Quantum Dots Solution Research Articles

Экспериментальное лечение эндофтальмита, вызванного синегнойной инфекцией с множественной лекарственной устойчивостью, с помощью конъюгатов на основе наночастиц

Relevance. Pseudomonas aeruginosa (PA) is an extremely dangerous microorganism whose elimination from the host organism is very difficult due to the presence of multidrug resistance (MDR) factors in PA. The outcome of endophthalmitis (EP) mediated by PA in 50% of cases will be evisceration of the eyeball, and more than 95% of patients receive visual acuity – hand movements near the face and below. In this regard, studies of quantum dots (QDs), which have shown high anti-infective activity in laboratory conditions, are of particular relevance. Purpose. Evaluation of the effectiveness of the treatment of EP caused by PA with MDR using QDs-based conjugates in the experiment. Material and methods. The object of the study was laboratory rabbits of the Chinchilla breed (n=27), male, aged from 3 to 3.5 months. As an EP inducer, all laboratory animals underwent intravitreal injection (IVI) of a multidrug-resistant PA strain in a volume of 0.05 ml in the right eye. QDs of the Ag (10%):InP/ZnS MPA type were taken as the basis for the creation of conjugates with antibiotics (AB). After the manifestation of EP, the animals underwent intravitreal injections (IVI) of dosage forms in accordance with the distribution into the following subgroups, 3 rabbits in each. Subgroups No. 1–3 – IVI 2.25 mg/0.1 ml Ceftazidime. Subgroups No. 4–6 – IVI 0.1 ml of QDs solution at concentrations of 10%, 0.1%, 0.01%, respectively. Subgroups No. 7–9 – IVI solution of QDs 0.05 ml (at concentrations of 10%, 0.1%, 0.01%, respectively) in combination with 2.25 mg/0.05 ml of Ceftazidime (conjugates). Efficacy was evaluated based on clinical parameters: the dynamics of hypopyon resorption, the presence of inflammatory cells in the anterior chamber, the dynamics of regression of pathological suspension in the vitreal cavity, the dynamics of pathological neovascularization of the iris, the dynamics of the cornea. Results. Rabbits from subgroups No. 1–3 (1st group) were characterized by the least dynamics in relation to the regression of symptoms during the 7-day observation period. Rabbits from subgroups No. 4–6 (2nd group) were characterized by moderate positive dynamics in relation to the regression of symptoms. Rabbits from subgroups No. 7–9 (3rd group) were characterized by the best positive dynamics in relation to the regression of symptoms. Conclusion. It was possible to prove the effectiveness of the treatment of experimental antibiotic-resistant EP caused by a strain of PA with MDR by means of QDs Ag(10%):InP/ZnS MPA at concentrations of 10%, 0.1% and 0.01%, especially in combination with 2.25 mg/0.05 ml of Ceftazidime in as a conjugate. Based on the results obtained, it can be assumed that active research and the use of QDs as conjugates with modern ABs can solve the overall problem of combating MDR strains. Key words: Pseudomonas Aeruginosa, quantum dots, endophthalmitis, multidrug resistance, antibiotic resistance, conjugates

Photolithographic patterning on multi-wavelength quantum dot film of the improved conversion efficiency for digital holography.

A triple-wavelength patterned quantum dot film was fabricated for the light source of digital holography to improve both the axial measurement range and noise reduction. The patterned quantum dot film was fabricated after optimizing the photolithography process condition based on the UV-curable quantum dot solution, which was capable of multiple patterning processes. In addition, an optimized pattern structure was developed by adding TiO2 nanoparticles to both the quantum dot and bank layers to increase the scattering effect for the improved photoluminescence intensity. Finally, the newly developed light source with the balanced spectral distribution was applied to the digital holography, rendering it applicable as an improved light source.

