Search Results (190)

Aquatic biomass—ranging from fish scales and crustacean shells to various algae species—offers an abundant, renewable source for carbon dot (CD) synthesis, aligning with circular economy principles. This review highlights recent studies for valorizing aquatic biomass into high-performance carbon-based nanomaterials—specifically aquatic biomass-based carbon dots (AB-CDs)—briefly summarizing green synthesis approaches (e.g., hydrothermal carbonization, pyrolysis, and microwave-assisted treatments) that minimize environmental impact. Subsequent sections highlight the varied applications of AB-CDs, particularly in biosensing (including the detection of marine biotoxins), environmental monitoring of water pollutants, and drug delivery systems. Physically AB-CDs show unique optical and physicochemical properties—tunable fluorescence, high quantum yields, enhanced sensitivity, selectivity, and surface bio-functionalization—that make them ideal for a wide array of applications. Overall, the discussion underlines the significance of this approach; indeed, transforming aquatic biomass into carbon dots can contribute to sustainable nanotechnology, offering eco-friendly solutions in sensing, environmental monitoring, and therapeutics. Finally, current challenges and future research directions are discussed to give a perspective of the potential of AB-CDs; the final aim is their integration into multifunctional, real-time monitoring and therapeutic systems—for sustainable nanotechnology innovations. Full article

The leaf diseases of Panax notoginseng (Panax notoginseng (Burk) F. H. Chen) are mainly spread by spores. To enable rapid and sensitive detection of spores for early warning of disease spread, we developed a carbon dot-based fluorescent probe encapsulated by MIL-101 using wax apple as a green carbon source (WA-CDs@MIL-101). The WA-CDs@MIL-101 was thoroughly characterized, and the detection conditions were optimized. The interaction mechanism between WA-CDs@MIL-101 and spores was investigated. The fluorescence of WA-CDs@MIL-101 was recovered due to electrostatic adsorption between spores and WA-CDs@MIL-101. Under the optimized detection conditions, the probe exhibited excellent sensing performance, showing a strong linear relationship (R² = 0.9978) between spore concentration (0.0025–5.0 mg/L) and fluorescence recovery ratio, with a detection limit of 5.15 μg/L. The WA-CDs@MIL-101 was successfully applied to detect spores on Panax notoginseng leaves, achieving satisfactory recoveries (94–102%) with relative standard deviations of 1.3–3.4%. The WA-CDs@MIL-101 shows great promise for detecting spores on Panax notoginseng leaves. Full article

Aloin, a kind of active phenolic component, is sourced from Aloe vera. Recently, the determination of aloin has received enormous attention, owing to its positive performance (including anti-tumor, antibacterial, detoxification, liver protection, anti-stomach damage, and skin protection activities) and painful side effects (increased carcinogenicity caused by excessive use of aloin) impacting human health. This investigation was inspired by the good fluorescence properties of carbon dots (CDs); CD-based sensors have aroused a great deal of interest due to their excellent sensitivity and selectivity. Thus, it is of great significance to develop novel CD-based sensors for aloin determination. Herein, N,F-CDs were designed and synthesized through a convenient hydrothermal strategy; the synthesized N,F-CDs possessed good fluorescence performance and a small particle size (near 4.3 nm), which demonstrated the successful preparation of N,F-CDs. The resulting N,F-CDs possessed a large Stokes shift and could emit a highly stable green fluorescence. The fluorescence of the N,F-CDs could be effectively quenched by aloin through the inner filter effect. Furthermore, the synthesis procedure was easy to operate. Finally, the N,F-CD-coated test strips were fabricated and combined with a miniaturized fluorimeter for the fluorescence detection of aloin via the inner filter effect for the first time. The N,F-CD-coated test strips were fabricated and used for the fluorescence sensing of aloin, and the results were compared with a typical ultraviolet (UV) method. The N,F-CD-coated test strips exhibited high recovery (96.9~106.1%) and sensitivity (31.8 nM, n = 3), good selectivity, low sample consumption (1 μL), high speed (5 min), good stability, and anti-interference properties. The results indicate that N,F-CD-coated test strips are applicable for the quantitative determination of aloin in bovine serum, orange juice, and urine samples. Full article

