Search Results (149)

The biological effects of nanoparticles are closely related to their intracellular content and location, both of which are influenced by various factors. This study investigates the effects of surface charge on the uptake, intracellular distribution, and exocytosis of CdSe/ZnS quantum dots (QDs) in Raw264.7 macrophages. Negatively charged 3-mercaptopropanoic acid functionalized QDs (QDs-MPA) show higher cellular uptake than positively charged 2-mercaptoethylamine functionalized QDs (QDs-MEA), and serum enhances the uptake of both types of QDs via protein corona-mediated receptor endocytosis. QDs-MEA primarily enter the cells through clathrin/caveolae-mediated pathways and predominantly accumulate in lysosomes, while QDs-MPA are mainly internalized through clathrin-mediated endocytosis and localize to both lysosomes and mitochondria. Exocytosis of QDs-MPA is faster and more efficient than that of QDs-MEA, though both exhibit limited excretion. In addition to endocytosis and exocytosis, cell division influences intracellular QD content over time. These results reveal the charge-dependent interactions between QDs and macrophages, providing a basis for designing biocompatible nanomaterials. Full article

Theranostic agents enable the simultaneous diagnosis and treatment of diseases, and they are particularly useful in fluorescent imaging and cancer therapies. In this study, carbon quantum dots were synthesized via a microwave-assisted method using citric acid and bovine serum albumin (BSA) as precursors. The resulting CQDs exhibited spherical morphology, an average size of 4 nm, and an amorphous graphitic structure. FT-IR characterization revealed the presence of amide bonds and oxygenated functional groups. At the same time, optical analysis showed excitation at 320 nm and emission between 360 and 400 nm, with fluorescent stability maintained for one month. Furthermore, the CQDs demonstrated good thermal stability and photothermal efficiency, reaching temperatures above 41 °C within 15 min under NIR irradiation, with a mass loss of less than 1%. Their stability was evaluated in media with different pH levels, simulating physiological and tumor environments. While their behavior was affected under acidic conditions, their excellent photothermal conversion capacity and overall stability in triple-distilled water positioned them as promising candidates for theranostic applications in cancer, effectively combining diagnostic imaging and thermal therapy. Full article

Graphene quantum dots (GQDs) obtained by microwave-induced pyrolysis of glutamic acid and triethylenetetramine (trien) are fairly stable, emissive, water-soluble, and positively charged nano-systems able to interact with negatively charged meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS₄). The stoichiometric control during the preparation affords a supramolecular adduct, GQDs@TPPS₄, that exhibits a double fluorescence emission from both the GQDs and the TPPS₄ fluorophores. These supramolecular aggregates have an overall negative charge that is responsible for the condensation of cations in the nearby aqueous layer, and a three-fold acceleration of the metalation rates of Cu²⁺ ions has been observed with respect to the parent porphyrin. Addition of various metal ions leads to some changes in the UV/Vis spectra and has a different impact on the fluorescence emission of GQDs and TPPS₄. The quenching efficiency of the TPPS₄ emission follows the order Cu²⁺ > Hg²⁺ > Cd²⁺ > Pb²⁺ ~ Zn²⁺ ~ Co²⁺ ~ Ni²⁺ > Mn²⁺ ~ Cr³⁺ >> Mg²⁺ ~ Ca²⁺ ~ Ba²⁺, and it has been related to literature data and to the sitting-atop mechanism that large transition metal ions (e.g., Hg²⁺ and Cd²⁺) exhibit in their interaction with the macrocyclic nitrogen atoms of the porphyrin, inducing distortion and accelerating the insertion of smaller metal ions, such as Zn²⁺. For the most relevant metal ions, emission quenching of the porphyrin evidences a linear behavior in the micromolar range, with the emission of the GQDs being moderately affected through a filter effect. Deliberate pollution of the samples with Zn²⁺ reveals the ability of the GQDs@TPPS₄ adduct to detect sensitively Cu²⁺, Hg^2+, and Cd²⁺ ions. Full article

