Synthesis Of Quantum Dots Research Articles

Live-cell synthesis of biocompatible quantum dots.

Quantum dots (QDs) exhibit fluorescence properties with promising prospects for biomedical applications; however, the QDs synthesized in organic solvents shows poor biocompatibility, limiting their use in biological systems. We developed an approach for synthesizing QDs in live cells by coupling a series of intracellular metabolic pathways in a precise spatial and temporal sequence. We have validated this approach in yeast (Saccharomyces cerevisiae), Staphylococcus aureus, Michigan Cancer Foundation-7 (MCF-7) and Madin-Darby canine kidney (MDCK) cells. The intracellularly synthesized QDs are inherently stable and biocompatible, making them suitable for the direct in situ labeling of cells and cell-derived vesicles. Here, we provide an optimized workflow for the live-cell synthesis of QDs by using S. cerevisiae, S. aureus or MCF-7 cells. In addition, we detail a cell-free aqueous synthetic system (quasi-biosynthesis) containing enzymes, electrolytes, peptides and coenzymes, which closely mimics the intracellular synthetic conditions used in our cell culture system. In this solution, we synthesize biocompatible ultrasmall QDs that are easier to purify and characterize than those synthesized in cells. The live-cell-synthesized QDs can be used for bioimaging and microvesicle detection, whereas the quasi-biosynthesized QDs are suitable for applications such as biodetection, biolabeling and real-time imaging. The procedure can be completed in 3-4 d for live-cell QD synthesis and 2 h for the quasi-biosynthesis of QDs. The procedure is suitable for users with expertise in chemistry, biology, materials science and synthetic biology. This approach encourages interested researchers to engage in the field of QDs and develop further biomedical applications.

Rapid synthesis of carbon quantum dots using organic solvents via combustion method and their role in enhancing polyurethane elasticity

Rapid synthesis of carbon quantum dots using organic solvents via combustion method and their role in enhancing polyurethane elasticity

High-Performance PbSe Quantum Dots with Palmitoyl Chloride and Their Application to Short-Wavelength Infrared Photodetector Devices.

Quantum dots (QDs), particularly those in the short-wavelength infrared (SWIR) range, have garnered significant attention for their unique optical and electrical properties resulting from 3D quantum confinement. Among the various chalcogenide-based QDs, lead chalcogenides, such as PbS and PbSe, are extensively studied for infrared photodetection applications. While PbSe QDs offer advantages over PbS, including a narrower bandgap and higher carrier mobility, they suffer from stability issues due to surface oxidation and particle aggregation. Conventional synthesis methods require additional post-synthesis treatments for surface passivation with halides, which complicates the process. In this work, a novel synthesis approach that incorporates palmitoyl chloride (PalCl) into the traditional PbSe QD synthesis is introduced, effectively passivating the surface with Cl- ions during the synthesis process. This method not only enhances the optical performance by producing a sharp exciton peak and allowing precise tuning of the absorption spectrum from 1100 to 1900nm but also significantly improves the stability of the QDs in solution. The resulting QDs are successfully integrated into SWIR photodetectors (PDs), demonstrating exceptional specific detectivity of 1.08 × 1012 Jones at 1460nm. This achievement draws great potential of the proposed synthetic method for advancing infrared optoelectronic devices.

Microwave-assisted synthesis of fluorescent graphene quantum dots from ferula asafoetida: a green approach for efficient nanomaterial production and selective detection of serum Fe3+ ions

Abstract In the pursuit of economical methods for nanomaterial synthesis, microwave-assisted techniques have garnered attention for their simplicity, efficiency, and reduced time requirements. This study presents a novel approach for the synthesis of fluorescent graphene quantum dots (FGQDs) via a one-pot microwave-assisted method, utilizing Ferula Asafoetida as a green precursor. The resulting FGQDs, synthesized without the need for a catalyst, exhibit high concentration and stability. Notably, these FGQDs display robust blue luminescence across a range of pH and temperature conditions, with the highest quantum yield (18.92%) achieved, as determined by comparison with quinine sulfate standards. The x-ray diffraction analysis shows slightly crystallizable carbonized nanomaterial with particle size ranging from 4–7 nm. The transmission electron microscopy presents unique structural, morphological while x-ray photoelectron spectroscopy shows embedded oxygen containing functional groups responsible for high luminescence intensity. Characterization through various analytical techniques including Raman spectroscopy, dynamic light scattering, verifies the carbon backbone and stability of FGQDs. Detection and quantification limits of Fe3+ ion were determined to be 0.05 mM and 0.01 nM respectively, with FGQDs enabling the estimation of low serum Fe3+ levels, reaching 4 ppm. Furthermore, the synthesized FGQDs hold promise for applications in drug delivery and intracellular sensing due to their high fluorescent intensity and stability.