Background/Objectives: Carbohydrate antigen 19-9 (CA19-9) is a clinically established biomarker primarily used for monitoring disease progression and recurrence in pancreatic and gastrointestinal cancers. Accurate and continuous quantification of CA19-9 in patient samples is critical for effective clinical management. This study aimed to develop dual-emitting molecularly imprinted nanopolymers (dual@nanoMIPs) for ratiometric and reliable detection of CA19-9 in serum. Methods: Dual-emitting nanoMIPs were synthesized via a one-step molecular imprinting process, incorporating both blue-emitting carbon dots (b-CDs) as internal reference fluorophores and yellow-emitting quantum dots (y-QDs) as responsive probes. The CA19-9 template was embedded into the polymer matrix to create specific recognition sites. Fluorescence measurements were carried out under 365 nm excitation in 1% human serum diluted in phosphate-buffered saline (PBS). Results: The dual@nanoMIPs exhibited a ratiometric fluorescence response upon CA19-9 binding, characterized by the emission quenching of the y-QDs at 575 nm, while the b-CDs emission remained stable at 467 nm. The fluorescence shift observed in the RGB coordinates from yellow to green in the concentration range of CA19-9 tested, improved quantification accuracy by compensating for matrix effects in serum. A linear detection range was achieved from 4.98 × 10⁻³ to 8.39 × 10² U mL⁻¹ in serum samples, with high specificity and reproducibility. Conclusions: The dual@nanoMIPs developed in this work enable a stable, sensitive, and specific detection of CA19-9 in minimally processed serum, offering a promising tool for longitudinal monitoring of cancer patients. Its ratiometric fluorescence design enhances reliability, supporting clinical decision-making in the follow-up of pancreatic cancer. Full article

Background: Ischemic stroke (IS) is probably the most important acute serious illness, where interdisciplinary approach is essential to offer the best chance for survival and functional recovery of patients. Carbon dots (CDs) with multifaceted advantages have provided hope for development brand-new nanodrug for treating thorny diseases. Methods: This study developed a green and environmentally responsible calcination method to prepare novel Gardenia jasminoides Carbonisata (GJC-CDs) as promising drug for ischemic stroke treatment. Results: In this work, we isolated and characterized for the first time a novel carbon dots (GJC-CDs) from the natural plant G. jasminoides. Results displayed that green GJC-based CDs with tiny sizes and abundant functional groups exhibited solubility, which may be beneficial for its settled biological activity. The neuroprotective effect of carbon dots from G. jasminoides were evaluated using the classical middle cerebral artery occlusion (MCAO) model. Assessing the infarct volume content of the ischemic cerebral hemisphere and determining the serum tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), reduced glutathione (GSH), superoxide dismutase (SOD), and malondialdehyde (MDA) levels of the mice in each group, it was evident that pre-administration of the drug by GJC-CDs significantly reduced the infarct volume as well as attenuated inflammatory responses and excessive oxidative stress in MCAO mice. Furthermore, in vitro cellular experiments demonstrated that GJC-CDs have good biosafety and anti-inflammatory and antioxidant capacity. Conclusions: Overall, GJC-CDs performs neuroprotective effect on cerebral ischemia and reperfusion injury, which not only provides evidence for further broadening the biological application of acute ischemic stroke but also offers novel strategy for the application of nanomedicine to treat acute diseases. Full article

The rapid development of wearable electronics requires multifunctional, transient electronic devices to reduce the ecological footprint and ensure data security. Unfortunately, existing transient electronic materials need to be degraded in chemical solvents or body fluids. Here, we report green luminescent, water-soluble, and biocompatible piezoelectric nanofibers developed by electrospinning green carbon quantum dots (G-CQDs), mulberry silk fibroin (SF), and polyvinyl alcohol (PVA). The introduction of G-CQDs significantly enhances the piezoelectric output of silk fibroin-based fiber materials. Meanwhile, the silk fibroin-based hybrid fibers maintain the photoluminescent response of G-CQDs without sacrificing valuable biocompatibility. Notably, the piezoelectric output of a G-CQD/PVA/SF fiber-based nanogenerator is more than three times higher than that of a PVA/SF fiber-based nanogenerator. This is one of the highest levels of state-of-the-art piezoelectric devices based on biological organic materials. As a proof of concept, in the actual scenario of a rope skipping exercise, the G-CQD/PVA/SF fiber-based nanogenerator is further employed as a self-powered wearable sensor for real-time sensing of athletic motions. It demonstrates high portability, good flexibility, and stable piezoresponse for smart sports applications. This class of water-disposable, piezo/photoactive biological materials could be compelling building blocks for applications in a new generation of versatile, transient, wearable/implantable devices. Full article

