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Alzheimer's disease (AD) is a common neurodegenerative disease characterized by progressive cognitive and physical impairment. Neuroinflammation is related to AD, and the misfolding and aggregation of amyloid protein in the brain creates an inflammatory microenvironment. Microglia are the predominant contributors to neuroinflammation, and abnormal activation of microglia induces the release of a large amount of inflammatory factors, promotes neuronal apoptosis, and leads to cognitive impairment. In this study, we used microglial membranes containing caffeic acid-coupled carbon quantum dots to prepare a novel biomimetic nanocapsule (CDs-CA-MGs) for the treatment of AD. The application of CDs-CA-MGs via nasal administration can bypass the blood‒brain barrier (BBB) and directly target the site of inflammation. After treatment with CDs-CA-MGs, AD mice showed reduced inflammation in the brain, decreased neuronal apoptosis, and significantly improved learning and memory abilities. In addition, CDs-CA-MGs affect inflammation-related JAK-STAT and Toll-like receptor signaling pathways in AD mice. CDs-CA-MGs significantly downregulated interleukins (IL-1β and IL-6) and tumor necrosis factor (TNF-α). This finding suggested that CDs-CA-MGs may improve cognitive impairment by modulating inflammatory responses. In conclusion, the use of CDs-CA-MGs provides a possible therapeutic strategy for the treatment of AD. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs) are promising luminophores for luminescent solar concentrators (LSCs) in transparent photovoltaic greenhouse covers due to their high ultraviolet (UV)‐light absorption coefficient, which is vital for plant growth. Herein, high quantum yield (75%) and large Stokes shift (0.706 eV) CQDs are synthesized by a simple, fast, cheap, and mass scalable method. A comprehensive study on the LSC engineering is carried out. Thin layers of CQDs with different concentrations of 1, 3, and 5 wt% and different number of layers (1–5) are coated on glass and poly(methyl methacrylate) (PMMA) waveguides, sized 5 × 5 × 0.6 and 15 × 15 × 0.6 cm3. The best performing single‐layer LCS exhibits power conversion efficiency (PCE) and optical efficiency as high as 1.6% and 6.5%, respectively (LSC size 5 × 5 × 0.6 cm3), and 1.19% and 3.27% (LSC size of 15 × 15 × 0.6 cm3), respectively. Over 90 days, stability tests show a 2% PCE decrease. Tests on a small‐scale greenhouse model demonstrate that transparent photovoltaic LSC roofs not only produce electricity but also control temperature inside the greenhouse. Hence, CQD‐based LSCs synthesized by the scalable method can be used in commercialization of transparent greenhouses photovoltaic covers. [ABSTRACT FROM AUTHOR]

Visible light driven catalytic hydrogen production over CdS based catalysts could be a good candidate strategy to help solve the global energy crisis. To improve the photocatalytic H 2 production activity of CdS, the series of Pd nanoparticles and carbon quantum dots (CQDs) co-modified CdS nanorods (NRs) composites were designed to simultaneously build the type I heterojunctions and Schottky junctions. The photocatalytic H 2 evolution activities of the samples were assessed under visible light (λ > 420 nm) irradiation and the reaction mechanism was proposed. The Pd-0.35CQDs/CdS catalyst exhibited excellent activity with the average hydrogen evolution rate (HER) of 47.1 mmol h−1 g−1, which is 36.2 times higher than that of the pure CdS. Its apparent quantum efficiency is 17.1% (450 nm light). The combined action of Schottky junctions and type I heterojunctions in the composite Pd-0.35CQDs/CdS greatly promoted charge transfer and separation, resulting in enhancement of the photocatalytic activity. Additionally, the synergistic effect of the Pd nanoparticles and CQDs resulted in enhanced visible light absorption and optimized band structure, helpful to enhancement of the photocatalytic activity. This study provides a simple and cost-effective strategy for improving visible light catalytic H 2 production performance of catalysts. [Display omitted] • Carbon quantum dots (CQDs) and Pd nanoparticles modified CdS nanorods were prepared. • Pd-0.35CQDs/CdS composite exhibits excellent visible light H 2 production activity. • Hydrogen evolution rate over the Pd-0.35CQDs/CdS is as high as 47.1 mmol h−1 g−1. • Type I heterojunctions/Schottky junctions greatly promote charge transfer/separation. • Synergistic effect of CQDs and Pd resulted in enhanced activity of Pd-0.35CQDs/CdS. [ABSTRACT FROM AUTHOR]

Currently, carbon nanomaterials are found to possess various shapes and sizes, where their potentiality is mainly governed by the functional groups and design parameters. The alteration of the material features through postprocessing or reformulation can produce these nanostructures for utilization in air/wastewater treatment, dyes, pharmaceuticals, pesticides, and so forth. In this work, three isomeric structures of toluidine were chosen, which contain a ─CH3 at the o‐, m‐, and p‐positions of the benzene ring along with an ─NH2 group. SEM and TEM images confirmed the formation of carbon nanoparticles at different times and temperatures under optimized reaction conditions. It was observed that uniform size of carbon quantum dots was obtained from all the isomeric structures, namely, after 60, 90, and 60 min in case of o‐, m‐, and p‐toluidine, respectively. The efficiency of the synthesized carbon nanoparticles for the degradation of toxic organochlorine pesticides, namely DDT, lindane, and fenvalerate was also studied. Interestingly, the synthesized carbon quantum dots were found to degrade the DDT up to 98.5%, lindane up to 83.02%, and fenvalerate up to 74.34% under visible light exposure. However, only 63.23%, 20.25%, and 30.41% degradation were observed under dark conditions for DDT, lindane, and fenvalerate, respectively. [ABSTRACT FROM AUTHOR]