Introducing carbon quantum dot-Capivasertib drug carrier complex for enhanced treatment of breast cancer.

Capivasertib (AZD5363) is a 2023 FDA-approved pyrrolopyrimidine-derived compound that treats hormone receptor positive, HER2 negative metastatic breast cancer in adult patients. It is a novel pan-AKT kinase catalytic inhibitor in ER + breast cancer cell lines, including MCF7. The dominant influence of carbon quantum dots (CQDs) in combination with multiple chemotherapy drugs is also demonstrated as a drug delivery system that significantly enhances the effectiveness of cancerous tumour treatments by providing reduced side-effects, through targeted delivery of the drug, controlled release, enhanced solubility, permeability and retention. In this study, the impact of the conjugation of AZD5363 drug to N-doped, S-doped, and N/S-doped CQDs was investigated on inducing apoptosis by inhibiting the AKT signalling pathway in the MCF7 cell line. Initially, hydrothermal and pyrolysis methods were used to construct CQDs. Then, the synthesized quantum dots were conjugated with AZD5363 at three different concentrations, i.e., 0.03, 0.3, and 3nM. The MTT test results, on MCF7 cells, showed that although all the studied CQDs were biocompatible, the complex of N/S-doped CQD-AZD5363 at a concentration of 0.03nM was the most effective. After obtaining immunocytochemistry results, flow cytometry and cell invasion tests were employed to demonstrate the high potential of the introduced drug carrier complex in reducing AKT protein expression, induction of apoptosis and prevention of cell metastasis and invasion. According to these results, the binding of N/S-doped CQD to AZD5363 increases the effectiveness of this drug, with reducing the IC50 concentration, and more specificity to cancerous cells, introducing it as a suitable candidate for the treatment of breast cancer.

Electrochemical DNA-based disposable chip for the detection of Klebsiella pneumoniae: a prominent causal agent for urinary tract infections

The aim of this study was to develop an electrochemical DNA sensor for the detection of Klebsiella pneumoniae, a prominent causal agent of UTI, by immobilizing a 5’NH2-labelled ssDNA probe specific to the fimH gene of Klebsiella pneumoniae (K. pneumoniae) on a GQD-modified, screen-printed, disposable electrode. The present study involved the synthesis of graphene quantum dot (GQD)-based nanoparticles using a hydrothermal method and characterized them using Fourier transform infrared (FTIR) spectroscopy, particle size analysis and fluorescence spectroscopy. The synthesized nanoparticles were drop cast onto a screen-printed carbon electrode (SPCE) surface and used in electrochemical biosensors for detecting Klebsiella pneumoniae, which is among the world’s leading pathogens causing urinary tract infections. In this study, a specific NH2-labelled probe was immobilized onto a GQD-fabricated electrode surface, and the electrochemical response was recorded by cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Electrode surface characterization was performed using FE-SEM and FTIR spectroscopy. This nanofabricated chip was found to be very specific, user friendly, less time consuming and affordable to everyone. The sensor was also validated with patient samples and showed an excellent sensitivity and LOD of 70.5 mA/mm2/ng and 0.002 pg/µl respectively using CV.

One-Pot Bottom-Up Synthesis of SiO2 Quantum Dots and Reduced Graphene Oxide (rGO) Nanocomposite as Anode Materials in Lithium-Ion Batteries

Here, crystalline SiO2 quantum dots (QDs) of 3–5 nm size were grown within the layers of reduced graphene oxide (rGO) by a solution mode chemical growth process at a relatively low temperature (100 °C). The composite was applied as a negative electrode in a Li-ion half-cell battery and the electrochemical investigation confirmed a distinct first-cycle discharge/charge capacity (~865 mAhg−1/387 @ 51 mAg−1). The battery could retain a capacity of 296 mAhg−1 after 60 charge/discharge cycles with 99% coulombic efficiency. Furthermore, at a high current rate of 1.02 Ag−1, the battery was able to display an apparent rate capability (214.47 mAhg−1), indicating the high chemical and mechanical stability of the composite at a high current rate. A structural analysis revealed clear distinct diffraction peaks of SiO2 and high-resolution transmission electron microscopy images showed discrete atomic planes, thereby confirming the growth of crystalline SiO2 QDs within the layers of rGO.