Background/Objectives: There is an increasing incidence of fungal infections in conjunction with the rise in resistance to medical treatment. Antimicrobial resistance is frequently associated with virulence factors such as adherence and the capacity of biofilm formation, which facilitates the evasion of the host immune response and resistance to drug action. Novel therapeutic strategies have been developed to overcome antimicrobial resistance, including the use of different type of nanomaterials: metallic (Au, Ag, Fe₃O₄ and ZnO), organic (e.g., chitosan, liposomes and lactic acid) or carbon-based (e.g., quantum dots, nanotubes and graphene) materials. The objective of this study was to evaluate the action of nanoparticles of different synthesis and with different coatings on fungi of medical interest. Methods: Literature research was conducted using PubMed and Google Scholar databases, and the following terms were employed in articles published up to June 2025: ‘nanoparticles’ in combination with ‘fungal biofilm’, ‘Candida biofilm’, ‘Aspergillus biofilm’, ‘Cryptococcus biofilm’, ‘Fusarium biofilm’ and ‘dermatophytes biofilm’. Results: The utilization of nanoparticles was found to exert a substantial impact on the reduction in fungal biofilm, despite the presence of substantial variability in minimum inhibitory concentration (MIC) values attributable to variations in nanoparticle type and the presence of capping agents. It was observed that the MIC values were lower for metallic nanoparticles, particularly silver, and for those synthesized with polylactic acid compared to the others. Conclusions: Despite the limited availability of data concerning the stability and biocompatibility of nanoparticles employed in the treatment of fungal biofilms, it can be posited that these results constitute a significant initial step. Full article

Graphene quantum dots (GQDs) have strong potential in optoelectronics, particularly in LEDs, photodetectors, solar cells, and nanophotonics. While challenges remain in efficiency and scalability, advances in functionalization and hybrid material integration could soon make them commercially viable for next-generation optoelectronic devices. In this work, we assess the stability of various epoxy positions and their impact on the electronic and optical properties of GQDs. The oxygen binding energies and the potential barrier heights at different positions of epoxy groups at the edges and in the core of the GQD were estimated. The effect of possible transformations of epoxy groups into other edge configurations on the structural and optical properties of GQDs was evaluated. The results demonstrate that the functionalization of the GQD surface and edges with an epoxy groups at varying binding sites can result in substantial modification of the electronic structure and absorption properties of the GQDs. The prospects of low temperature annealing for controlling optical properties of epoxidized GQDs were discussed. The present computational work offers atomistic insights that can facilitate the rational design of optoelectronic systems based on GQD materials. Full article

Nanomaterials are interesting due to their unexpected and unique properties arising from phenomena occurring at the so-called mesoscale (that is, between single atoms and bulk solids). Among nanomaterials, one may distinguish quantum dots, which are highly crystalline nanocrystals with sizes up to c.a. 10 nm. Due to the quantum confinement effect, quantum dots exhibit extraordinary electronic and optical properties and may be utilized in photocatalysis. Semiconducting quantum dots may absorb photons, which results in the excitation of electrons from valence to conducting bands. Excited electrons in the conducting band and positive holes in the valence band may interact with chemical molecules (e.g., with water molecules), forming highly reactive radicals. Consequently, quantum dots may be utilized in advanced oxidation processes based on the action of light (i.e., photo-based advanced oxidation processes). Furthermore, quantum dots have advantages, such as having a tunable energy band gap and relative cost-effectiveness. Advanced oxidation processes are very important in the context of the constantly increasing pollution of the natural environment. Contaminants of emerging concern, such as pesticides, endocrine-disrupting compounds, and flame retardants, are still being detected in naturally present water. Such compounds may be degraded using advanced oxidation processes, utilizing quantum dots as photocatalysts. However, many operational parameters (such as quantum dots’ properties, including the means of their preparation) influence the efficiency of such processes; thus, detailed studies are being conducted. Full article