Under the dual pressures of environmental protection and energy security, the development and application of coal-based nanocarbon materials, supported by the technical concepts of molecular chemical engineering and nanomaterial science, is of significant importance for achieving the high-value clean utilization of coal. Furthermore, it serves as an effective means to assist in the realization of dual carbon goals. Coal, with its abundant reserves, high carbon content, and aromatic and hydrogenated aromatic groups, exhibits great advantages and potential in the synthesis of nanocarbon materials. In addition to its applications in traditional power and chemical industries, coal-based nanocarbon materials also demonstrate significant value in the field of environmental pollution control. This article succinctly summarizes the preparation methods and properties of coal-based carbon nanotubes, coal-based carbon quantum dots, and coal-based graphene, elucidates their current applications in water pollution control and governance, and anticipates their development trends in water pollution control, aiming to provide support for the clean and efficient utilization of coal and water pollution control. [ABSTRACT FROM AUTHOR]

Foam drainage agents enhance gas production by removing wellbore liquids. However, due to the ultra-high salinity environments of the Hechuan gas field (salinity up to 32.5 × 104 mg/L), no foam drainage agent is suitable for this gas field. To address this challenge, we developed a novel nanocomposite foam drainage system composed of quaternary ammonium and two types of nanoparticles. This work describes the design and synthesis of a quaternary ammonium foam drainage agent and nano-engineered stabilizers. Nonylphenol polyoxyethylene ether sulfosuccinate quaternary ammonium foam drainage agent was synthesized using maleic anhydride, sodium chloroacetate, N,N-dimethylpropylenediamine, etc., as precursors. We employed the Stöber method to create hydrophobic silica nanoparticles. Carbon quantum dots were then prepared and functionalized with dodecylamine. Finally, carbon quantum dots were incorporated into the mesopores of silica nanoparticles to enhance stability. Through optimization, the best performance was achieved with a (quaternary ammonium foam drainage agents)–(carbon quantum dots/silica nanoparticles) ratio of 5:1 and a total dosage of 1.1%. Under harsh conditions (salinity 35 × 104 mg/L, condensate oil 250 cm3/m3, temperature 80 °C), the system exhibited excellent stability with an initial foam height of 160 mm, remaining at 110 mm after 5 min. Additionally, it displayed good liquid-carrying capacity (160 mL), low surface tension (27.91 mN/m), and a long half-life (659 s). These results suggest the effectiveness of nanoparticle-enhanced foam drainage systems in overcoming high-salinity challenges. Previous foam drainage agents typically exhibited a salinity resistance of no more than 25 × 104 mg/L. In contrast, this innovative system demonstrates a superior salinity tolerance of up to 35 × 104 mg/L, addressing a significant gap in available agents for high-salinity gas fields. This paves the way for future development of advanced foam systems for gas well applications with high salinity. [ABSTRACT FROM AUTHOR]

A compact organic electrochemical transistors (OECT) sensor enriched with carbon quantum dots (CQDs) was developed to enhance the transconductance of an electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) film, enabling the precise and selective detection of dopamine (DA). Accurate monitoring of DA levels is critical for diagnosing and managing related conditions. Incorporating CQDs, we have achieved a remarkable up to threefold increase in current at the DA detection peak in differential pulse voltammetry. This enhancement showcases superior selectivity even in the presence of high concentrations of interferents like uric acid and ascorbic acid. This material significantly boosts the sensitivity of OECTs for DA detection, delivering an amperometric response with a detection limit of 55 nM and a broader detection range (1 − 500 µM). Our results underscore the potential of low-dimensional carbonaceous materials in creating cost-effective, high-sensitivity devices for detecting DA and other biomolecules. This breakthrough sets the stage for the development of next-generation biosensors for point-of-care diagnostics. [ABSTRACT FROM AUTHOR]

Background/Objectives: Metformin (Met), an oral drug used to treat type II diabetes, is known to control blood glucose levels. Metformin carbon quantum dots (MetCQDs) were prepared to enhance the bioavailability and effectiveness of metformin. Several studies have shown that carbon quantum dots (CQDs) have attractive properties like small particle size, high penetrability, low cytotoxicity, and ease of synthesis. CQDs are made from a carbon source, namely, citric acid, and a heteroatom, such as nitrogen. The active molecule can be a carbon source or a heteroatom, as reported here. Methods: This study aims to produce MetCQDs from an active molecule. MetCQDs were successfully produced by microwave-based production methods and characterized. The effect of the MetCQDs was tested in Wistar albino rats following a Streptozocin-induced diabetic model. Results: The results show that the products have a particle size of 9.02 ± 0.04 nm, a zeta potential of −10.4 ± 0.214 mV, and a quantum yield of 15.1 ± 0.045%. Stability studies and spectrophotometric analyses were carried out and the effectiveness of MetCQDs evaluated in diabetic rats. The results show a significant reduction in blood sugar levels (34.1–51.1%) compared to the group receiving only metformin (37.1–55.3%) over a period of 30 to 360 min. Histopathological examinations of the liver tissue indicate improvement in the liver health indicators of the group treated with MetCQDs. Conclusions: Based on these results, the products have potential therapeutic advantages in diabetes management through their increased efficacy and may have reduced side effects compared to the control group. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs), as a novel type of carbon nanomaterial, are widely used in fields such as drug delivery, biosensing, fluorescent probes, and photocatalysis, benefiting from their excellent photostability, water solubility, biocompatibility, fluorescence, low-cost, and green non-toxicity. Meanwhile, due to the conjugated π structure of CQDs and surface defects generated by sp2 hybridization, they possess unique optoelectronic properties, including tunable fluorescence, good upconversion photoluminescence, and efficient photoelectron transfer. These properties are key to the role of CQDs in the field of photocatalysis. This review summarises CQDs' research progress and reaction mechanisms in photocatalysis, including their optical properties and synthesis strategies. Emphasis was placed on the application of CQDs in the field of photocatalysis, including photocatalytic CO2 conversion, degradation of organic and heavy metal pollutants, hydrogen production, and nitrogen fixation. In addition, the challenges and prospects of CQDs in the field of photocatalysis are discussed, providing new ideas for studying CQDs photocatalytic materials. [ABSTRACT FROM AUTHOR]

