Carbon Quantum Dots Research Articles

Enhanced photodetection in organic semiconductor single crystal sensitized by a tailored synergistic absorption of capsule-shaped chlorophyll derived CQDs

Organic single-crystal phototransistors have emerged as one of the most promising light signal detectors for their minimal defects, high mobility and light sensitivity. However, fully exploiting their advantages in advanced flexible optoelectronic applications remains great difficulty and challenging due to the lack of efficient methods for upgrading the photoresponse of delicate organic crystalline materials. Herein, we developed a capsule-shaped chlorophyll derived carbon quantum dots (Chl-CQDs) to enhance the single-crystal photodetection. Through a multi-site carbonization of chlorophyll peripheral substituents, the CQDs were produced around the chlorophyll tetrapyrrole macrocyclicvia. It makes Chl-CQDs combine the light absorption advantages of chlorophyll and CQDs, and exhibit an amazing synergistic absorption behavior. Compared to pristine devices of 2,6-diphenyl anthracene (DPA), the key figures of merit such as P, R, and D* of the Chl-CQDs/DPA heterophototransistors are improved by over 6000 times, 5 times, and 200 times, respectively. Additionally, an ultra fast charge transfer dynamics (τrise = 35 ms and τdecay = 45 ms) is observed at such unique type II heterointerface. These results not only offer a new approach for improving the photoresponse of single crystal organic phototransistors, but also make it possible to be superior to that of silicon-based devices.

Hydrogen peroxide enhanced glow-type chemiluminescence of hydrazine hydrate modified carbon quantum dots-potassium persulfate system

Most known chemiluminescence (CL) systems are flash-type that generate weak luminescence and decline quickly after dozens of seconds, while the glow-type CL systems have stable emission for an extended period to achieve accurate quantitation. In this work, a long-term CL system based on hydrazine-hydrate (N2H4·H2O) modified carbon quantum dots (N-CQDs) as a luminescent probe, with K2S2O8 and H2O2 as co-reactants, was proposed. The CL emission enhanced by H2O2 increased 18-fold more than that of N-CQDs and K2S2O8 direct reaction, and decayed by 5% of the maximum intensity over 700 s. In the reaction system, K2S2O8 and H2O2 co-reactants can promote each other to continuously generate corresponding radicals (•OH, O2•−, 1O2), which in turn trigger the CL emission of N-CQDs. This phenomenon was identified as the primary cause for the production of persistent CL. In addition, a stable and selective CL sensor based on the N-CQDs-K2S2O8-H2O2 CL enhancing system was developed for ascorbic acid quantitation in the linear range from 0.1 to 10.0 mM with a detection limit of 0.036 mM. The method has been applied to the analysis of tablet samples and holds potential in pharmaceutical analysis field.

A fluorescence switch-off nanosensor for sensitive determination of the antiandrogen drug flutamide in pharmaceutical and environmental samples. Analytical method greenness, blueness, and whiteness assessment

A fast, practical, and non-hazardous switch-off fluorescent nanosensor for the non-fluorescent antiandrogen drug flutamide (FLU) was developed from nitrogen/sulfur co-doping of carbon quantum dots (N,S-CQDs). For the first time, the highly fluorescent N,S-CQDs were generated via one-pot microwave-assisted synthesis in only 3 min using facilely available precursors (sweet yellow pepper and thiourea). The sensor is characterized by a narrow particle size distribution, high doping efficiency (N, 42.05 % and S, 8.28 %), reproducibility, and high emission at 410 nm after excitation at 330 nm. FLU efficiently and quantitatively turned off the fluorescence of the prepared N,S-CQDs via a synergistic combination of static quenching and inner filter effect. The furnished nanosensor showed good linearity (r = 0.9999) for FLU analysis within concentrations ranged from 1.0 to 30.0 µg mL−1 with a detection limit of 0.293 µg mL−1 and quantitation limit of 0.886 µg mL−1. The selectivity of the probe was confirmed in the presence of co-administered drugs, possible co-existing materials, and various metal ions. The N,S-CQDs interestingly showed acceptable cytocompatibility and low toxicity, as revealed by the MTT assay. This feature bestows the N,S-CQDs a practicability as an environmental sensor. Thus, the proposed approach was implemented for FLU analysis in pharmaceutical tablets, tap water, and river water with good percentage recoveries (99.59 ± 1.28%, 99.49 ± 1.75%, and 101.21 ± 1.67%, respectively) and without interferences. Furthermore, the approach was positively assessed with respect to greenness, blueness, and whiteness. The high values of the analytical greenness score AGREE (0.78), the chiefly green ComplexGAPI pictogram, the Blue Applicability Grade Index BAGI (72.5), and the RGB12 (93.6) show the high greenness, blueness, and whiteness features of the method that confirm its minor environmental impact, excellent applicability, and sustainability, respectively.