Substrate interaction of graphene quantum dots in solution studied by hyperpolarized NMR

The reversible adsorption of CO2-derived species to graphene quantum dots in CO2 electroreduction reaction was characterized by nuclear spin hyperpolarized NMR. Hyperpolarization of 13C-labeled sodium bicarbonate by the dissolution dynamic nuclear polarization (DNP) technique provided a 5000-fold signal enhancement and enabled real-time and in-situ 13C NMR experiments. The R1 and R2 relaxation rates were measured using time-resolved DNP-NMR experiments, and the bound species were confirmed to be carbonic acid and its conjugates. A significant difference in the relaxation rates of bound and free species was found, indicating a reversible binding. In addition to relaxation rates, kinetic rate constants were fitted from the small-flip angle experiments and compared to theoretical calculations. The pH-dependent adsorption and desorption rate constants were found in the range of 3.5–9.5 and 0.7–2.0 s−1, with the average binding distance at 279 - 291 pm. The DNP-NMR technique was demonstrated as an effective way to study surface adsorption, with potential in electrochemistry and kinetics applications.

Fluorescence properties and laser-induced enhancement of CsPbBr3 quantum dot with three different ligand amine systems

Inorganic perovskites have attracted much attention due to their excellent optical properties, making them a potential material for optoelectronic devices. In order to better apply it to optoelectronic devices, researchers have developed many synthesis schemes, for example, hot injection method, ligand-assisted reprecipitation method, template method, etc. to accurately control chemical composition, dimension, size, photoelectric and other properties. Here, we used oleylamine, octylamine, and phenylethylamine as amine ligands, and synthesized quantum dots (QDs) through the hot injection method. We found that quantum dot solutions prepared with long-chain ligands exhibit better luminescence performance, while quantum dot films prepared with shorter-chain phenethylamine ligands exhibit better luminescence performance, revealing the regulatory mechanism of amine ligands in the quantum dot growth process. In addition, we have enhanced the optical properties of perovskite films through laser direct writing, providing a reference for the synthesis and control of perovskite materials and their applications in the display.

High‐Stability Flexible Patterned Perovskite Optoelectronic Structures Fabricated by a Laser Pyrolysis Assisted Process

AbstractFlexible patterned metal halide perovskites (MHPs) are promising to improve the perovskite‐based optoelectronic devices for applications in healthcare monitoring, flexible displays, solar cells, etc. However, their poor environmental stability and device robustness are the main obstacles for commercialization. Herein, a laser pyrolysis assisted process is developed to fabricate flexible patterned CsPbBr3 structures with high stability and flexibility. A CO2 laser is applied to micromachine the designed patterns on the flexible polydimethylsiloxane (PDMS) substrates by inducing the pyrolysis of PDMS. The CsPbBr3 quantum dots (QDs) solution is precisely filled into the patterned PDMS substrates, and subsequently sealed by another layer of PDMS on the top. To ensure the surface smoothness of the patterned PDMS for CsPbBr3 QDs embedment, the mechanism of the laser pyrolysis process is investigated by characterizing the PDMS pyrolysis products obtained at different laser energy densities. To demonstrate the high stability of the fabricated flexible patterned CsPbBr3 structures, the photoluminescent (PL) spectra of the samples are monitored for 60 days both in air and in the water. The flexibility of the fabricated structures is estimated by monitoring their PL emission under applied tension and bending. These flexible patterned CsPbBr3 structures are promising for applications in flexible optical/optoelectronic devices.

Variation of Nonlinear Refraction and Three-Photon Absorption of Indium-Tin Oxide Quantum Dot Thin Films and Solutions in Near Infrared Range.

