Incorporation Of Quantum Dots Research Articles

Protective effect of nanoemulsions containing CdTe quantum dots with potential application as a diagnostic agent.

A nanoemulsion containing CdTe quantum dots (NE-CdTe-QD) was developed to shield cells from cadmium toxicity and shown to be a promising candidate for brain tumor diagnosis. CdTe-QD was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. CdTe-QD exhibited high luminescence emission at 700nm, and their stability was maintained when encapsulated in lipidic/polymeric nanoemulsions (198 ± 2.0nm; PDI = 0.174; - 49.0mV). The biological effects of free and nanoemulsified CdTe-QD were tested in normal cells (NHF) and glioblastoma cell lines (U87-MG and T98G). Membrane colocalization of NE-CdTe-QD by T98G cells was observed. Instead, intracellular endoplasmic reticulum localization of NE-CdTe-QD was verified in U87-MG cells. Cell viability was reduced only when NE-CdTe-QD permeated the membrane of GBM cells, as observed in U87-MG cells, whereas no cytotoxic effects were observed in normal fibroblasts. Incorporating quantum dots directly into the brain cells is difficult. However, the nanoemulsions reduced the toxicity of CdTe-QD in zebrafish larvae and increased their circulation time, and direct injection into the zebrafish brain did not affect neural cell viability. This validates the potential application of these nanomaterials as diagnostic agents and satisfies the necessary criteria for their use as photosensitizers in photodynamic therapy.

Scalable Ammonia Synthesis in Fermentors Using Quantum Dot-Azotobacter vinelandii Hybrids

AbstractThis study introduces a scalable synthesis of ammonia through photochemical reactions, wherein nitrogen-fixing bacterial cells, Azotobacter vinelandii (A. vinelandii), form hybrids with colloidal quantum dots (QDs). Irradiation of the QD-A. vinelandii hybrids with visible light is found to significantly enhance ammonia production efficiency. The inherently low ammonia conversion rate of wild-type A. vinelandii is substantially increased upon incorporation of QDs. This increase is attributed to the electron transfer from QDs within the bacterial cells to intracellular bio-components. Transferring this chemistry to a large-scale reaction presents a tremendous challenge, as it requires precise control over the growth conditions. We explore the scalability of the QD-A. vinelandii hybrids by conducting the photochemical reaction in a 5-L fermentor under various parameters, such as dissolved oxygen, nutrient supply, and pH. Interestingly, ammonia was produced in media depleted of carbon sources. Consequently, a two-step fermentation process was designed, enabling effective ammonia production. Our findings demonstrate that the QD-A. vinelandii hybrid system in a bioreactor setup achieves an ammonia turnover frequency of 11.96 s−1, marking a more than sixfold increase in efficiency over that of nitrogenase enzymes alone. This advancement highlights the potential of integrating biological and nanotechnological elements for scalable ammonia production processes.

Enhancing the Performance of Light-Emitting Electrochemical Cells by Incorporating Quantum Dots

Enhancing the Performance of Light-Emitting Electrochemical Cells by Incorporating Quantum Dots

P‐141: Ultrafine‐pitch AlGaN Ultraviolet‐C microLED Displays for Quantum Dots Color Conversion

Aluminum Gallium Nitride (AlGaN) ultraviolet‐C (UV‐C) micro‐light‐emitting diodes (microLEDs) offer significant advantages in terms of convenience, cost‐effectiveness, and environmental friendliness, positioning them as promising candidates for display applications. However, achieving the desired high efficiency and scalability for large displays with ultra‐fine pixels necessitates substantial progress beyond current experimental outcomes. This study showcases the application of AlGaN UV‐C microLED display panels and micro‐displays incorporating quantum dots (QDs) for color conversion. Sidewall treatment and atomic layer deposited (ALD) passivation effectively address dangling bonds and etching damages, leading to a notable enhancement of TM‐polarized light extraction efficiency (LEE). Moreover, dedicated strain modulation efforts successfully reduce the high Al content (over 50%) wafer bowling effect, facilitating the modularization of ultrafine‐pitch AlGaN UV‐C microLED panels. Consequently, the devices achieve a peak performance of over 5% external quantum efficiency (EQE) as the mesa size scales down to 3 μm. The highlighted 0.18‐inch UV‐C microLED display panels, featuring a 9 μm pixel size, are precisely controlled by a CMOS IC driver to achieve desired patterns. Serving as an efficient pumping source for perovskite quantum dots paper (PQDP), this UV‐C microLED display suggests the potential to revolutionize the full‐color display industry by providing an innovative and unconventional solution.