Copyright of Rare Metals is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Iraqi Journal of Physics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Crayfish treatment leads to the production of waste and byproducts up to 80% of the total initial seafood amount. The current common method to handle such waste is the landfilling practice which produces remarkable amounts of hazardous gasses and substances due to the anaerobic decomposition process. In this study, an integrated procedure is proposed for the valorization of wastes produced by a fish and crustaceous enterprise. Methods: According to the circular economy and environmentally friendly practices spirit, integrated vertical production and waste valorization methods are adopted globally to reduce food waste. In this study, a process consisting of four sequential steps was proposed to valorize crayfish-treatment waste. Four final added-value materials were produced during this study. The first was chitosan which was identified via the NMR technique exhibiting 91% deacetylation degree. The other two were calcium hydroxide particles of size 6.32 μm and calcium carbonate particles of size 16.9 μm exhibiting meso-macro-pore structure with Sg = 46m2/g and Sg = 20m2/g respectively. Pore specific surface area values of these two products are similar to values reported in the literature for applications such as drug carriers etc. The last product was nitrogen/sulfur-doped carbon quantum dots which exhibited an identified via AFM technique mean size of 5.01 nm. This material was successfully tested for its advanced antioxidant capabilities via the DPPH assay and for its antimicrobial properties via MIC routine measurements with E. coli and L. monocytogenes. Results: Experimental data indicated that the valorization process proposed in this study could lead to a yield of 10% w/w for chitosan after three stages treatment, to a yield of 35% w/w for Ca(OH)2 or CaCO3 after 1 stage treatment, and to a yield of 5% w/w N-S co-dopped Carbon QDs. Conclusion: The globally big amount of waste-shells from Crayfish and other crustaceous could be integratedly exploited for added-value materials production yielding economic and environmental benefits. Highlights: Crayfish waste shells are valorized. Integrated valorization of waste shells of crustaceous is feasible. Calcium carbonate and Calcium hydroxide powders exhibiting very good properties for different applications could be produced from waste shells valorization. High added value materials such as chitin and chitosan biopolymers could be produced from waste shells valorization. Advanced quantum dots such as nitrogen/sulfur dopped could be produced from waste shells valorization. [ABSTRACT FROM AUTHOR]

This study introduces a novel approach for transforming the cationic surfactant, cetyltrimethylammonium bromide (CTAB), into fluorescent carbon dots (CDs) capable of detecting cadmium ions at ultralow concentrations. The current approach involves preparing CDs through hydrothermal process at various pH levels. The CDs synthesized using pH 10, CTAB-CDs-10, exhibited the highest fluorescence quantum yield (QY), 14.22%. UV-Vis spectroscopy helped identify specific peaks between 210 and 300 nm, corresponding to the π–π* transitions of the aromatic C=C bonds. Transmission electron microscopic (TEM) analysis verified the uniform spherical morphology with a particle size < 2.45 nm. FT-IR analysis confirmed the presence of C=C stretching vibrations. The Box–Behnken (BB) Design was used to reconnoiter the influence of three variables on the response parameter: the F0/F ratio. The best performance could be achieved at a pH of 9, after only 300 s, and a temperature of 50 °C. The developed CTAB-CDs-based nanoprobe showed an ON–OFF behavior when came in contact with cadmium (II) and demonstrated high sensitivity with a limit of detection as low as 0.06 µM (0.007 ppm) over a wide linear range of 2–103 µM. Validation tests confirmed the applicability of the CTAB-CDs-based nanoprobe for detecting cadmium (II) in tap and drinking waters with high accuracy and precision. [ABSTRACT FROM AUTHOR]

Metal‐organic frameworks (MOFs) exhibit excellent crystalline, hierarchical porous structures and have garnered great scientific interest as a key material for supercapacitor applications. However, the low conductivity of MOFs poses a great challenge to fully utilize their potential. Carbon quantum dots (CQDs) prepared from waste edible soybean oil have been skillfully incorporated into NiCo MOF to enhance supercapacitive performance with its high electronic conductivity and rapid charge transfer kinetics. Symmetrical, spherical CQDs synthesized using the hydrothermal method have been decorated on NiCo MOF nanosheets using a facile solvothermal technique to form the NiCo MOF@CQDs composite. The new composite retains the desirable crystalline structure and hierarchical porosity of MOFs, while the integration of CQDs contributes to enhanced conductivity, yielding a superior specific capacitance of 1063.02 Fg−1 (0.5 Ag−1). An asymmetric supercapacitor device has been fabricated using NiCo MOF@CQDs as positive electrode and waste soybean oil‐derived activated‐carbon as negative electrode. The assembled device shows a remarkable energy and power density of 30.61 Whkg−1 and 0.62 kWkg−1, respectively. Moreover, the device demonstrates a promising Coulombic efficiency of 84.53%, with capacitance retention of 88.61% over 5000 charge–discharge cycles. This work highlights existing challenges and potential sustainable solutions in the realm of emerging energy storage devices. [ABSTRACT FROM AUTHOR]