Emerging Trends in Nanomedicine: Carbon-Based Nanomaterials for Healthcare.

Carbon-based nanomaterials, such as carbon quantum dots (CQDs) and carbon 2D nanosheets (graphene, graphene oxide, and graphdiyne), have shown remarkable potential in various biological applications. CQDs offer tunable photoluminescence and excellent biocompatibility, making them suitable for bioimaging, drug delivery, biosensing, and photodynamic therapy. Additionally, CQDs' unique properties enable bioimaging-guided therapy and targeted imaging of biomolecules. On the other hand, carbon 2D nanosheets exhibit exceptional physicochemical attributes, with graphene excelling in biosensing and bioimaging, also in drug delivery and antimicrobial applications, and graphdiyne in tissue engineering. Their properties, such as tunable porosity and high surface area, contribute to controlled drug release and enhanced tissue regeneration. However, challenges, including long-term biocompatibility and large-scale synthesis, necessitate further research. Potential future directions encompass theranostics, immunomodulation, neural interfaces, bioelectronic medicine, and expanding bioimaging capabilities. In summary, both CQDs and carbon 2D nanosheets hold promise to revolutionize biomedical sciences, offering innovative solutions and improved therapies in diverse biological contexts. Addressing current challenges will unlock their full potential and can shape the future of medicine and biotechnology.

Green synthesis of biomass-derived carbon quantum dots for photocatalytic degradation of methylene blue.

Water pollution, significantly influenced by the discharge of synthetic dyes from industries, such as textiles, poses a persistent global threat to human health. Among these dyes, methylene blue, particularly prevalent in the textile sector, exacerbates this issue. This study introduces an innovative approach to mitigate water pollution through the synthesis of nanomaterials using biomass-derived carbon quantum dots (CQDs) from grape pomace and watermelon peel. Utilizing the hydrothermal method at temperatures between 80 and 160 °C over periods ranging from 1 to 24 h, CQDs were successfully synthesized. A comprehensive characterization of the CQDs was performed using UV-visible spectroscopy, Fourier-transform infrared spectroscopy, dynamic light scattering, Raman spectroscopy, and luminescence spectroscopy, confirming their high quality. The photocatalytic activity of the CQDs in degrading methylene blue was evaluated under both sunlight and incandescent light irradiation, with measurements taken at 20 min intervals over a 2 h period. The CQDs, with sizes ranging from 1-10 nm, demonstrated notable optical properties, including upconversion and down-conversion luminescence. The results revealed effective photocatalytic degradation of methylene blue under sunlight, highlighting the potential for scalable production of these cost-effective catalytic nanomaterials for synthetic dye degradation.