Green synthesis of carbon quantum dots from nutshells for enhanced performance in dye-sensitized solar cells.

This study presents a sustainable approach to large scale synthesis of carbon quantum dots (CQDs) from nutshells, a widely available waste from biomass, using hydrogen peroxide (H2O) as the oxidizing agent in a hydrothermal process. The conditions of synthesis, including concentration of H2O2, reaction temperature and time, have been systematically optimized. The results show that optimal conditions include a concentration of 2.5% H2O2, a reaction temperature of 180 °C and a reaction time of 12 hours. The obtained CQDs have an average size of 3 nm and excellent fluorescence. The 2 L Parr reactor has been used to increase the production process and make it more viable for industrial applications. By-products of the reaction, including gas, liquid and solid residues, have been analyzed to understand the distribution of carbon. In addition, CQDs have been incorporated in dye-sensitive solar cells (DSSCs) where they have significantly improved the photovoltaic performance, with increased current density and overall efficiency. This work highlights the potential of biomass-based CQDs for the sustainable production of nanomaterials and for energy conversion applications, and offers a scalable and environmentally friendly alternative to synthesis of CQDs.

Connectivity-Dependent Exciton-Phonon Coupling in Cesium Bismuth Halide Quantum Dots.

Metal halide octahedra form the fundamental functional building blocks of metal halide perovskites, dictating their structures, optical properties, electronic structures, and dynamics. In this study, we show that the connectivity of bismuth halide octahedra in Cs3Bi2Br9 and Cs3Bi2I9 quantum dots (QDs) changes with different halide elements. We use first-principles calculations to reveal the key role of the connectivity of bismuth halide octahedra on the wave function symmetry, Huang-Rhys factor, and exciton-phonon interaction strength. Following QD synthesis via a ligand-mediated transport method, the effect of connectivity is verified with transient absorption spectroscopy, where we contrast Cs3Bi2Br9 and Cs3Bi2I9 QD exciton dynamics. In photoexcited Cs3Bi2I9 QDs, phonons related to the vibrational motions of face-sharing [BiI6]3- bioctahedra couple strongly to the electronic state and drive rapid carrier relaxation. Equivalent signals are not observed for photoexcited Cs3Bi2Br9 QDs, implying a lack of phonon involvement in band-edge absorption and subsequent exciton relaxation. Our findings suggest that structural engineering can effectively tune the exciton-phonon coupling and therefore influence exciton relaxation and recombination in perovskite nanomaterials.

Urea-based carbon quantum dots for recognition of Fe3+ by fluorescence quenching and Pb2+ by fluorescence enhancement.

The present study focuses on synthesis of Urea-based carbon quantum dots (UCQDs) using a non-toxic, low-cost hydrothermal method without consumption of any harmful chemical. The synthesized UCQDs were characterized via UV-Vis absorbance, Photoluminescence (PL), and FTIR spectroscopy. Distinct UV-Vis absorption peaks due to π-π* and n-π* transitions and existence of excitation-independent PL emission peaks at ~450 nm and ~525 nm, validated the presence of carbogenic core and nitrogen-enriched surface states. For water dissolved iron (Fe3+) ions UCQD proves its sensitivity by "Turn Off" fluorescence response, while it shows a "Turn On" sensing for Pb2+ ions. Bensei Hildebrand analysis, Stern-Volmer plots, Job plot and FTIR analysis established the sensing capability of UCQDs by the formation of UCQD: Metal ion complexation. The high quantum yield (~38%), high sensitivity and the low detection limit highlight UCQD's real life applicability for environmental pollution monitoring. The successful detection and quantification of metal ions in real samples validates UCQD as potential future metal ion sensor.