Printable Light-Emitting Metasurfaces with Enhanced Directional Photoluminescence.

Nanoimprint lithography is gaining popularity as a cost-efficient way to reproduce nanostructures in large quantities. Recent advances in nanoimprinting lithography using high-index nanoparticles have demonstrated replication of photonic devices, but it is difficult to confer special properties on nanostructures beyond general metasurfaces. Here, we introduce a novel method for fabricating light-emitting metasurfaces using nanoimprinting lithography. By utilizing quantum dots embedded in resin, we successfully imprint dielectric metasurfaces that function simultaneously as both emitters and resonators. This approach to incorporating quantum dots into metasurfaces demonstrates an improvement in photoluminescence characteristics compared to the situation where quantum dots and metasurfaces are independently incorporated. Design of the metasurface is specifically tailored to support photonic modes within the emission band of quantum dots with a large enhancement of photoluminescence. This study indicates that nanoimprinting lithography has the capability to construct nanostructures using functionalized nanoparticles and could be used in various fields of nanophotonic applications.

Silicon solar cell efficiency improvement employing electrostatically assembled polyelectrolyte–quantum dot multilayers

Down-shifting (DS) has proven to be an effective technique to address thermalization losses in photovoltaic devices. It involves the modification of the incident solar spectrum by luminescent species to better suit solar cell’s optimal absorption regions. Despite the number of favorable characteristics of quantum dots (QDs) as DS materials, their incorporation into highly ordered close-packed films remains the major drawback of QD-based DS applications. This limitation can be overcome by the sequential integration of QDs into a multilayered film via the layer-by-layer assembly technique, that allows the precise control of composition and thickness. The experimental results discussed herein indicate that upon optimization employing a model-assisted design approach, the spectral response of a silicon solar cell benefits from the down-shifting and antireflection capabilities of the QD film, as evinced by their quantum efficiency. For the optimum design, the incorporation of QDs triggered an increment of 26.1% in the power conversion efficiency driven by an increase of 29.2% in the short circuit current density. The controlled assembly of QD multilayers offers unique opportunities in light harvesting for new hybrid photovoltaic technologies.

Evaluating a targeted Palbociclib-Trastuzumab loaded smart niosome platform for treating HER2 positive breast cancer cells

In this study, we present a targeted and pH-sensitive niosomal (pHSN) formulation, incorporating quantum dot (QD)-labeled Trastuzumab (Trz) molecules for the specific delivery of Palbociclib (Pal) to cells overexpressing human epidermal growth factor receptor 2 (HER2). FTIR analyses confirmed the successful preparation of the pHSNs and their bioconjugation. The labeled Trz-conjugated Pal-pHSNs (Trz-Pal-pHSNs) exhibited a size of approximately 170 nm, displaying a spherical shape with a neutral surface charge of −1.2 mV. Pal encapsulation reached ∼86%, and the release pattern followed a two-phase pH-dependent mechanism. MTT assessments demonstrated enhanced apoptosis induction, particularly in HER2-positive cells, by Trz-Pal-pHSNs. Fluorescence imaging further validated the internalization of particles into cells. In conclusion, Trz-Pal-pHSNs emerge as a promising platform for personalized medicine in the treatment of HER2-positive breast cancer.