Clostridium perfringens is a major cause of necrotizing enteritis in chickens. This study aimed to investigate the effects of zinc oxide quantum dots (ZnO-QDs) on growth performance, redox status, and gut microbiota in broilers challenged with C. perfringens. A total of 320 1-day-old chicks were divided into five groups: negative control (NC) without treatment; positive control (PC) infected with C. perfringens; and the other three groups (40, 80, and 120 Zn) were given ZnO-QDs at doses of 40, 80, and 120 mg/kg, respectively, under C. perfringens infection, respectively. The results show that, compared to the NC group, the PC group exhibited negative effects on growth performance, intestinal morphology, and antioxidant status in broilers. However, compared to the PC group, 120 mg Zn increased (p < 0.05) the body weight of broilers at 21 days, while 40 mg Zn reduced (p < 0.05) serum diamine oxidase activity. The intestinal macroscopic evaluation showed that the PC group had the highest lesion scores, whereas the 120 mg Zn group exhibited the lowest lesion score. Meanwhile, compared to the PC group, the 40 mg Zn group had higher (p < 0.05) CAT and GPX activities and a lower (p < 0.05) MDA concentration. Moreover, the 40 mg Zn group up-regulated (p < 0.05) the gene expression of Cathelicidin-1, IL-10, Claudin-1, and MLCK in the jejunum. Furthermore, the 120 mg Zn group increased (p < 0.05) the abundance of Blautia, Parasutterella, and Lachnospiraceae FCS020 in the cecum. In conclusion, ZnO-QDs exerted a beneficial effect on improving growth performance and overall health in broilers under C. perfringens infection, potentially by regulating redox balance and gut microbiota. Full article

Nitrogen-doped graphene quantum dots (NGQDs) are made by heating a mixture of GQDs and ammonia using a thermochemical method. The optical properties of the samples were studied. Here, the role of the temperature used in the annealing process is investigated. It is found that with the increase in heating temperature, the sp² fraction content continuously increases, and the photoluminescence (PL) blue shift continuously increases. The 550 nm peak of GQDs shifts from 550 nm to 513 nm NGQDs synthesized at 300 °C. The normalized PL intensity shows a significant blue shift in the emission peak of the NGQD samples compared to the GQDs. The peak position of the GQDs is 555 nm, while the peak positions of the NGQDs are 511 nm for NGQDs-250, 488 nm for NGQDs-300, and 480 nm for NGQDs-350. Using a simple thermochemical method, we can effectively dope N into GQDs, and it is evident from the electron energy loss spectra that N doping induces the emergence of a new energy level in the electronic structure, which alters the optical properties of NGQDs. Full article

Heavy metal ion (HMI) contamination poses significant threats to public health and environmental safety, necessitating advanced detection technologies that are rapid, sensitive, and field-deployable. While conventional methods like atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) remain prevalent, their limitations—including high costs, complex workflows, and lack of portability—underscore the urgent need for innovative alternatives. This review consolidates advancements in the last five years in microfluidic technologies for HMI detection, emphasizing their transformative potential through miniaturization, integration, and automation. We critically evaluate the synergy of microfluidics with cutting-edge materials (e.g., graphene and quantum dots) and detection mechanisms (electrochemical, optical, and colorimetric), enabling ultra-trace detection at parts-per-billion (ppb) levels. We highlight novel device architectures, such as polydimethylsiloxane (PDMS)-based labs-on-chip (LOCs), paper-based microfluidics, 3D-printed systems, and digital microfluidics (DMF), which offer unparalleled portability, cost-effectiveness, and multiplexing capabilities. Additionally, we address persistent challenges (e.g., selectivity and scalability) and propose future directions, including AI integration and sustainable fabrication. By bridging gaps between laboratory research and practical deployment, this review provides a roadmap for next-generation microfluidic solutions, positioning them as indispensable tools for global HMI monitoring. Full article

