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Citrate is a potential biomarker for early stage detection of prostate cancer (PC), its concentration significantly dropped to 2-20 mM in PC patients. Herein, a cheap, simple, and reliable citrate sensor was proposed based on the biogenic synthesis of nitrogen-doped carbon dots (N-CDs) derived from the biowaste of Syzygiumcumini (S. cumini) seeds. The prepared N-CDs were characterized by TEM, FT-IR and spectral studies. The average size of the N-CDs was found to be 2.4 nm, the presence of -OH and -NH 2 functional groups on the surface of N-CDs was confirmed by FT-IR analysis. The N-CDs possess the highest emission at 414 nm and cause quenching after reacting with citrate, which is due to the possible hydrogen bonding interactions between the probe and citrate. The probe expressed the lowest limit of detection of 3.5 nM, high selectivity, high interfering ability (1000-fold), provided a stable response at 5 min of reaction time, good biocompatibility, and delivered a contrast bioimage with different concentrations of citrate. The N-CDs were utilized to detect citrate in human urine samples, obtained good recovery results, and validated with the high-performance liquid chromatography method., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Development of a rapid and sensitive detection method for hazardous dyes attracts considerable research interest. In this work, L-Tryptophan-based Carbon dots were developed as a fluorescence sensor for the detection of Malachite green (MG). Green fluorescent L-Trp-C-dots were synthesized by a simple pyrolysis technique using L-Trp as the starting precursor. L-Trp-C-dots exhibited different quenching responses to MG, and other interfering species, consequently offering a selective strategy to detect MG. The proposed sensor shows a limit of detection (LOD) of 0.06 μM and a limit of quantification (LOQ) of 0.22 μM with in the linearity range of 0 to 60 µM concentration. Additionally, the relative standard deviation (RSD) was found to be below 1.7 %. Furthermore, the recovery of MG from the real-time samples (green peas) was investigated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Propranolol, a medication used to treat cardiovascular diseases, can be harmful when overdosed and hazardous to ecosystems if released into the environment. Here, a new molecularly imprinted fluorescent sensor was developed from carbon dots through a sol-gel method. Carbon dots served as both the fluorescent signal and the carrier, with propranolol as the template molecule and 3-aminopropyltriethoxysilane as the functional monomer to be grafted on carbon dots' surface. A novel detection method was established for the efficient, rapid, and cost-effective detection of propranolol in human plasma through quantitative analysis by using a fluorescence spectrophotometer and an ultraviolet spectrophotometer. Under the optimal conditions, the detection range of 0.5-4 mg L -1 , the detection limit of 0.092 mg L -1 , the imprinting factor of 2.42, and the detection response time of 2 min were achieved. The prepared carbon dot-based molecularly imprinted fluorescent sensor was proved to have a wide accurate linear range, low detection limit, and very short response time, and can detect lower analyte concentrations with higher detection accuracy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this work, a simple and sensitive ratiometric fluorescence probe to detect isoniazid (INH) was developed on the basis of carbon dots and MnO 2 nanosheets (MnO 2 NS). Nitrogen-doped carbon dots (FMT-CDs) were synthesized by microwave method using formononetin (FMT) in ammonia water. The oxidase-like activity of MnO 2 NS was utilized to oxidize non-fluorescent o-phenylenediamine (OPD) to 2, 3-diaminophenazine (DAP) with orange fluorescence. It was demonstrated that DAP could effectively quench the fluorescence of FMT-CDs through the inner filtering effect (IFE). Due to the reducing nature of INH, MnO 2 NS was decomposed and thus lost its oxidase-like activity after the addition of INH. Therefore, the production of DAP was reduced, and the fluorescence intensity was decreased, while IFE on FMT-CDs was weakened and the fluorescence of FMT-CDs was recovered. Based on the above principle, a sensitive method for the detection of INH was established based on the fluorescence intensity ratio of the two fluorescent substances, FMT-CDs and DAP, and was successfully applied to the detection of INH in human urine samples. The limit of detection (LOD) could reach to 0.16 μM in human urine samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Biothiol analysis is significant to health assessment and early detection of potential diseases. Considering practical requirements, simple and rapid identification and determination of biothiols are still a great challenge due to the similar structures. Fortunately, the recently emerging colorimetric sensor array technique makes such a task possible. Herein, one-component dual-mode sensor array consisting of carbon dots (CDs) and Ag nanoparticles (AgNPs) system was designed for identification and quantification of biothiols. The identification principle is based on the inner filter effect (IFE) and different binding constants. Due to the IFE between CDs and AgNPs, the fluorescence of CDs was quenched, but recovered again after addition of biothiols because of the binding of biothiols with AgNPs. Significantly, the fluorescence recovered in varying degree due to the different binding constants of biothiols to AgNPs. Meanwhile, the absorbance of the system decreased and the color of the solution deepened. Therefore, the CDs-AgNPs system with fluorescence and absorbance response was used as the single sensing unit and generated the cross-responsive signal for different biothiols. The sensor array achieved 100 % accuracy in identifying biothiols and biothiol mixtures. Moreover, the rapid quantification of biothiols in serum samples was also achieved by RGB-based smartphone colorimetry. The way to construct one component sensor array with dual mode signal outputs tremendously saves cost and time, providing a powerful tool for the identification of different biothiols. In addition, the rapid quantification of biothiols in serum samples based on RGB-based smartphone colorimetry demonstrated its powerful application prospects in disease diagnosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Chlortetracycline (CTC), a widely used antibiotic, poses potential health risks due to its residues in animal products, making its detection crucial for environmental and human health. This study introduces a novel, rapid, and sensitive method for CTC detection utilizing nitrogen-doped green fluorescent carbon dots (G-CDs) synthesized through a simple hydrothermal process. The G-CDs exhibit strong green fluorescence and high quantum yield, demonstrating excellent selectivity and sensitivity for CTC detection. An investigation of the fluorescence quenching mechanism revealed a combination of static quenching and the inner filter effect (IFE). Additionally, the incorporation of G-CDs into a polyvinyl alcohol (PVA) film resulted in a fluorescent hybrid polymer film with potential applications in optoelectronics. This research not only provides a cost-effective and reliable approach for CTC detection but also expands the utility of high-fluorescence carbon dots in practical applications, contributing to advancements in both environmental monitoring and materials science., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

For the first time, advanced chemometric models were utilized to determine florescence induced by carbon dots. In an endeavor to regulate anthelmintic drug usage by facilitating the determination of veterinary formulations in animals' biological fluids, a novel fluorometric-assisted chemometric method has been developed for detecting two nonfluorescent drugs, Ivermectin (IVR) and Clorsulon (CLR). The method relies on the linear quenching effect of the drugs on the fluorescence intensity of carbon dots (CDs) synthesized from natural sources. Despite the significant overlap, chemometric models such as partial least squares (PLS) and artificial neural networks (ANN), assisted by genetic algorithms (GA), successfully resolved the issue and achieved high-precision recovery of both drugs. The method demonstrates a linearity range of 50-6000 ng/mL, rendering it suitable for determining both drugs in biological animal fluids. To ensure practical application, the method was applied to veterinary formulations and spiked animal plasma, yielding satisfactory results. Finally, a comparison of the proposed method with official ones revealed no significant differences. According to principles of white analytical chemistry (WAC), the method also obeys sustainability rules. The method was therefore proven to be a novel, safe and applicable alternative approach for this formulation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A rapid, eco-friendly, and selective monitoring of Fe(III) in real media utilizing carbon dots (CDs) as a luminescence detector has been reported. CDs were fabricated by a hydrothermal route from empty fruit bunch biochar. The as-synthesized CDs were analyzed using various analytical tools. The results reveal that CDs have spherical shapes with a narrow particle size distribution and are enriched with multiple active sites, which impart excellent hydrophilicity and photostability. The CDs displayed bright blue emission under UV light with emission/excitation maxima at 452/350 nm, respectively, and a QY of 7.54%. The CDs exhibited high resistance to photobleaching and high salt conditions and pose a long lifetime of up to 6 months with no agglomeration. The detection variables, including pH, temperature, and CDs concentration, were optimized via response surface methodology. The statistical data verified the precision of the quadratic model for predicting the sensing performance of the nanoprobe. Under optimal environments, a linear range from 0 to 50 μM and a detection limit of 0.17 μM was obtained. The turn-off process includes the strong coordination between Fe(III) and electron-donating oxygen species on the edge of CDs. The rapid luminescence recognition using acid-free materials renders CDs a promising option for water treatment., (© 2025 John Wiley & Sons Ltd.)