Metal-doped carbon dots (CDs) have become one of the most popular catalytic materials for Fenton-like reactions, mainly due to their low production cost, minimal toxicity, and high catalytic efficiency. Theses reactions not only provide an efficient decontamination method for the degradation of organic pollutants in wastewater but also demonstrate a wide range of sensing applications. Metal doping introduces new catalytically active centres, which increase the binding selectivity to the reactants and offer an additional advantage of improved catalytic degradation and sensing activity. The metal-doped CDs optimise the electronic structure of pristine CDs, thereby enhancing their catalytic properties and reaction rates. These enhancements make them an attractive option for water treatment and sensor design. The objective of this review is to provide a comprehensive overview of the current research progress in the utilisation of metal-doped CDs as Fenton-like reaction catalysts for the degradation of pollutants and sensing applications. This review examines the advantages of metal-doped carbon dots in terms of catalytic efficiency, selectivity, and application scope and discusses the potential challenges and future research directions. The aim is to promote further the sustainable application and green development of CD technology in environmental governance and analytical chemistry. Full article

Background/Objectives: The development of effective therapies for brain disorders is highly correlated with the ability of drugs or nanosystems to cross the blood–brain barrier (BBB), which has been limited. Recently, carbon dots (CDs) have been receiving attention to be used as BBB-crossing theranostic agents due to their inherent advantages, such as low size, excellent biocompatibility, high quantum yield (QY), tunable fluorescence, high drug loading, and relatively easy synthesis at low cost. The aim of this study was to design CDs with precisely controlled fluorescence properties for advanced bioimaging and an in-depth assessment of BBB permeability. Methods: CDs were synthesized using a microwave-assisted approach, optimized through microwaves’ irradiation time, and employing citric acid, urea, and sodium fluoride as precursors. The optimized sample was labeled as NF-CD. Results: A comprehensive physicochemical, photoluminescence, and biological characterization revealed the ability of NF-CD to diffuse across a neuromimetic-BBB model, mainly due to their small size (average diameter of 4.0 ± 1.1 nm), exhibiting excitation-dependent fluorescence in the blue and green wavelengths, high biocompatibility and QY, and exceptional photostability. Conclusions: Owing to the exceptional fluorescence characteristics and biological compatibility, NF-CD presents promising opportunities in theranostic applications, particularly in brain-targeted bioimaging, nanocarrier-based drug and immunotherapy delivery, early-stage diagnostics, and personalized medicine. NF-CD’s ability to cross the BBB further underscores the relevance of pioneering nanomaterial-based strategies for neurological disorder diagnostics and precision-targeted therapeutic interventions. Overall, this research contributes to the broader field of nanotechnology-driven biomedical advancements, fostering innovations in neurological diagnostics and therapeutic delivery systems. Full article

In this study, we report a green, one-step synthesis of fluorescent carbon quantum dots (PET-FCQDs) derived from polyethylene terephthalate (PET) waste using an environmentally friendly pyrolytic method. The PET-FCQDs were systematically characterized using techniques such as UV-Vis spectroscopy, fluorescence spectroscopy, ATR-FTIR, TGA, and fluorescence microscope, confirming their nanoscale size (2–50 nm), rich functional groups and thermal stability. Thermal stability and dynamics evaluated by the Coats–Redfern method showed endothermic reactions with an activation energy of 88.84–125.05 kJ/mol. Density functional theory studies showed a binding energy, highest occupied molecular orbital, lowest unoccupied molecular orbital, and energy gap of −675.39, −5.23, −5.07, and 0.17 eV, respectively. The as-synthesized PET-FCQDs demonstrated excellent optical properties with quantum yield ($\Phi$) of 49.6% and were applied as a dual-mode fluorescent sensing probe for the detection of Pd²⁺, ciprofloxacin (CIP), and fluoxetine (FLX) in aqueous systems via fluorescence quenching and enhancement mechanisms. For Pd²⁺, the fluorescence emission intensity at 470 nm was quenched proportionally to the increasing concentration, while CIP and FLX induced fluorescence enhancement. The Stern–Volmer analysis confirmed strong interaction between the analytes and PET-FCQDs, distinguishing dynamic quenching for Pd²⁺ and static interactions for CIP and FLX. The method exhibited linear detection ranges of 1–10 mg/L for Pd²⁺, 50–150 µg/L for CIP, and 100–400 ng/L for FLX, with corresponding limits of detection (LOD) of 1.26 mg/L, 3.3 µg/L, and 134 ng/L, respectively. Recovery studies in spiked tap water and river water samples demonstrated the practical applicability of PET-FCQDs, although matrix effects were observed, particularly for FLX. This work not only highlights a sustainable route for PET waste upcycling but also demonstrates the potential of PET-FCQDs as cost-effective, sensitive, and versatile fluorescent probes for environmental monitoring of heavy metal ions and pharmaceutical pollutants. Further optimization of the sensing platform could enhance its selectivity and performance in real-world applications. Full article

