Nanoparticles	Platelets	Nanoparticles shielded by platelet membranes	Cancer therapy, leveraging innate tumor-homing and cancer cell interaction capabilities	Leverages platelets’ innate tumor-homing and cancer cell interaction capabilities for efficient drug delivery in cancer therapy	Potential clotting risks	[108]
Exosomes and Engineered Extracellular Vesicles	Various cell types	Natural or engineered extracellular vesicles	Targeted therapy	Specific targeting and improved therapeutic outcomes	Manufacturing scalability; batch-to-batch variation	[104]
Cancer Cell Membrane-Derived Biomimetic NPs	Breast cancer cells	Mesoporous silica	TNBC metastasis	Enhanced tumor interaction	Batch-to-batch variation	[109]

illustrates various biomimetic nanocarrier types with their application and challenges.

5. Mechanisms of Nanoparticle-Mediated Therapeutic Action

NPs have revolutionized disease management by enhancing imaging, improving drug delivery, and enabling personalized medicine [110]. Notably, its theranostic potential facilitates image-guided drug delivery, monitoring the intra-tumor drug distribution, and early assessment of treatment response [111]. Nanotheranostics is widely applicable across various medical disciplines, including but not limited to cancer [112,113,114,115,116,117,118,119,120,121], neurological diseases [121,122,123], cardiovascular diseases [124,125,126,127], and kidney diseases [128,129]. For instance, in cancer therapeutics, NPs, including inorganic NPs, lipid-based NPs, lipid-polymer hybrids, metal–organic frameworks, and biomimetic NPs, are engineered to detect tumour heterogeneity, enable image-guided personalized treatment, and monitor therapeutic effectiveness [130,131]. Additionally, in cancer diagnostics, these NPs incorporate imaging agents that monitor drug delivery, facilitate tumor targeting, and evaluate treatment response [132].

Mehanistically, following administration, the NPs circulate and accumulate in tumors via the enhanced permeability and retention (EPR) effect and/or active targeting moieties (such as antibodies, aptamers, proteins, peptides, radiolabels, fluorescent probes and small molecules) that bind to the overexpressed antigens or receptors on the cancer cell surface [130,133,134]. The EPR effect is typified by high permeability and prolonged retention of the macromolecules in solid tumors. The higher permeability is primarily due to defective vasculature of tumor, often characterized by defects in its basement membrane with discontinuous epithelium. This abnormal vasculature enables extravasation of NPs in tumors [71,135,136]. Conversely, the cancer cells have a deficient lymphatic drainage system, restricting interstitial fluid transportation, thereby retaining the NPs in the tumor interstitium for a prolonged duration [71,137,138].

While EPR-mediated drug delivery has been widely recognized, accumulating evidence indicates substantial limitations of this passive approach in humans, owing to pronounced interindividual heterogeneity in tumor type, vascular architecture, and tumor microenvironmental conditions [139,140]. Intertumoral variability induces disparities in vascular permeability and interstitial pressure, limiting EPR effectiveness across distinct tumor types [141]. To illustrate, patients with hepatocellular or renal cell carcinoma exhibit a higher microvessel density and, therefore, more efficient EPR than individuals diagnosed with prostate or pancreatic cancer [142,143,144]. Another significant limitation is the marked differences in tumor architecture and immune responses between human and animal models. These variations in tumor biology affect NP accumulation and function across individuals, thereby complicating clinical translation [141]. The EPR display significant effect in the highly proliferative subcutaneous xenograft model of tumors, however, its effect on humans needs to be validated to confirm its potential [145].

As a result, to obtain precise and efficient drug delivery, researchers are seeking targeting strategies that are beyond the EPR effect, particularly active targeting. This approach involves surface functionalization of NPs with moieties that selectively recognize and bind to the overexpressed receptors present on the cancer cell surface [146]. Additionally, active targeting enables precise drug delivery to intracellular organelles or specific biomolecules involved in tumor progression [147]. The surface decoration can be achieved by conjugating various targeting ligands, such as antibodies, aptamers, peptides, and small molecules to NPs [146]. For instance, monoclonal antibodies can identify tumor-specific antigens in breast cancer cells, such as epidermal growth factor receptor (EGFR) or human epidermal growth factor receptor 2 (HER2), facilitating precise binding and cellular internalization [148]. Aptamers encompass higher affinity towards tumor-associated proteins, providing enhanced receptor-mediated nanoparticle uptake [149]. Peptides can be engineered to bind with surface markers, such as integrins, owing to their higher affinity and small size. For instance, RGD peptides are developed to specifically target αvβ3 integrins in angiogenic endothelial cells [150]. Small molecules, such as folate and hyaluronic acid, are developed to selectively target upregulated receptors, like folate receptors or CD44, enhancing NPs accumulation within cancer cells [151].

Following a moiety-cancer cell receptor attachment, NPs are effectively internalized through endocytosis mechanisms, primarily receptor-mediated endocytosis, enhancing intracellular drug concentration, cytotoxicity, and reducing off-target effects [29,151,152,153]. From a diagnostic perspective, binding to the receptor initiates a series of events that modulate the reporter signal for imaging modalities, such as fluorescence via activation or dequenching, relaxivity alterations for Magnetic resonance imaging (MRI) contrast, and modulated radionuclide distribution for Positron Emission Tomography (PET)/Single-Photon Emission Computerized Tomography (SPECT) through accumulation or retention (Figure 3) [154,155,156,157,158].

Beyond active targeting strategies, photodynamic therapy (PDT) represents a promising targeted approach in cancer therapy [159]. Principally, PDT involves local or systemic application of photosensitizers (PS), which, upon entering the targeted tumor cell, accumulate within the tissues [160,161,162,163]. Following external photo stimulation of a specific wavelength, it produces cytotoxic reactive oxygen species (ROS), including singlet oxygen, hydroxyl radicals, and superoxide anions, ultimately inducing cancer cell death [160,161,162,163]. Notably, a majority of PS are hydrophobic in nature, possessing low-water solubility, and tend to aggregate under physiological environment, reducing ROS production efficiency [164]. As a result, the integration of nanoparticles with PS serves as a potential approach, as it enhances the stability and targeting ability of PS. In addition, various other anti-cancer agents can be co-delivered using NPs, thereby achieving combination cancer therapy [165]. Moreover, surface-functionalized NPs can achieve precise delivery of PS to tumors, reducing off-target effects [166,167]. Apart from therapy, integrating contrast agents or fluorescent markers may offer a theranostic approach [168]. Notably, NPs commonly employed in cancer include Gold NPs (AuNPs), Silver NPs (AgNPs), Silicon dioxide (SiO₂) NPs, Titanium dioxide (TiO₂) NPs, Upconversion nanoparticles (UCNPs), Quantum dots (QDs), and Polymeric nanoparticles (PNPs) [169].

6. Nanoparticles in Therapeutic Applications

NPs constitute a versatile theranostic platform capable of integrating therapeutic and diagnostic functionalities within a single system, thereby enabling precision and personalized treatment strategies. Their preferential accumulation at tumor sites and other pathologic tissues enhances both imaging sensitivity and therapeutic efficacy [170,171]. Moreover, NP-based systems facilitate accurate disease detection, targeted drug delivery, and spatiotemporally controlled drug release, collectively minimizing treatment delays and improving clinical outcomes [172,173]. Strategic surface functionalization further augments targeting specificity, biological stability, and functional performance in vivo. Consequently, functionalized NPs are being explored across multiple therapeutic modalities, including photothermal and photodynamic therapies, chemotherapy, immunotherapy, MRI-guided gene therapy, and magnetic hyperthermia, underscoring their transformative potential in modern medicine [173,174].