Carbon dots in biosensing have advanced significantly, adding improvements to different detection techniques. In this study, an amperometric immunosensor for Salmonella Thyphimurium was designed using antibodies labeled with carbon dots (Cdots) from pequi almond (Caryocar brasiliensis). Cdots were synthesized by pyrolysis and characterized by FTIR, UV/fluorescence, electrochemistry, zeta potential, and transmission electron microscopy (TEM). A particle size of 6.80 ± 2.13 nm was estimated, and the zeta potential was - 47.4 mV, indicating the preponderant presence of acidic groups, as confirmed by FTIR. The impedance evaluation of the response of biosensors assembled for live (Rct = 13.4 kΩ) and dead (Rct = 499.7 Ω) Salmonella showed a significant difference in their values, in agreement with chronoamperometric analyses, which had their current values drastically reduced from - 2.2 mA (live) to 0 mA (dead). An analytical curve for Salmonella was established with the limit of detection lower than 1 CFU/mL. This electrochemical biosensor using pequi carbon dots for antibody labeling showed promising results for detecting the pathogen. Thus, carbon dots can be used as substitutes for enzymes in labeling antibodies used in the design and production of sensors., Competing Interests: Declarations. Competing interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2025. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Nanozymes, a revolutionary category of engineered artificial enzymes based on nanomaterials, have been developed to overcome the inherent limitations of natural enzymes, such as the high cost associated with storage and their fragility. Carbon dots (CDs) have emerged as compelling candidates for various applications due to their versatile properties. Particularly noteworthy are CDs with a range of surface functional groups that exhibit enzyme-like behavior, combining exceptional performance with catalytic capabilities. This review explores the methodologies used for synthesizing CDs with enzyme mimicking capabilities, highlighting potential avenues such as doping and hybrid nanozymes to enhance their catalytic efficacy. Moreover, a comprehensive overview of CDs that mimick the activities of various oxidoreductases-like peroxidase, catalase, oxidase/laccase, and superoxide dismutase-like is provided. The focus is on the in-depth exploration of the mechanisms, advancements and practical applications of each oxidoreductase-like function exhibited by CD nanozymes. Drawing upon these exhaustive summaries and analyses, the review identifies the prevailing challenges that hinder the seamless integration of CDs into real-world applications and offers forward-looking perspectives for future directions., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier B.V.)

Potassium ions (K + ) perform a variety of functions in biological systems, including the regulation of blood pressure, enzyme activation, maintenance of muscular strength, regulation of extracellular osmolarity and facilitation of nerve transmission. Thus, a one-step hydrothermal-assisted method was used to prepare small-sized photoluminescent carbon dots (CDs) from Chocolate Brown HT food dye for the first time. The resulting CDs exhibited strong blue emission, with sizes ranging from 1.8 to 3.2 nm (average 2.5 nm) and an estimated quantum yield of 42.76 %. The complex functional groups present on the surface of the CDs enhance their affinity for certain ions. Leveraging the effective fluorescence quenching effect of K + , we developed a highly sensitive CD-based fluorescence analytical system with a limit of detection of 0.32 nmol/L. Linearity was established between 1.0 nmol/L and 400 nmol/L. Furthermore, K + detection in staple food samples was accomplished using this sensor. The use of 1200 nmol/L sodium ions as an interfering agent resulted in an error of less than 5 %. To validate the accuracy of the proposed method, the results were compared to those obtained using flame atomic emission spectroscopy as a reference method, yielding recovery values ranging from 97.69 % to 103.19 %., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The predominant adverse health effects in care delivery result from hospital-acquired (nosocomial) infections, which impose a substantial financial burden on global healthcare systems. Integrating contact-killing antibacterial action, gas permeability, and antioxidant properties into textile coatings offers a transformative solution, significantly enhancing both medical and everyday protective applications. This study presents an innovative, pollution-free physical compounding method for creating a fluorescent biopolymer composite embedded with silicene-based heteroatom-doped carbon quantum dots for the production of functional textiles. The resulting coated fabric shows superior ultraviolet (UV) protection behavior (UV A and UV B ), thermal stability, breathability, mechanical strength, and antioxidant capabilities as demonstrated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) experiment (>78%) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) ABTS assay (>90%). Rigorous testing against both gram positive and gram negative bacteria confirms that the coated fabric has excellent antibacterial activity. Results from time-dependent antibacterial assays indicate that the nanocomposite can markedly inhibit bacterial proliferation within a few hours. Molecular dynamics modeling, in conjunction with experimental investigations, is employed to elucidate the intermolecular interactions influencing the components of the treated cotton fabrics. The ongoing research can result in the creation of cost-effective smart textile substrates aimed at inhibiting microbial contamination in healthcare and medical applications, possibly rendering them commercially viable., (© 2025 The Author(s). Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

Inspired by the emerging potential of photoluminescent hydrogels, this work unlocks new avenues for advanced biosensing, bioimaging, and drug delivery applications. Carbon quantum dots (CDs) are deemed particularly promising among various optical dyes, for enhancing polymeric networks with superior physical and chemical properties. This study presents the synthesis of CDs derived from Prunella vulgaris, a natural plant resource, through a single-step hydrothermal process, followed by their uniform integration into hydrogel matrices via an in situ free radical graft polymerization. The resulting CD-integrated hydrogels exhibit multifunctionality in biomedical applications, featuring a diffusion-controlled drug release mechanism, permit concurrent delivery of photoluminescent CDs and therapeutic agents, enabling real-time monitoring over 32 h. In addition, these hydrogels function as a broad-range optical pH sensor (pH 3-11), provide robust ultraviolet (UV) shielding, and demonstrate nanozyme-like peroxidase activity. Critically, biocompatibility tests confirm their non-cytotoxicity toward fibroblast cells, establishing these hydrogels as promising candidates for diverse biomedical applications. These include advanced wound dressings that monitor the healing process and detect infection through pH sensing, and promote healing through the nanozymatic activity, all while maintaining a moist wound microenvironment. These hydrogels demonstrate exceptional suitability for advanced smart drug delivery, effective UV-blocking, and as innovative platforms for in vivo sensing and bioimaging., (© 2025 The Author(s). Advanced Healthcare Materials published by Wiley‐VCH GmbH.)

Bioimaging probes based on carbon dots (CDs) can become a useful replacement for existing commercial probes, benefiting clinical diagnostics. While the development of dual-mode CD-based probes for magnetic resonance imaging (MRI), which provides the ability for photoluminescence (PL) detection at the same time, is ongoing, several challenges have to be addressed. First, most of the CD-based probes still emit at shorter wavelengths (blue/green spectral range), which is harmful to biological objects or have very low PL intensity in the biological window of tissue transparency (red/near-infrared spectral range). Second, the relaxation characteristics of the proposed CD-based probes are still similar or only slightly larger than those of commercial contrast agents. Herein, we introduce a dual-mode probe allowing for simultaneous PL detection and MRI analysis, based on CDs doped with gadolinium ions (Gd 3+ ) with a PL peak in the red (640 nm), a PL quantum yield up to 24%, and high longitudinal and transverse relaxivities reaching 25.76 and 40.57 L mmol -1 s -1 , respectively. Moreover, Gd-doped CDs show good biocompatibility, which was studied on H9c2 and 4T1 cell lines with a cell viability above 70%. The developed Gd-doped red-emissive CDs can be utilized as efficient and nontoxic dual-mode probes for PL and MRI measurements carried out simultaneously.