Morphological insights into uncompetitive fluorescence of coal-based carbon dots and strategies for improvement

The findings of the research indicate that coal-derived carbon dots (CDs), produced through top-down methods, exist as a blend of graphene quantum dots (GQDs), carbon quantum dots (CQDs), and carbon nanodots (CNDs). Within this mixture, numerous individual particles are dispersed, each containing multiple sp2-carbon domains, suggesting the presence of multiple fluorescent centers of varying sizes. These fluorescent centers scatter photon energy, leading to a wide full width at half maximum (FWHM >80 nm). To tackle this issue, the study significantly improves the fluorescence efficiency of coal-based CDs by employing a nitrogen-doping approach. Additionally, these nitrogen-doped CDs are combined with polyvinyl alcohol (PVA) to formulate secure inks exhibiting solid-state fluorescence and room-temperature phosphorescence (RTP) properties, showcasing their potential for anti-counterfeiting applications in safeguarding important documents and artworks.

Quantum Dots as a Potential Multifunctional Material for the Enhancement of Clinical Diagnosis Strategies and Cancer Treatments.

Quantum dots (QDs) represent a class of nanoscale wide bandgap semiconductors, and are primarily composed of metals, lipids, or polymers. Their unique electronic and optical properties, which stem from their wide bandgap characteristics, offer significant advantages for early cancer detection and treatment. Metal QDs have already demonstrated therapeutic potential in early tumor imaging and therapy. However, biological toxicity has led to the development of various non-functionalized QDs, such as carbon QDs (CQDs), graphene QDs (GQDs), black phosphorus QDs (BPQDs) and perovskite quantum dots (PQDs). To meet the diverse needs of clinical cancer treatment, functionalized QDs with an array of modifications (lipid, protein, organic, and inorganic) have been further developed. These advancements combine the unique material properties of QDs with the targeted capabilities of biological therapy to effectively kill tumors through photodynamic therapy, chemotherapy, immunotherapy, and other means. In addition to tumor-specific therapy, the fluorescence quantum yield of QDs has gradually increased with technological progress, enabling their significant application in both in vivo and in vitro imaging. This review delves into the role of QDs in the development and improvement of clinical cancer treatments, emphasizing their wide bandgap semiconductor properties.

L-cysteine modified N-doped carbon quantum dots derived from peach palm (Bactris gasipaes) peels for detection of mercury ions

Establishing an effective strategy for Hg2+ determination with good sensitivity and high selectivity is of particular concern. In this work, N-doped carbon quantum dots (NCQDs) were obtained for the first time from peels of peach palm fruit (Bactris gasipaes) through microwave-assisted one-pot synthesis. Surface NCQDs was modified with l-cysteine (NCQDs/CYS) by a chemical reaction (known as amide coupling) between the nitrogen-containing groups (amine group) of l-cysteine ligand and the carboxyl groups of NCQDs. The chemical bonding was examined by Fourier Transform Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). NCQDs/CYS nanoparticles exhibited a quantum yield of fluorescence (ΦFL) of 25.4%, high solubility in water, and a surface with thiol groups from l-cysteine. Mercury ions induced quenching of fluorescence of NCQDs/CYS at low concentrations (Limit of Detection, LOD = 0.19 μM) with great sensitivity. A significant preference for Hg2+ ions was found because of the high affinity between the thiolate groups of NCQDs/CYS and the analyte. Time-resolved fluorescence measurements were done to study the way that led to fluorescence quenching when Hg2+ ions were present, evidencing a static quenching fluorescence mechanism. The new NCQDs/CYS material could be applied to accurately measure the concentration of Hg2+ ions in water samples in a fast and cost-effective way.

High-performance supercapacitor electrode materials from composite of bamboo tar pitch activated carbon and tannic acid carbon quantum dots

A novel composite electrode material comprising bamboo tar pitch-based activated carbon (BTPAC) and tannic acid-derived carbon quantum dots (TACDs) was prepared. The integration of TACDs into the composite BTPAC-60/TACD not only preserved the high conductivity characteristic of BTPAC but also enhanced its hydrophilicity, pore structure, and specific surface area. Electrochemical evaluations revealed that BTPAC-60/TACD delivers a specific capacitance of 677.7 F/g at 0.5 A/g in a three-electrode system, and 281.8 F/g at 1 A/g in a two-electrode setup. Impressively, it achieves an energy density of 56.4 Wh/kg at a power density of 600 W/kg and maintains 95.7 % of its capacitance after 10,000 cycles. This research not only capitalizes on the high-value application of bamboo tar pitch but also provides a new perspective for the development of high-performance supercapacitor electrodes.

