Search Results (4,236)

Moxifloxacin-based Schiff-base ligands provide a useful platform for tuning the coordination and biological properties of fluoroquinolone derivatives. Here, a moxifloxacin–salicylaldehyde hydrazone ligand (MOX-S) was prepared and coordinated with cobalt(II), nickel(II), copper(II), oxovanadium(IV), and gadolinium(III) ions to obtain a series of metal complexes. Citrate-stabilized gold nanoparticles (AuNPs) were also prepared and functionalized with MOX-S and the Cu(II) complex to evaluate the effect of nanoformulation on biological performance. The compounds were characterized using complementary analytical, spectroscopic, magnetic, thermal, and microscopic techniques. The combined data support 1:2 metal-to-ligand formulations for the complexes and indicate coordination mainly through the azomethine nitrogen and oxygen donor sites of MOX-S. In antimicrobial screening, the activity was strongly metal- and organism-dependent. Cu–MOX-S and VO–MOX-S showed the most pronounced activity against Gram-positive bacteria, with inhibition zones of up to 30 mm, while Cu–MOX-S displayed MIC values of 19.53 and 39.06 µg mL⁻¹ against Bacillus subtilis and Staphylococcus aureus, respectively. Cytotoxicity assays showed that MOX-S was more active than moxifloxacin against MCF-7 and HepG2 cells, while Cu–MOX-S showed enhanced potency, particularly toward HepG2 cells, with an IC₅₀ of 0.98 µM and a selectivity index of 5.97. AuNP formulations further increased the apparent antiproliferative potency in the tested cancer cell lines, giving sub-micromolar IC₅₀ values. Computational analyses, including DFT-based electronic descriptors and molecular docking, provided qualitative support for the experimentally observed coordination and cytotoxicity trends. Overall, metal coordination and AuNP formulations provide complementary strategies for modulating the physicochemical and in vitro biological behavior of this moxifloxacin-derived hydrazone scaffold. Full article

Green synthesis of gold nanoparticles is an effective approach to create biocompatible nanomaterials. In this study, gold nanoparticles (BC-AuNPs) were prepared by reducing chloroauric acid with black corncob (BC) extract at relatively low temperatures. The optimal preparation conditions were obtained through a single-factor experiment, which included 5 mL of black corncob extract and 0.12 mL of 3% HAuCl₄ solution at a pH of 5.0, and the reaction was carried out at 50 °C in a water bath for 3 h. The prepared BC-AuNPs were characterized by ultraviolet–visible (UV-Vis) spectroscopy, Fourier-transform infrared (FTIR) analysis, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), and Zeta-potential measurement, which showed that they were dispersed spherical particles with an average size of approximately 23.0 nm and their surfaces were covered with various black corncob active components. The photothermal performance test indicated a good photothermal effect with a conversion efficiency of 41.3%. Antibacterial experiments revealed that BC-AuNPs had excellent antibacterial activity. The minimum inhibitory concentrations (MICs) for E. coli and Salmonella were 25.00 and 50.00 µg/mL, respectively. Overall, this study proved a potential application for gold nanoparticles in photothermal antibacterial fields. Full article

Reagentless glucose biosensors with redox mediator—polymerized 1,10-phenanthroline-5,6-dione (pPD)—were developed and electrochemically investigated. Three types of biosensors based on graphite rod (GR) electrodes modified by (i) 13 nm of gold nanoparticles (AuNPs), (ii) electrochemically synthesized dendritic gold nanostructures (DAuNSs), and (iii) platinum nanostructures (PtNSs) were prepared. All electrodes were modified by glucose oxidase (GOx), and the pPD was polymerized for 2 h. Thus, GR/AuNPs/GOx/pPD, GR/DAuNSs/GOx/pPD, and GR/PtNSs/GOx/pPD electrodes were developed and electrochemically characterized. The electrode without noble metal nanostructures (GR/GOx/pPD) was used as the control. The biosensor based on the GR/DAuNSs/GOx/pPD electrode exhibited the best performance, with the sensitivity of 2.58 μA/(mM cm²), the linear range up to 93.7 mM, the limit of detection 0.182 mM, the reproducibility and repeatability of 4.99 and 4.80%, and the storage stability (50% of initial current responses (t_1/2)) for up to 19 days. The achieved high resistance to interfering materials enabled precise glucose detection in real samples, including human serum and beverages. The technological solutions presented in this paper are anticipated to provide opportunities and benefits of developing novel enzymatic reagentless glucose biosensors based on noble metal nanostructures for use in clinical assays and general diagnostics, including blood glucose monitoring in people with diabetes. Full article