6.1. Cancer

A growing body of literature has investigated NP-enabled theranostic strategies for cancer management. These studies (summarized in Table 2) highlight the intrinsic capability of nanoplatforms to integrate diagnostic imaging with targeted therapeutic interventions. For instance, Zhao et al. [175] investigated the theranostic potential of novel zirconium-based metal organic framework (MOF) core shell composite (Fe₃O₄@UiO-66) conjugated with doxorubicin (DOX) for in vitro and in vivo drug delivery and MR imaging in HeLa cell lines. They evaluated the in vitro cytotoxicity of Fe₃O₄@UiO-66, Fe₃O₄@UiO-66-DOX, and free DOX on HeLa cells by MTT assay. The results demonstrated nearly 100% cell viability with no toxicity when treated with Fe₃O₄@UiO-66, indicating good biocompatibility (Figure 4A). On the other hand, upon treatment with Fe₃O₄@UiO-66-DOX, the anti-cancer activity increased significantly with an increase in the loaded DOX concentration (Figure 4B). Approximately 60% of the HeLa cells were eliminated following incubation with Fe₃O₄@UiO-66-DOX, with the nanocomposite exhibiting cytotoxicity similar to that of free DOX. In addition to this, Fe₃O₄@UiO-66-DOX exhibited higher lethality after incubation for a longer duration (48 h), indicating sustained DOX release from Fe₃O₄@UiO-66 composites. Moreover, when Fe₃O₄@UiO-66 and Fe₃O₄@UiO-66-DOX were evaluated on 3T3 cells, they showed high viability and negligible toxicity (Figure 4C), further indicating good biocompatibility of the nanocomposite. Concurrently, the high transverse relaxivity of Fe₃O₄@UiO-66 enabled concentration-dependent signal attenuation in MR imaging of HeLa cells (Figure 5), directly correlating cellular uptake with therapeutic exposure [175].

Parallel to this, Zhou et al. [176] developed ferrocene-functionalized core-shell lanthanide-doped upconversion NPs, followed by their modification into Fenton-like nanoparticle (FNP). Upon confocal laser scanning using 2′-7′-Dichlorodihydrofluorescein diacetate (DCFH-DA) probe, it was observed that Lipo-FNPs efficiently induce intracellular reactive oxygen species (ROS) under near-infrared (980 nm) laser irradiation. The pronounced DCF fluorescence in AGS (human gastric adenocarcinoma cell line) cells treated with Lipo-FNPs reflects elevated intracellular ·OH production, confirming effective photo-activation and ROS generation within the cellular environment. In contrast, the absence of significant fluorescence in control cells suggests minimal background ROS formation. This strong concordance between confocal imaging and in vitro spectroscopic findings further validates that Lipo-FNPs act as an efficient ROS-generating system under NIR irradiation, which is critical for mediating oxidative damage and therapeutic efficacy in photodynamic or chemodynamic cancer therapy.

In another study, Wang et al. [177] employed radiofrequency (RF) irradiation to achieve efficient tumor hyperthermia. RF-responsive gold nanorods (AuNRs) were selected as an effective thermal transducer, followed by their co-encapsulation with poly(lactic-co-glycolic acid) (PLGA) NPs and docetaxel (DTX). To further enhance functionality, ultrathin manganese dioxide (MnO₂) nanofilms were deposited onto the surface of PLGA/AuNR/DTX nanoparticles via in situ reduction of KMnO₄, yielding PLGA/AuNR/DTX@MnO₂ nanocomposites. Upon in vitro MRI and computed tomography (CT) imaging, it was observed that AuNRs and MnO₂ exhibited dual imaging for the precise diagnosis of tumor. Moreover, T1-weighted MRI demonstrated contrast enhancement, which was strongly influenced by both nanoparticle concentration and the presence of glutathione (GSH). Notably, samples containing GSH exhibited markedly higher signal brightness compared with GSH-free counterparts at equivalent concentrations, indicating GSH-triggered activation of MR contrast (Figure 6). These findings confirm that PLGA/AuNR/DTX@MnO₂ NPs function as an efficient, stimuli-responsive T1-weighted MRI contrast agent. Additionally, the cellular uptake ratio of PLGA/AuNR/DTX and PLGA/AuNR/DTX@ MnO₂ NPs was determined to be 99.7 ± 0.14 and 98.5% ± 0.53%, respectively, within 5 h, indicating no significant difference (p > 0.05). Moreover, cell viability assays showed that PLGA/AuNR@MnO₂ exhibited negligible cytotoxicity, with no significant differences among DTX, PLGA/DTX@MnO₂, and PLGA/AuNR/DTX@MnO₂ groups (p > 0.05) (Figure 7). Collectively, these studies underscore the critical potential of NPs as integrated theranostic platforms and support their advancement toward clinical translation. Additional investigations evaluating NP-enabled theranostic strategies in chemotherapy are systematically summarized in Table 2.

Table 2. Overview of nanoparticles in cancer therapy as therapeutic and diagnostic agents. (NPs: Nanoparticles; DOX: Doxorubicin; HAS: Human serum albumin; DTX: Docetaxel; PTX: Paclitaxel; AuNRs: Gold nanorods; MR: Magnetic resonance imaging; TMV: Tobacco Mosaic Virus; MSCs: mesenchymal stem cells; PDI: Polydispersity index, ZP: Zeta potential, EE: Encapsulation efficiency).