Revolutionizing Agriculture with Nanotechnology: Advances, Applications, and Sustainability Considerations

The integration of nanotechnology into agriculture has garnered significant interest due to its potential to revolutionize agricultural practices. This paper explores the application of nanotechnology in crop protection, nutrient delivery, soil management, and environmental sustainability. Nanopesticides and nanofertilizers represent notable advancements, offering enhanced efficacy, reduced environmental impact, and improved targeted delivery of active ingredients. Nanomaterials such as nanoparticles and nanocapsules encapsulate nutrients and agrochemicals, ensuring gradual release and optimized plant uptake. Nanosensors, based on materials like carbon nanotubes and quantum dots, enable real-time monitoring of soil health, crop growth, and environmental conditions, facilitating precision agriculture. Nanomaterials also play a role in soil remediation and pollution control by degrading pollutants and enhancing soil fertility. Additionally, nanobiotechnology offers eco-friendly solutions for pest and disease management through nanoscale delivery systems for biocontrol agents and plant vaccines. Despite the transformative potential of nanotechnology in agriculture, considerations of safety, regulatory oversight, and ethical implications are essential. Interdisciplinary collaboration and stakeholder engagement will be crucial to harness the full benefits of nanotechnology for sustainable agriculture.

Fabrication and characterization of bio-nanocomposite from sweet potato starch and Moringa oleifera leaf extract loaded with carbon quantum dots from Coffea arabica grounds

The study aims to generate and characterize a bio-nanocomposite film derived from sweet potato starch and Moringa oleifera leaf extract and carbon quantum dots (CQDs) derived from Arabica coffee grounds employing the solvent casting method. The effect of various concentrations of CQDs (0–400 ppm) was investigated on the physicochemical properties, UV-barrier, antioxidant properties, and biodegradability of the bionanocomposite (BNC) films. The morphological surface of the bio-nanocomposite was examined using scanning electron microscopy (SEM). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were performed to evaluate the thermal stability of the samples. Mechanical properties, including tensile strength (TS) and elongation at break (EB), were also assessed. The results show that the incorporation of CQDs with starch-based biofilms had a remarkable impact on the properties of BNC. SEM images confirm the homogeneous structure of the films with slight granulations. Colorimetric analysis indicates the increase in color difference of BNCs as the concentration of CQDs varied. The BNC100 formulation confirmed batter opacity, transparency, and UV-barrier properties while BNC50 possessed significant improvement in tensile, elongation as well as a substantial increase in the melting point. FTIR and XRD analysis confirmed proper chemical interactions among the components within the polymeric structure of the BNC film. In addition, CQD integration has also steadily enhanced the antioxidant properties and biodegradability of BNC films. The fabricated films with CQDs have demonstrated a better quality in terms of optical properties, physical properties, thermomechanical properties, biodegradation rate, and antioxidant behavior that suggest the film's application in food packaging or other relevant fields.

Investigation of electro-optical and dielectric properties of pure and dispersed nematic liquid-crystal

ABSTRACT In this study, 4-(Trans-4ʹ-n-Pentylcyclohexyl) Benzonitrile (PCH5) has been employed as a host liquid crystal (LC) to disperse carbon quantum dots (CQDs). The investigation delves into the dielectric behaviour and electro-optical properties of dispersed nematic systems featuring both pure and CQD-incorporated compositions. We examined the impact of CQD dispersion on various parameters such as relative permittivity, dielectric loss, AC conductivity, birefringence, and threshold voltage in the nematic liquid crystal (NLC) PCH5 at concentrations of 0.1, 0.3, and 0.5 wt%. These properties demonstrate notable changes upon the addition of CQDs to the nematic PCH5 system, influenced by both the dopant concentration and the applied electric field. Birefringence, determined using the transmittance method, reveals higher values in dispersed systems, influenced by factors such as dopant concentration, temperature range, and chemical composition. Furthermore, the composite systems with dispersed CQDs exhibit significantly reduced threshold voltages. The observed findings are attributed to the interactions between CQDs and nematic molecules. Also, we explored potential applications for the dispersed systems investigated in this study.