C-reactive protein (CRP) is one of the most essential biomarkers for the early detection of inflammation and infection. In this study, we developed a sensitive and selective electrochemical immunosensor for CRP detection, leveraging the unique properties of gold nanoparticles (AuNPs). A nanostructured layer of AuNPs was deposited onto a screen-printed carbon electrode (SPCE), followed by the formation of a self-assembled monolayer (SAM) of L-cysteine and EDC/sulfo-NHS chemistry. The antibody was covalently immobilized onto the modified electrode through optimized dual-crosslinking chemistry. Detection conditions were systematically optimized, with pH 8.0 in Tris buffer providing the best electrochemical response. Electrochemical characterization was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a 5 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆] redox probe solution containing 0.1 M KCl. CRP detection was achieved by monitoring the increase in charge transfer resistance (Rct) upon specific binding of the target CRP antigen to the immobilized antibody. Spiked recovery experiments showed spiked recovery rates ranging from 98.01% to 107.14%, with a standard deviation below 4%. Regeneration studies demonstrated high efficiency, confirming the suitability of the sensor interface for repeated and reliable measurements. Under optimized conditions, the immunosensor exhibited excellent analytical performance, including a low limit of detection (LOD) of 0.16 µg/mL, a wide linear detection range of 5–100 µg/mL, high selectivity against 13 potential interferents (including inflammatory cytokines), and good reproducibility with a relative standard deviation (RSD) of 3.69%. The sensor also showed strong stability, retaining more than 95% of its signal after 15 days, and high regeneration efficiency of 97% over seven cycles. These results highlight the strong potential of the proposed immunosensor for point-of-care (POC) applications due to its simple fabrication, cost-effectiveness, user accessibility, and robust analytical performance. Full article

Bowl-shaped gold nanoparticles (BAuNPs) are of significant interest due to their tunable localized surface plasmon resonance (LSPR) properties. This report presents a new synthesis method that uses hemispherical hydrogen nanobubbles on planar, non-conducting surfaces as templates for gold shell deposition. Initial synthesis under stagnant conditions yielded non-uniform sub-micron particles, attributed to localized hydrogen concentration gradients. The cyclonic flow was introduced aiming to reduce these gradients, although simultaneously inducing significant particle aggregation, obscuring the open structure. To overcome these challenges, an electrochemical microfluidic system was implemented to create a laminar flow environment. This configuration optimizes ion distribution and introduces shear forces that promote particle detachment, successfully limiting particle dimensions to below 200 nm, and preventing the accumulation. Systematic optimization identified optimal parameters: an ideal channel length of 7.5 mm, an applied potential of −0.6 V, and a flow rate of 0.028 µL s⁻¹. These parameters that strike a balance between nanobubble growth and gold deposition kinetics can produce highly uniform BAuNPs with a well-defined open structure and thin solid gold shells, with an outer diameter of 105.3 ± 12.1 nm and a core diameter of 80.1 ± 11.9 nm. These structural parameters successfully shift the plasmonic resonance to 760 nm, which responds perfectly with the first biological window for potential in vivo biomedical applications. Full article

Gold and silver nanoparticles have attracted extensive attention in SERS detection due to their excellent plasmonic properties. In this study, a high-performance SERS substrate was successfully prepared by a liquid–liquid self-assembly strategy. Driven by the Marangoni effect, Au-Ag nanoparticles spontaneously form a uniform and dense monolayer structure on the silicon wafer, constructing an efficient plasmon ”hotspot” region, which significantly improves the detection sensitivity of the substrate. The performance of the SERS substrate was systematically evaluated using CV and Me B as Raman probe molecules. The results show that the substrate exhibits an excellent enhancement effect and good SERS sensitivity for both probe molecules. The characteristic vibration peak can be clearly identified, and the detection limit (LOD) of crystal violet is 6.76 × 10⁻¹¹ M. The substrate was applied to detect thiram residues in lake water with a LOD of 1.084 × 10⁻⁷ M, achieving highly sensitive detection. This study shows that Au-Ag nanoparticles deposited on silicon wafers by liquid–liquid self-assembly strategy can be used as a high-performance SERS substrate. It can be used for rapid and sensitive detection of thiram pesticide residues in water, and provides an efficient and feasible analysis tool for water environment safety monitoring. Full article