Background/Objectives: To compare and analyze the application of a Helicobacter pylori (H. pylori, Hp) serum antibody typing test (Hp-sATT) and the ¹³C-urea breath test (¹³C-UBT) in the diagnosis of Hp infection against an empirical therapy background. Methods: The detection of Hp-sATT using a combination of the quantum dot immunofluorescence method and the ¹³C-UBT was carried out in 237 patients who visited the Department of Gastroenterology at Beijing Tsinghua Changgung Hospital. The diagnostic consistency and correlation with gastric lesions of the two detection methods were analyzed by integrating the detection results, clinical information, and special staining of Hp in histopathological tissues (SS-Hp). Results: For the ¹³C-UBT, 104 (43.88%) cases were positive and 133 (56.12%) were negative. Positive results were found in 127 (53.59%) patients by using the Hp-sATT, with 67 (28.27%) cases of Type I Hp infection and 60 (25.32%) cases of Type II Hp infection. The consistency analysis between the Hp-sATT and ¹³C-UBT for all the patients showed a Kappa value of 0.339 (p < 0.001); the consistency analysis between the Hp-sATT and the 127 patients with SS-Hp showed a Kappa value of 0.427 (p < 0.001); and the consistency analysis between the ¹³C-UBT and the 127 patients with SS-Hp indicated a Kappa value of 0.621 (p < 0.001). However, in 191 patients without a history of Hp eradication, the consistency analysis results for the three methods improved, with Kappa values of 0.467 (p < 0.001) and 0.457 (p < 0.001) for the Hp-sATT with the ¹³C-UBT and SS-Hp, respectively, and 0.646 (p < 0.001) for the ¹³C-UBT with SS-Hp. In addition, a positive correlation was found between the signal values of anti-urease antibodies and the Delta Over Baseline (DOB) values of the ¹³C-UBT. The results also indicated that Hp-infected patients exhibited more pronounced gastric lesions, while cases with Type I Hp infection did not. Conclusions: In patients without a history of Hp eradication, the consistency between the Hp-sATT and ¹³C-UBT is moderate. However, Hp eradication therapy can reduce the consistency of the test results. When screening for Hp infection using the Hp-sATT, it is necessary to consider the patient’s history of Hp eradication. Full article

We propose a simple and innovative configuration consisting of a quantum dot and micro-optical resonator that emits single photons with good directionality in a plane parallel to the substrate. In this device, a single quantum dot is placed as a light source between the slits of a triangular split-ring micro-optical resonator (SRR) supported in an optical polymer film with an air-bridge structure. Although most of the previous single photon emitters in solid-state devices emitted photons upward from the substrate, operation simulations confirmed that this configuration realizes lateral light emission in narrow regions above, below, left, and right in the optical polymer film, despite the absence of a light confinement structure such as an optical waveguide. This device can be fabricated using silica-coated colloidal quantum dots, focused ion beam (FIB) lithography, and wet etching using an oxide layer on a silicon substrate as a sacrificial layer. The device has a large tolerance to the variation in the position of the SRR in the optical polymer film and the height of the air-bridge. We confirmed that Pt-SRRs can be formed on the optical polymer film using FIB lithography. This simple lateral photon emitter is suitable for coupling with optical fibers and for fabricating planar optical quantum solid-state circuits, and is useful for the development of quantum information processing technology. Full article

Nanotheranostics integrates diagnostic and therapeutic functionalities using nanoscale materials, advancing personalized medicine by enhancing treatment precision and reducing adverse effects. Key materials for nanotheranostics include metallic nanoparticles, quantum dots, carbon dots, lipid nanoparticles and polymer-based nanocarriers, each offering unique benefits alongside specific challenges. Polymer-based nanocarriers, including hybrid and superparamagnetic nanoparticles, improve stability and functionality but are complex to manufacture. Polymeric nanoparticles with aggregation-induced emission (AIE) present promising theranostic potential for cancer detection and treatment. However, challenges such as translating the AIE concept to living systems, addressing toxicity concerns, overcoming deep-tissue imaging limitations, or ensuring biocompatibility remain to be resolved. Recently, cluster-triggered emission (CTE) polymers have emerged as innovative materials in nanotheranostics, offering enhanced fluorescence and biocompatibility. These polymers exhibit increased fluorescence intensity upon aggregation, making them highly sensitive for imaging and therapeutic applications. CTE nanoparticles, crafted from biodegradable polymers, represent a safer alternative to traditional nanotheranostics that rely on embedding conventional fluorophores or metal-based agents. This advancement significantly reduces potential toxicity while enhancing biocompatibility. The intrinsic fluorescence allows real-time monitoring of drug distribution and activity, optimizing therapeutic efficacy. Despite their potential, these systems face challenges such as maintaining stability under physiological conditions and addressing the need for comprehensive safety and efficacy studies to meet clinical and regulatory standards. Nevertheless, their unique properties position CTE nanoparticles as promising candidates for advancing theranostic strategies in personalized medicine, bridging diagnostic and therapeutic functionalities in innovative ways. Full article