In the ever-advancing field of nanotechnology and nanoscience, luminescent carbon dots, or carbon quantum dots, have emerged as one of the most up-and-coming carbon-based nanomaterials in recent years due to their diverse physicochemical properties, which include low toxicity, ease of synthesis, superior photostability, excellent water solubility, high specific surface areas with ease of surface functionalization, and unique electronic and optical properties. They exhibit two-photon absorption and unique tunable fluorescence emission across a wide range of wavelengths, which can be precisely controlled by surface modifications and particle size. These characteristics have led to their widespread usage in a variety of applications, including optical/fluorescent sensing, electrochemical sensing, and energy-related fields, such as light-emitting diodes, photovoltaic supercapacitors, bioimaging, drug delivery, and antimicrobial research. Recently, focus has shifted to the green synthesis of carbon dots, with significant success achieved in this area, opening a plethora of opportunities in both basic and applied sciences. This review is a comprehensive study of milestones achieved in the area of green carbon dots. This review starts with the historical background of luminescent materials and how carbon dots/carbon quantum dots have been emerging as the stars among all luminescent nanomaterials. The challenges of conventional synthesis methods for nanoparticles are also discussed, with a detailed review of the various green synthesis processes reported to date. This section provides insights into widely accepted formation mechanisms and their influence on the shapes and sizes of CDs. In the next section, various physical properties of CDs are discussed, highlighting characteristics such as high quantum yield, photoluminescence stability, and chemical inertness, which make them exceptional nanomaterials. Last but not least, various CD-related challenges and future prospects are highlighted. Overall, this review provides details of recent developments in the area of green CDs. Full article

Green carbon dots (GCDs) have emerged as a revolutionary tool in precision medicine, offering transformative capabilities for personalized diagnostics and therapeutic strategies. Their unique optical and biocompatible properties make them ideal for non-invasive imaging, real-time monitoring, and integration with genomics, proteomics, and bioinformatics, enabling accurate diagnosis and tailored treatments based on patients’ genetic and molecular profiles. This study explores the potential of GCDs in advancing individualized patient care by examining their applications in precision medicine. It evaluates their utility in non-invasive diagnostic imaging, targeted therapy delivery, and the formulation of personalized treatment plans, emphasizing their interaction with advanced genomic, proteomic, and bioinformatics platforms. GCDs demonstrated exceptional versatility in enabling precise diagnostics and delivering targeted therapies. Their integration with cutting-edge technologies showed significant promise in crafting personalized treatment strategies, enhancing their functionality and effectiveness in real-time monitoring and patient-specific applications. The findings underscore the pivotal role of GCDs in reshaping healthcare by advancing precision medicine and improving patient outcomes. The ongoing development and integration of GCDs with emerging technologies promise to further enhance their capabilities, paving the way for more effective, individualized medical care. Full article

The structure of nitrofen is stable and resistant to natural degradation, persisting in environments for extended periods. It can accumulate through the food chain, posing risks to human health. Here, we report a sensor based on carbon quantum dots (CQDs) and molecular imprinting technology (CQDs@MIPs). It not only possesses the specificity and stability of MIPs but also incorporates the environmental friendliness and signal amplification capabilities of CQDs, making it an ideal material for the specific detection of nitrofen residues in the environment. The interaction between CQDs@MIPs and nitrofen, as well as the successful removal of nitrofen, were confirmed through transmission electron microscopy (TEM) and Zeta potential analysis, which evaluated the morphology and particle size of the prepared CQDs@MIPs. After binding with nitrofen, the CQDs@MIP sensor exhibited a low detection limit (2.5 × 10⁻³ mg·L⁻¹), a wide detection range (0.01–40 mg·L⁻¹), a good linear relationship (R² = 0.9951), and a short detection time (5 min). The CQDs@MIP sensor also demonstrated excellent stability, with the fluorescence intensity of CQDs@MIPs remaining above 90% of the initial preparation after 20 days. At the same time, Red, Green, Blue (RGB) color model extraction technology is used to fit the color of the sample under different concentrations, and the smart phone application is integrated to realize the visual detection of nitrofen. Furthermore, acceptable accuracy was achieved in real water samples (recovery rates ranging from 84.1% to 115.7%), indicating that our CQDs@MIP sensor has high analytical potential for real samples. Full article