Sr No.	Cancer Type	Nanocarrier Type	Therapeutic Payload	Diagnostic/ Imaging/ Theranostic Component	Study Type	Particle Characteristics	Key Findings	References
1	Breast Cancer	Iron Oxide NPs	DOX	chlorine e6 (Ce6)	In vitro (4T1 cell line) In vivo (Balb/c mice)	-	Combination of DOX@RBC-IONP-Ce6-PEG and 660-nm laser irradiation destroyed the cancer cells (4T1) Ex vivo fluorescence imaging revealed optimal magnetic field (MF)-enhanced tumor accumulation of the formulation MRI imaging confirmed efficient tumor targeting and accumulation by the engineered magnetic RBCs. In vivo experiments demonstrated pronounced tumor-growth inhibition effect of combination therapy with magnetic targeting (tumor inhibition ratio: 67%) compared with MF-guided chemotherapy (44.7%) or photodynamic therapy (35.4%) alone at day 14.	[178]
2	Breast Cancer	Albumin-modified melanin-silver hybrid NPs	-	HSA	In vitro (HS578T, and MCF10a cell lines)	Particle size increased from 190 ± 3.5 (PDI 0.20) to 230 ± 4.0 nm (PDI 0.24) after HSA conjugation ZP: −25 ± 1.7 mV	Specific internalization Concentrations ranging from 25 to 100 µg/mL have a negligible influence on cell viability No hematotoxicity Enhanced photostability	[179]
3	Cancer	poly(lactic-co-glycolic acid) (PLGA) NPs loaded with AuNRs	DTX	MnO2 nanosheets	In vitro (MCF-7 human breast cancer cell line) In vivo (female Kunming mice (~18–20 g)	Size: PLGA/DTX: 239.0 ± 3.7 nm PLGA/AuNR/DTX: 263.3 ± 4.5 nm PLGA/AuNR/DTX@MnO2: 282.1 ± 6.2 nm PDI: PLGA/DTX: 0.16 ± 0.01 PLGA/AuNR/DTX: 0.16 ± 0.02 PLGA/AuNR/DTX@MnO2: 0.18 ± 0.02 ZP: AuNRs: 27.4 ± 2.2 mV PLGA/AuNR/DTX NPs: −12.3 ± 1.5 mV Cellular uptake ratio: 98.5% ± 0.53%	Clear MR or CT contrast imaging at the tumor site Higher biodistribution at 4 h after administration Efficient tumor inhibition and cellular apoptosis	[177]
4	Breast Cancer	Hybrid silica/melanin NPs	DOX	HSA	In vitro (HS578T Cells)	Increase in size from 394 ± 32 (PDI 0.26) to 407 ± 29 nm (PDI 0.45) and ZP from −27.2 ± 1.65 mV and −17 ± 2.16 mV after DOX loading Absorbance value: 0.69 at 808 nm wavelength	At the lowest concentration, 53% toxic effects NPs loaded with DOX are more effective than the free drug Enhanced cytotoxicity at photothermal laser irradiation	[180]
5	Breast Cancer	pH-sensitive near-infrared (NIR) croconaine (Croc) dyes-loaded copolymeric PEG−PLGA	-	PPC815	In vitro (MDA-MB-231 cells) In vivo (BALB/c nude female mice)	Croc770: Particle size: 182.3 ± 3.0 nm PDI: 0.09 ± 0.01 ZP: −24.2 ± 2.1 mV DL: 20.2% EE: 43.4% Croc815: Particle size: 183.3 ± 2.1 nm PDI: 0.10 ± 0.02 ZP: −21.2 ± 1.4 mV DL: 19.8% EE: 40.4 PPC815: Particle size: 185.1 ± 3.3 nm PDI: 0.07 ± 0.03 ZP: −1.2 ± 0.7 mV DL: 19.8% EE: 40.4	IC50 values of CPC815 and PPC815 NPs were 75.7 and 60.2 μg/mL Upon NIR laser irradiation, IC50 values of CPC815 and PPC815 decreased to 27.8 and 11.2 μg/m Efficient tumor inhibition No acute toxicity to major organs	[181]
6	Cervical adenocarcinoma	Fe3O4 NPs (Fe3O4@UiO-66 core–shell composites)	DOX	Fe3O4	In vitro (HeLa cells) In vivo (Kunming mouse)	Diameter of Fe3O4 NPs: 150 nm Fe3O4@UiO-66 composites: Particle size: 241.5 ± 28.5 nm PDI: 0.340	60% HeLa cells killed Enhanced lethality against HeLa (48 h) Potential contrast agent for cancer diagnosis Darkening effect observed in the liver region of Kunming mouse (10 min post-injection) High cancer cell mortality	[175]
7	Breast Cancer	Gold-nanoshelled poly (lactic-co-glycolic acid) (PLGA) magnetic hybrid NPs carrying anti-HER-2 antibody	HER-2 antibodies	Her2 functionalized gold-nanoshelled magnetic hybrid NPs (HER2-GPH-NPs)	In vitro (SKBR3 and MDA-MB-231 cells)	Mean diameter: 248.3 nm PDI: 0.037 ZP: −14.7 mV	Act as an excellent contrast enhancement in vitro US and T2-weighted MR imaging Enhanced tumor inhibition In vivo data still needed	[182]
8	Metastatic Breast Cancer	Albumin-based NPs (PSN-HSA-PTX-IR780)	PTX	HSA	In vitro (4T1 cells) In vivo (tumor-bearing mice)	Size: PSN HSA-PTX-IR780: 142.2 ± 4.86 nm HAS-PTX-IR780: 128.1 ± 1.7 ZP of both NPs: ~−30 mV DL of both NPs: ~7.5%	Activated platelet-targeting albumin-based nanoparticles to inhibit 4T1 primary tumor Increased tumor permeability Enhanced tumor-infiltrating platelets Higher PTX accumulation Suppressed tumor growth	[183]
9	Breast and prostate cancer	Albumin-Coated Tobacco Mosaic Virus NPs	DOX	TMV	In vitro In vivo	-	Can be utilized for theranostic uses Enhanced efficacy	[184]
10	Head and neck squamous cell carcinoma	Iron-oxide NPs functionalized with integrin-targeting fibronectin-mimetic peptide (Fmp)	Silicon phthalocyanine 4 (Pc 4)	Iron-oxide NPs	In vitro In vivo	Size: 10 nm in in a molar ratio of 30:1 Conjugation efficiency of Fmp: 89.5% Hydrodynamic size of Fmp-IO-Pc 4:41 nm	Both targeted (Fmp-IO-Pc 4) and nontargeted (IO-Pc 4) NPs had greater efficacy than free Pc4 Elevated intratumoral accumulation relative to free photosensitizer Significant tumor growth suppression utilizing a 10-fold lower photosensitizer dose	[185]
11	Head and neck squamous cell carcinoma	Cholesterol/vitamin E-doped distearoylphosphatidylcholine liposomes	Rhenium-186 (186Re) radionuclide	β-emitting radionuclides	In vivo	Size: 135.1 ± 18.0 nm	Sustained local radiation retention Substantial tumoricidal radiation dosing (526.3 ± 93.3 Gy) resulting in pronounced tumor volume regression	[186]
12	Cancer	Pluronic F127 polymer micelles	-	TPVTR (aggregation-induced emission fluorogen) dots	In vitro In vivo	Uniform particle size (~100 nm)	Strong near-infrared fluorescence, high photostability, and robust reactive oxygen species production upon aggregation Effective photodynamic tumor destruction in vivo with negligible toxicity to healthy tissues	[187]
13	Bladder cancer	Self-assembled porphyrin-cholic acid-PEG micelles decorated with PLZ4 targeting ligand	DOX and Pyropheophorbide-a	PLZ4-nanoporphyrin	In vitro In vivo	Size of PNP-DOX: 23 ± 6 nm PNP-DOX exhibited 10.6 times higher area under the curve (AUC) than free DOX	Highly specific cellular uptake in neoplastic urothelium, yielding precise fluorescence demarcation of tumors Complete eradication of orthotopic patient-derived xenografts and improved overall survival	[188]
14	Non-small cell lung cancer, bladder cancer, and murine fibroblast	Anisamide-targeted lipid-calcium-phosphate (LCP) NPs	Lutetium-177 (177Lu) radionuclide	Lutetium-177 (177Lu) radionuclide	In vitro In vivo	Size: 36 ± 9 nm EE: approximately 70% PDI: 0.27 ± 0.05 ZP: −6.7 ± 3.5 mV	Solid calcium phosphate core facilitated massive specific loading of trivalent radiometals without disrupting particle morphology or loading efficiency Durable tumor growth suppression	[189]
15	Thyroid cancer	Polyethylene glycol-functionalized copper sulfide (CuS) NPs	Copper-64 (64Cu) radionuclide	CuS photothermal agent	In vivo	Size of PEG-CuS NPs: 11.9 nm Hydrodynamic size: 29.8 nm	High intratumoral retention (approximately 50% at 48 h post-administration), allowing for precise anatomical visualization via micro-PET	[190]
16	Colorectal cancer	Polyethylene glycol-coated gold NPs	Zinc sulfothiolphthalocyanine (ZnPcS4)	ZnPcS4	In vitro	Size: 57.18 ± 3.04 nm ZP: 36.5 ± 2.6 mV PDI: 0.353	Highly specific cellular internalization and targeted subcellular localization of the photosensitizer elevated rates of late-apoptotic cellular death (34%) relative to untargeted free photosensitizer (15%)	[191]
17	Breast cancer	Rare earth (RE 3+)-doped NPs (RENPs)	Human MSCs	chlorine6 (Ce6)	In vitro	Size: 33.5 ± 1.7 × 30.8 ± 1.4 nm (dNP core/shell)	Successful internalization of the inorganic theranostic payloads without toxicity, enabling deep penetration into three-dimensional tumor spheroids	[192]
18	RAW264.7murinemacrophage and breast cancer	M1-like macrophage membrane-camouflaged zinc 2-methylimidazole (ZIF-8) metal-organic framework	BN-O (hypoxia-responsive phototheranostic molecule) and Combretastatin-A4 phosphate (CA4P)	BN-O	In vitro In vivo	Size 134 nm ZP: −8.7 mV	The biomimetic metal-organic framework localized to neoplastic tissues and degraded under acidic conditions, releasing vascular disrupting agents that restricted perfusion and exacerbated tumor hypoxia	[193]

Table 2. Overview of nanoparticles in cancer therapy as therapeutic and diagnostic agents. (NPs: Nanoparticles; DOX: Doxorubicin; HAS: Human serum albumin; DTX: Docetaxel; PTX: Paclitaxel; AuNRs: Gold nanorods; MR: Magnetic resonance imaging; TMV: Tobacco Mosaic Virus; MSCs: mesenchymal stem cells; PDI: Polydispersity index, ZP: Zeta potential, EE: Encapsulation efficiency).