Quantum dot (QD)-based single-photon emitter devices today are based on self-assembled random position nucleated QDs emitting at random wavelengths. Deterministic QD growth in position and emitter wavelength would be highly appreciated for industry-scale high-yield device manufacturing from wafers. Local droplet etching during molecular beam epitaxy is an all in situ method that allows excellent density control and predetermines the nucleation site of quantum dots. This method can produce strain-free GaAs QDs with excellent photonic and spin properties. Here, we focus on the emitter wavelength homogeneity. By wafer rotation-synchronized shutter opening time and adapted growth parameters, we grow QDs with a narrow peak emission wavelength homogeneity with no more than 1.2 nm shifts on a 45 mm diameter area and a narrow inhomogeneous ensemble broadening of only 2 nm at 4 K. The emission wavelength of these strain-free GaAs QDs is <800 nm, attractive for quantum optics experiments and quantum memory applications. We can use a similar random local droplet nucleation, nanohole drilling, and now, InAs infilling to produce QDs emitting in the telecommunication optical fiber transparency window around 1.3 µm, the so-called O-band. For this approach, we demonstrate good wavelength homogeneity and excellent density homogeneity beyond the possibilities of standard Stranski–Krastanov self-assembly. We discuss our methodology, structural and optical properties, and limitations set by our current setup capabilities. Full article

Quantum dots (QDs) have emerged as promising tools in advancing multiphoton microscopy (MPM) for deep brain imaging, addressing long-standing challenges in resolution, penetration depth, and light–tissue interactions. MPM, which relies on nonlinear photon absorption, enables fluorescence imaging within defined volumes, effectively reducing background noise and photobleaching. However, achieving greater depths remains limited by light scattering and absorption, compounded by the need for balanced laser power to avoid tissue damage. QDs, nanoscale semiconductor particles with unique optical properties, offer substantial advantages over traditional fluorophores, including high quantum yields, large absorption cross-sections, superior photostability, and tunable emission spectra. These properties enhance signal to background ratio at increased depths and reduce scattering effects, making QDs ideal for imaging subcortical regions like the hippocampus without extensive microscope modifications. Studies have demonstrated the capability of QDs to achieve imaging depths up to 2100 μm, far exceeding that of conventional fluorophores. Beyond structural imaging, QDs facilitate functional imaging applications, such as high-resolution tracking of hemodynamic responses and neural activity, supporting investigations of neuronal dynamics and blood flow in vivo. Their stability enables long-term, targeted drug delivery and photodynamic therapy, presenting potential therapeutic applications in treating brain tumors, Alzheimer’s disease, and traumatic brain injury. This review highlights the impact of QDs on MPM, their effectiveness in overcoming light attenuation in deep tissue, and their expanding role in diagnosing and treating neurological disorders, positioning them as transformative agents for both brain imaging and intervention. Full article

The hot carrier multi-junction solar cell (HCMJC) is an advanced-concept solar cell with a theoretical efficiency greater than 65%. It combines the advantages of hot carrier solar cells and multi-junction solar cells with higher power conversion efficiency (PCE). The thermalization coefficient (Q_th) has been shown to slow down by an order of magnitude in low-dimensional structures, which will significantly improve PCE. However, there have been no studies calculating the Q_th of MAPbBr₃ quantum dots so far. In this work, the Q_th values of MAPbBr₃ quantum dots and after BABr addition were calculated based on power-dependent steady-state photoluminescence (PD-SSPL). Their peak positions in PD-SSPL increased from 2.37 to 2.71 eV after adding BABr. The fitting shows that, after adding BABr, the Q_th decreased from 2.64 ± 0.29 mW·K⁻¹·cm⁻² to 2.36 ± 0.25 mW·K⁻¹·cm⁻², indicating a lower relaxation rate. This is because BABr passivates surface defects, slowing down the carrier thermalization process. This work lays the foundation for the theoretical framework combining perovskite materials, which suggests that the appropriate passivation of BABr has the potential to further reduce Q_th and make MAPbBr₃ QDs with BABr modified more suitable as the top absorption layer of HCMJCs. Full article