Search Results (118)

Pulsed laser deposition (PLD) is widely used for functional film fabrication, but traditional nanosecond-laser-induced thermal effects and interface roughness severely limit the quality of multilayer structures. To address this critical challenge, a picosecond pulsed laser with collinear pulse train output was adopted for TiO₂/ZnO multilayer preparation, achieving dual advantages of thermal diffusion suppression and roughness reduction. A systematic investigation was conducted on the properties of TiO₂ and ZnO films, establishing a “constant-deposition-rate multi-pulse regulation” strategy that yielded low roughness (4.43 nm for TiO₂, 3.27 nm for ZnO) and optimized refractive index matching. Through 500 °C oxygen annealing, TiO₂’s refractive index was enhanced to 2.6, forming a large refractive index difference (Δn = 0.77) with ZnO (~1.83) for efficient photonic band gap (PBG) regulation. Integral annealing was identified as the optimal post-treatment, enabling the four-layer TiO₂/ZnO multilayer to reach a maximum reflectance of 75% with excellent structural uniformity. The multifunctional applications of the multilayers exhibit excellent ability in photocatalytic degradation of tetracycline hydrochloride (TCH) and fluorescence enhancement of CdSe quantum dots (QDs). This work pioneers a high-quality PLD-based multilayer fabrication route and opens new avenues for its application in environmental remediation and optoelectronic devices. Full article

Effective in situ pH sensing holds exciting prospects in environmental and biomedical applications, but still faces a great challenge. Until now, pH sensors with small size, high sensitivity, good stability and repeatability, great biosafety, wide detection range, and flexible structure have rarely been reported. Herein, we propose a novel dual-emission ratiometric fluorescent pH sensor by decorating ethyl cellulose (EC)-encapsulated CdSe/ZnS quantum dots (QDs) and oxazine 170 perchlorate (O170 dye) on the surface of the spider silk. When a 473 nm excitation light is coupled into the pH sensor, the evanescent wave transmitting along the surface of the spider silk will excite the CdSe/ZnS QDs and then the O170 dye based on the fluorescence resonance energy transfer (FRET) effect from the QDs; thus, the pH sensing of the surrounding liquid environment can be achieved in real time by collecting the photoluminescence (PL) spectra of the pH sensor and measuring the emission intensity ratio of the two fluorescent materials. The sensor has also demonstrated a high sensing sensitivity (0.775/pH unit) within a wide pH range of 1.92–12.11, as well as excellent reusability and reversibility, structure and time stability, biocompatibility, and biosafety. The proposed pH sensor has a potential application in an in situ monitor of water microenvironments, cellular metabolism, tumor microenvironments, etc. Full article

The CdSe/CdZnS colloidal quantum wells, with their exceptionally high carrier mobility and ultrafast response characteristics, emerge as highly promising candidate material for high-performance active terahertz modulators—indispensable core components critical for next-generation communication technologies. A high-performance, cost-effective terahertz modulator was fabricated through spin-coating CdSe(4ML)/CdZnS nanosheets onto a silicon substrate. This all-optical device demonstrates broadband modulation capabilities (0.25–1.4 THz), achieving a remarkable modulation depth of 87.6% at a low power density of 2 W/cm^2. Demonstrating pump-power-efficient terahertz modulation characteristics, this core–shell composite shows immediate applicability in terahertz communication systems and non-destructive testing equipment. Full article

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

Real-time, high-resolution monitoring of chemically diverse water pollutants remains a critical challenge for smart water management. Here, we report a fully integrated, multi-modal nano-sensor array, combining graphene field-effect transistors, Ag/Au-nanostar surface-enhanced Raman spectroscopy substrates, and CdSe/ZnS quantum dot fluorescence, coupled to an edge-deployable CNN-LSTM architecture that fuses raw electrochemical, vibrational, and photoluminescent signals without manual feature engineering. The 45 mm × 20 mm microfluidic manifold enables continuous flow-through sampling, while 8-bit-quantised inference executes in 31 ms at <12 W. Laboratory calibration over 28,000 samples achieved limits of detection of 12 ppt (Pb²⁺), 17 pM (atrazine) and 87 ng L⁻¹ (nanoplastics), with R² ≥ 0.93 and a mean absolute percentage error <6%. A 24 h deployment in the Cherwell River reproduced natural concentration fluctuations with field R² ≥ 0.92. SHAP and Grad-CAM analyses reveal that the network bases its predictions on Dirac-point shifts, characteristic Raman bands, and early-time fluorescence-quenching kinetics, providing mechanistic interpretability. The platform therefore offers a scalable route to smart water grids, point-of-use drinking water sentinels, and rapid environmental incident response. Future work will address sensor drift through antifouling coatings, enhance cross-site generalisation via federated learning, and create physics-informed digital twins for self-calibrating global monitoring networks. Full article