Masked cryptic kidney injury (MCKI), an early stage of acute kidney injury (AKI), is challenging to detect and diagnose, especially in the modern context where toxic substances, such as surfactants, are increasingly misused. Consequently, there is an urgent need for methods for the visual diagnosis of MCKI. In this study, we synthesized environmentally friendly spirulina-derived carbon dots (SpiCDs) using spirulina as a biobased raw material through a simple hydrothermal process. These SpiCDs, with their ultrasmall size, enable efficient renal clearance. In cellular experiments, SpiCDs rapidly entered SDS-damaged cells, facilitating dynamic monitoring of the cell membrane damage process. In vivo animal experiments demonstrated that SpiCDs were efficiently excreted through the kidneys and began to accumulate in the bladder within 10 min after tail vein injection. The detection of red fluorescence in excreted urine confirmed the renal metabolic pathway of the SpiCDs. Furthermore, in an MCKI model induced by SDS, SpiCDs showed accelerated excretion and earlier accumulation in the bladder, indicating an increased sensitivity to kidney injury. These results suggest that SpiCDs provide a promising approach for the early diagnosis of MCKI, offering insights into its visual detection and monitoring.

Nanomaterials and nanotechnology have garnered significant attention in the realm of agricultural production. Carbon dots (CDs), as a class of nanomaterials, play a crucial role in the field of plant growth due to their excellent properties. This review aims to summarize recent achievements on CDs, focusing on their methods of preparation and applications in plants systems. The effects of CDs on seed germination, growth, photosynthesis, nutritional quality, and stress resistance were studied. It has been demonstrated that CDs can promote seed germination and growth, as well as improve photosynthetic efficiency, ultimately leading to increase plants yield. The nutritional quality of the plants treated with CDs was significantly improved. Specifically, the levels of essential mineral elements, vitamins, amino acids, and other constituents that are beneficial to human health increased notably. Additionally, CDs show positive effects on augmenting plant resistance against environmental stresses, such as drought conditions, heavy metal toxicity, and high salinity. Finally, the prospects and challenges of the application of CDs in plant systems are also discussed, which provide a scientific basis for the future application of CDs in agricultural production.

Low cure rate and high death rate of cancers have seriously threatened human health. The combining multiple therapies is a promising strategy for cancer treatment. In this study, we construct a novel multinucleated nanocomplex loaded with carbon dots (CDs-SA@TAMn) that responds to tumor microenvironment for combined photothermal/chemodynamic cancer therapy. Fluorescence imaging results show that CDs-SA@TAMn can effectively accumulated in tumor sites. In acidic tumor microenvironment, CDs-SA@TAMn will release Mn 2+ , activating chemodynamic therapy and producing substantial reactive oxygen species (ROS) to kill tumor. Additionally, when irradiated by an 808 nm laser, CDs-SA@TAMn will exert the photothermal effect to realize high performance of cancer hyperthermia treatment. The nanocomplexes feather simple preparation, low toxicity, controlled release and imaging-guided therapy, showcasing the potential of precise and high-performance anti-tumor combination therapy in biomedical applications., (© 2025 Wiley-VCH GmbH.)

Changes in the neurotransmitters are indications for several diseases. Several sensors were reported for monitoring dopamine (DA), but the simple and accurate DA detection in biological samples still faces many challenges. The research proposal aims to develop an optical sensor for detecting neurotransmitters based on luminescence emission spectra in different biological samples. Carbon dots (CDs) were fabricated based on a green synthesis route. Then the prepared CDs were decorated with varying concentrations of gold nanoparticles (Au NPs). The synthesis process was optimized, and the obtained CDs/Au NPs nanocomposites were applied as neurotransmitters' optical nanosensors. The optical nanosensor approach provides easy and sensitive multiplex analysis. A wide range of neurotransmitters was monitored. The developed sensor's sensitivity, selectivity, and reproducibility were investigated. Au NPs act as CDs' stabilizers, enhancing the emission effect, and scaffolds for binding DA with CDs' surface. DA moieties bind to CDs through the interaction between the DA-NH 2 groups and Au NPS. Due to electron transfer, the bonding of DA molecules leads to fluorescence quenching of AuNPs/CDs. The Au-CDs-based DA fluorescence showed high sensitivity with adetection limit, and limit quantification of 2.04 nM and 6.18 nM, respectively. Furthermore, the selectivity of the sensor was investigated in the presence of glucose, uric acid (UA), and ascorbic acid (AA), which showed no interference effect at 10 times higher concentrations. Moreover, the proposed sensor has been successfully utilized for DA detection in human serum samples with a high recovery efficiency between 98.83 % and 103.5 %., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Carbon dots (CDs) derived from biomass are promising fluorescent probes for specific analyte detection due to their specificity, biocompatibility, selectivity, and sensitivity. In this work, carbon dots were prepared hydrothermally from natural material, Myrica esculenta fruits (hereafter referred to as MPCDs), without adding any chemicals. The prepared MPCDs were characterized using optical, microscopic, and spectroscopic methods that revealed the presence of numerous functional groups and fluorescent properties. MPCDs exhibited exceptional characteristics such as water solubility, photostability, excitation-dependent fluorescence emission, and ionic stability. Transmission electron microscopy found that the average size of the MPCDs was 8 nm. MPCDs exhibited remarkable sensing ability for hemin, with a good linearity (R 2 = 0.999) and a lower limit of detection of 14.1 nM. MPCDs demonstrated fluorescence quenching-based detection of hemin, primarily owing to ground state complex formation and the inner filter effect. Furthermore, the prepared material exhibited excellent antioxidant potential against 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals with EC 50 values of 25.4 and 205.4 µg/mL, respectively. The study suggests that CDs from Myrica esculenta fruits could be used as optical sensors for hemin detection as well as to scavenge selected radicals.

Carbon quantum dots (CQDs), a new class of carbon-based nanomaterials, have emerged as nano-scaled probes with photoluminescence that have an eco-friendly and bio-compatible nature. Their cost-efficient synthesis and high photoluminescence quantum yields make them indispensable due to their application in opto-electronic devices, including biosensors, bioimaging, environmental monitoring, and light sources. This review provides intrinsic properties of CQDs such as their excitation-dependent emission, biocompatibility, and quenching properties. Diverse strategies for their easy synthesis are divided into bottom-up and top-down approaches and detailed herein. In particular, we highlight their luminescence properties, including quenching mechanisms that could even be utilized for the precise and rapid detection of biomolecules. We also discuss methodologies for the mitigation of fluorescence quenching, which is pivotal for the application of CQDs in biosensors and bioimaging.