We characterize the nonlinear optical properties of indium-tin oxide (ITO) quantum dots (QDs) in the IR range using the Z-scan method. We present results of three-photon absorption (3PA), third harmonic generation (3HG), and Kerr-effect-induced nonlinear refraction in ITO QDs. Z-scan measurements were carried out for the QDs solution, while 3HG was demonstrated using QD thin films. The Kerr-induced nonlinear refractive index was analyzed along the 800-950 nm range showing an increase in this parameter from -6.7 × 10-18 to -1.5 × 10-17 m2 W-1. At longer wavelengths (1000-1100 nm), the higher-order effects started to contribute to a nonlinear refractive index. The 3PA coefficient at 950 nm was measured to be 1.42 × 10-25 m3/W2. We discuss the peculiarities in the wavelength-dependent variation of the coefficient of nonlinear absorption responsible for 3PA in the range of 800-1150 nm. Third harmonic generation was analyzed in the 1200-1550 nm spectral range. The absolute value of 3HG conversion efficiency in the 150 nm thick film at the wavelength of laser radiation (1350 nm) was estimated to be ~10-5.

Bi-functional aqueous starch capped CdS quantum dots synthesis and their application as sensor of heavy metal-ions as well as photocatalytic dye degradation

CdS quantum dots (QDs) have emerged as the promising nanomaterial for various applications. This study reported bi-functional usage of aqueous starch capped CdS QDs as heavy metal-ion sensor for selective detection of Hg2+ and Cu2+ in aqueous medium as well as sunlight driven photocatalyst for degradation of organic dyes. CdS QDs exhibited colorimetric, spectroscopic, and compositional change with Hg2+ and Cu2+ via cation exchange reaction (CER). The CER of yellow color CdS QDs solution with Hg2+ showed rapid colour change to orange, red and white with composition Cd1-xSHgxS, HgS/CdS, and mixture of HgS and Hg sol, respectively whereas, CER of CdS QDs with Cu2+ resulted in pale brown, brown and greenish brown with composition Cd1-xCuxS, CuxS/CdS and Cu2-xS, respectively. Further, CdS QDs displayed excellent sunlight driven photocatalytic degradation of cationic, anionic and hair dye with good efficiency, reusability, and stability.

Fluorescent quantum dots-based hydrogels: Synthesis, fabrication and multimodal biosensing

Hydrogels have a significant impact on the fields of biological study and medical diagnosis. They are becoming more useful in bioanalytical and biosensing applications. The intriguing new nanomaterials quantum dots-hydrogel composites have gained a lot of interest because of their unmatched biocompatibility and tolerable biodegradability, which opens up a wide range of possible applications. Focusing on synthesis techniques, this review describes current developments in quantum dots-hydrogel composites, such as hydrogel gelation in quantum dots (QDs) solution, inserting prepared QDs into hydrogels after gelation, generating QDs in situ inside the preformed gel, and cross-linking through QDs. Biomedical applications such as bioimaging and biosensing are specifically examined, and then the inherent problems of design optimisation, biocompatibility, and bimodal applications, as well as the potential of future development, are discussed.

Optical properties of Ag2S quantum dots

Colloidal solutions of silver sulfide quantum dots of various sizes were synthesized from low-concentration water solutions of silver nitrate, sodium sulfide and sodium citrate as stabilizer. The size of Ag2S quantum dots in colloidal solutions was determined by dynamic light scattering. The produced Ag2S quantum dots were dispersed in a polyvinyl alcohol (PVA) film matrix. The transmission and absorption spectra of PVA films containing Ag2S were measured in the wavelength interval 190–900 nm. A comparative study of the optical properties of PVA films with Ag2S quantum dots showed that a decrease of quantum dots to ∼ 6 nm leads to an increase in the band gap Eg of silver sulfide to ∼ 1.6 eV, which is almost twice larger than the band gap of bulk Ag2S. The optical properties of PVA films with Ag2S quantum dots smaller than 5 nm exhibit specific features associated with exciton transitions.