Quantum dots (QDs) are nanoparticles with intrinsic fluorescence. Recent studies have found that metal-based QDs often impart toxic effects on the biological systems they interact with. Their undefined limitations have offset their potential for biomedical application. Our study aimed to address the research gap regarding QDs’ impacts on the intracellular actin cytoskeleton and the associated structures. Our XTT viability assays revealed that QDs only reduced viability in transformed human liver epithelial (THLE-2) cells, whereas HeLa cells remained viable after QD treatment. We also used confocal microscopy to evaluate the morphological changes in THLE-2 induced by QDs. We further investigated cell protrusion morphology using phalloidin-Alexa488 which selectively labels F-actin. The fluorescent microscopy of this phalloidin label revealed that QD treatment resulted in the redistribution of actin filaments within both THLE-2 and HeLa cells. We also report that the average number of focal adhesions decreased in QD-treated cells. As actin filaments at the cell are peripherally linked to the extracellular matrix via talin and integrin and are thus a crucial component of cell motility, we conducted a migration assay. The migration assay revealed that cell motility was significantly reduced in both THLE-2 and HeLa cells following QD treatment. Our findings establish that the internalization of QDs reduces cell motility by rearranging actin filaments. Full article

The current research developed an optical carbon dioxide (CO₂) sensor using anodized aluminum oxide (AAO) as the substrate. We developed an optical carbon dioxide (CO₂) sensor utilizing CdSe/ZnS quantum dots (QDs) as the fluorescent dye and Phenol Red as the pH indicator. The QDs acted as the CO₂-responsive fluorophore and were embedded in a polyimide butyl methacrylate (polyIBM) matrix. This sensing solution was applied to an anodized aluminum oxide (AAO) substrate, which provided a porous and stable platform for sensor fabrication. Photoluminescence measurements were conducted using the coated AAO substrate, with excitation from a 405 nm LED light source. The sensor exhibited red fluorescence emission at 570 nm and could detect CO₂ concentrations in the linear range of 0–100%. Experimental results showed that fluorescence intensity increased with CO₂ concentration, achieving a sensitivity of 211. A wavelength shift of 0.1657 nm/% was observed, indicating strong interactions among CO₂ molecules, Phenol Red, and the QDs within the AAO matrix. The sensor demonstrated a response time of 55 s and a recovery time of 120 s. These results confirm the effectiveness of this optical sensing approach in minimizing fluctuations from the excitation light source and highlight the potential of the AAO-supported QDs and Phenol Red composite as a reliable CO₂ sensing material. This advancement holds promise for applications in both medical and industrial fields. Full article

Colloidal quantum dots (QDs) provide an ideal platform for the development of integrated optoelectronic devices due to their excellent solution processability and size-tunable optical properties. In this paper, we investigate the self-assembly process of QD micro-rings based on the solution patterning method and the lasing phenomenon in the micro-rings. The characterization of the QD micro-rings demonstrates that they possess a high-quality morphological structure and excellent optical properties. The photoluminescence spectra of the QD micro-rings with different pump fluences are studied, and photon lasing with a narrow linewidth (0.3 nm) is found to have been achieved in the micro-rings above the threshold ($23 \mathsf{\mu }\mathrm{J} \mathrm{c}{\mathrm{m}}^{-2}$). The high coherence of the lasing in the QD micro-rings is revealed by angle-resolved photoluminescence (ARPL) spectra at room temperature. Moreover, the interference pattern of the coherent lasing obtained with Young’s double-slit interference method based on the far-field Fourier optical system in the ARPL spectrum reflects the distribution of the optical field in the QD micro-rings. Our research on the self-assembly of colloidal QDs and the lasing of QD micro-rings is expected to further promote the development of on-chip integrated QD optoelectronic devices. Full article

Vomitoxin is a member of the monotrichous mycotoxin family with a complex chemical structure and significant biological activity. This toxin has strong immunosuppressive toxic effects and can cause serious damage to human and animal health. In this study, an on-site immune detection method based on an immune SiO₂@QD fluorescent probe was developed, which realized the rapid and quantitative detection of emetic toxins in grains. Polyethyleneimine (PEI) is a polymer containing a large number of amino groups, and the binding of PEI to the surface of quantum dots can serve to regulate growth and provide functionalized groups. A SiO₂@QD nanotag with good dispersibility and a high fluorescence intensity was synthesized by combining a PEI interlayer on the surface of SiO₂ nanospheres. Utilizing the electrostatic adsorption of the amino group in PEI, CdSe/ZnS QDs were self-assembled on the surface of SiO₂ nanospheres. In the stability test, the SiO₂@QDs could maintain basically the same fluorescence intensity for 90 consecutive days in the dark at 4 °C, showing a high fluorescence stability. The fluorescence-enhanced QD immune probe was formed by coupling with anti-DON monoclonal antibodies through carbodiimide chemical synthesis. For the detection of spiked wheat flour samples, the immuno-SiO₂@QD fluorescent probe showed excellent sensitivity and stability, the detection limit reached 0.25 ng/mL, and the average recovery rate was 92.2–101.6%. At the same time, the immuno-SiO₂@QD fluorescent probe is simple to operate, is capable of rapid responses, and has great potential in the rapid detection of vomitoxins in grains. Full article