Multichannel Sensor for Detection of Molybdenum Ions Based on Nitrogen-Doped Carbon Quantum Dot Ensembles

Trace elements such as cobalt (Co), molybdenum (Mo), and zinc (Zn) play necessary roles in different biological functions. Co is a microelement that influences the vascular system. Mo works as an enzymatic cofactor of three enzymes (aldehyde oxidase, sulfite oxidase, and xanthine oxidase dehydrogenase). However, these elements are difficult to detect, since the analytical methods developed have a high cost, which restrict their applicability. In this sense, fluorescent sensors are an alternative for detecting trace elements, such as Mo4+ ions. Herein, a new multichannel trace elements sensor has been proposed to detect Mo entities. In this sense, two different N-CQDs were synthesized and fully characterized. The N-CQDs presented quantum yield values of 25.93% and 6.02% and excellent solubility in water. Also, a mixture of these two carbon-based nanoparticles was used to identify and to quantify Mo in water between seven different trace elements. The method was found to reach 1.28 and 3.88 ppm for limit of detection (LOD) and quantification (LOQ), respectively. To further verify the potential of the detection platform, the multichannel sensor was applied to identify the different concentrations of metal ions (Fe2+, Co2+, Mn2+, Cu2+, Zn2+, Mg2+, and Mo4+) in water. The data matrix was treated using different algorithms, such as K-Means and Discriminant Analysis (DA). The detection strategy has successfully identified the molybdenum ions at 5 ppm. This result shows the potential application of a multichannel sensor toward the detection of Mo entities, since it is comparable with the molybdenum test already available on the market.

The Role of Carbon Quantum Dots in Environmental Protection

The Role of Carbon Quantum Dots in Environmental Protection

Fluorescence turn-on detection of arsenite in rice and seawater samples using bisphosphonate-functionalised carbon quantum dots

ABSTRACT In this paper, we illustrate an efficient and simple fluorescence (FL) sensing approach for the specific determination of arsenite (As(III)) in aqueous solution by alendronate-functionalised carbon quantum dots (A-CQDs) as a turn-on fluorescent probe. A-CQDs exhibit linear FL turn-on response towards the increasing concentration of As(III) analyte with a limit of detection of 0.007 µM and a linear range of 0.03–1.87 µM. The selectivity study demonstrates that the A-CQDs are very selective for As(III) detection, even at a higher concentration of other interfering ions. The sensing pathway for the sensitivity of A-CQDs assay to quantify As(III) ions is expected to rely on the chelation-enhanced FL (CHEF) mechanism between A-CQDs and the analyte. This mechanism is verified by the density functional theory methodology. The practical application of this simple and reliable sensor is demonstrated by assaying As(III) in rice and seawater samples, which confirms that A-CQDs have good potential for real sample analysis in food and environmental samples.

Perfluorosulfonic acid membranes with reduced hydrogen permeation by filling with carbon quantum dots for fuel cells

Perfluorosulfonic acid membranes with reduced hydrogen permeation by filling with carbon quantum dots for fuel cells

Nanocomposite coating based on nitrogen-doped carbon dots in extending shelf life of fresh-cut pears from the perspective of microorganism