COVID-19 pandemic has significantly influenced the dietary habits of humans, emphasizing the incorporation of natural ingredients to enhance immunity towards viral and bacterial infections. Curcumin (Cur), a widely used traditional medicine in various Asian countries and a natural coloring agent, has gained popularity, leading to surge in its usage specially in post COVID-19 era. This surge has led to increased scrutiny of the potential side effects of excessive Cur use, with recent reports suggesting it may result in inactivation of DNA and reduce adenosine triphosphate levels, leading to health risks. In this work, we synthesized highly fluorescent nitrogen-doped carbon dots with a photoluminescence quantum yield of 72.9 % for the sensitive and selective detection of Cur. The developed fluorescent probe exhibits excellent sensory response towards Cur within a concentration range of 0.081-51.45 µM, achieving an ultra-low detection limit of 15.91 nM. The sensor was successfully tested on real food samples like ginger powder, turmeric powder, and curry powder, demonstrating good recovery rates. To assess the practicality of the sensor system, we developed a 3D-printed smartphone-integrated device platform for curcumin detection through fluorescence image analysis. This developed platform exhibited promising results, achieving a limit of detection (LoD) of 132.28 nM across a curcumin concentration range of 0.13-54.00 µM. This device platform holds significant potential for the development of efficient sensors for real-time detection of Cur in food samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

How to accurately diagnose and treat bacterial infections in vivo remains a huge challenge. Therefore, we have developed a targeted delivery nanosystem by coextruding the pretreated macrophage membrane of S. aureus with carbon dots (M@CD). The M@CD nanosystem demonstrates potent antibacterial effects both in vivo and in vitro through the generation of reactive oxygen species (ROS). Furthermore, M@CD exhibits enhanced targeting ability and stable fluorescence properties, addressing issues such as poor targeting efficiency and high immunogenicity in vivo. This innovative approach enables infection site specific aggregation and elimination of bacterial infections, thereby providing a promising strategy for the integrated diagnosis, treatment, and monitoring of bacterial infections.

Sulfur ion (S 2- ) plays a significant and considerable role in many living organisms and ecosystems, while its abnormal content can pose a serious hazard to human health and ecological environment. Hence, it is extremely meaningful to construct a highly sensitive and selective analytical platform for S 2- detection in complex microenvironment, particularly in biological systems. In this study, phosphomolybdic acid and L-Arg were utilized to prepare a new molybdenum doped carbon-dots nanozyme (Mo-CDs) with great peroxidase-like activity by one-step hydrothermal approach. In the presence of H 2 O 2 , Mo-CDs converted 3,3',5,5'-tetramethyl benzidine (TMB) into blue oxTMB, but S 2- strongly reduced the blue solution to colorless and then brown, which established significant selectivity toward S 2- . Mo-CDs illustrated a wide linear range (2.5 μM-900 μM) and low detection limit (LOD = 76 nM) by ultraviolet and smartphone-assisted visualized colorimetric analysis. Especially, the smartphone-assisted analysis platform successfully realized quick, portable, sensitive and visible identification of S 2- with high recovery (95.7-106.7 %) and excellent specificity in water samples. More importantly, Mo-CDs was developed to antibacterial applications based on good peroxidase-like activity. This research not only constructed a new and efficient carbon-dots nanozyme and a low-cost, portable, visual analysis platform for real-time detection of S 2- , but also proposed a novel design strategy and methodology for exploiting multifunctional nanozyme detection tool with great practical application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Carbon dot-based fluorescence sensors have attracted research interest for the selective determination of anti-inflammatory drugs in biological fluids and environments. The overdose and accumulation of anti-inflammatory drugs in tissues can cause chronic side effects including abdominal pain, and renal damage. Herein, we report a new fluorescent probe, bamboo stem waste-derived carbon dots (BS-CDs) for highly sensitive detection of Flufenamic acid (FA), a hazardous anti-inflammatory drug. The UV-vis absorption spectra of BS-CDs show a redshifted absorption peak at 283 nm upon the addition of FA suggesting strong binding interaction between BS-CDs and FA molecule. The BS-CDs showed a fluorescence enhancement (∼2-fold) detection for FA (400 μM) in the linear concentration range (0.40 → 0.65 μM) with a limit of detection (LoD; 17 nM) and binding constant (K a  = 1.33 × 10 -3 M -1 ). The time-resolved fluorescence decay analysis showed that the average lifetime of BS-CDs has slightly changed (4.42 → 4.67 ns) by the interaction with FA through the aggregation-induced emission (AIE) process. The interference, pH, and effect of time results suggest that BS-CDs are highly selective probes for FA detection and do not show any interference involvement during FA detection. The confirmation of the structure and morphology changes of BS-CDs after interaction with FA was carried out by XRD, FESEM, HRTEM, FTIR, and Raman spectroscopy. The practicability of the BS-CDs probe was proved by the detection of FA in human urine samples with recovery of 103-109 %. This suggests that the proposed BS-CDs-based 'turn-on' sensor could be used to determine the FA in biological fluids., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The low cure rate and high mortality associated with cancer pose significant threats to human health. Photodynamic and photothermal therapies have emerged as promising treatment strategies for various types of cancers. In this study, we successfully synthesized a novel type of carbon dot (CD) using 1,2,4-aminobenzene and ethylenediamine as precursors. Surprisingly, these CDs exhibited outstanding nucleolus-targeting capabilities coupled with a remarkable photothermal effect. Through the integration of these nucleolus-targeting CDs with indocyanine green (ICG) and folic acid (FA), we created CDs-ICG-FA nanocomplexes suitable for combined photodynamic and photothermal therapy. In vitro experiments demonstrated that CDs-ICG-FA maintained a robust photothermal ability, achieving a conversion efficiency of up to 34.3%. Furthermore, CDs-ICG-FA generated abundant reactive oxygen species, effectively inducing cancer cell death and demonstrating its potential for photodynamic therapy. In MCF-7 cancer cells, CDs-ICG-FA exhibited a pronounced synergistic photothermal/photodynamic anticancer effect. Subsequent in vivo experiments in mice revealed that CDs-ICG-FA could selectively accumulate at tumor sites, significantly inhibiting tumor growth upon exposure to an 808 nm laser. These findings suggest that the developed nucleolus-targeting CDs-ICG-FA hold promising potential for cancer targeting and the application of combined photothermal/photodynamic therapy.

Theranostic applications in atherosclerosis plaque microenvironment-triggered nanoplatforms are significantly compromised by the complex synthesis procedure, non-specific distribution, and limited therapeutic function. Therefore, development of a facile and feasible method to construct a pathology-based stimuli-responsive nanoplatform with satisfactory theranostic performance remains a demanding and highly anticipated goal. Herein, a novel class of multifunctional supra-carbon dots (CDs), denoted as MM@Ce-CDs NPs, by a simple nanoassembly and a subsequent coating with macrophage membrane (MM), is developed for the targeted reactive oxygen species-trigged theranostic and positive regulation of the pathological plaque microenvironment in AS. The harvested MM@Ce-CDs NPs exhibit activatable fluorescence properties, photoacoustic characteristics, and cascade enzyme performances, which can be effectively activated under ROS stimulation in the plaque pathological microenvironment, enabling precise control over theranostic functions, while markedly enhancing diagnostic accuracy and therapeutic efficacy for AS management. Besides, MM@Ce-CDs NPs can effectively manipulate the plaque microenvironment by reducing ROS levels and inflammation, alleviating M1 macrophage infiltration, and inhibiting foam cell formation, all together suppressing the pathological plaque development through the synergistic mechanisms. In addition, MM@Ce-CDs NPs inherit the biomimetic biological functions from MM, facilitating a highly specific target delivery to AS., (© 2025 Wiley‐VCH GmbH.)