Sr No.	Cancer Type	Nanocarrier Type	Therapeutic Payload	Diagnostic/ Imaging/ Theranostic Component	Study Type	Particle Characteristics	Key Findings	References
1	Breast Cancer	Iron Oxide NPs	DOX	chlorine e6 (Ce6)	In vitro (4T1 cell line) In vivo (Balb/c mice)	-	Combination of DOX@RBC-IONP-Ce6-PEG and 660-nm laser irradiation destroyed the cancer cells (4T1) Ex vivo fluorescence imaging revealed optimal magnetic field (MF)-enhanced tumor accumulation of the formulation MRI imaging confirmed efficient tumor targeting and accumulation by the engineered magnetic RBCs. In vivo experiments demonstrated pronounced tumor-growth inhibition effect of combination therapy with magnetic targeting (tumor inhibition ratio: 67%) compared with MF-guided chemotherapy (44.7%) or photodynamic therapy (35.4%) alone at day 14.	[178]
2	Breast Cancer	Albumin-modified melanin-silver hybrid NPs	-	HSA	In vitro (HS578T, and MCF10a cell lines)	Particle size increased from 190 ± 3.5 (PDI 0.20) to 230 ± 4.0 nm (PDI 0.24) after HSA conjugation ZP: −25 ± 1.7 mV	Specific internalization Concentrations ranging from 25 to 100 µg/mL have a negligible influence on cell viability No hematotoxicity Enhanced photostability	[179]
3	Cancer	poly(lactic-co-glycolic acid) (PLGA) NPs loaded with AuNRs	DTX	MnO2 nanosheets	In vitro (MCF-7 human breast cancer cell line) In vivo (female Kunming mice (~18–20 g)	Size: PLGA/DTX: 239.0 ± 3.7 nm PLGA/AuNR/DTX: 263.3 ± 4.5 nm PLGA/AuNR/DTX@MnO2: 282.1 ± 6.2 nm PDI: PLGA/DTX: 0.16 ± 0.01 PLGA/AuNR/DTX: 0.16 ± 0.02 PLGA/AuNR/DTX@MnO2: 0.18 ± 0.02 ZP: AuNRs: 27.4 ± 2.2 mV PLGA/AuNR/DTX NPs: −12.3 ± 1.5 mV Cellular uptake ratio: 98.5% ± 0.53%	Clear MR or CT contrast imaging at the tumor site Higher biodistribution at 4 h after administration Efficient tumor inhibition and cellular apoptosis	[177]
4	Breast Cancer	Hybrid silica/melanin NPs	DOX	HSA	In vitro (HS578T Cells)	Increase in size from 394 ± 32 (PDI 0.26) to 407 ± 29 nm (PDI 0.45) and ZP from −27.2 ± 1.65 mV and −17 ± 2.16 mV after DOX loading Absorbance value: 0.69 at 808 nm wavelength	At the lowest concentration, 53% toxic effects NPs loaded with DOX are more effective than the free drug Enhanced cytotoxicity at photothermal laser irradiation	[180]
5	Breast Cancer	pH-sensitive near-infrared (NIR) croconaine (Croc) dyes-loaded copolymeric PEG−PLGA	-	PPC815	In vitro (MDA-MB-231 cells) In vivo (BALB/c nude female mice)	Croc770: Particle size: 182.3 ± 3.0 nm PDI: 0.09 ± 0.01 ZP: −24.2 ± 2.1 mV DL: 20.2% EE: 43.4% Croc815: Particle size: 183.3 ± 2.1 nm PDI: 0.10 ± 0.02 ZP: −21.2 ± 1.4 mV DL: 19.8% EE: 40.4 PPC815: Particle size: 185.1 ± 3.3 nm PDI: 0.07 ± 0.03 ZP: −1.2 ± 0.7 mV DL: 19.8% EE: 40.4	IC50 values of CPC815 and PPC815 NPs were 75.7 and 60.2 μg/mL Upon NIR laser irradiation, IC50 values of CPC815 and PPC815 decreased to 27.8 and 11.2 μg/m Efficient tumor inhibition No acute toxicity to major organs	[181]
6	Cervical adenocarcinoma	Fe3O4 NPs (Fe3O4@UiO-66 core–shell composites)	DOX	Fe3O4	In vitro (HeLa cells) In vivo (Kunming mouse)	Diameter of Fe3O4 NPs: 150 nm Fe3O4@UiO-66 composites: Particle size: 241.5 ± 28.5 nm PDI: 0.340	60% HeLa cells killed Enhanced lethality against HeLa (48 h) Potential contrast agent for cancer diagnosis Darkening effect observed in the liver region of Kunming mouse (10 min post-injection) High cancer cell mortality	[175]
7	Breast Cancer	Gold-nanoshelled poly (lactic-co-glycolic acid) (PLGA) magnetic hybrid NPs carrying anti-HER-2 antibody	HER-2 antibodies	Her2 functionalized gold-nanoshelled magnetic hybrid NPs (HER2-GPH-NPs)	In vitro (SKBR3 and MDA-MB-231 cells)	Mean diameter: 248.3 nm PDI: 0.037 ZP: −14.7 mV	Act as an excellent contrast enhancement in vitro US and T2-weighted MR imaging Enhanced tumor inhibition In vivo data still needed	[182]
8	Metastatic Breast Cancer	Albumin-based NPs (PSN-HSA-PTX-IR780)	PTX	HSA	In vitro (4T1 cells) In vivo (tumor-bearing mice)	Size: PSN HSA-PTX-IR780: 142.2 ± 4.86 nm HAS-PTX-IR780: 128.1 ± 1.7 ZP of both NPs: ~−30 mV DL of both NPs: ~7.5%	Activated platelet-targeting albumin-based nanoparticles to inhibit 4T1 primary tumor Increased tumor permeability Enhanced tumor-infiltrating platelets Higher PTX accumulation Suppressed tumor growth	[183]
9	Breast and prostate cancer	Albumin-Coated Tobacco Mosaic Virus NPs	DOX	TMV	In vitro In vivo	-	Can be utilized for theranostic uses Enhanced efficacy	[184]
10	Head and neck squamous cell carcinoma	Iron-oxide NPs functionalized with integrin-targeting fibronectin-mimetic peptide (Fmp)	Silicon phthalocyanine 4 (Pc 4)	Iron-oxide NPs	In vitro In vivo	Size: 10 nm in in a molar ratio of 30:1 Conjugation efficiency of Fmp: 89.5% Hydrodynamic size of Fmp-IO-Pc 4:41 nm	Both targeted (Fmp-IO-Pc 4) and nontargeted (IO-Pc 4) NPs had greater efficacy than free Pc4 Elevated intratumoral accumulation relative to free photosensitizer Significant tumor growth suppression utilizing a 10-fold lower photosensitizer dose	[185]
11	Head and neck squamous cell carcinoma	Cholesterol/vitamin E-doped distearoylphosphatidylcholine liposomes	Rhenium-186 (186Re) radionuclide	β-emitting radionuclides	In vivo	Size: 135.1 ± 18.0 nm	Sustained local radiation retention Substantial tumoricidal radiation dosing (526.3 ± 93.3 Gy) resulting in pronounced tumor volume regression	[186]
12	Cancer	Pluronic F127 polymer micelles	-	TPVTR (aggregation-induced emission fluorogen) dots	In vitro In vivo	Uniform particle size (~100 nm)	Strong near-infrared fluorescence, high photostability, and robust reactive oxygen species production upon aggregation Effective photodynamic tumor destruction in vivo with negligible toxicity to healthy tissues	[187]
13	Bladder cancer	Self-assembled porphyrin-cholic acid-PEG micelles decorated with PLZ4 targeting ligand	DOX and Pyropheophorbide-a	PLZ4-nanoporphyrin	In vitro In vivo	Size of PNP-DOX: 23 ± 6 nm PNP-DOX exhibited 10.6 times higher area under the curve (AUC) than free DOX	Highly specific cellular uptake in neoplastic urothelium, yielding precise fluorescence demarcation of tumors Complete eradication of orthotopic patient-derived xenografts and improved overall survival	[188]
14	Non-small cell lung cancer, bladder cancer, and murine fibroblast	Anisamide-targeted lipid-calcium-phosphate (LCP) NPs	Lutetium-177 (177Lu) radionuclide	Lutetium-177 (177Lu) radionuclide	In vitro In vivo	Size: 36 ± 9 nm EE: approximately 70% PDI: 0.27 ± 0.05 ZP: −6.7 ± 3.5 mV	Solid calcium phosphate core facilitated massive specific loading of trivalent radiometals without disrupting particle morphology or loading efficiency Durable tumor growth suppression	[189]
15	Thyroid cancer	Polyethylene glycol-functionalized copper sulfide (CuS) NPs	Copper-64 (64Cu) radionuclide	CuS photothermal agent	In vivo	Size of PEG-CuS NPs: 11.9 nm Hydrodynamic size: 29.8 nm	High intratumoral retention (approximately 50% at 48 h post-administration), allowing for precise anatomical visualization via micro-PET	[190]
16	Colorectal cancer	Polyethylene glycol-coated gold NPs	Zinc sulfothiolphthalocyanine (ZnPcS4)	ZnPcS4	In vitro	Size: 57.18 ± 3.04 nm ZP: 36.5 ± 2.6 mV PDI: 0.353	Highly specific cellular internalization and targeted subcellular localization of the photosensitizer elevated rates of late-apoptotic cellular death (34%) relative to untargeted free photosensitizer (15%)	[191]
17	Breast cancer	Rare earth (RE 3+)-doped NPs (RENPs)	Human MSCs	chlorine6 (Ce6)	In vitro	Size: 33.5 ± 1.7 × 30.8 ± 1.4 nm (dNP core/shell)	Successful internalization of the inorganic theranostic payloads without toxicity, enabling deep penetration into three-dimensional tumor spheroids	[192]
18	RAW264.7murinemacrophage and breast cancer	M1-like macrophage membrane-camouflaged zinc 2-methylimidazole (ZIF-8) metal-organic framework	BN-O (hypoxia-responsive phototheranostic molecule) and Combretastatin-A4 phosphate (CA4P)	BN-O	In vitro In vivo	Size 134 nm ZP: −8.7 mV	The biomimetic metal-organic framework localized to neoplastic tissues and degraded under acidic conditions, releasing vascular disrupting agents that restricted perfusion and exacerbated tumor hypoxia	[193]