Digitizing protocols into single reactors for the one-pot synthesis of nanomaterials

Digitizing protocols into single reactors for the one-pot synthesis of nanomaterials

Room-temperature efficient photoluminescence mechanism of indium doping lead-free colloidal MA3Bi2Br9 quantum dots solution

Lead halide perovskite quantum dots (QDs) are promising candidates for future optoelectronic devices due to their excellent photonic and electronic properties. However, poor stability and toxicity problems limit their further development. This work demonstrates the doping tactics to boost the optical properties of lead-free colloidal MA3Bi2Br9 QDs, the indium ion (In3+) doping presented herein is found to be effective in improving the photoluminescence (PL) properties of MA3Bi2Br9 (CH3NH2 = MA) QDs without alerting their favorable electronic structure. It has been elucidated by microscopy and diffraction results that the In3+ doping optimizes the QDs solution octahedron structure, and the PL red-shifted phenomenon coincides well with the analogous red-shifted obtained in the ultraviolet/visible (UV–Vis) absorption spectroscopy, which is due to the quantum confinement effect. And the nanosecond transient absorption (ns-TA) spectroscopy elucidates that the enhanced radiative recombination process contributes to enhanced stability and luminescence. The photoluminescence quantum yield (PLQY) of MA3Bi2Br9 QDs is increased by 60.7%. This work offers a valid strategy for improving the quality of the lead-free perovskite QDs.

Solution‐Mediated Hybrid FAPbI3 Perovskite Quantum Dots for Over 15% Efficient Solar Cell

AbstractOrganic–inorganic formamidinium lead triiodide (FAPbI3) hybrid perovskite quantum dot (QD) is of great interest to photovoltaic (PV) community due to its narrow band gap, higher ambient stability, and long carrier lifetime. However, the surface ligand management of FAPbI3 QD is still a key hurdle that impedes the design of high‐efficiency solar cells. Herein, this study first develops a solution‐mediated ligand exchange (SMLE) for preparing FAPbI3 QD film with enhanced electronic coupling. By dissolving optimal methylammonium iodide (MAI) into antisolvent to treat the FAPbI3 QD solution, the SMLE can not only effectively replace the long‐chain ligands, but also passivate the A‐ and X‐site vacancies. By combining experimental and theoretical results, this study demonstrates that the SMLE engineered FAPbI3 QD exhibits lower defect density, which is beneficial for fabricating high‐quality QD arrays with desired morphology and carrier transport. Consequently, the SMLE FAPbI3 QD based solar cell outputs a champion efficiency of 15.10% together with improved long‐term ambient storage stability, which is currently the highest reported value for hybrid perovskite QD solar cells. These results would provide new design principle of hybrid perovskite QDs toward high‐performance optoelectronic application.

Preparing and properties of films with Ag2S quantum dots in a polyvinyl alcohol matrix

Stable colloidal solutions of Ag2S quantum dots with a size of 2–3 to 28–30 nm were synthesized by a hydrochemical deposition in low-concentration water solutions of silver nitrate, sodium sulfide, and sodium citrate. A large absolute value of the measured zeta potential of colloidal solutions, a small change in the size of quantum dots and zeta potential during long-term storage of solutions for 1000 days after synthesis indicate their high temporal stability. The synthesized colloidal solutions were dispersed in a solution of polyvinyl alcohol. The resulting films of Ag2S quantum dots in a PVA matrix are flexible and have a thickness of no more than 0.03 mm. The use of the PVA matrix to prepare films with Ag2S quantum dots promotes the preservation and increase in the stability of colloidal particles due to their fixation in the polymer matrix. For the first time, the optical properties of Ag2S quantum dots of different sizes in PVA films were determined. Decreasing the size of Ag2S quantum dots to 2.6 nm leads to an increase in the band gap of silver sulfide to 1.85 eV. It is shown that repeated bending of the films has practically no effect on the Eg value of Ag2S quantum dots.