Diabetic mellitus management extends beyond blood glucose monitoring to the essential task of mitigating the overexpression of reactive oxygen species (ROS), particularly vital for cellular repair, especially within the nervous system. Herein, antioxidant carbon dots (Arg-CDs) were designed and prepared using anhydrous citric acid, L-arginine, and ethylenediamine as sources through a hydrothermal method. Arg-CDs exhibited excellent scavenging ability to 2,2-Diphenyl-1-picrylhydrazyl (DPPH∙), and fluorescence response to hydroxyl radicals (∙OH), a characteristic representative of reactive oxygen species (ROS). Assisted by glucose oxidase and Fe 2+ , Arg-CDs showed a sensitive and selective response to glucose. The quenching mechanism of Arg-CDs by formed ∙OH was based on the static quenching effect (SQE). The analytical performance of this method for glucose detection encompassed a wide linear range (0.3-15 μM), a low practical limit of detection (0.1 μM) and practical applicability for blood glucose monitoring. In an in vitro model employing glial cells (BV2 cells), it was observed that high glucose medium led to notable cellular damage ascribed to the excessive ROS production from hyperglycemia. The diminished and apoptotic glial cells were gradually recovered by adding increased contents of Arg-CDs. This work illustrates a promising area that designs effective carbon dots with antioxidant capacity for the dual applications of detection and cell repairing based on the utilization of antioxidant activity., Competing Interests: Declarations. Ethical Approval: Ethical approval for the obtaining healthy human blood samples was granted by The Ethics Committee for Human Research, The First Affiliated Hospital of Fujian Medical University. The Medical ethics approval number is MTCA,ECFAH of FMU [2015]084 − 2. Competing Interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: The intellectual progress in fabricating artificial probes for selective appraisal of biologically admissible amino acids has displayed exponential growth in recent era.The neoteric era in material science has witnessed the significant application of carbon quantum dots (CQDs). However, the hybrid microgel of CQDs was less explored., Results: Herein, a highly fluorescent hybrid microgel for Tryptophan (Trp) sensing has been successfully prepared by in-situ addition of biocompatible carbon dots (CQDs) with poly-N isopropylacrylamide (PNIPAM). This bio-probe was successfully prepared by precise control over the size and shape of CQDs by effective surface passivation with PNIPAM. This inventive methodology facilitates the accurate and selective recognition of Trp. The operative features such as concentration, pH and temperature of this process were optimized to establish integrity, sensitivity, selectivity and efficiency towards Trp. The integrated hybrid microgel was effectively useful for the quantification of Trp with a wide linear range of 10 μM-500 μM, with a limit of detection as low as 0.1 μM., Significance: The current integrated system displayed desirable selectivity in the presence of comparable bio-molecules illustrating its booming performance towards Trp sensing. Further advancing the performance of developed sensor, the application of this strategy was extended for selective recognition of Trp in presence of various real water samples from different sources. The combining effect of high biocompatibility and fluorescent property of CQDs with thermo-responsive behaviour of PNIPAM provide smart hybrid gels with intriguing potential in diagnosis and hold remarkable potential in practical applications including healthcare and environmental remediation application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A nano-sensor based on N-doped carbon dots (NCDs)@ZnO (NCZ) composite was fabricated and efficacy for detecting glucose from human blood and urine samples in a straightforward manner was examined. The composite was prepared following a green hydrothermal method under ambient condition using a novel plant material, Dregea volubilis fruit and structural and optical properties were evaluated using standard techniques. The composite exhibited excellent characteristics including good photostability, biocompatibility, low toxicity, and strong fluorescence, with a decent quantum yield of up to 59%. The NCZ composite has been very sensitive and could selectively detect glucose in urine and blood samples. Selective glucose quenching was efficacious at different concentrations of glucose (1-6 mM) and in the pH range of 7-8, limit of detection was 0.25 mM. The potential uses of carbon-based materials have grown, thanks to the excellent sensing/detection capabilities of the NCZ composite as well as the capacity to prevent nanoparticle aggregation, opening up new possibilities for the development of environmentally benign nano-sensors., Competing Interests: Declarations. Ethical Approval: Not Applicable. Competing Interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This research introduces a novel fluorescence sensor 'on-off-on' employing nitrogen-doped carbon dots (N-CDs) with an 'on-off-on' mechanism for the selective and sensitive detection of Hg(II) and L-cysteine (L-Cys). N-CDs was synthesized using citric acid as the carbon precursor and urea as the nitrogen source in dimethylformamide (DMF) solvent, resulting in red emissive characteristics under UV light. Comprehensive spectroscopic analyses, including UV-Vis, fluorescence, FT-IR, XRD, XPS, Raman, and Zeta potential techniques, validated the structural and optical characteristics of the synthesized N-CDs. The maximum excitation and emission of N-CDs were observed at 548 and 622 nm, respectively. The quantum yield of N-CDs was calculated to be 16.1%. The fluorescence of N-CDs effectively quenches upon the addition of Hg(II) due to the strong coordination between Hg(II) and the surface functionalities of N-CDs. Conversely, upon the subsequent addition of L-Cys, the fluorescence of N-CDs was restored. This restoration can be attributed to the stronger affinity of the -SH group in L-Cys towards Hg(II) relative to the surface functionalities of N-CDs. This dual-mode response enabled the detection of Hg(II) and L-Cys with impressive detection limits of 15.1 nM and 8.0 nM, respectively. This sensor methodology effectively detects Hg(II) in lake water samples and L-Cys levels in human urine, with a recovery range between 99 and 101%. Furthermore, the N-CDs demonstrated excellent stability, high sensitivity, and selectivity, making them a promising fluorescence on-off-on probe for both environmental monitoring of Hg(II) and clinical diagnostics of L-Cys., Competing Interests: Declarations. Ethical Approval: Not applicable. Consent to Participate: Not applicable. Consent for Publication: All the authors consent to publishing the paper. Conflict of Interest: The authors have no conflicts of interest., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The present study proposes a new approach for detecting trace amounts of creatinine (Cre) through the utilization of a fluorescence sensor system consisting of nitrogen doped carbon dots (NCDs) and gold ions (Au 3+ ). Yellow fluorescent carbon dots were prepared using a one-step hydrothermal method with o-phenylenediamine and isopropanol as raw materials. First, gold ions are reduced to gold nanoparticles (Au NPs), which bind to NCDs, resulting in electron transfer and fluorescence quenching of NCDs. After adding creatinine, Cre and Au NPs were preferentially combined to form non-fluorescent complexes, and the NCDs fluorescence was restored. The study achieved a detection limit of 1.06 × 10 -7 M for Au 3+ and 9.29 × 10 -9 M for creatinine, indicating a high level of sensitivity. The sensing system has also been successfully utilized for detecting Au 3+ in lake water and Cre in human urine, indicating its promising potential and practical applications in the areas of environmental monitoring and biosensing., Competing Interests: Declarations. Ethical Approval: Not applicable. Consent to Participate: Not applicable. Consent to Publish: Not applicable. Competing Interests: The authors declare no competing interests., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

The green synthesis of carbon dots (CDs) from natural sources is a challenging goal. Herein CDs are produced from Agapanthus africanus (L.) Hoffmann leaves by carbonization at 200/300 °C for 2/3 h. Samples are named CZ-X-Y, where Z, X, and Y represent carbonization, temperature, and time, respectively. CZ-200-3, CZ-300-2, and CZ-300-3 CDs have average sizes of 3.7 ± 0.7, 5.3 ± 1.2, and 5.1 ± 1.6 nm, respectively. Their surface, devoid of chlorophyll, contains ─OH, ─C═O, and ─C(═O)OH groups and sylvite. Isolated CZ-300-3 emits at 400 nm (excited at 260 nm) and exhibits an emission quantum yield (QY) value of 2 ± 1%. Embedding in the d-U(600)/d-(900) di-ureasil matrices resulted in transparent films with emission intensity maxima at 420/450 nm (360 nm), and QY values of 7 ± 1/16 ± 2% (400 nm). The enhancement of the QY value of the bare CDs agrees with an efficient passivation provided by the hybrid host. The hydrophilic CZ-300-3 CDs also exerted a marked surface modifying role, changing the surface roughness and the wettability of the hybrid films., (© 2024 Wiley‐VCH GmbH.)