There are many disadvantages such as small detection range and environmental restrictions on application conditions, when the single quantum dot powder or solution is used for fluorescent probe detection. In this paper, the blue fluorescent silicon quantum dots and green fluorescent carbon quantum dots were prepared, and their fluorescence color changes after mixing in different proportions were investigated under different pH conditions. When the two quantum dots were mixed with a concentration of 0.1 mg·mL−1 and a mass ratio of 1:1, the fluorescence color change could be better displayed at a pH from 1 to 14. Meanwhile, the double quantum dots were prepared into two forms (ink and film), successfully realizing the device application of the fluorescent probe. The films and inkjet-printed labels were used to test the spoilage of food (pork, milk, etc.), and the color change data of the labels were collected during the spoilage test. These data were used for neural network training to predict the spoilage changes of foods. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CDs) would gradually replace metal-based quantum dots due to their advantages of excellent photo-physical properties, low toxicity, and outstanding water solubility. In the current study, the hydrothermal synthesis method was simple, convenient, and fast, and herein was used to prepare nitrogen-doping carbon dots (N-CDs) from the combination of Ginkgo biloba L. leaves and ethylenediamine as carbon and nitrogen precursors, respectively. Furthermore, butocarboxim, a carbamate pesticide, can quench the fluorescence of proposed N-CDs. Therefore, the fluorescent signal changes of N-CDs caused by butocarboxim contributed to robust and sensitive butocarboxim sensing. Under the optimal condition, the fluorescent sensor based on the as-prepared N-CDs demonstrated a good linear response for butocarboxim detection in the range of 0.625–40.0 μg/L with a limit of detection (LOD) of 0.2 μg/L. In addition, the sensor was successfully applied to butocarboxim determination in real water samples and obtained acceptable results with the recoveries ranging from 97.2 to 106.8% and the RSD less than 6%. [ABSTRACT FROM AUTHOR]

We have developed carbon quantum dots (CQDs) with excellent photoluminescence (PL) properties from macaúba (Acrocomia aculeate) fibers; a widely available cellulosic biomass species of palm trees in South America. As-prepared CQDs showed quasi-spherical morphology with high aqueous solubility and strong excitation-dependent fluorescence behaviour. Interestingly, the CQDs display fluorescence 'turn-off' response with excellent sensitivity toward multi-metal ions including Fe3+, Cu2+ and Hg2+ with very low detection limits of 0.69 μM, 0.99 μM, 0.25 μM, respectively. Notably, ascorbic acid (AA) induced a change in the (turn-off) fluorescence of Fe3+-CQDs, which caused an almost 70% revival of fluorescence (turn-on) by displacing Fe3+ ions. We have also harnessed CQDs as the visible-light-induced photocatalyst to reduce CO2 in water. Especially, the CQDs efficiently promote the photocatalytic reduction of CO2 into methane (CH4) with an evolution rate of 99.8 nmol/g at 436 nm in aqueous conditions. This indicates that the CQDs provide abundant active sites for CO2 adsorption and thus enhance the separation and migration of photo-induced charge carriers that efficiently reduce CO2 into CH4 without any co-catalyst in 100% water. [ABSTRACT FROM AUTHOR]

AbstractThis study reports the design and development of a disposable amperometric biosensor for the determination of L-glutamate. Glutamate oxidase (GlOx) was immobilized onto a screen-printed carbon electrode (SPE) modified with poly-L-Aspartic acid (PAsp), carbon quantum dots (CQD), and platinum nanoparticles (PtNP) for the construction of the biosensor. The surface composition of the modified SPE was optimized using the one variable at a time method. The morphological properties of the biosensor were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The electrochemical behavior of the modified electrodes was studied by cyclic voltammetry. Under the optimized experimental conditions the linear working range, detection limit and sensitivity of the GlOx/PtNP/CQD/PAsp/SPE were found to be 1.0 − 140 µM, 0.3 µM and 0.002 µA µM−1, respectively. The GlOx/PtNP/CQD/PAsp/SPE biosensor also exhibited good measurement repeatability. The as-developed biosensor was applied for the determination of L-glutamate in spiked serum samples and the average analytical recovery of added glutamate was 98.9 ± 3.9%. [ABSTRACT FROM AUTHOR]