Near-Field Direct Writing of the Photoluminescent Lattice Structures Pattern with RGB Colours Quantum Dots

The near-field direct writing technology represents a cutting-edge micro-nano additive manufacturing technique capable of printing intricate lattice structures with high precision. Leveraging the nanoscale self-luminous properties of quantum dots (QDs), a novel RGB QDs ink is developed by integrating QDs with polycaprolactone (PCL), specifically tailored for near-field direct writing applications. Based on the synergistic benefits offered by the aforementioned materials and technology, we present a groundbreaking approach to fabricating lattice structures patterns featuring RGB quantum dots. Firstly, a specialized printing ink is formulated for the production of lattice structures, aiming to achieve precise and intricate patterns. Subsequently, comprehensive investigations are conducted to determine the optimal parameters for the RGB quantum dots ink. Finally, an in-depth analysis is performed to evaluate the deposition process and luminescence properties of the resulting lattice structures pattern. The micron-scale lattice structures, incorporating quantum dots, hold great potential for applications in displacement encoders.

General Strategies for Preparing Hybrid Polymer/Quantum Dot Nanocomposites for Color Conversion

Quantum dots (QDs), with their exceptional optical properties, have emerged as promising candidates to replace traditional phosphors in lighting and display technologies. This study delves into the integration strategies of QDs within glass and polymer matrices to engineer advanced quantum dot color converters (QDCCs) at the industrial scale for practical applications. To achieve enhancements in the photostability and thermal stability of QDCCs, we explore two distinct approaches: the dispersion of QDs in a hydrophilic glass matrix via a sol–gel process and the incorporation of QDs into a non-polar acrylate monomer to formulate QD/polymer nanocomposites. This research further investigates the optical behaviors of these composites, focusing on their light-scattering and propagation mechanisms, which are critical for optimizing light extraction efficiency in QDCCs. Additional optical film and light-scattering particles can improve color conversion efficiency by ~140%. These advancements present a significant step forward in the development of high-performance, energy-efficient, QD-based lighting and display systems.

Fluoropolymer Coated DNA Nanoclews for Volumetric Visualization of Oligonucleotides Delivery and Near Infrared Light Activated Anti-Angiogenic Oncotherapy.

The potential of microRNA regulation in oncotherapy is limited by the lack of delivery vehicles. Herein, it is shown that fluoropolymer coated DNA nanoclews (FNCs) provide outstanding ability to deliver oligonucleotide through circulation and realize near infrared (NIR) light activated angiogenesis suppression to abrogate tumors. Oligonucleotides are loaded in DNA nanoclews through sequence specific bindings and then a fluorinated zwitterionic polymer is coated onto the surface of nanoclews. Further incorporating quantum dots in the polymer coating endows the vectors with NIR-IIb (1500-1700nm) fluorescence and NIR light triggered release ability. The FNC vector can deliver oligonucleotides to cancer cells systemically and realize on-demand cytosolic release of the cargo with high transfection efficiency. Taking advantage of the NIR-IIb emission, the whole delivery process of FNCs is visualized volumetrically in vivo with a NIR light sheet microscope. Loaded by FNCs, an oligonucleotide can effectively silence the target miRNA when activated with NIR light, and inhibit angiogenesis inside tumor, leading to complete ablation of cancer. These findings suggest FNCs can be used as an efficient oligonucleotide delivery platform to modulate the expression of endogenous microRNA in gene therapy of cancer.

High-performance Ta2O5-based resistive random-access memory with embedded graphene quantum dots and Pt–Ag composite active layer

Resistive random-access memory (RRAM) has garnered significant interest in developing nonvolatile memory systems due to its ability to provide external field tunable resistive states with fast speed and low power consumption. This tunable resistive state primarily results from the formation and breakage of conductive pathways triggered by active ion migration. However, due to the stochastic nature of ion migration, the stability of the switching process is a long-standing bottleneck. Here, we investigate the impact of device kinetic parameters on the stability of resistive switching behavior and propose a high-performance RRAM with a Pt–Ag/Ta2O5/GQDs/Pt structure. Incorporating quantum dots can regulate the direction of Ag ion migration, while the Pt–Ag composite electrode can manipulate the oxidation rate of Ag atoms. Compared to the Ag/Ta2O5/GQDs/Pt device, the Pt–Ag/Ta2O5/GQDs/Pt device exhibited a 15-fold reduction in operating voltage, a 10-fold increase in on/off ratio, and superior endurance and uniformity. These findings demonstrate that tuning kinetic parameters has the potential to enhance resistive switching performance, which offers an effective pathway for designing high-performance memory systems.