Continuous intraocular pressure (IOP) monitoring is crucial for glaucoma management. Currently, traditional static IOP measurements often fail to detect circadian fluctuations, leading to a clinical dilemma where “normal IOP” is observed despite persistent visual field deterioration. This study presents a wireless, passive localized surface plasmon resonance (LSPR) sensing platform integrated into flexible silicone hydrogel contact lenses. Gold nanoparticles (AuNPs), synthesized via the sodium citrate reduction method, were incorporated into the lens periphery using a “swelling-induced nano-doping” technique to transduce IOP-induced corneal strain into detectable spectral shifts. Ex vivo porcine eye investigations established a physical mapping model, confirming significant LSPR peak wavelength response trends in correlation with IOP variations (10–50 mmHg) and corneal curvature changes. Subsequent 21-day in vivo rabbit studies demonstrated excellent ocular surface biocompatibility; quantitative histopathological analysis (HE, PAS, and Ki67 staining) revealed no significant adverse alterations in corneal endothelial cell density or conjunctival goblet cell function compared to control groups (p > 0.05). Furthermore, the platform maintained high structural integrity and anterior segment tolerance under transient high-IOP conditions. While currently a proof-of-concept, these results indicate that the LSPR-active hybrid system effectively captures dynamic IOP fluctuation patterns as an optical response to acute interventions, providing a foundational engineering path for next-generation, battery-free wearable diagnostics in personalized glaucoma care without the need for built-in electronics. Full article

Cell-based immunotherapies require noninvasive tools that can quantify the migration, biodistribution, and persistence of administered immune cells. This review focuses primarily on oncologic immune cell therapy, while also considering selected inflammatory disease models in which immune-cell trafficking is biologically relevant. We critically compare direct radionuclide labeling, sodium iodide symporter (NIS)-based reporter gene imaging, radionuclide-integrated nanoplatforms, and Cerenkov-based hybrid optical conversion strategies. Direct labeling with agents such as [⁸⁹Zr]Zr-oxine, [¹¹¹In]In-oxine, and [⁹⁹ᵐTc]Tc-HMPAO enables early positron emission tomography (PET)/single-photon emission computed tomography (SPECT) biodistribution assessment, usually within hours to several days after cell administration. NIS reporter imaging with [¹²⁴I]NaI, [¹²³I]NaI, [⁹⁹ᵐTc]TcO₄⁻, or [¹⁸F]TFB supports repeated viability-dependent imaging, because signal generation depends on active transporter expression in living engineered cells. Radionuclide-integrated gold nanoplatforms can improve intracellular retention and offer theranostic potential through combined imaging, photothermal, radiotherapeutic, or immunomodulatory functions. We further discuss PET/SPECT balance, radiopharmaceutical nomenclature, nanoparticle stabilization, ethical aspects of genetic modification, tumor-on-a-chip systems for preclinical testing, and limitations of narrative evidence synthesis. Together, these platforms provide complementary strategies for image-guided immune cell therapy, with translational relevance for patient selection, treatment optimization, safety monitoring, and oncology practice. In conclusion, NIS-centered nuclear imaging and radionuclide-integrated nanoplatforms represent complementary, clinically actionable tools for quantitative immune-cell tracking, therapeutic optimization, and safety monitoring in translational oncology and inflammatory disease research. Full article

Currently, gold nanoparticles are increasingly used in targeted drug delivery nanostructures. However, their intrinsic catalytic activity is often overlooked when using them as a carrier. In this study, the interaction between the sotalol drug from the beta-blocker family and gold nanoparticles was investigated using capillary electrophoresis and high-performance liquid chromatography. Both methods showed that sotalol undergoes catalytic oxidation on the surface of citrate-stabilized gold nanoparticles into three products. Together with a cleavage of the isopropyl group from the nitrogen atom, the oxidation at the hydroxyl group occurs with the formation of a ketone. Analysis of electropherograms showed 100% conversion of sotalol after 48 h of incubation at a surface coverage of 1.2 × 10¹⁹ molecules per m². To examine the role of reactive oxygen species, the experiments were performed in oxygen-saturated and oxygen-deficient gold nanoparticle dispersions. The effects of radical scavenger additives and pH of nanoparticle dispersion were also assessed. The influence of surface ligands on sotalol conversion was studied using gold nanoparticles coated with thiols, surfactants, and polyelectrolytes. Based on comprehensive data, the mechanism of gold-nanoparticle-assisted multicenter oxidation of sotalol is proposed. Full article