Bilirubin plays a significant role in human health management, particularly in the case of jaundice. Because of the need for the monitoring of bilirubin levels in jaundice patients, the development of a robust sensitive method becomes essential. Here, we describe the development of a highly sensitive and selective turn-off fluorometric detection method for bilirubin in blood serum samples using nitrogen-doped carbon dots (N-CDs). N-CDs was synthesized by the pyrolysis process, using citric acid and L-asparagine as the carbon and nitrogen sources, respectively. The prepared N-CDs solution showed highly intense blue emission with good stability. The HR-TEM image of N-CDs revealed spherical dot-like structures with an average size calculated to be 7.16 nm. Further, the surface functional groups of N-CDs were analyzed by FT-IR, Raman, XRD, and XPS techniques. Fluorescence spectra showed the maximum emission intensity at 443 nm (λ ex ). The linear range of addition was performed from 1 to 150 µM, and the limit of detection (LOD) was determined to be 1.97 nM. The emission of N-CDs was quenched by Förster Resonance Energy Transfer (FRET) by adding bilirubin. These N-CDs showed extraordinary sensitivity and selectivity in the detection of bilirubin. Hence, this fluorescent probe has been proven successful in detecting the concentration of free bilirubin in human serum samples., Competing Interests: Declarations. Ethical Approval: Not applicable. Consent to Participate: Not applicable. Consent for Publication: All the authors are agreed to publishing the paper. Competing interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

2,4,6-Trinitrophenol (TNP) has high explosive risks and biological toxicity, and there has been considerable concern over the determination of TNP. In the present work, fluorescent carbon dots (CDs) stemmed from a green carbon source of pinecone by the facile hydrothermal approach. A novel environment- friendly fluorescent probe was developed to efficiently detect TNP by using the obtained CDs with remarkable fluorescence stability. The fluorescent CDs exhibited obvious excitation dependence with the highest peaks for excitation and emission occurring at 321 and 411 nm, respectively. The fluorescence intensity is significantly reduced by TNP owing to the inner filter effect with the CDs. The probe exhibited good linearity with TNP concentrations in the range of 0.025-20 μg mL -1 , and the limit of detection was as low as 8.5 ng mL -1 . Additionally, the probe proved successful in sensing TNP quantitatively in actual environmental samples with satisfied recoveries of 95.6-99.6%. The developed fluorescent probe offered an environment-friendly, efficient, rapid, and reliable platform for detecting trace TNP in the environmental field. Highlights Novel carbon dots were synthesised from green precursors of pineal powder.The highly effective quenching process was put down to the inner filter effect.The as-constructed fluorescent probe was successfully utilised for sensing 2,4,6-trinitrophenol in environmental samples.The proposed method was simple, rapid, efficient, economical, and eco-friendly.

Accurately and promptly detecting Fe 3+ and ascorbic acid (AA) is a crucial objective. In this study, nitrogen-doped carbon dots (N-CDs) were synthesized using a one-step hydrothermal synthesis method with 6,9-diamino-2-ethoxyacridine lactate as the precursor. The introduction of Fe 3+ and AA resulted in both fluorescence (FL) quenching and enhancement of the synthesized N-CDs. The fluorescent response of the N-CDs probe to Fe 3+ was observed in the concentration range of 5-20 µM and 25-50 µM, with a limit of detection (LOD) of 290 nM. Remarkably, the fluorescence of the N-CDs was recovered upon the addition of AA to the N-CDs-Fe 3+ system. Using the "off-on" fluorescent N-CDs probe, a linear range of 40-90 µM was achieved with an LOD of 0.69 µM. Additionally, the feasibility of employing a smartphone equipped with an RGB Color Picker was demonstrated for the analysis of Fe 3+ and AA concentrations, providing a novel visual detection method. Furthermore, the application of N-CDs in solution demonstrated considerable potential for visually detecting Fe 3+ and AA. The proposed dual-mode detection sensor was found to be simple, efficient, and stable, enabling the successful determination of Fe 3+ and AA in practical samples with satisfactory results., Competing Interests: Declarations. Ethical Approval: This article does not contain any studies with human or animal subjects. Consent to Participate: All authors provided their consent for the inclusion of their work in the manuscript. Competing Interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: The current synthetic strategies for carbon dots (CDs) are usually time-consuming, rely on complicated processes, and need high temperatures and energy. Recent studies have successfully synthesized CDs at room temperature. Unfortunately, most CDs synthesized at room temperature are obtained under harsh reaction conditions, prepared using aromatic precursors, or need a long time to generate. Therefore, an energy-free room-temperature rapid synthesis of CDs under mild conditions using aliphatic substrates is important. We aim to provide an innovative approach to synthesizing CDs to be used to develop the first fluorescence-based assay of the non-fluorescent anti-hyperlipidemic drug, fenofibrate., Results: We report an innovative, energy-free, and room-temperature preparation of fluorescent N-doped CDs utilizing aliphatic substrates in only 20 min. The synthesis was based on a self-exothermic Schiff base condensation reaction between methylglyoxal and ethylenediamine. The prepared CDs' antibacterial properties, biocompatibility, and cell-imaging ability were investigated. The fluorescence signal of the CDs was quantitively quenched upon adding increasing concentrations of fenofibrate in the range of 0.50-15.0 μg/mL. Therefore, the prepared CDs were applied as a nanosensor to develop the first fluorescence-based assay of fenofibrate. The reliability of the synthesized nanosensor was confirmed by the successful quantification of fenofibrate in pharmaceutical dosage forms, environmental water, weight loss herbal products, and dietary supplements. The obtained recovery ranged from 95.33 to 104.58 %. In addition, the minimal environmental impact of the developed fenofibrate sensing strategy was confirmed using the recently reported metrics., Significance and Novelty: The key advantage of this work is the use of an energy-free approach to synthesize CDs rapidly under mild conditions without aromatic substrates. This opens a new window for the eco-friendly synthesis of CDs that avoids the drawbacks of the traditional methods. Additionally, it is the first fluorescence nanosensor for sensing fenofibrate in various matrices, avoiding the limitations of the previous methods, such as high cost, poor selectivity, and low sensitivity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

A ratiometric fluorescent nanoprobe (CDs-Rho), synthesized through the simple covalent amide linkage between carbon dots (CDs) and pH-sensitive rhodamine dye (Rho), was designed for the precise sensing and imaging of extremely alkaline environments. The sensing mechanism involves the opposite pH-dependent fluorescence changes in CDs and Rho, respectively, coupled with pH-regulated FRET efficiency from CDs to Rho. The nanoprobe features a wide pH response window from pH 7.0 to 12.0 with a pK a value of 11.3 and shows high sensitivity, robust anti-interference capability, and high reversibility. Moreover, the significant shifts in emission wavelength following the pH fluctuations result in two well-separated emission signals, thus ensuring the visualization of reversible and distinct color changes (from green to red) during in vivo fluorescence imaging. This work furnished a facile protocol that contributes to the advancement of a novel method for the accurate sensing and imaging of extreme alkaline environments., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

The synthesis of nanomaterials from renewable resources has emerged as an environmentally friendly alternative. This approach helps to reduce the use of chemical fertilizers in agricultural production, further reducing the potential harm to the ecosystem and effectively reducing the burden on the environment. In this work, we synthesized Rosa roxburghii derived carbon dots (CDs) using the microwave hydrothermal method (RR-CDs) and the electrolytic oxidation method (GRR-CDs), and the results showed that RR-CDs had a wider ultraviolet absorption range and emitted blue fluorescence. These properties make RR-CDs more effective as light-harvesting materials in plants, thus promoting photosynthesis. In the cultivation of lettuce, RR-CDs significantly enhanced both the biomass and the quality of the lettuce. In addition, compared to the control group, the chlorophyll content of lettuce treated with RR-CDs increased by 31.83%, the net photosynthetic rate increased by 60.76%, and the electron transport rate of photosystem II increased by 38.72%. Therefore, we found that the microwave hydrothermal method could bring better benefits, with a yield of up to 40.20% after just 2 h of reaction. RR-CDs promote photosynthesis by promoting light conversion and improving nutrient efficiency while also boasting the dual advantages of low cost and easy large-scale production, thus opening up avenues for sustainable agricultural production.