6.2. Infectious Disease

Nanotechnology offers multi-functional nano-platforms for both anti-microbial therapeutics and diagnostics, which are pivotal for combating antimicrobial resistance (AMR) and improving early diagnosis (Figure 8) [194,195]. For instance, mesoporous silica nanoparticles (MSNs) are being explored for their large surface area, tailored structure, and high drug-loading capacity, making them suitable for the diagnosis of bacterial infections. Moreover, plasmonic nanomaterials such as AgNPs and AuNPs, which exhibit surface plasmon resonance (SPR), are used for bacterial detection. Upon surface modification with recognition elements, such as aptamers, antibodies, and phages, the detection of particular bacteria becomes easy. After specific binding of NPs to the bacteria, they are visible to the naked eye [196].

A study conducted by Yang et al. [197] demonstrated a broad-spectrum bacterial detection system based on D-amino acid-capped AuNPs. The researchers synthesized gold D-Alanyl-D-alanine (Au-DADA) and used transmission electron microscopy (TEM) to characterize their aggregation on Staphylococcus aureus. Moreover, to test the applicability of the detection system in real settings, they incubated Au-DADA with Stenotrophomonas maltophilia, Staphylococcus aureus, Pseudomonas aeruginosa, and Staphylococcus epidermidis. When compared with the control group, a colour change was observed in the Au-DADA group after incubation with different kinds of pathogens. The colour of Au-DADA changed from red to blue when the pathogens were present in the sample. The absorption spectra and ratio of A_600nm/A_520nm are represented in Figure 9 [197]. Furthermore, the evaluation of cytotoxicity and stability of Au-DADA revealed a complete loss of cell viability, demonstrating that they are well-dispersed. This clearly underscores their exceptional biocompatibility and stability.

In addition to this, NP-based systems enable the penetration of antibiotics, thereby enhancing controlled drug release and reducing systemic toxicity. This is particularly beneficial for the treatment of intracellular bacterial infections such as Mycobacterium tuberculosis and methicillin-resistant Staphylococcus aureus (MRSA) [198]. Furthermore, studies have consistently demonstrated the efficacy of nanovaccines in preventing experimental toxoplasmosis, highlighting their role as both immunomodulatory adjuvants and effective vehicles for immunogen delivery [199]. Similarly, in the realm of other viral infections, such as hepatitis, AuNPs have emerged as reliable theranostic agents. They play a crucial role in the design of advanced detection biosensors, while chitosan serves as an exceptional nanocarrier for the delivery of therapeutic drugs and vaccines [200]. Moreover, in addressing infections such as tuberculosis, innovative biomimetic erythrocyte-like nanoparticles are being developed featuring granuloma-targeting and self-oxygenation properties for combined phototherapy. These advancements have been shown to significantly prolong blood circulation and enhance selective accumulation within tuberculosis granulomas in mouse models [201].

Table 3. Application of NP-based formulation in various infectious diseases.

Application	Nanoparticle Type	Outcome	References
Diagnostics for bacterial infections	Mesoporous silica nanoparticles (MSN)	Suitable for diagnosis due to the tailored structure, large surface area, and high loading capacity	[195]
Antimicrobial therapy	Metal oxide nanoparticles (MONPs)	Demonstrate wide-ranging antimicrobial activities against bacteria, viruses, and protozoans, reducing resistance development through multiple mechanisms of action	[202]
Treatment of intracellular bacterial infections (e.g., Mycobacterium tuberculosis, MRSA)	Nanoparticle-based systems	Enhance intracellular penetration of antibiotics, allow controlled release, and reduce side effects	[198]
Prevention of experimental toxoplasmosis	Nanovaccines	Act as immunostimulatory adjuvants and vehicles for immunogen delivery	[199]
Detection sensors for hepatitis	Gold nanoparticles	Effective for designing detection sensors	[200]
Drug delivery and vaccination for hepatitis	Chitosan NPs	Promising nanocarriers	[200]
Biosensing for hepatitis	Carbon dots	Show potential for biosensing	[200]
Combined phototherapy for tuberculosis	Biomimetic erythrocyte-like nanoparticles (with aggregation-induced second near-infrared emission, granuloma-targeting, and self-oxygenation)	Significantly prolonged blood circulation and increased selective accumulation in tuberculosis granulomas in mouse models, inhibiting granuloma and M. tb colony growth	[201]

compellingly summarizes the diverse applications of nanoparticles in the landscape of infectious diseases. Moreover, studies evaluating NP-enabled theranostic strategies in infectious diseases are summarized in

Table 4. Overview of nanoparticles in infectious disease as therapeutic and diagnostic agents. (PDI: Polydispersity index, ZP: Zeta potential, EE: Encapsulation efficiency; NPs: Nanoparticles; RSV: Respiratory syncytial virus; PLA: Poly(lactic acid; DOX: Doxorubicin).

Sr No.	Type of Infection	Nanoparticle	Therapeutic Payload	Diagnostic/ Imaging/ Theranostic Component	Study Type	Particle Characteristics	Key Findings	References
1	Hepatitis B	PEGylated liposomes (Myr-preS2-31 modified)	Carboxyfluorescein, propidium iodide, DOX, FITC-labeled peptide or DNA vector	111In, carboxyfluorescein	In vitro In vivo	Size: 89.10 ± 4.38 nm PDI: 0.10 ± 0.02 ZP: −9.82 ± 0.87 mV	Specific binding and cellular internalization via the sodium-taurocholate cotransporting polypeptide receptor 0.25 mol% myristoylated ligands evaded rapid systemic clearance	[203]
2	Canine distemper virus	Polyvinylpyrrolidone and hydrolyzed collagen-coated NPs	Silver NPs (intrinsic antiviral)	-	In vivo	Size: 10–35 nm	Oral and intranasal administration of 3% colloidal silver dispersions increased survival metrics in canines presenting with both non-neurological and advanced neurological stages of the viral infection Treated cohorts experienced a complete resolution of clinical signs without residual neurological deficits	[204]
3	Tuberculosis	PLA NPs	Ethionamide and BDM41906 booster	-	In vitro In vivo	Size: 274 ± 4 nm PDI: 0.090 ZP: −5.0 ± 0.5 Mv EE: 76 ± 5% (Ethionamide), 51 ± 8% (Booster)	Co-encapsulation of the antibiotic and its booster molecule prevented premature drug crystallization and bypassed aqueous solubility limitations Direct aerosolization into the respiratory tract resulted in a 3-log reduction in bacterial load after six doses, without affecting local macrophage and immune cell populations	[205]
4	COVID-19 (SARS-CoV-2)	LNPs	Full-length S protein mRNA (PTX-COVID19-B)	-	In vitro In vivo	-	Immunization with the mRNA transcript coding for the modified full-length spike protein induced substantial neutralizing antibody titers The formulation prevented pulmonary and upper respiratory tract infections in challenged cohorts	[206]
5	Biofilm-associated infections (Streptococcus mutans, Staphylococcus aureus)	Dextran-coated gold-in-gold cage NPs	-	Gold-in-gold cage photo thermal NPs (PTNPs)	In vitro In vivo	Size (hydrodynamic): 87.7 ± 1.4 nm ZP: −17 ± 1.5 mV	Exposure to near-infrared irradiation triggered localized photothermal heating Rapid bacterial ablation with superior efficacy to chlorhexidine	[207]
6	Ovine toxoplasmosis (Toxoplasma gondii)	Maltodextrin NPs with a lipid core	Total extract of T. gondii proteins	DiR (fluorophore)	In vitro In vivo	-	Pathogen-specific Th1 cellular immune response mediated by interferon-gamma and interleukin-12 secretion Prevention of transplacental transmission in pregnant hosts	[208]
7	RSV	Polyvinylpyrrolidone-coated silver NPs	Silver NPs (intrinsic antiviral)	-	In vitro In vivo	Size: 8–12 nm	Suppressed viral replication in epithelial cultures and murine lungs Localized decrease in pro-inflammatory cytokines Upregulation of specific chemokines, requiring neutrophil recruitment for optimal in vivo antiviral activity	[209]
8	Carbapenem resistant Escherichia coli	Pectin-capped platinum coated NPs	Platinum NPs (plasmid-curing agent) + Meropenem	-	In vitro In vivo	Size: 2–6 nm ZP: −38.9 ± 6.7 mV	Sub-inhibitory concentrations of the platinum formulations induced plasmid DNA cleavage, eliminating the genetic element harboring resistance genes	[210]
9	Newcastle disease virus	Chitosan NPs	F gene plasmid DNA	-	In vitro In vivo	Size: 199.5 nm ZP: +12.11 mV EE: 98.37 ± 0.87%	High loading capacity Sustained release kinetics Prolonged systemic immune responses in avian models compared to unencapsulated plasmid controls	[211]
10	Hepatitis C virus-induced advanced hepatic fibrosis	Retinoid-conjugated NPs	Heat shock protein 47 siRNA	-	Human	-	Intravenous infusion of the targeted silencing RNA vectors over a 12-week regimen was tolerated without severe adverse events Repeated dosing reduced target mRNA translation in hepatic stellate cells Improvements in histological fibrosis scoring systems	[212]

.