Nitrogen-doped quantum carbon dots were prepared based on Ethylenediaminetetra acetic acid disodium salt (EDTA-Na2) and citric acid, characterized for their structures and properties, and blended with chitosan to make nanocomposite coating film applied in the preservation of fresh-cut pears. The results showed that the PER-CDs (Pleurotus eryngii by-products carbon quantum dots), EDTANa2-doped PER carbon quantum dots (EPER-CDs), EDTANa2 and citric acid doped PER carbon quantum dots (E/NPER-CDs) prepared by hydrothermal method successfully introduced N–H groups on the surfaces, and the doped carbon dots showed good antibacterial on Escherichia coli and Staphylococcus aureus and antioxidant properties. At the end of storage (5 d), the total bacterial count of fresh-cut pears coated with CS (chitosan)/2%E/NPER-CDs was 5.59 log CFU/g significantly lower than that of the control group (7.29 log CFU/g). The E/NPER-CDs inhibited the accumulation of reactive oxygen species (ROS), delayed degradation of total phenol, ascorbic acid and glutathione, as well as significantly reduced the activities of superoxide dismutase (SOD), catalase (CAT), polyphenol oxidase (POD), peroxidase (PPO), and ascorbic acid oxidase (APX) to achieve the effect of enhancing the quality of fresh-cut pears during storage.

Application of Quantum Dots for Photocatalytic Hydrogen Evolution Reaction

There is increased interest in the conversion of solar energy into green chemical energy because of the depletion of fossil fuels and their unpleasant environmental effect. Photocatalytic hydrogen generation from water involves the direct conversion of solar energy into H2 fuels, which exhibits significant advantages and immense promise. Nevertheless, photocatalytic efficiency is considerably lower than the standard range of industrial applications. Low light absorption efficiency, the rapid recombination of photogenerated electrons and holes, slow surface redox reaction kinetics and low photostability are well known to be key factors negatively affecting photocatalytic hydrogen production. Therefore, to construct highly efficient and stable photocatalysts is important and necessary for the development of photocatalytic hydrogen generation technology. In this review, quantum dots (QDs)-based photocatalysts have emerged with representative achievements. Due to their excellent light-harvesting ability, low recombination efficiency of photogenerated electrons and holes, and abundant surface active sites, QDs have attracted remarkable interest as photocatalysts and/or cocatalyst for developing highly efficient photocatalysts. In this review, the application of QDs for photocatalytic H2 production is emphatically introduced. First, the special photophysical properties of QDs are briefly described. Then, recent progress into the research on QDs in photocatalytic H2 production is introduced, in three types: semiconductor QDs (e.g., CdS, CdMnS, and InP QDs), metal QDs (e.g., Au, Pt and Ag QDs), and MXene QDs and carbon QDs (CDQs). Finally, the challenges and prospects of photocatalytic H2 evolution with QDs in the future are discussed.

The Speciation of Heavy Metal Chromium in Water Environment by Carbon Quantum Dots System

The Speciation of Heavy Metal Chromium in Water Environment by Carbon Quantum Dots System

A ratiometric fluorescence sensing system for rapid detection of glyphosate in miscellaneous beans

To establish a ratiometric fluorescence sensing system for the detection of glyphosate, nitrogen-sulfur doped carbon quantum dots nano-fluorescent probe was prepared by one-step hydrothermal method. At an excitation wavelength of 360 nm, the emission peak with maximum fluorescence intensity was obtained at 470 nm. The generation of 2.3-diaminophenazine by o-phenylenediamine oxidation produces a new fluorescence emission peak at 570 nm and a decrease in fluorescence at 470 nm. The fluorescence peaks at 470 and 570 nm form a ratio state. In the presence of glyphosate, reduces the oxidation of 2.3-diaminophenazine, this results in enhanced fluorescence at 470 nm and weakened fluorescence at 570 nm. Under the best conditions, the ratiometric fluorescence sensing system has good selectivity, the linear at glyphosate concentrations of 0.005–10 µg/mL, the limit of detection was 2.88 µg/kg, the limit of quantitation was 4.07 µg/kg. In addition, it is worth mentioning that this developed sensing system has shown good detection performance in 10 miscellaneous samples, the simple, efficient, and highly sensitive ratiometric fluorescence detection sensing strategy is provided.