A novel fluorescence sensing nanoplatform (CDs/AuNCs@ZIF-8) encapsulating carbon dots (CDs) and gold nanoclusters (AuNCs) within a zeolitic imidazolate framework-8 (ZIF-8) was developed for ratiometric detection of formaldehyde (FA) in the medium of hydroxylamine hydrochloride (NH 2 OH·HCl). The nanoplatform exhibited pink fluorescence due to the aggregation-induced emission (AIE) effect of AuNCs and the internal filtration effect (IFE) between AuNCs and CDs. Upon reaction between NH 2 OH·HCl and FA, a Schiff base formed via aldehyde-diamine condensation, releasing hydrochloric acid. The acid triggered the degradation of ZIF-8, releasing CDs and AuNCs, and thereby shifting the fluorescence to blue as the CDs disperse. The nanoplatform demonstrated high sensitivity (LOD of 0.26-2.19 μM), exceptional selectivity, and rapid response time (<1 min) toward FA. Additionally, test strips and hydrogel films integrated with smartphones were prepared for on-site and visual detection of FA. The portable and smartphone-assisted test strips effectively detected indoor FA gas, while wearable and intelligent hydrogel films provided reliable surface measurements of FA on fruits and vegetables. Real sample analyses achieved satisfactory FA recoveries (99.06-115.30%) with relative standard deviations (RSD) from 1.86% to 3.81%. The innovative sensing nanoplatform served as a promising approach for FA detection in food, construction materials, and indoor air quality, offering both analytical accuracy and convenient visualization., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Elevated dopamine (DA) levels in urine denote neuroblastoma, a pediatric cancer. Saccharide-derived carbon dots (CDs) were applied to assay DA detection in simulated urine (SU) while delineating the effects of graphene defect density on electrocatalytic activity. CDs were hydrothermally synthesized to vary graphene defect densities using sucrose, raffinose, and palatinose, depositing them onto glassy carbon electrodes (GCEs). Co 3 O 4 nanoparticles (NPs) were encapsulated by the CDs. Cyclic (CV) and linear sweep (LSV) voltammetry measurements were obtained, drop-casting the CDs onto GCEs and measuring DA in a phosphate-buffer solution (pH = 7). DA had an oxidation peak at +0.2 V with SucCDs, with the highest current correlating with the highest defect density. PalCD-Co 3 O 4 exhibited the largest signal for DA detection in simulated urine (SU) using the oxidation peak at +0.5 V; the composite had a lower defect density compared to SucCD-Co 3 O 4 . The Co 3 O 4 -PalCDs had a DA detection range of 1 to 90 µM with an LOD of 0.88 μM in SU. SEM-EDX analysis of the electrode surface revealed semi-spherical structures with an average particle diameter of 80 ± 19 nm (n = 347) with PalCDs decorating the Co 3 O 4 NPs. XRD characterization showed the incorporation of PalCD and Co 3 O 4 within the composite. XPS showed electron density donation from the PalCD to Co 3 O 4 .

Carbon dots (CDs) are carbon-based nanomaterials that have garnered immense attention owing to their exceptional photophysical and optoelectronic properties. They have been employed extensively for biomedical imaging and phototherapy due to their superb water dispersibility, low toxicity, outstanding biocompatibility, and exceptional tissue permeability. This review summarizes the structural classification of CDs, the classification of CDs according to precursor sources, and the luminescence mechanism of CDs. The modification in CDs via various doping routes is comprehensively reviewed, and the effect of such alterations on their photophysical properties, such as absorbance, photoluminescence (PL), and reactive oxygen species generation ability, is also highlighted. This review strives to summarize the role of CDs in cellular imaging and fluorescence lifetime imaging for cellular metabolism. Subsequently, recent advancements and the future potential of CDs as nanotheranostic agents have been discussed. Herein, we have discussed the role of CDs in photothermal, photodynamic, and synergistic therapy of anticancer, antiviral, and antibacterial applications. The overall summary of the review highlights the prospects of CD-based research in bioimaging and biomedicine., (© 2024 Wiley-VCH GmbH.)

Carbon dots (CDs) have garnered significant interest owing to their distinctive optical properties. However, their bioimaging and biomedical applications are limited by pronounced fluorescence (FL) quenching in aqueous media and low tumor accumulation efficacy associated with their ultra-small size. This study proposes a simple surface modification approach using functioning d-arginine on CDs (d-Arg@CDs) to improve their near-infrared (NIR) FL in aqueous solution and maintain their high photothermal conversion properties. Because of the low utilization rate of dextral amino acids in animals, modifying CDs with low molecular weight d-arginine did not increase particle size but extended the metabolism time in blood circulation, thereby leading to enhanced accumulation efficacy at tumor sites in the mice model. The enhanced tumor accumulation of d-Arg@CDs resulted in significantly superior tumor NIR FL imaging and photothermal therapy performance compared with pure CDs and l-arginine functionalized CDs. This dextral amino acid modification approach is expected to be an effective tool for enhancing the biomedical applications of CDs., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Herein, a novel chemiluminescence (CL) sensor was successfully developed based on chlorine doped carbon dots (Cl/CDs) for the rapid determination of bisphenol A (BPA) and nitrite. The Cl/CDs were synthesized through a hydrothermal method, using ascorbic acid as the precursor and hydrochloric acid as the dopant. It was found that Cl/CDs significantly enhanced the CL intensity of the acid-KMnO 4 system, while BPA and nitrite quenched the CL intensity of the Cl/CDs-sensitized acid-KMnO 4 system. Under optimal conditions, BPA exhibited a linear detection range of 0.05-10 μM, with limits of detection (LOD) and quantification (LOQ) of 0.86 nM and 2.8 nM, respectively. Nitrite showed a linear detection range of 0.7-100 μM, with LOD and LOQ of 22.5 nM and 75 nM, respectively. The CL sensor was successfully use to determine BPA in water samples and nitrite in pickles, ham and celery, with spike recovery rates of 96.3 %-104.8 % and 96.0 %-104.9 %, respectively., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

A switchable ratiometric fluorescent smartphone-assisted sensing platform based on nitrogen-doped carbon dots (N-CDs) and Rhodamine B was fabricated for the determination of the ascorbic acid (AA) content in fruits by quenching the fluorescence of N-CDs with Hg 2+ (turn-off) and recovering with AA (turn-on). The blue-emission N-CDs was synthesized by liquid dielectric barrier discharge microplasma with an average size of 3.65 nm and an absolute quantum yield of 18 % (excited at 345 nm). In addition, the fluorescence color was converted to RGB values, enabling visual and quantitative determination of AA. Under optimal parameters, the linear ranges for detecting AA were found to be 3-170 μM and 5-170 μM for fluorescence spectrometer and smartphone sensing platform. The detection limits were 0.98 μM and 2.90 μM, respectively. Furthermore, the satisfactory recoveries in fruits were obtained by RF probe and smartphone platform. This smartphone-assisted platform will facilitate sensitive and visual determination for AA., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