It is of great significance to develop carbon quantum dots (CQDs) using green carbon sources, which are cheap, non-toxic and harmless, and further expand their application scopes, e.g., fluorescence sensors, blue light screening. In this study, we have prepared Peperomia tetraphylla-based carbon quantum dots (PT-CQDs) with strong water solubility, good salt resistance, specific quenching reactions and excellent optical properties via a simple one-step hydrothermal method. In one application, PT-CQDs are utilized as a fluorescence sensor due to their high selectivity and sensitivity to ferric ions (Fe³⁺). The limit of detection (LOD) was 2.7 μmol·L⁻¹. On the other hand, PT-CQDs/polyvinyl alcohol (PVA) films with excellent ultraviolet- (UV) and high-energy blue light (HEBL)-blocking properties were obtained. The obtained films exhibited a high blue light weight blocking rate of 100% in UV and 80% in HEBL. The concentrations of the composites could also be controlled to achieve the desired light-blocking rate. In addition, the composites were able to absorb blue light and convert it to other forms of light. These properties suggest their potential applications in the development of advanced blue light screening and fluorescence sensors. Full article

Over the years, the abuse of antibiotics has increased, leading to their presence in the environment. Therefore, a sustainable method for detecting these substances is crucial. Researchers have explored biomass-based carbon dots (CDs) to detect various contaminants, due to their low cost, environmental friendliness, and support of a circular economy. In our study, we reported the synthesis of CDs using pinecones (PCs) and pinebark (PB) through a sustainable microwave method. We characterized the PCCDs and PBCDs using X-ray diffraction, Raman spectroscopy, Transmission Electron Microscope, and Fourier transform infrared, Ultraviolet-visible, and photoluminescence (PL) spectroscopy. The PCCDs and PBCDs were tested for the detection of amoxicillin (AMX) and tetracycline (TC). The results indicated that the sizes of the PCCDs and PBCDs were 19.2 nm and 18.39 nm, respectively, and confirmed the presence of the 002 plane of the graphitic carbon structure. They exhibited excitation wavelength dependence, good stability, and quantum yields ranging from 6% to 11%. PCCDs and PBCDs demonstrated “turn-off” detection for TC and AMX. The limits of detection (LOD) for TC across a broader concentration range were found to be 0.062 µM for PCCDs and 0.2237 µM for PBCDs. For AMX detection, PBCDs presented an LOD of 0.49 µM. Full article

This study investigates the synthesis and photoluminescent properties of carbon quantum dots (CQDs) derived from Actinidia deliciosa using the hydrothermal method. The effect of concentration and pH on the composition, structure, and optical properties of CQDs was analyzed using characterization techniques such as TEM, EDS, FTIR, UV-Vis, and photoluminescence (PL) spectroscopy. The CQDs exhibited particle sizes ranging from 1 to 10 nm, with a graphitic structure and oxygen-containing functional groups, as identified by FTIR bands corresponding to OH, C=O, and C=C. The stability analysis revealed particle agglomeration over 30 days, increasing the size up to <40 nm. Regarding the optical properties, the CQDs displayed absorption peaks at 225 and 280 nm and a bandgap of ~3.78–3.82 eV. The PL characterization demonstrated tunable emission from violet to green, depending on the excitation wavelength. CQDs synthesized at an acidic pH of 2 exhibited enhanced luminescence due to protonation effects, whereas an alkaline pH led to a reduction in emission intensity. The hydrothermal method enabled a simple and eco-friendly synthesis, using water as the sole solvent, yielding stable CQDs with a luminescence lifespan exceeding 30 days. Their optical and electronic properties make them promising candidates for photocatalysis, heavy metal detection, and bioimaging applications. Full article