6.3. Neurological and Cardiovascular Diseases

While the majority of nanotheranostics research has focused on cancer and infectious diseases, this platform is not limited to these indications. Owing to their ability to integrate targeted therapy with real-time diagnostic feedback, nanotheranostics are increasingly being applied to a broad spectrum of therapeutic applications, such as neurological and cardiovascular disorders.

Nanotheranostics is crucial in effectively managing neurological disorders, including brain tumors (glioma), Parkinson’s disease, Alzheimer’s disease, and neurovascular conditions [213,214,215]. One of the significant advantages of nanoparticle-based therapies in treating neurological diseases lies in their ability to overcome the challenges associated with crossing the BBB, a common limitation of traditional therapies [214,216]. The diagnostic and therapeutic capabilities of nanomaterials, such as iron–oxide nanoparticles (IONPs), lipid-based particles, polymeric particles, quantum dots, and mesoporous silica, are transformative in addressing issues within the central nervous system [217]. They ameliorate neuroinflammation, psychiatric disorders, brain dysfunction, and nerve injuries while offering the potential for single-cell resolution in diagnosis, monitoring, and treatment. Furthermore, these materials serve as effective contrast agents for imaging techniques like MRI and fluorescence, as well as drug carriers for personalized treatment strategies [218,219]. The integration of nanotheranostics marks a significant advancement in the approach to neurological disorders.

Nanotheranostics are revolutionizing the treatment of cardiovascular disorders, including atherosclerosis, myocardial infarction, and aneurysm, by seamlessly integrating diagnostic and therapeutic functions into a single nanoscale platform [124,220]. These innovative platforms significantly enhance imaging techniques such as positron emission tomography (PET), CT, photoacoustic imaging, ultrasound, and fluorescence imaging [124,221]. There is a burgeoning interest in FDA-approved nanoparticle platforms, including PLGA, hyaluronic acid-based systems, and liposomes, specifically designed for atherosclerosis treatment [220]. These advanced nanomaterials effectively mimic the structural and functional features of high-density lipoproteins (HDLs), which are known to protect against atherogenesis. However, the translation of these nanotheranostics platforms into clinical practice faces major hurdles. Key challenges include ensuring sustained and targeted delivery of nanoparticles to specific cardiovascular lesions, which necessitates overcoming issues related to target identification and developing effective functionalization strategies [222,223,224]. These strategies must enhance stability and target delivery while minimizing off-target effects. Furthermore, the complex cellular and extracellular environments complicate the precise transmission and therapeutic regulation of specific agents like non-coding RNAs (ncRNAs), where challenges in specificity, delivery, and tolerance have severely hindered clinical applications [225]. Furthermore, studies investigating NP-enabled theranostic strategies in cardiovascular and neurological diseases are summarized in

Table 5. Overview of nanoparticles in infectious disease as therapeutic and diagnostic agents. (PDI: Polydispersity index, ZP: Zeta potential, EE: Encapsulation efficiency; NPs: Nanoparticles).

Sr No.	Disease	Nanoparticle	Therapeutic Payload	Diagnostic/ Imaging/ Theranostic Component	Study Type	Particle Characteristics	Key Findings	References
1	Parkinson’s disease	-	Salivary small extracellular vesicles (sEV)	Fluorescence-tagged	Human	-	The native nanovesicles demonstrated potential as susceptibility risk biomarkers for the early detection and tracking of pathological progression in presymptomatic and symptomatic patients	[226]
2	Atherosclerosis	Macrophage membrane-coated ROS-responsive NPs	Targeted pharmacotherapy	-	In vivo	Size: 227 nm	Nanoparticles camouflaged with macrophage membranes successfully evaded systemic clearance and homed to inflamed vascular sites Biomimetic coating actively sequestered local proinflammatory cytokines, operating synergistically with the ROS-triggered release of the therapeutic payload to attenuate vascular inflammation	[227]
3	Ischemic Stroke	Neutrophil-hijacking nanoplatform (APTS)	A151 (telomerase repeat sequence)	-	In vivo	-	Inhibition of the formation of neutrophil extracellular traps via reactive oxygen species scavenging	[228]
4	Glioblastoma multiforme	Mixed gold and superparamagnetic iron oxide nanoparticle (SPION) micelles	Gold NPs (radiosensitization)	SPIONs (T2-weighted MRI) and Vascular CT contrast	In vivo	Single micelle of ~75 nm diameter, with smaller Au nanoparticles interspersed with larger Fe nanoparticles.	Micellar complexes integrating gold and iron oxide achieved a 97:1 uptake ratio in brain tumor tissue The construct maintained highly specific retention at 120 h post-administration Effective T2-MRI signal dampener and a robust blood pool agent for computed tomography	[229]
5	Alzheimer’s disease	LNPs	-	Proteomic enrichment tool	In vivo	Size: 126.10 ± 0.379 ZP: −31.2 ± 0.361 PDI: 0.047 ± 0.004	Facilitated the longitudinal analysis of the plasma proteome, identifying specific systemic molecular pathways corresponding with neurodegenerative progression	[230]
6	Atherosclerosis	Metal-free nanozyme (HCN@DS)	NR (nanozyme acts intrinsically)	Photoacoustic and photothermal imaging contrast	In vivo	ZP: −20 mV	Specific affinity for macrophage scavenger receptor A Precise targeted localization Dual photoacoustic and photothermal capabilities guided the therapeutic activation of macrophage autophagy Inhibition of formation and potential rupture of vulnerable lipid-laden plaques	[231]
8	Acute ischemic stroke	Macrophage-disguised honeycomb manganese dioxide (MnO2) nanospheres	Fingolimod (FTY)	-	In vivo	Size: 120 nm	Biomimetic nanospheres leveraged macrophage membrane proteins to target damaged vascular endothelium in the ischemic penumbra	[232]
9	Glioblastoma	Ferric chloride α-cyano-4-hydroxycinnamate (Fe-CHC) NP	Chemodynamic therapy agents	-	In vivo	Size: 151 nm PDI: 0.12	By artificially re-establishing localized acidosis, the platform accelerated Fenton-like reactions Generation of toxic hydroxyl radicals that significantly amplified the cytocidal efficacy of chemodynamic treatments	[233]

.

7. Current Clinical Landscape

Following the successful approval of Doxil^® in 1995, nanoparticles have gained pronounced traction in biomedical research [234]. A 2016 study highlighted that the majority of FDA-approved NPs were of liposomal or polymeric origin [235]. In 2018, Onpattro^® received FDA approval for a nanoparticle (NPs)-based gene therapy, thereby expanding the scope of the field of NPs beyond oncological applications [234]. Since then, the field has continued to evolve, with nano-based gene therapies gaining significant momentum, particularly following the global success of mRNA-based COVID-19 vaccines, such as Pfizer and Moderna, leading to a growing number of ongoing clinical trials and expanded therapeutic applications. The nano-gene therapies have received substantial growth since the global success of mRNA-based COVID-19 vaccines, including Pfizer and Moderna [234]. Compared to 700 nanomedical clinical trials in 2011–2015 and 1072 in 2016–2020, 2021–2024 reported nearly 1476 new clinical trials, marking a 38% surge in the number of clinical trials [236]. In terms of the distribution of conditions, oncology dominated the distribution profile, accounting for 30 % of the studies, followed by infections (14%) and respiratory tract diseases (10%) [236].