Direct Laser Writing of Functional QD–Polymer Structure with High Resolution

Promising direct laser writing (DLW) technology has been introduced to process functional quantum dot (QD)-polymer nanocomposites. The results reveal that after surface modification, the QDs are compatible with the SR399 monomer, and the homogeneous incorporation of QDs is accordingly obtained owing to the copolymerization and resultant cross-linking of QDs into SR399 resin under DLW processing with a laser wavelength (λ) of 532 nm. Moreover, compared with other scholars, we have proved that the surface modified QDs incorporated into the nanocomposites that can be successfully processed via DLW can reach a concentration of up to 150 mg/mL. Owing to the threshold behavior and nonlinear nature of the DLW process, it is feasible to modify the attendant exposure kinetics and design lines of any small size by selecting an appropriate laser power (P) and scan speed (v). The superfine feature size of 65 nm (λ/8) of the red QD-polymer suspended line can be tailored by applying the optimized P of 15 mW and v of 700 μm/s, and the finest green QD-polymer suspended line also reaches 65 nm (λ/8) with the optimized P of 14 mW and v of 250 μm/s used. Moreover, DLW processed QD-polymer structures present strong and homogeneous photoluminescence emission, which shows great potential for application in high-resolution displays, anti-counterfeit technology, and optical encryption. Additionally, the two types of long pass QD-polymer absorptive filters prepared by DLW exhibit superior optical performance with a considerably high transmittance of more than 90% for red QD-polymer block filter, and over 70% for green QD-polymer block filter in the transmittance region, which means that different filters with specific performance can be easily customized to meet the demand of various microdevices. Therefore, the DLW process can be applied to produce geometrically complex micro- and nanoscale functional structures, which will contribute to the development of advanced optoelectronic devices.

CdSe quantum dots enhancing blue emission of nematic liquid crystals

Herein, we report the enhancement in blue emission of nematic liquid crystals (NLCs) doped with CdSe quantum dots (QDs) at room temperature. CdSe QDs were synthesized by a high temperature wet chemical method. X-ray diffraction pattern suggest zinc blend crystal structure of CdSe QDs without impurity phase formation. The absorption peak and PL emission of QDs is observed at 503 nm and 526 nm respectively. The QDs size is found to be 2.3 nm calculated by excitonic peak. The polarization states of the QD-based NLCs were studied by using polarising optical microscopic (POM) images under crossed geometry of polarizer and analyser. The uniform colour distribution throughout the cell indicates uniform cell thickness with a planar alignment of liquid crystal molecules. Moreover, dark, and bright states of POM images are used to analyse the defects in alignment of NLC molecules. It is worthwhile to note here that the incorporation of QDs in NLCs helps in reducing defects and light leakage centres which further increases the absorption and hence emission of NLCs. The significant enhancement in the PL intensity of the NLC of about 60% upon CdSe QDs doping is observed at room temperature which attributed to the increase in molecular alignment of NLCs composite.

Luminescent quantum dot films improve light use efficiency and crop quality in greenhouse horticulture.