Colloidal Chemistry in Molten Inorganic Salts: Direct Synthesis of III-V Quantum Dots via Dehalosilylation of (Me3Si)3Pn (Pn = P, As) with Group III Halides.

Gallium pnictides, such as GaAs and GaP, are among the most widely used semiconductors for electronic, optoelectronic, and photonic applications. However, solution syntheses of gallium pnictide nanomaterials are less developed than those of many other colloidal semiconductors, including indium pnictides, II-VI and IV-VI compounds, and lead halide perovskites. In this work, we demonstrate that the Wells dehalosilylation reaction can be carried out in molten inorganic salt solvents to synthesize colloidal GaAs, GaP, and GaP1-xAsx nanocrystals. We demonstrate that discrete colloidal nanocrystals can be nucleated and grown in a molten salt with control over their size and composition. Additionally, we found that reaction temperatures above 400 °C are crucial for annealing structural defects in GaAs nanocrystals. We also highlight the utility of the as-synthesized GaP nanocrystals by showing that GaP can be solution-processed into high-refractive-index coatings and patterned by direct optical lithography with micron resolution. Finally, we demonstrate that dehalosilylation reactions in molten salts can be generalized to synthesize indium pnictide (Pn = As, P) and ternary (In1-xGaxAs and In1-xGaxP) quantum dots.

Fabrication of PbSe quantum dot based flexible photodetector device arrays

Near-infrared spectroscopic detection has attracted great attention due to its extensive applications in various fields. Colloidal quantum dots exhibit significant potential for flexible and large-scale manufacturing, owing to their distinctive optoelectronic properties and versatile preparation methods. The present work investigates the synthesis of PbSe colloidal quantum dots via the thermal injection method and their application in the fabrication of photoconductive detector arrays. The effect of two different short-chain ligands [1, 2-ethanedithiol (EDT) and tetrabutylammonium iodide] on infrared detector performance is investigated, and it is found that EDT is better for improving device performance. Large-area electrode arrays were fabricated on flexible polyethylene terephthalate substrates using an inkjet deposition process. The cut-off wavelength of this detector is 0.71 eV, exhibiting excellent optical response in the visible-near-infrared range. The devices achieve a sensitivity of 9 A/W and a normalized detectivity of 6.5 × 1012 Jones under illumination from a 1550 nm laser light source. This study underscores the potential of PbSe quantum dots for advanced large-area photodetector arrays in infrared detection.

CoSe QDs/Sn3O4 PCNFs with high catalytic conversion kinetics towards high-efficiency Li-S batteries

CoSe QDs/Sn3O4 PCNFs with high catalytic conversion kinetics towards high-efficiency Li-S batteries

Synthesis of carbon quantum dots (CQD) from Archidendron bubalinum pods and its compatibility for voltammetric detection of cadmium ion

Synthesis of carbon quantum dots (CQD) from Archidendron bubalinum pods and its compatibility for voltammetric detection of cadmium ion

Green synthesis of carbon quantum dots derived from mango-leaves (M−CQDs): M−CQDs/ZnO nanorods heterostructure thin films for efficient self-powered UV photodetector applications

Green synthesis of carbon quantum dots derived from mango-leaves (M−CQDs): M−CQDs/ZnO nanorods heterostructure thin films for efficient self-powered UV photodetector applications

Room temperature synthesis of graphene quantum dots coated KGdF4: Eu3+, Sm3+ nanophosphors with negative luminescence thermal bursts

Room temperature synthesis of graphene quantum dots coated KGdF4: Eu3+, Sm3+ nanophosphors with negative luminescence thermal bursts

Fluorescence based cadmium detection by protein-assisted synthesis of quantum dots

Fluorescence based cadmium detection by protein-assisted synthesis of quantum dots

Synthesis of Quantum Dots Using Biomaterials Derived from Blue Crab and Their Potential Applications