3D printing provides a lot of varieties for the manufacturing of personalized biomedical devices. Incorporation of the nanoparticles with potential antibacterial activity to the printed materials is another added value. One example of such nanoparticles are hydrophobic carbon quantum dots (hCQDs), which are zero-dimensional redox-active materials with high chemical stability and low production costs. They produce singlet oxygen only when activated by a specific wavelength of visible blue light which allows for controlled antibacterial action and minimizes the chances of bacterial resistance emergence. We prepared and characterized polymer composites based on thermoplastic elastomers (TPE) doped with hCQDs (TPE/hCQDs). The composites were 3D printed using fused deposition modeling method. In the first set of samples, a filament of pure TPE was immersed in a solution of hCQDs (0.5 mg/mL), then 3D printed, and compared with unmodified TPE filament. The mechanical properties, swelling behavior, hardness, and thermal stability of TPE/hCQDs were compared with the pure TPE printed samples. The production of singlet oxygen was confirmed by the electron paramagnetic resonance method. The antibacterial activity of the samples was tested according to ISO 22196 against Staphylococcus aureus and Escherichia coli after one hour of exposure to blue light, which completely inhibited bacterial growth. Besides, the cytotoxicity of samples was evaluated by MTT assay, and no significant effect of the materials on cell viability was observed. 3D printed materials with antibacterial activity represent a perspective for the future, especially in the field of personalized medicine, as well as in products for other industries. [ABSTRACT FROM AUTHOR]

A nanohybrid-modified glassy carbon electrode based on conducting polypyrrole doped with carbon quantum dots (QDs) was developed and used for the electrochemical detection of anti-tissue transglutaminase (anti-tTG) antibodies. To improve the polypyrrole conductivity, carrier mobility, and carrier concentration, four types of carbon nanoparticles were tested. Furthermore, a polypyrrole-modified electrode doped with QDs was functionalized with a PAMAM dendrimer and transglutaminase 2 protein by cross-linking with N-hydroxysuccinimide (NHS)/N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC). The steps of electrode surface modification were surveyed via electrochemical measurements (differential pulse voltammetry (DPV), impedance spectroscopy, and X-ray photoelectron spectroscopy (XPS)). The surface characteristics were observed by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and contact angle measurements. The obtained modified electrode exhibited good stability and repeatability. DPV between − 0.1 and 0.6 V (vs. Ag/AgCl 3 M KCl reference electrode) was used to evaluate the electrochemical alterations that occur after the antibody interacts with the antigen (transglutaminase 2 protein), for which the limit of detection was 0.79 U/mL. Without the use of a secondary label, (anti-tTG) antibodies may be detected at low concentrations because of these modified electrode features. [ABSTRACT FROM AUTHOR]

A ratiometric fluorescence probe based on carbon quantum dots with 420 nm emission (bCQDs) and a p-phenylenediamine-derived fluorescence probe with 550 nm emission (yprobe) is constructed for the detection of Mn2+. The presence of Mn2+ results in the enhanced absorption band at 400 nm of yprobe, and the fluorescence of yprobe is significantly enhanced based on the chelation-enhanced fluorescence mechanism. The fluorescence of bCQDs is then quenched based on the inner filtration effect. The ratio (I550/I420) linearly increases with the increase of Mn2+ concentration within 2.00 × 10−7–1.50 × 10−6 M, and the limit of detection is 1.76 × 10−9 M. Given the fluorescence color changing from blue to yellow, the visual sensing of Mn2+ is feasible based on bCQDs/yprobe coupled with RGB value analysis. The practicability of the proposed method has been verified in tap water, lake water, and sparkling water beverage, indicating that bCQDs/yprobe has promising application in Mn2+ monitoring. [ABSTRACT FROM AUTHOR]

The present study explores the synthesis and bio-safety evaluation of gadolinium-doped carbon quantum dots (GCQDs) as a potential dual-contrast agent for diagnostic imaging. GCQDs exhibit both fluorescent and magnetic properties, making them suitable for UV–Vis and magnetic resonance imaging (MRI). The synthesis of GCQDs was achieved via hydrothermal treatment, incorporating gadolinium into the carbon quantum dot matrix. The magnetic properties of GCQDs were analyzed, showing significantly enhanced values compared to gadobutrol, a common MRI contrast agent. However, synthesis constraints limit the gadolinium content achievable in nanodots. To assess the safety of GCQDs, their effects on the embryonic development of zebrafish (Danio rerio) were examined. Various concentrations of GCQDs were tested, observing mortality rates, hatchability, malformations, heartbeats, spontaneous movement, and GCQDs uptake. Dialysis studies indicated that gadolinium ions are incorporated into the internal structure of the carbon nanodots. Zebrafish toxicity tests revealed that while survival rates were comparable to control groups, hatchability decreased significantly with higher gadolinium concentrations in GCQDs. Fluorescence microscopy showed no statistical differences in the fluorescence intensity between groups. These findings suggest that GCQDs could serve as an effective dual-contrast agent, combining the optical imaging capabilities of CQDs with the enhanced MRI contrast provided by gadolinium. This study underscores the need for further research on the synthesis methods and biological interactions of GCQDs to ensure their safety and efficacy in medical applications. [ABSTRACT FROM AUTHOR]

This science popularization experiment is themed around the beloved magical literature character Harry Potter and his tour in China, specifically focusing on his journey at Wuhan. The experiment showcases the bronze restoration technology used in museums, the sacrificial anode anti-corrosion technology of the "Zhiyin" cruise ship, the cement solidification and 3D printing technology used in the Wuhan Yangtze River Bridge, and the preparation of carbon quantum dots depicted in the Yellow Crane Tower. Through these demonstrations, chemical knowledge is subtly disseminated. [ABSTRACT FROM AUTHOR]