A study on the mechanism of Indium phosphide/zinc sulfide core/shell quantum dots influencing embryo incubation of rare minnow (Gobiocypris rarus)

Quantum dots (QDs) inhibit fish hatching, but the mechanism is still unclear. In this study, the effect of Indium phosphide/zinc sulfide quantum dots (InP/ZnS QDs) on the embryo incubation of rare minnow was investigated. Five experimental concentration groups were set up according to the preliminary experimental results, which were 0, 50, 100, 200 and 400 nM. A direct exposure method was adopted to expose embryos to InP/ZnS QDs solution. The results showed that InP/ZnS QDs significantly inhibited the embryo hatching rate, delayed embryo emergence, affected the expression of genes associated with hatching gland cells and hatching enzymes. InP/ZnS QDs also destroy the structure of the embryo chorion. In addition, QDs can cause oxidative stress in embryos. Transcriptional sequencing analysis showed that InP/ZnS QDs InP/ZnS QDs may have induced the production of a hypoxic environment and triggered induce abnormal cardiac muscle contraction, inflammatory response and apoptosis process in embryos. In conclusion, QDs influences embryo hatchability largely through egg chorion mediation.

Spectrally Stable Pure Red CsPbI3 Quantum Dots Light‐Emitting Diodes via Effective Low Temperature Gradient Centrifugation Separation and Surface Modification

AbstractDevelopment of high‐performance and stable pure red perovskite light‐emitting devices (LEDs) promotes commercialization of perovskite. Benefiting from the quantum confinement effect, pure red CsPbI3 quantum dots (QDs) can avoid the color drift issue for mixed halide systems. Herein, a facile temperature‐dependent hot‐injection method combined with low temperature gradient centrifugation is employed to prepare 5.60 ± 0.05 nm pure red QDs. The QDs exhibit 642 nm photoluminescence (PL) with 37 nm full width at half maximum, and their Commission Internationale de l'Eclairage (CIE) coordinates located at (0.708, 0.292) match well with standard pure red for Rec. 2020. The PL half‐lifetime for pure red QDs solution is 210 days under ambient conditions, and both the X and Y coordinates of CIE only fluctuate within (0.002, 0.002). Finally, a simple NH4I post‐treatment to decrease ligand length further boosts the QDs conductivity, and the pure red LED exhibits 9.4% maximum external quantum efficiency. The electroluminescence spectra exhibits a sharp peak at 645 nm, and their CIE coordinates are located at (0.707, 0.290). Furthermore, the pure red LED exhibits both good working and color stability. Its half‐lifetime is 25.1 min and color drifts are only (0.002, 0.002) after 30.0 min of continuous working at 60 cd m−2 with a constant current density of 3.5 mA cm−2.

Latest Advances in Narrow‐Band Phosphors and Their Role in Color Management

Latest Advances in Narrow‐Band Phosphors and Their Role in Color Management

Modulation of Optical Properties by ZnSe Shell Thickness Control in InP/ZnSe/ZnS Quantum Dots Front Cover: (ChemNanoMat 5/2023)

The cover picture illustrates how the optical properties of InP/ZnSe/ZnS quantum dots (QDs) can be modulated by controlling the thickness of the ZnSe intermediate shells. The circles in the top left, center, and bottom right represent QDs with thick, middle, and thin ZnSe shells, respectively. Upon excitation by blue light, they emit different colors and intensities depending on the number of photons entering and exiting the QDs. A model of the QD is presented in the top right, while a photograph of a dispersed solution of QDs emitting light is shown in the bottom left. More information can be found in the Research Article by Akihito Okamoto, Shintaro Toda et al.

High-Radiance Shortwave Infrared Light-Emitting Diodes Based on Highly Stable PbS Colloidal Quantum Dots

PbS quantum dot light-emitting diodes (QLEDs) emitting around 1550 nm promise important applications in optical communications. However, due to insufficient suppression of surface traps for large-size PbS quantum dots (QDs), their performance under large driving current density was not satisfactory. In this work, octanethiol surfactant was added into a PbS QD solution and adsorbed onto the dot surface. As a result, the surface traps and the continuous oxidation of the unprotected (100) facets in PbS QDs were greatly suppressed. Therefore, the PbS QDs with octanethiol doubled their photoluminescence efficiency and showed outstanding stability. The PbS-based QLEDs with benchmark device structure showed a breakthrough high radiance of 18.3 W sr-1 m-2 with >2000 mA/cm2 driving current density. The efficient passivation of surface traps with octanethiol surfactant and the suppressed coupling between excitons and surface states under large working current were the main reasons for achieving the breakthrough high radiance.