The spectral quality of sunlight reaching plants remains a path for optimization in greenhouse cultivation. Quantum dots represent a novel, emission-tunable luminescent material for optimizing the sunlight spectrum in greenhouses with minimal intensity loss, ultimately enabling improved light use efficiency of plant growth without requiring electricity. In this study, greenhouse films containing CuInS2/ZnS quantum dots were utilized to absorb and convert ultraviolet and blue photons from sunlight to a photoluminescent emission centered at 600nm. To analyze the effects of the quantum dot film spectrum on plant production, a 25-week tomato trial was conducted in Dutch glass greenhouses. Plants under the quantum dot film experienced a 14% reduction in overall daily light integral, resulting from perpendicular photosynthetically active radiation transmission of 85.3%, mainly due to reflection losses. Despite this reduction in intensity, the modified sunlight spectrum and light diffusion provided by the quantum dot film gave rise to 5.7% improved saleable production yield, nearly identical total fruiting biomass production, 23% higher light use efficiency (g/mol), 10% faster vegetative growth rate, and 36% reduced tomato waste compared to the control, which had no additional films. Based on this result, materials incorporating quantum dots show promise in enabling passive, electricity-free spectrum modification for improving crop production in greenhouse cultivation, but extensive controlled crop studies are needed to further validate their effectiveness.

Surface defects and particle size determine transport of CdSe quantum dots out of plastics and into the environment

Polymers incorporating quantum dots (QDs) have attracted interest as components of next-generation consumer products, but there is uncertainty about how these potentially hazardous materials may impact human health and the environment. We investigated how the transport (migration) of QDs out of polymers and into the environment is linked to their size and surface characteristics. Cadmium selenide (CdSe) QDs with diameters ranging from 2.15 to 4.63 nm were incorporated into low-density polyethylene (LDPE). Photoluminescence was used as an indicator of QD surface defect density. Normalized migration of QDs into 3% acetic acid over 15 days ranged from 13.1 ± 0.6–452.5 ± 31.9 ng per cm2 of polymer surface area. Migrated QD mass was negatively correlated to QD diameter and was also higher when QDs had photoluminescence consistent with larger surface defect densities. The results imply that migration is driven by oxidative degradation of QDs originating at surface defect sites and transport of oxidation products along concentration gradients. A semi-empirical framework was developed to model the migration data. The model supports this mechanism and suggests that QD surface reactivity also drives the relationship between QD size and migration, with specific surface area playing a less important role.

Circularly Polarized Light Source from Self‐Assembled Hybrid Nanoarchitecture

AbstractCircularly polarized luminescent inorganics arouses attentions due to scalable preparation and versatile chiral optoelectronic applications. Here, strong circularly polarized luminescence (CPL) activity has been developed from self‐assembled cellulose nanocrystals decorated with blue emitting silicon quantum dots (QDs). The electrostatic attraction promotes the successful incorporation of QDs into chiral template matrix to form homogeneous hybrid nanoarchitecture films. It is found that their circular dichroism behaviors are closely related to the photonic band gap (PBG) while the CPL behaviors are determined by the QDs and PBG simultaneously. Furthermore, the as‐prepared chiral composite thin films have been employed as an efficient circularly polarized light source for preparing enantioselective polymer, which can induce chirality and photopolymerization simultaneously. Such strong CPL activity in nanoarchitecture films is highly promising for future inorganic optoelectronics.

Quantum dots’ size matters for balancing their quantity and quality in label materials to improve lateral flow immunoassay performance for C-reactive protein determination

Incorporating quantum dots (QDs) into dendritic mesoporous silica nanoparticles (DMSNs) for signal amplification of label materials represents an efficient strategy to improve the performance of lateral flow immunoassays (LFIAs). In this work, it is found that the CdSe/ZnS QD's size matters for balancing their loading amount and quantum yields (QYs) in the DMSNs-QDs based label materials and ultimately determining the performance of LFIA. The impacts of three CdSe/ZnS QDs with diameters of 9.1, 10.5 and 11.7 nm on CdSe/ZnS QDs incorporation and LFIA applications are studied. The increase of CdSe/ZnS QDs size from 9.1 to 11.7 nm results in a decrease in CdSe/ZnS QDs loading amount and an increase in QYs of incorporated CdSe/ZnS QDs. This trade-off leads to an optimized CdSe/ZnS QDs size of 10.5 nm, which exhibits the best LFIA performance due to the balanced QDs loading (2.26 g g−1) and QY (57.1%). The 10.5 nm CdSe/ZnS QDs incorporated DMSNs-QDs for C-reactive protein (CRP) detection achieved a limit of detection of 5 pg mL−1 (equivalent to 4.2 × 10−14 M) with naked eye, which is lower than literature reports and commercial LFIA products. This study demonstrates that the CdSe/ZnS QD's size matters for improving the quality of DMSNs-QDs and their LFIA performance for CRP determination, providing new insights into the rational design of advanced label materials for improving LFIA performance.