In this work, planar-heterojunction organic phototransistors (OPT) have been constructed from solution process, by combining a semiconducting diketopyrrolopyrrole polymer PDVT-10 and a novel carbon nano-material-carbon quantum dots (CQDs). The PDVT-10/CQDs planar heterojunction films, possessing the optical properties of both PDVT-10 and CQDs, reveal strong optical absorption in a wide spectral region from ultraviolet to near infra-red. Compared with pristine PDVT-10 phototransistors, such planar-heterojunction OPTs exhibit a remarkably higher performance on broad-spectrum photo-detection, with a photoresponsivity of 2.6 x 104 A/W, a specific detectivity of 2.4 x 1013 Jones, and maximum light sensitivity higher than 104 under the 450-nm laser irradiation, as well as with a responsivity of 4.4x104 A/W and a specific detectivity of 1.2 x1013 Jones under the 808-nm laser irradiation. Based on the study of the photo-response mechanism for these devices, the performance improvement of the PDVT-10/CQDs based OPTs should be attributed to the favorable energy level alignment at the PDVT-10/CQDs interfaces, which enhances interfacial exciton dissociation and charge separation, meanwhile effectively suppresses the hole-electron recombination in the light-absorption layer. Furthermore, the formation of efficient carrier conduction pathway is benefited from high hole-mobility of PDVT-10 for the OPT performance enhancement. Our work offers a valuable avenue for the development of high performance light detectors. [ABSTRACT FROM AUTHOR]

The development of portable and cost-effective sensing system for Hg2+ quantitation is highly demanded for environmental monitoring. Herein, an on-site, rapid and portable smartphone readout device based Hg2+ sensing system integrating nitrogen-doped carbon quantum dots (NCDs) modified paper strip was proposed, and the physicochemical properties of NCDs were characterized by high resolution TEM, FTIR, UV–vis absorption spectrum and fluorescence spectral analysis. The modified paper strip was prepared via "ink-jet" printing technology and exhibits sensitive fluorescence response to Hg2+ with fluorescence color of bright blue (at the excitation/emission wavelength of 365/440 nm). This portable smartphone-based sensing platform is highly selective and sensitive to Hg2+ with the limit of detection (LOD) of 10.6 nM and the concentration range of 0–130 nM. In addition, the recoveries of tap water and local lake water were in the range of 89.4% to 109%. The cost-effective sensing system based on smartphone shows a great potential for trace amounts of Hg2+ monitoring in environmental water samples. [ABSTRACT FROM AUTHOR]

The development of a fluorescent pH sensor and the treatment of wastewater with nanoparticles are both critical topics. Variations in pH impact the morphology and subsequent properties of nanoparticles, affecting their utilization in various fields, while using nanoparticles offers an improved approach for treating industrial waste. The present study examines the effects of these variables on biologically produced nitrogen-doped carbon quantum dots (NCQDs). The synthesis was achieved through a hydrothermal process using Rubus niveus leaf extract as a precursor. UV-Vis spectroscopy analysis revealed absorption spectra over a wide range from 200 nm to 800 nm, with prominent peaks at 236 nm and 392 nm. Additionally, the direct energy band gap of the NCQDs was found to be 3.65 eV. SEM imaging displayed flower-shaped particles, and FT-IR analysis indicated the presence of amide, CHO, N-H, and C-N functional groups. The XRD pattern revealed that the surface morphology of NCQDs is amorphous in nature. A significant response in fluorescence intensity with varying pH values was observed, confirming the potential of NCQDs as pH sensors. The reaction kinetics of Rhodamine-B (Rh-B) dye was analyzed to assess the potential of NCQDs for dye degradation, revealing pseudo-first-order kinetics with a correlation coefficient of 0.80. [ABSTRACT FROM AUTHOR]

Carbon quantum dots (CQDs), an emerging nanomaterial, are gaining attention in ophthalmological applications due to their distinctive physical, chemical, and biological characteristics. For example, their inherent fluorescent capabilities offer a novel and promising alternative to conventional fluorescent dyes for ocular disease diagnostics. Furthermore, because of the excellent biocompatibility and minimal cytotoxicity, CQDs are well-suited for therapeutic applications. In addition, functionalized CQDs can effectively deliver drugs to the posterior part of the eyeball to inhibit neovascularization. This review details the use of CQDs in the management of ophthalmic diseases, including various retinal diseases, and ocular infections. While still in its initial phases within ophthalmology, the significant potential of CQDs for diagnosing and treating eye conditions is evident. [ABSTRACT FROM AUTHOR]