Gold nanoparticles offer a versatile platform for cancer theranostics because their high atomic number can enhance X-ray energy deposition, their plasmonic properties support photothermal and photoacoustic applications, and their surfaces allow drug loading and molecular targeting. However, therapeutic benefit remains heterogeneous because tumor uptake, intratumoral coverage, and subcellular localization determine whether deposited gold can be converted into biologically effective damage. Redox context further shapes this conversion by determining whether AuNP-triggered physical or catalytic events can overcome local buffering and propagate into durable injury. During radiotherapy, AuNPs increase local secondary electron release and ROS formation, which can intensify DNA damage when GSH-dependent peroxide detoxification, thioredoxin-related buffering, and KEAP1-NRF2-regulated antioxidant responses are insufficient to contain the redox burden. In catalytic systems, Au-containing nanozymes can convert endogenous H₂O₂ into highly reactive radicals and may simultaneously deplete glutathione, thereby amplifying mitochondrial dysfunction and lipid peroxidation. During photoactivation, plasmonic heating and photosensitizer coupling further reshape ROS generation in a time-dependent and location-dependent manner. On the diagnostic side, CT or spectral CT can quantify tumor gold burden and coverage, whereas ROS-responsive photoacoustic, SERS, or fluorescence probes can report treatment-related oxidants and verify whether redox activation has occurred within the tumor. Clinical translation will therefore depend on quantification-guided dosing, definition of spatial coverage and activation timing, standardized redox-response readouts, and long-term safety evaluation. Full article

The creation of innovative systems that are able to combine diagnosis and therapy is a crucial opportunity in nuclear medicine. Here, we propose a methodological and multiscale approach for the development of a theranostic platform based on AuNRs functionalized with radiopharmaceuticals. AuNRs offer a versatile and effective system due to their unique physicochemical properties and the possibility of surface functionalization with targeting molecules. Within this framework, key challenges include the functionalization of AuNRs to target the cell nucleus, the loading of AuNRs with radiopharmaceuticals, and the investigation of Auger electron emission from AuNRs under gamma irradiation. Multiscale modelling is employed to describe the behaviour of the system within the cellular environment and to predict potential radiobiological enhancement effects, including synergistic interactions between functionalized AuNRs and radiopharmaceutical agents such as ^99mTc-sestaMIBI. The experimental activity includes gamma irradiation studies, along with the structural and physical characterization of nanomaterials and in vitro biological investigations on T98G cells, to evaluate cytotoxicity and metabolic alterations, with the aim of assessing the potential synergistic effects of the combined system. Full article

A semi-distributed interferometer is a low-reflectivity device with refractive index sensing capability, exploiting the random reflectivity of a nanoparticle-doped fiber to form a weak distributed cavity. In this work, we extend this concept to an extrinsic semi-distributed interferometer (ESDI), using an overlay made of polydimethylsiloxane (PDMS) around the fiber tip; this structure can then be surface-modified using a thin metallic film or a nanoparticle coating. We report gold-sputtered and gold-nanoparticle-coated ESDI structures for refractive index sensing capability, with the latter achieving superior performances with an average sensitivity of 62.8 dB/RIU (refractive index units) with resolution of 3.9 × 10⁻⁵ RIU over the range of 1.34790–1.35981. We also report a possible biological application using a biofunctionalized version of this probe for the detection of VEGF (vascular endothelial growth factor); the gold-sputtered probe achieves the highest sensitivity, 0.0565 dB for each 10× concentration increase, with 355 fM detection limit. Full article