Based on dual-template molecular imprinting polymerization technology, a fluorescent molecularly imprinted polymer doped with CdSe/ZnS quantum dots was developed to construct a “Turn-on” fluorescence sensor for the rapid, sensitive, and specific detection of two biogenic amines. The biogenic amines bind to the quantum dots, which eliminates surface defects and enhances the fluorescence emission intensity of the quantum dots. By optimizing both the polymerization and detection processes, the results demonstrate that the sensor can detect biogenic amines within the range of 0.01–10 mmol/L, with a low detection limit of 14.57 μmol/L and a detection time of only ten minutes. Moreover, the sensor is cost-effective and does not require specialized instrument operation, offering a practical approach for the rapid detection of biogenic amines in complex food matrices. This study advances the development of simultaneous recognition and rapid detection technologies for multiple target molecules. Full article

The introduction of side-emitting lenses into white light-emitting diodes (LEDs) has enabled thin panel lighting technology based on LED technology, but also presents the disadvantage of low color rendering due to insufficient red components in the spectra of typical white LEDs. Additional application of remote quantum dot (QD) components such as QD films or caps presents the issues of increased numbers of components and higher costs. In this study, we incorporated red QDs directly into a lens placed on white LEDs and analyzed the effects of QD lenses on the optical characteristics of a lighting device through experiments and simulations. By incorporating red CdSe/ZnS QDs into UV-curable resin to fabricate QD lenses and applying them to white LEDs, we significantly improved the color rendering index and were able to adjust the correlated color temperature over a wide range between 2700 and 9900 K. However, as the concentration of QDs in the lens increased, scattering by the QD particles was enhanced, strengthening the Lambertian distribution in the intensity plot. Following the development of optical models for QD lenses under experimental conditions, comprehensive optical simulations of white LED lighting systems revealed that increasing the device height proved more effective than modifying TiO₂ scattering particle concentration in the diffuser plate for mitigating QD-induced bright spots and enhancing illumination uniformity. Full article

In this paper, we demonstrate a broadband and simultaneous waveguide array light source based on water-soluble CdSe/ZnS quantum dots (QDs). We initially measure the fluorescence intensity for various cladding solution concentrations along the fiber axis to assess their impact on the propagation loss; the experimental results show that the fluorescent intensity decreases with fiber length, with higher concentrations showing a more pronounced decrease. Then, we showcase a synchronous QD light source in an optofluidic chip that fluoresces in red, green, and blue (RGB) within a microfluidic channel. Finally, a 3 × 3 QD array of a fluorescent display on a single PDMS chip is demonstrated. The QD waveguide represents a compact and stable structure that is readily manufacturable, making it an ideal light source for advancing high-throughput biochemical sensing and on-chip spectroscopic analysis. Full article

The chemical transport method is a process that occurs naturally; however, it is also very useful in the chemical laboratory environment for the synthesis of inorganic crystals. It was successfully used for the syntheses of simple and complex inorganic compounds, from binary (e.g., ZnS, CdSe) to quaternary (e.g., Cu₂ZnSnS₄) compounds. Many experimental parameters influence the quality of products of chemical transport reactions, and among them, one may distinguish the used precursors and applied temperature gradient. The careful selection of experimental conditions is crucial for the production of high-quality crystals. Mathematical descriptions of the chemical transport phenomena, however, may potentially help in the design of proper conditions. Full article

Escherichia coli (E. coli) detection suffers from slow analysis time and high costs, along with the need for specificity. While state-of-the-art electrochemical biosensors are cost-efficient and easy to implement, their sensitivity and analysis time still require improvement. In this work, we present a paper-based electrochemical biosensor utilizing magnetic core-shell Fe₂O₃@CdSe/ZnS quantum dots (MQDs) to achieve fast detection, low cost, and high sensitivity. Using electrochemical impedance spectroscopy (EIS) as the detection technique, the biosensor achieved a limit of detection of 2.7 × 10² CFU/mL for E. coli bacteria across a concentration range of 10²–10⁸ CFU/mL, with a relative standard deviation (RSD) of 3.5781%. From an optical perspective, as E. coli concentration increased steadily from 10⁴ to 10⁷ CFU/mL, quantum dot fluorescence showed over 60% lifetime quenching. This hybrid biosensor thus provides rapid, highly sensitive E. coli detection with a fast analysis time of 30 min. This study, which combines the detection advantages of electrochemical and optical biosensor systems in a graphite-based paper sensor for the first time, has the potential to meet the needs of point-of-care applications. It is thought that future studies that will aim to examine the performance of the production-optimized, portable, graphite-based sensor system on real food samples, environmental samples, and especially medical clinical samples will be promising. Full article