Evaluation of the impact of the latest root canal disinfectant, that is carbon quantum dots (CQDs), synchronized microbubble‐photodynamic activation (SYMPA), and Nd: YAG laser along with ethylenediaminetetraacetic acid (EDTA) as a final irrigant on the Marten hardness (MH), smear layer (SL) removal, and extrusion bond strength (EBS) of zirconia post to the canal dentin. Eighty intact single‐rooted premolars were obtained and disinfected using 0.5% chloramine‐T solution. Root canal preparation was performed using ProTaper files followed by obturation. The post space was prepared for prefabricated zirconia post and all the teeth were randomly divided into four groups based on the disinfection used (n = 20 each) Group 1: 5.25% NaOCl + 17% EDTA (Control), Group 2: Nd: YAG laser + 17% EDTA, Group 3: SYMPA + 17% EDTA, and Group 4: CQDs + 17% EDTA. MH, SL removal, and EBS of zirconia post‐bonded to root dentin were performed using a microhardness tester, scanning electron microscope (SEM), and universal testing machine, respectively. Both intragroup and intergroup comparisons were performed using one‐way analysis of variance (ANOVA) and posthoc‐Tukey test for significant difference (p <.05). Group 2 samples (Nd: YAG laser + 17% EDTA) (0.24 ± 0.06 GPa) exhibited highest values of MH. Samples in group 3 (SYMPA + 17% EDTA) treated teeth unveiled the lowest MH scores (0.13 ± 0.02 GPa). Moreover, the coronal third of Group 3 specimens (SYMPA and 17% EDTA) (1.54 ± 0.31) eliminated SL from the canal with the greatest efficacy as well as presented the highest EBS (10.13 ± 0.69 MPa). However, the apical third of Group 1 samples (5.25% NaOCl + 17% EDTA) (2.95 ± 0.33) exhibited the least efficient elimination of SL from the radicular dentin as well as the lowest bond strength (5.11 ± 0.19 MPa) of zirconia post to the dentin. The SYMPA technique with 17% EDTA proved highly effective in removing the SL from canal dentin and enhancing the EBS of zirconia posts. The least preferable method for SL removal and MH improvement was found to be 5.25% NaOCl + 17% EDTA. CQDs and Nd: YAG laser demonstrated satisfactory smear layer removal properties from the canal, along with achieving appropriate bond strength of zirconia posts. Research Highlights: Nd: YAG laser and 17% EDTA as canal disinfectant exhibited the highest values of MH.Specimens irrigated with SYMPA and 17% EDTA eliminated SL from the canal with the greatest efficacy.The coronal third of Group 3 (SYMPA + 17% EDTA) samples unveiled the highest zirconia post‐bond integrity score to the canal dentin.Cohesive failure was a dominant failure type among different experimental groups. [ABSTRACT FROM AUTHOR]

As an emerging information device that adapts to development of the big data era, memristor has attracted much attention due to its advantage in processing massive data. However, the nucleation and growth of conductive filaments often exhibit randomness and instability, which undoubtedly leads to a wide and discrete range of switching parameters, damaging the electrical performance of device. In this work, a strategy of inserting carbon quantum dots (CQDs) into graphene oxide (GO) resistance layer is utilized to improve the stability of the switching parameters and the reliability of the device is improved. Compared with GO-based devices, GO/CQDs/GO-based devices exhibit a more stable resistance switching curve, low power, lower and more concentrated threshold voltage parameters with lower variation coefficient, faster switching speed, and more stable retention and endurance. The cause-inducing performance improvement may be attributed to the local electric field generated by CQDs in resistance switching that effectively guides the formation and rupture of conductive filaments, which optimizes the effective migration distance of Ag+, thereby improving the uniformity of resistance switching. Additionally, a convolutional neural network model is constructed to identify the CIFAR-10 data set, showing the high recognition accuracy of online and offline learning. The cross-kernel structure is used to further implement convolutional image processing through multiplication and accumulation operations. This work provides a solution to improve the performance of memristors, which can contribute to developing digital information processing. [ABSTRACT FROM AUTHOR]

Mercury ion (Hg2+) is one of the most toxic pollutants that can exist throughout the environment and be diffused into water, soil, air, and eventually the food chain. Even a very low level of Hg2+ diffused in living organisms can hurt their DNA and cause the permanent damage of the central nervous system and a variety of consequential disorders. Hence, the development of a sensitive and specific method for the detection of Hg2+ at trace ranges is extremely important as well as challenging. Fluorometric detection assays based on graphene quantum dots (GQDs) and carbon quantum dots (CQDs) offer considerable potential for the determination and monitoring of heavy metals due to their fascinating properties. Although the quantum yield of GQDs and CQDs is sufficient for their use as fluorescent probes, doping with heteroatoms can significantly improve their optical properties and selectivity toward specific analytes. This review explores the primary advances of CQDs and GQDs in their great electronic, optical, and physical properties, their synthetic methods, and their use in Hg2+ fluorimetry detection. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, the properties of the photodetector were improved by using carbon quantum dots (CQDs) and tris (8-hydroxyquinoline) aluminium (III) (Alq3) polymer when deposited on glass and silicon substrates. CQDs were prepared using an electrochemical method. Two methods of deposition were used; the first was drop casting, and the other was spin coating. The structural, electrical, and optical properties were studied. Measurements were made of the manufactured photoconductive detector's current-voltage (I–V) properties, photocurrent gain, response time, and quantum efficiency, responsivity. The constructed detector's performance was measured without light and using a 250-watt tungsten lamp, whose wavelength range was between 500 and 800 nm. The results showed that the best photodetector was when carbon quantum dots were used with Alq3 deposited on a silicon substrate using the drop-casting method (CQD:Alq3/Si). It was observed that the best gain, fastest rise, fall, and response times were 7.97, 0.98, 1.1, and 0.34 s, respectively.

Spermine is a polyamine that participates in ion channel regulation and cell proliferation. It is considered a biomarker for pancreatic cancer. In this study, a carbon nanostructure-based aptasensor has been developed to rapidly detect spermine in solution by relying on Förster resonance energy transfer (FRET). The FRET donor, carbon quantum dots (CDs), are bioconjugated to aptamers specific for spermine. CDs have an average diameter of 5.0 ± 2.5 nm and have the maximum fluorescence intensity emitting at 510 nm when excited at 400 nm. Due to the π-π* interaction between DNA-based aptamer and GO, a FRET quencher, CDs bioconjugated with aptamer (CDs-aptamer) can directly attach on the surface of GO, resulting in significant FRET quenching. In the presence of spermine, GO and CDs-Aptamer separate, and the fluorescence intensity of CDs is restored. The restored fluorescence intensity of CD-aptamer can be observed when the concentration of spermine increases from 0.1 to 250 nM. The sensing system in this study could be a cost-effective, user-friendly method to quickly detect spermine, a biomarker for pancreatic cancer.