The literature collected from various search engines and high-quality scientific databases reveals that amino acid (AA)-functionalized nanoparticles have emerged as a promising field for selective detection and remediation of heavy metals (HMs). Among the various nanoparticles (NPs), gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) have drawn considerable attention, attributed to their unique optical, catalytic, and surface plasmon resonance properties. Functionalization with amino acids significantly enhances nanoparticle stability, biocompatibility, and metal-binding affinity through diverse functional groups. AA-functionalized AuNPs, including glycine, cystine, leucine, methionine, tyrosine, aspartic acid, histidine, and lysine-capped systems, exhibit tunable selectivity toward heavy metal ions. Bifunctionalization strategies further enhance sensitivity by inducing nanoparticle aggregation or signal amplification. Beyond single amino acids, polypeptides and protein-functionalized AuNPs offer enhanced molecular recognition and multivalent binding, expanding their applicability in complex matrices. Similarly, amino acid-functionalized AgNPs, such as those capped with similar amino acids stated above, exhibit strong interactions with heavy metals, AA bifunctionalization, and bimetallic nanoparticles (BNPs), particularly amino acid-functionalized Au–Ag systems, which combine the advantages of both metals, leading to improved sensitivity, selectivity, and signal strength. Although these advances have been made, a major gap remains in the systematic comparison of different amino acids, peptides, and bimetallic systems under real-world conditions. This gap can be addressed by standardized testing methods, clearer structure–function relationships and combined experimentation to guide the rational design of more efficient AA-functionalized nanoparticles. Full article

Gold nanospheres (AuNPs) and gold nanoflowers (AuNFs) are widely used as platforms for DNA aptamer functionalization, while conjugation behavior and colloidal tolerance remain important factors affecting subsequent sensing-oriented optimization. In this study, 82-nt thiolated DNA aptamer constructs bearing either 3′-SH or 5′-SH terminal modification were immobilized onto citrate-stabilized AuNPs and AuNFs under matched stepwise salt-aging conditions. Apparent nanoparticle-associated DNA output was estimated by Qubit-based measurement of unbound ssDNA in the supernatant and expressed as mass-based loading output (ng). Under the tested stock-dispersion conditions, AuNP samples showed higher apparent conjugation output than AuNF samples. Specifically, the apparent conjugation yields for AuNPs were 80.65 ± 1.64% (3′-SH) and 84.76 ± 1.98% (5′-SH), whereas those for AuNFs were 66.64 ± 3.36% (3′-SH) and 73.65 ± 1.36% (5′-SH). The corresponding apparent DNA loading outputs were 2329.7 ± 47.4 ng and 2448.7 ± 57.1 ng for AuNPs, and 1925.1 ± 97.0 ng and 2127.4 ± 39.3 ng for AuNFs. DLS size increases and zeta potential shifts toward more negative values were consistent with the formation of a DNA-associated interfacial layer, while TEM images supported morphology retention after conjugation. A qualitative visual salt-challenge assessment indicated that aptamer-functionalized nanoparticles displayed improved resistance to salt-induced aggregation relative to bare particles under the tested conditions. Because the commercially supplied AuNP and AuNF dispersions were not normalized to identical particle number or accessible surface area, the reported values should be interpreted as comparative apparent outputs rather than intrinsic loading capacities. Within this scope, the present study provides a convenient preliminary materials-level evaluation of thiolated aptamer conjugation behavior and may support future glyphosate aptasensor optimization. Full article

The design of metal nanoparticle-on-a-mirror (NPOM) provides a powerful strategy for optical enhancement in gap plasmonics. Here, we report a systematic numerical study on an NPOM structure composed of gold nanocubes (GNC) and a continuous gold film via the finite element method (FEM). First, we simulated the near-electric field distribution of isolated GNC in a homogeneous medium and compared it with that of the GNC-based NPOM structure, revealing the dominant role of plasmon coupling in the gap region. Second, we systematically investigated the influence of the thickness of the dielectric layer between the GNC and the gold film on the optical enhancement characteristics in the gap region. The results show that the maximum electric field intensity of the resonance peak decays rapidly when the thickness of the dielectric layer is less than 2 nm, decreasing from 5048 (t = 0.5 nm) to 1032 (t =2 nm). Third, we further investigated the influence of the polarization angle of the incident light on the optical enhancement in the gap region. Finally, the dielectric environment n₀ and the refractive index n of the dielectric layer were studied. This work elucidates the unique gap plasmon coupling mechanisms of GNC-based NPOM structures and provides a precise tuning strategy for key structural and optical parameters, endowing the structure with important application prospects in sensing, energy conversion, and photodetection. Full article