Synthesis and characterisation of copper vanadate quantum dots / nanostructured zinc oxide

0D/3D heterojunction photocatalyst, specifically copper vanadate (CuVA) quantum dots (0D) / nanostructured zinc oxide (ZnO) (3D), has been prepared using in-situ reaction method. pH of 8 yielded the optimum nanostructure for the hydrothermal synthesis of ZnO nanorods. Characterisation of heterojunction photocatalysts obtained using Fourier transform infrared (FTIR) spectrometer, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis indicates that this method is effective for incorporating quantum dots (QDs) onto ZnO. FTIR at wavenumber 3537, 1360 and 734 cm−1 showed a decreasing transmission peak as the amount of CuVA increases with respect to ZnO. EDX had showed an increasing trend in copper and vanadium elemental percentage in CuVA-ZnO as the targeted CuVA loading increases. 30 wt% CuVA QDs loaded onto ZnO was found to be the optimal mass loading to degrade sulfadiazine (SDZ), at 17.01% with initial concentration of 10 mgL−1. This work is expected to provide a suitable alternative as a photocatalyst to degrade pollutants, with antibiotics being the focus of this work.

Bright and Stable Light-Emitting Diodes Based on Perovskite Quantum Dots in Perovskite Matrix.

Light-emitting diodes (LEDs) based on metal halide perovskite quantum dots (QDs) have achieved impressive external quantum efficiencies; however, the lack of surface protection of QDs, combined with efficiency droop, decreases device operating lifetime at brightnesses of interest. The epitaxial incorporation of QDs within a semiconducting shell provides surface passivation and exciton confinement. Achieving this goal in the case of perovskite QDs remains an unsolved challenge in view of the materials' chemical instability. Here, we report perovskite QDs that remain stable in a thin layer of precursor solution of perovskite, and we use strained QDs as nucleation centers to drive the homogeneous crystallization of a perovskite matrix. Type-I band alignment ensures that the QDs are charge acceptors and radiative emitters. The new materials show suppressed Auger bi-excition recombination and bright luminescence at high excitation (600 W cm-2), whereas control materials exhibit severe bleaching. Primary red LEDs based on the new materials show an external quantum efficiency of 18%, and these retain high performance to brightnesses exceeding 4700 cd m-2. The new materials enable LEDs having an operating half-life of 2400 h at an initial luminance of 100 cd m-2, representing a 100-fold enhancement relative to the best primary red perovskite LEDs.

Quantum-dots-dispersed bent-core nematic liquid crystal and cybotactic clusters: Experimental and theoretical insights.

We study a quantum-dots (QDs) dispersed bent-core nematic liquid crystalline system in planar geometry and present experimental measurements of the birefringence (Δn), order parameter (S), dielectric dispersion, absorption spectra, and optical textures with attention to variations with temperature. A bent-core liquid crystal (LC) 14-2M-CH_{3} is used as the host material and CdSe/ZnS core-shell type QDs are used as the dopant. The nematic (N) phase of the pristine (undoped) LC 14-2M-CH_{3} contains cybotactic clusters, which are retained by its QDs incorporated LC nanocomposite. Our experimental findings support: (i) reduced orientational order parameter of the QDs dispersed LC system compared to its pristine counterpart at fixed temperatures, (ii) reduced cybotactic cluster sizes due to the incorporation of QDs, and (iii) increased activation energies related to reduced cluster sizes. We complement the experiments with a novel Landau-de Gennes-type free energy for a doped bent-core LC system that qualitatively captures the doping-induced reduced order parameter and its dependence on the properties of the QDs and its variation with temperature.