In this work we show a procedure of treating of the graphene oxide in alkaline environment as a function of the treatment time in order to obtain novel structures with strong luminescence properties, water-stable, useful as potential replacement for critical raw materials employed as example in optical and optoelectronic devices or for diagnostic and therapeutic technology. These structures have distinct blue and green-luminescence properties which derived most likely from different structural conformations, one associable with that of carbon quantum dots (or as an alternative to that of the Oxidative Debris), the other, lighter and more similar to organic compounds, reported in literature as fulvic-like molecules, but whose nature has to be further investigated. We show that the lighter fraction has a dual mechanism of photoemission: the excitation-independent PL for excitation wavelength within 350 nm and the excitation-dependent component for excitation wavelength ranging in the visible spectrum. The PL dual behaviour could depend on fluorescent nanoclusters composed by specific organic fluorophores with a carbonaceous core. FTIR analysis shows reasonably the same functional groups unless of some difference discussed in the text, meanwhile UV–Vis and PL analysis clearly highlight two distinct emissions (450 nm and 530 nm) in the visible region of the electromagnetic spectrum. Excitation-dependent photoluminescence, water stability and organic fluorescent nanostructures are issues particularly required for application in the biological field but also in materials science.

Carbon quantum dots (CQDs) are carbon-based biocompatible quantum dots that have low toxicity, are more soluble in water, have broad application areas, and the surface modification of these can be performed easily. In this study, we present a new CQD synthesis method with cost-effective reactants that can be easily found in laboratories are used. Besides, there is a definitive indication (bubble) for CQD production, unlike the other methods in the literature. The purification method of the CQDs was also optimized in this study. In the beginning of the synthesis, 3 times centrifugation (x3 CF) of the mixture was performed and the optimization of the purification method indicated that x3 CF before 3 days of dialysis membrane tubing (x3 CF & 3 DM) resulted in the formation of the purest CQDs. The characterization of the CQDs was done utilizing UV–VIS spectrophotometer, Fourier Transfer Infrared Spectroscopy (FT-IR), Zetasizer, fluorescence microscopy, Dynamic Light Scattering (DLS), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Transmission Electron Microscopy (TEM). It was concluded that the CQD formation depended on the mixing of sulphuric acid:acetone (2:1) ratio in a hot (140–165 °C) and an inert environment, and bubble coverage of the mixture surface (30–60 s). The bubble formation due to the reaction between sulphuric acid and pure acetone at high temperatures gives the developed method’s name of “Hot Bubble Synthesis” (HBBBS).

This study investigates the green synthesis of carbon quantum dots (CQDs) from spent coffee grounds using a hydrothermal method, offering an eco-friendly, cost-effective, and straightforward approach to nanomaterial production. The synthesized CQDs, with particle sizes ranging from 1.6 to 4.4 nm, exhibited notable fluorescence, achieving quantum yields of 37.0 %, 54.3 %, and 63.3 % depending on the coffee source. Characterization technique, including XRD, FTIR, SEM, TEM, and BET, confirmed their structural suitability of these CQDs for energy storage applications. Their electrochemical performance was evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the CQDs tested, those derived from spent Liberica coffee ground (medium roasted) demonstrated superior performance, with a discharging specific capacitance of 97.5 F/g, an energy density of 4.3 Wh/kg, and a power density of 130.6 W/kg at a current density of 0.5 A/g. Additionally, they exhibited acceptable internal resistance (Ra = 0.01 kΩ and Rab = 16.9 kΩ), indicating favourable charge transfer characteristics. These results underscore the enhanced energy storage potential of CQDs derived from spent coffee grounds. The findings not only highlight the excellent electrochemical performance but also support the viability of biomass waste as a valuable resource for advanced energy storage applications, promoting sustainable, eco-friendly technologies.

Carbon Quantum Dots from Natural Sources (NACQDs) is a novel type of carbon-based material that have garnered significant attention due to their remarkable features, including luminescence, photostability, nanoscale size, water solubility, low toxicity, biocompatibility, and cost-effectiveness. The synthesis of NACQDs involves a diverse range of natural sources, such as fruits, foods, beverages, human and animal derivatives, vegetables, leaves, and waste materials. Various synthesis methods, including electrochemical approach, chemical oxidation, hydrothermal carbonization, ultrasonic techniques, microwave-assisted synthesis, solvothermal method, laser ablation technique, thermolysis, and atmospheric plasma-based synthesis, have been explored to tailor the size and properties of NACQDs. Characterization techniques like Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TЕM), ultraviolet absorption, fluorescence properties, and nuclear magnetic resonance (NMR) have provided invaluable insights into the physical and chemical characteristics of NACQDs. This review highlights the immense potential of NACQDs in metal ion sensing applications and underscores the need for further investigation to enhance their reproducibility and precise control over their properties. NACQDs hold great promise as versatile nanomaterials for metal ion sensing and are poised to revolutionize diverse fields, ranging from environmental monitoring to biomedical diagnostics and chemical analysis.