Until now, there are over 50 approved and marketed nanomedicines for various distinct disorders. A complete picture of these approved nanomedicines can be found in excellent reviews by Desai et al. [237], Jia et al. [238], and Raj et al. [239]. In this review, the authors summarize the ongoing clinical trials of nanoparticles in the diagnosis and treatment of diseases (

Table 6. Ongoing clinical trials investigating NP-based formulations across disease indications. (N/A: Not Available).

S.N.	NCT Number	Nanoparticle Platform	Payload/Active Agent	Indication	Phase	Primary Outcome	Status
1	NCT06693375	Iron oxide NPs	NanoEcho Particle-1 (NEP-1)	Rectal Cancer	Phase II	Trace value for all lymph nodes	Recruiting
2	NCT06791005	Carbon NPs	N/A	Papillary Thyroid Cancer	N/A	Intra- and post-operative conditions	Recruiting
3	NCT06146751	Superparamagnetic Iron Oxide NPs	Ferumoxytol	Heart Aneurysm	N/A	Detection rate of intracardiac thrombus in dynamic chamber and static chamber	Recruiting
4	NCT07327996	Mesoporous silica NPs	Calcium Hydroxide	Necrotic Pulp	N/A	Post-operative pain	Active, not recruiting
5	NCT06271564	Zinc Oxide Composite NPs	N/A	Oral Potentially Malignant Lesions	Early phase I	Change in the clinical size in low to moderate dysplastic OPLs	Recruiting
6	NCT04899908	N/A	Gadolinium	Brain Cancer	Phase II	Local recurrence	Recruiting
7	NCT06567301	Chitosan	N/A	Knee Osteoarthritis	N/A	Anatomical improvement	Recruiting
8	NCT04881032	N/A	Temozolomide (TMZ) and AGuIX (Polysiloxane Gadolinium-Chelates)	Glioblastoma	Phase I, II	Recommended dose of AGuIX (phase I) along with TMZ and radiotherapy during the radio-chemotherapy period 6-month Progression Free Survival (PFS) rate (phase II)	Active, not recruiting
9	NCT04484909	N/A	Hafnium Oxide	Locally Advanced or Borderline-Resectable Pancreatic Cancer	Phase I	Phase II dose (RP2D) of Hafnium Oxide-containing nanoparticles (NBTXR3)	Recruiting
10	NCT04751786	Poly(lactic-co-glycolic acid) (PLGA)- based NPs	Threitolceramide-6	Advanced Solid Tumor	Phase I	Safety of PRECIOUS-01 (PLGA nanoparticle containing the combination of Threitolceramide-6 and and the New York Esophageal Squamous Cell Carcinoma-1 (NY-ESO-1) cancer-testis antigen peptides)	Active, not recruiting
11	NCT07308470	SLNs	Etodolac	Knee Osteoarthritis	Phase II	Pain severity	Not yet recruiting
12	NCT04744506	Carbon NPs	N/A	Breast Cancer	N/A	Lymph node retrieval rate. Number of sentinel and marked lymph nodes Complication rate	Recruiting
13	NCT07347080	LNPs	Exenatide	Type II Diabetes mellitus (T2DM)	Early Phase I	Safety and tolerability of a single dose of Exenatide Circular RNA-Lipid NP Injection (CR059)	Not yet recruiting
14	NCT05039632	N/A	Hafnium Oxide and Immunotherapy (anti-PD-1/L-1)	Advanced Solid Malignancies	Phase I, II	Efficacy and safety of NBTXR3 activated by radiation (Abscopal or RadScopal™) in combination with immunotherapy (anti-PD-1/L-1)	Recruiting
15	NCT05264974	LNPs	N/A	Melanoma	Phase I	Maximum tolerated dose	Recruiting
16	NCT06977126	N/A	Porphysomes	Gynecological Cancers	Phase I	Incidence of Dose Limiting Toxicities (DLTs)	Recruiting
17	NCT04789486	N/A	Gadolinium	Non-small Cell Lung Cancer and Pancreatic Cancer	Phase I, II	Maximum tolerated dose (MTD) (Phase 1) Compare Local Control at 12 months of MTD (Phase II)	Recruiting
18	NCT06271421	N/A	-	Glioblastoma Multiforme	N/A	Survival following the surgery (units months 1–24) Progression-free survival (units months 1–24)	Recruiting
19	NCT04167969	Silica NPs	Copper-64 (64Cu) radiolabeled PSMA-targeting C′ dot tracer (64Cu-NOTA-PSMAi-PEG-Cy5.5-C′ dots) or zirconium-89 (89Zr) radiolabeled PSMA-targeting C′ dot tracer (89Zr-DFO-PSMAi-PEG-Cy5.5-C′ dots)	Prostate cancer	Phase I	Side effects	Recruiting
20	NCT02106598	Silica NPs	Fluorescent cRGDY-PEG-Cy5.5-C dots	Head and Neck Melanoma	Phase I, II	Feasibility of conducting pre-operative SLN mapping	Active, not recruiting
21	NCT05903339	Ferritin NPs, mRNA LNPs	Alum ACU-026-001-1	HIV	Phase I	Local and systemic reactogenicity signs Number of SAEs	Active, not recruiting
22	NCT06908096	EBV gH/gL/gp42-ferritin NPs	N/A	Epstein-Barr Virus (EBV) infection	Phase I	Local and systemic reactogenicity signs and symptoms during the 7 days after each vaccination Unsolicited AEs	Recruiting
23	NCT04682847	SPION	Ferumoxytol injection	Hepatic Cancers	NA	Platform to maintain liver functionality during treatment for liver cancer	Active, not recruiting
24	NCT01525966	Paclitaxel albumin-stabilized NP formulation	Carboplatin	TNBC	Phase II	Whether carboplatin + nab-paclitaxel therapy will achieve a promising neoadjuvant pathologic complete response (pCR) rate	Active, not recruiting
25	NCT00616967	NA	Carboplatin Vorinostat Paclitaxel albumin-stabilized NP formulation	Breast Cancer	Phase II	To determine pCR rates in patients with HER2-negative primary operable breast cancer	Active, not recruiting
26	NCT06628076	Zinc oxide NPs	NA	Acinetobacter baumannii infection	NA	Susceptibility profile	Not yet recruiting
27	NCT01730833	NA	Pertuzumab Trastuzumab Paclitaxel albumin-stabilized NP	HER2-positive advanced breast cancer	Phase II	Efficacy of pertuzumab in combination with trastuzumab with nab-paclitaxel in subjects with stage IV in HER-2 overexpressing metastatic breast cancer (MBC)	Active, not recruiting
28	NCT01463072	NA	Nab-paclitaxel	Advanced or metastatic breast cancer	Phase II	Tolerability of weekly nab-paclitaxel	Active, not recruiting
29	NCT00609791	NA	Nab-paclitaxel	MBC	Phase II	Age-related changes in the pharmacokinetics (pK) and pharmacodynamics of weekly nab-paclitaxel	Active, not recruiting
30	NCT07034248	Graphene Quantum dot decorated Gold NPs	NA	Breast Cancer	NA	Sensitivity and selectivity on an electrochemical biosensor	Not yet recruiting
31	NCT04615013	Hafnium oxide-containing NPs	Capecitabine, carboplatin, docetaxel, fluorouracil, leucovorin, oxaliplatin, paclitaxel	Esophageal Cancer	Phase I	Recommended phase II dose of NBTXR3 activated by radiotherapy with concurrent chemotherapy	Recruiting
32	NCT07321301	Polymer LNPs	CD19/CD20 Dual-Targeting InViVoCAR1920 mRNA	Relapsed/refractory B-cell lymphoma/leukemia	Phase II	Safety and maximum tolerated dose of CAR-T cell immunotherapy mediated by polymer-lipid nanoparticles delivering CD19/CD20 dual-targeting InViVoCAR1920 mRNA	Recruiting
33	NCT06577532	mRNA NPs	ABO2102 Toripalimab	KRAS -mutated solid tumors	Early phase I	Incidence and nature of dose-limiting toxicity (DLT) for ABO2102 as monotherapy or in combination with toripalilmab Overall Response Rate (ORR) per RECIST version 1.1.	Recruiting
34	NCT04645147	Ferritin NPs	EBV gp350-ferritin vaccine	EBV infection	Phase I	Safety and immunogenicity	Active, not recruiting
35	NCT05816694	NA	NAB-Paclitaxel plus Cisplatin Cisplatin plus Epirubicin plus Cyclophosphamide	Thymoma	Phase II	ORR	Not yet recruiting
36	NCT07183709	NA	PepGNP-COVID19	COVID-19	Phase I	Proportion of participants experiencing solicited and unsolicited AEs	Recruiting
37	NCT06686654	LNPs	Investigational RSV + hMPV vaccine	Human metapneumovirus (HMPV)/Respiratory syncytial virus (RSV)	Phase I Phase II	Presence of solicited and unsolicited AEs	Active, not recruiting
38	NCT02336087	NA	Gemcitabine HCl, nab-Paclitaxel, metformin HCl	Pancreatic Cancer	Phase I	Compliance, toxicity, and feasibility of administered formulation	Active, not recruiting
39	NCT07019883	mRNA-LNP	H5 AC-Anhui RNA Vaccine	Influenza	Phase I	Proportion of participants experiencing AE and SAE	Active, not recruiting
40	NCT05945485	mRNA-LNP	DCVC H1 HA mRNA vaccine Quadrivalent Recombinant Seasonal Influenza Vaccine	Influenza	Phase I	Proportion of participants experiencing AE and SAE	Active, not recruiting
41	NCT03337087	Liposome	Fluorouracil, irinotecan sucrosofate, leucovorin calcium, and rucaparib	Metastatic pancreatic, colorectal, GI, or biliary Cancer	Phase I Phase II	Number of participants with dose-limiting toxicities (Phase I)	Active, not recruiting