Application of InP/ZnSe/ZnS Quantum Dots in the Treatment of Experimental Antibiotic-Resistant Endophthalmitis <i>in vivo</i>

Purpose: modeling of experimental antibiotic-resistant endophthalmitis on laboratory animals model describing the interaction of quantum dots and a biological organism and its physicochemical and kinetic aspects.Material and methods. The object of the study is laboratory New Zealand rabbits (2 male, age 4 months, weight 3.5 kg). The inflammation inductor is the culture of Methicillin-Resistant Staphylococcus Aureus (MRSA). 1 mg/0.05 ml of vancomycin in combination with 0.5 μg (0.01 %)/0.05 ml by a solution of quantum dots InP/ZnSe/ZnS 660 was intravitreally administrated to the first rabbit. 1 mg/0.1 ml of vancomycin was intravitreally administrated to the second rabbit. Dynamic observation of the clinical process was performed daily by photo registration of the front segment and ultrasonic sonography.Results. The conjugate based on 1 mg/0.05 ml vancomycin coupled with 0.5 μg (0.01 %)/0.05 ml quantum dots InP/ZnSe/ZnS 660 demonstrated high anti-infectious activity against vancomycin-resistant MRSA. It was shown that the effect of the above solution on MRSA is described by the one-time ability of quantum dots by using electron microscopy. The presence of superoxide radicals O2–• generation in an aqueous solution of quantum dots under the action of blue light has also been proven by spectrophotometric method.Conclusion. Conjugates based on quantum dots can be considered as one of the promising directions of treatment of antibiotic-resistant endophthalmitis.

P‐11.3: Manufacturing Quantum Dot Pixel Array via Self‐Assembling on Hydrophobic‐Hydrophilic Transformation Substrate

Quantum dots (QDs) have been considered next-generation display fluorescent conversion materials due to their excellent color purity and photoluminescence quantum yield. In order to integrate QD with Micro/Mini-LED and other microdevices efficiently, it is necessary to fabricate micro-scale QD pixel arrays. Photolithography is an effective method for fine pattern processing, but conventional photolithographic procedures need to compound QD with a photosensitive curing matrix, which is not conducive to obtaining high color purity QD pixels. Therefore, a QD self-assembly strategy based on a hydrophobic-hydrophilic transformation substrate is proposed, combining ultraviolet (UV) mask exposure and surface charge modification technology to manufacture a high-purity QD pixel array. In this paper, the hydrophobic-hydrophilic transformation substrate is prepared by polyvinylidene fluoride (PVDF)/TiO2 hybrid fibrous membrane substrate. By changing the thickness of the substrate and analyzing its threshold of the photocatalysis time and pattern accuracy combined with the transmittance after encapsulation, the optimal substrate thickness is about 30 um. On this basis, the surface charge of the fibrous membrane is further modified by poly(diallyldimethylammonium chloride) (PDDA) to enhance the self-assembly performance of the QD in the hydrophilic region. The dimensional accuracy and optical characteristic of the QD pixel array have been studied in detail. The color average degree is 96.4%, the consistency is 94.5%, and the dimensional accuracy error is 5.2%. The spectrum of the QD pixel is almost the same as the QD solution, and the transmittance of the films is up to 88.8% under the visible light wave band, which has excellent optical performance. Therefore, this strategy is beneficial for efficiently manufacturing the high-purity QD pixel array, which has a broad application prospect in the high-resolution display field of Micro/Mini light-emitting diodes (LEDs).