As an antioxidant and preservative agent, nitrite (NO 2 - ) plays an essential role in the food industry to maintain freshness or inhibit microbial growth. However, excessive addition of NO 2 is critical for food quality control. Notably, the selectivity of most carbon dots (CDs)-based fluorescence sensors was not enough due to the nonspecific interaction mechanism of hydrogen bond, electrostatic interaction and inner filter effect etc. Herein, a novel fluorescence/UV-vis absorption (FL/UV-vis) dual-mode sensor was developed on basis of mC-CDs, which were prepared by simple solvothermal treatment of m-Phenylenediamine (m-PDA) and cyanidin cation (CC). The fluorescence of these mC-CDs could be selectively responded by NO - is detrimental to health, so accurate and portable detection of NO 2 - is critical for food quality control. Notably, the selectivity of most carbon dots (CDs)-based fluorescence sensors was not enough due to the nonspecific interaction mechanism of hydrogen bond, electrostatic interaction and inner filter effect etc. Herein, a novel fluorescence/UV-vis absorption (FL/UV-vis) dual-mode sensor was developed on basis of mC-CDs, which were prepared by simple solvothermal treatment of m-Phenylenediamine (m-PDA) and cyanidin cation (CC). The fluorescence of these mC-CDs could be selectively responded by NO 2 - through the specific diazo coupling reaction between NO 2 - and amino groups on the surface of mC-CDs, thus effectively improving the selectivity of NO 2 - detection. The CDs-based fluorescence sensor possessed a low detection limit of 0.091 μM and 0.143 μM for FL and UV-vis methods and the excellent linear range of 0.0-60.0 μM. Furthermore, the mC-CDs sensor was employed to detect NO 2 - in real samples with a recovery rate of 97.11 %-104.15 % for quantitative addition. Moreover, the smartphone-assisted fluorescence sensing platform developed could identify the subtle color changes that could not be distinguished by the naked eye, and had the advantages of fast detection speed and intelligence. More importantly, the portable solid phase sensor based on mC-CDs had been successfully applied to the specific fluorescence identification and concentration monitoring of NO 2 - . Accordingly, the designed sensor provided a new strategy for the highly selective and convenient sensing of NO 2 - in food substrates, and paved the way for the wide application of CDs-based nanomaterials in the detection of food safety., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Sulfur dioxide (SO 2 ) derivatives are typically employed as antioxidants in food and pharmaceutical processing. However, excessive sulfite intake could trigger serious health problems. Hence, it is urgent to establish a rapid and effective system for monitoring SO 2 . This study adopted a one-step hydrothermal method to synthesize dual-emitting nitrogen-doped carbon quantum dots (CECDs) and developed a ratiometric sensor for sulfite using CECDs-Cr (VI) composites. The emission intensity ratio (I 440 /I 500 ) of the CECDs-Cr (VI) composites increased considerably with the addition of HSO 3 - . A method based on the ratiometric sensor was established for SO 2 derivatives with advanced efficiency and excellent linearity over a broad concentration range of 0-500 μM (R 2  = 0.9946). Four medicine-food homology materials (MFHMs) fumigated with sulfur have been accurately detected using this approach. Furthermore, a portable test tube was prepared to achieve rapid and semi-quantitative detection of SO 2 residues and applied to real samples. This work presents an effective approach to develop a rapid on-site detection platform for sulfite residues in food and pharmaceuticals., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Carbon dots doped with metals and non-metals have gained much popularity due to the enhancement in their optical and electronic properties. In this study, polyethyleneimine-functionalized transition metal (nickel or copper) doped carbon dots (CD, NiCD and CuCD) were synthesized through hydrothermal method. The carbon dots exhibited a blue fluorescence at 470 nm when excited at 350 nm. The as-synthesized carbon dots were utilised for the fluorimetric detection of bilirubin in the range 0.5 µM - 280 µM, with CuCD exhibiting the highest sensitivity of 155.38 a.u/log µM in the concentration range 0.5 to 10 µM and 84.01 a.u/ log µM in the concentration range 10 to 280 µM. CuCD also exhibited the lowest limit of detection of 0.0907 µM and the lowest limit of quantification of 0.3023 µM. All the carbon dots showed negligible interference in the presence of biomolecules and metal ions present in human serum implying the remarkable selectivity of the method to bilirubin detection. Further, the carbon dots were successfully tested for their real-time application in human serum using bilirubin-spiked serum samples., Competing Interests: Declarations. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

The rapid expansion of the biodiesel industry has substantially increased crude glycerol residue (CG) production, creating sustainability and economic challenges due to surplus glycerol generation. Conventional purification methods are costly and environmentally demanding, necessitating innovative strategies to utilize this residue effectively. This study innovates by exploring the microwave-assisted synthesis of carbon dots (CDs) from CG, exemplifying a shift toward sustainable biodiesel production by transforming the residue into a multifunctional material. CDs exhibited a nanometric spherical morphology of 2.6 ± 0.3 nm diameter verified by HRTEM analysis. The reduction of oxygen confirmed the transformation of CG into CDs-H bands and the formation of polyaromatic structures. The graphitic structures were verified by Raman spectroscopy, electron paramagnetic resonance, and X-ray diffraction. The quantum yield (QY) was calculated to be 1.3%. The multifunctionality of CDs has been proven in sensing and photocatalysis. In the sensor applications, the CDs demonstrated strong fluorescence quenching in the presence of Fe 3+ and Cu 2+ ions, with a limit of detection of 1.80 ± 0.01 and 4.00 ± 0.04 mg.L -1 , respectively, indicating the potential use of CDs in detecting these ions in wastewater samples. When complexed with titanium dioxide (TiO 2 ), the TiO 2 /CDs composite showed an extended photoresponse of TiO 2 to the UV-visible region, improving the efficiency of photocatalytic reactions for Victoria Blue B (VBB) dye degradation (98% degradation after 150 min). This research highlights the potential of utilizing CG to produce versatile CDs, contribute to more sustainable biodiesel production, and offer promising applications in environmental sensing and photocatalysis., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Maraisa Goncalves reports financial support and equipment, drugs, or supplies were provided by Fundação de Amparo à Pesquisa do Estado de São Paulo. Carolina Inacio Portela reports financial support was provided by Fundação de Amparo à Pesquisa do Estado de São Paulo. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Mercury ions (Hg 2+ ) seriously harm the central nervous system of humans, leading to brain damage and even heart failure and death. Therefore, effective detection of Hg 2+ in water quality has become an urgent research field. It is very important to develop economically efficient fluorescent sensors to achieve rapid and sensitive detection of Hg 2+ . Therefore, the high fluorescence quantum yield fluorescent carbon dots (CDs) with amide group were prepared. The process of preparing CDs was regulated by multiple key factors (carbon source, proportion, time), and the CDs with the best fluorescence performance were selected. It was comprehensively characterized, including fluorescence performance, surface structure, phase, and morphological characteristics. The amide group endows CDs with the ability to act as both donors and acceptors for hydrogen bonding, forming complexes with metal ions, thus making them suitable for the detection of Hg 2+ . It is worth noting that CDs can quickly detect Hg 2+ within 1 min, and there is a good linear relationship within the ranges of 0.001-200 μM and 200-500 μM. The detection limit of UC-CDs is 8.2 nM. This study provides a fluorescent sensor with fast reaction, excellent sensitivity, and selectivity for the efficient detection of Hg 2+ in water., (© 2025 John Wiley & Sons Ltd.)

Based on nitrogen and phosphorus co-doped carbon dots (NP-CDs), a direct, quick, and selective sensing probe for fluorometric detection of rutin has been developed. Utilizing ethylene diamine tetra acetic acid (EDTA) as a carbon and nitrogen source and diammonium hydrogen phosphate (NH 4 ) 2 HPO 4 as a nitrogen and phosphorus source. The NP-CDs were synthesized in less than 3 min with a straightforward one-step microwave pyrolysis process with a high quantum yield (63.8%). After being excited at λ = 360 nm, the produced NP-CDs displayed a maximum bluish fluorescence at λ em of 420 nm. Rutin quenched the fluorescence of the produced NP-CDs based on the inner filter effect and static quenching processes. Along with the International Council of Harmonization (ICH) requirements, the developed spectrofluorometric method was validated. The linearity range was 0.50-35.00 μg/mL of rutin. The developed NP-CDs were successfully employed to determine rutin concentrations in marketed tablets. The developed method is quick, simple, consistent, sensitive, and selective, and it does not require expensive chemicals or specialized instruments. This study paves the path for future application of NP-CD in pharmaceutical analysis., (© 2025 John Wiley & Sons Ltd.)