). The trials were identified using the keywords “Nanoparticles” and “Diagnosis” and/or “Treatment” using the website clinicaltrial.gov. Notably, active trials were included, and completed or terminated trials were excluded from this review.

8. Challenges in Clinical Translation

Despite the increasing application of nanotechnology in clinical trial settings, its clinical translational impact remains modest relative to its success in other fields [236]. As of October 2024, Gultepe et al. reported that nearly 4114 nanotechnology-related clinical trials were identified among 520,889 trials registered in the Aggregate Content of ClinicalTrials.gov (AACT) database, representing approximately 0.8 % of all recorded trials [236]. Notably, recent years have witnessed a declining trend in the distribution of clinical trial phases within nanotechnology-related trials. For instance, from 1991–2000, nanomedical trials accounted for nearly 70% of Phase I/II studies; nevertheless, this proportion dropped to 40% between 2021 and 2024. Moreover, the proportion of Phase III/IV remained constant, highlighting an overall downward trajectory in trial phase distribution [236]. Collectively, these trends underscore significant translational challenges in nanotechnology.

The nano-bio interaction is one of the major challenges faced by NPs [240]. Upon its entry into the systemic circulation, the NPs interact with biological material. Instead of providing the desired theranostic effects, a majority of NPs induce toxic effects, predisposing individuals to conditions, including inflammation and immunoreaction, among others [241]. These toxicities are predominantly dependent upon the size, zeta potential, and solubility of NPs. For instance, the formation of a protein corona on the NP surface may result in complement activation-related pseudo-allergies [242,243]. Additionally, inorganic NPs, including zinc oxide, CNTs, and gold NPs, induce neurotoxicity and exhibit long-term safety profiles [244,245]. Moreover, inorganic NPs have been linked to histopathological damage in the liver and spleen, compromising organ function [246,247]. Furthermore, AgNPs have been shown to increase ROS production, resulting in neuronal injury and cognitive impairment [248]. Silicon dioxide (SiO₂) NPs have been associated with route-dependent neurotoxicity, with intranasal administration inducing substantial cerebral damage [249]. The current preclinical data lack a comprehensive understanding of how NPs interact with patient-specific biology and disease heterogeneity across distinct clinical settings [250]. Humans display significant interindividual physiological and pathological variability [251]. As the disease progresses, conditions, such as cancer, demonstrate pronounced inter-individual and intra-individual variability. Therefore, employing the concept of a one-size-fits-all approach in NP research further impacts the successful clinical translation of NPs [251].

Another potential translational barrier for theranostic NPs lies in achieving robust, controllable, and reproducible NPs synthesis. Despite significant advances, the clinical translation of NP-based systems remains constrained by several critical challenges. Regulatory pathways for nanomedicine are often complex and not fully standardized, requiring extensive safety, toxicity, and pharmacokinetic evaluation. Furthermore, large-scale manufacturing of NPs exhibits potential issues related to: poor batch-to-batch consistency, poor yield, elevated material and production costs, and loss of chemical stability of the payload during formulation [252,253,254,255]. Pharmaceutical manufacturing is primarily driven by quality and cost considerations. In addition, discrepancies between pre-clinical outcomes and clinical performance, coupled with challenges in long-term safety assessment and real-world applicability, continue to limit successful clinical implementation. It has been observed that NPs containing complex synthesis processes have limited translational potential as it becomes challenging to synthesize on a large scale [251,256]. Additionally, theranostic NPs often encompass multiple surface functionalization and integration of various components, thereby requiring stringent chemistry, manufacturing, and controls (CMC) frameworks aligned with Good-manufacturing practices (GMP) requirements to translate from laboratory to clinic [240]. Addressing these barriers is essential to bridge the gap between experimental promise and therapeutic reality.

9. Conclusions and Future Perspectives

NPs have emerged as transformative platforms in modern medicine, enabling the integration of therapeutic and diagnostic functions within a single multifunctional system. This comprehensive review highlighted the diversity of nanoparticle classes, their fundamentals, and their applications in targeted therapy, imaging, and theranostic interventions. A comparative evaluation of nanoparticle platforms indicates that lipid-based systems offer superior biocompatibility and clinical translatability, whereas polymeric NPs provide enhanced control over drug release, and inorganic NPs exhibit unique diagnostic and theranostic capabilities. However, they are often limited by long-term safety concerns. Importantly, while substantial advances have been achieved at the preclinical level, the clinical translation of these systems remains limited by challenges related to safety, scalability, regulatory frameworks, and biological complexity. Overcoming these barriers through rational design, standardized evaluation, and interdisciplinary collaboration will be critical for advancing nanoparticle-based platforms toward routine clinical implementation.

Future research must prioritize the integration of artificial intelligence (AI) and machine learning (ML), harnessing techniques like Quantitative Structure-Activity Relationship (QSAR) and Alchemite to revolutionize nanoparticle formulation. These advanced techniques are essential for accurately predicting biodistribution and will facilitate optimal design by enabling rapid screening of extensive libraries and extraction of structure-function relationships. This approach, highlighted by the Quality by Digital Design (QbDD) framework, would aid in batch reproducibility and significantly reduce dependence on resource-intensive experimental testing. Furthermore, cutting-edge computational tools are crucial for predicting the behavior and functional composition of proteins and cell receptors on bio-based nanoparticle surfaces, which is vital for engineering specific properties for applications such as vaccination and targeted drug delivery. AI will be instrumental in developing smart nanomedicines for neurodegenerative diseases by directing nanoparticle design and ensuring stringent quality control throughout preclinical and clinical stages. In addition, ML predictive models, including Generative Adversarial Networks (GANs), will accelerate the virtual screening of millions of lipid combinations for RNA-loaded LNPs, enhancing tumor targeting and encapsulation efficiency in cancer vaccine development. Likewise, techniques such as Random Forest Regression and XGBoost are highly effective for predicting critical traits of drug delivery systems, including cumulative drug release profiles from chitosan nanoparticles.

Furthermore, advanced research is advancing the development of self-propelled NPs and smart nanorobots for targeted and highly efficient therapeutic interventions. These innovative systems operate as intelligent nano-carriers or nano-drug-delivery mechanisms, significantly enhancing the safety and efficacy of various treatments. Beyond their therapeutic applications, these cutting-edge nanodevices hold immense potential in imaging and diagnostics. They are actively utilized for bioimaging, disease monitoring, and biosensing, leveraging sophisticated sensor systems such as nanocantilevers and biosensors for precise molecular recognition and site-specific targeting. Furthermore, next-generation biosensing is effectively integrating nanotechnology, including nano-enzymes, with AI and deep learning to enhance performance through real-time signal processing, pattern recognition, predictive modeling, and adaptive decision-making. This integration enables calibrated predictive outputs and effective drift monitoring. It is imperative to incorporate these advancements to transform the efficacy of theranostic nanoparticles into tangible clinical applications, fundamentally revolutionizing modern medicine.