The blue crab (Callinectes sapidus, Rathbun 1896) has become a significant source of raw materials in biotechnology and nanotechnology due to the biomaterials present in its shell. Natural polymers such as chitin and chitosan, derived from the crab's shell, are particularly noteworthy for their environmentally friendly and biologically compatible properties. These biopolymers provide an innovative alternative in the synthesis of quantum dots (QDs). Quantum dots are favored in various applications, including biomedical imaging, environmental sensors, and energy storage, due to their superior optoelectronic properties. Chitosan obtained from blue crab shells acts as both a stabilizer and a coating agent in the green synthesis of quantum dots. This process minimizes the use of toxic chemicals, thus promoting environmental sustainability. Moreover, the antimicrobial and biodegradable properties of chitosan enhance its usability in biomedical applications. For instance, biocompatible carbon-based quantum dots have shown promising results in cancer diagnostics and drug delivery systems. The synthesis of quantum dots using biomaterials is more cost-effective and environmentally friendly compared to traditional methods. Furthermore, utilizing blue crab shells as a waste material contributes to both marine ecosystem preservation and the circular economy. These synthesis methods are reported to create a significant paradigm shift in the field of sustainable technology development. In conclusion, the synthesis of quantum dots using biomaterials derived from blue crabs has the potential to reduce environmental impacts while serving advanced technological applications. This approach significantly contributes to the development of biotechnological innovations and sustainable development goals.

Fluorescence Quenching of Graphene Quantum Dots from Orange Peel for Methyl Orange Detection.

Methyl orange (MO) is an organic synthetic dye widely used in laboratory and industrial applications. In laboratory settings, it serves as an acid-base indicator due to its distinct color change in both acidic and alkaline environments. Industrially, it is primarily utilized in the textile industry for its ultraviolet (UV) absorption properties. However, the discharge and leakage of methyl orange into the environment can cause severe ecological damage and pose potential carcinogenic and teratogenic risks to human health. Therefore, detecting and quantifying the concentration of methyl orange in various matrices is crucial. This study reports the synthesis of graphene quantum dots (GQDs) from orange peel as a precursor, using ethanol and dimethylformamide (DMF) as solvents. Cyan (c-GQDs) and yellow (y-GQDs) graphene quantum dots were synthesized through a bottom-up hydrothermal method. The difference in color is attributed to the redshift caused by the varying ratio of pyridine nitrogen to pyrrole nitrogen. These GQDs exhibited notable optical properties, with c-GQDs emitting cyan fluorescence and y-GQDs emitting yellow fluorescence under UV light. To investigate fluorescence quenching effects, nine commonly used dyes were tested, and all were found to quench the fluorescence of y-GQDs, with methyl orange having the most significant effect. The fluorescence quenching of orange peel-derived GQDs in the presence of methyl orange is attributed to poor dispersion in DMF solution. Additionally, the GQDs possess high specific surface area, abundant surface functional groups, and excellent electronic conductivity, which contribute to their effective fluorescence quenching performance. The average thickness of y-GQDs (the vertical dimension from the substrate upwards) was 3.51 nm, confirming their graphene-like structure. They emitted yellow fluorescence within the wavelength range of 450-530 nm. Notably, a significant linear correlation was found between the concentration of methyl orange and the fluorescence intensity of y-GQDs (regression coefficient = 0.9954), indicating the potential of GQDs as effective sensing materials for organic pollutant detection.

Van der Waals quantum dots on layered hexagonal boron nitride

Semiconductor quantum dots (QD) promise unique electronic, optical, and chemical properties, which can be exquisitely tuned by controlling the composition, size, and morphology. Semiconductor QDs have been synthesized primarily via two approaches, namely, epitaxial growth and wet-chemical synthesis. However, the properties of epitaxial QDs (eQDs) are susceptible to wetting layer formation and substrate dislocations, while colloidal QDs (cQDs) face fluorescence intermittency issues. Here, we report on the synthesis of a class of QDs that can overcome the fundamental limitations of eQDs and cQDs. By exploiting the sp2 bonding of layered hexagonal boron nitride (hBN), we show that GaN QDs can be epitaxially grown through a weak van der Waals (vdW) interaction without two-dimensional wetting layer formation. The photoluminescence intensity of GaN van der Waals quantum dots (vQDs) is more than six times stronger than that of conventional GaN eQDs and no optical blinking was observed from vQDs. We show that the interadatom bond strength is about one order of magnitude stronger compared with that between the adatoms and the hBN substrate. This work shows that vQDs have unique properties that are difficult to achieve using existing QDs synthesis methods and thus can potentially enable new classes of high-performance optoelectronic and quantum devices.