Green synthesis of fluorescent carbon dots from discarded cigarette butts as an effective fluorescence probe for sensing iron ions

Environmentally benign conversion of waste polyethylene terephthalate to fluorescent carbon dots for “on-off-on” sensing of ferric and pyrophosphate ions

Novel synthesis of fluorescent carbon dots from bio-based Carica Papaya Leaves: Optical and structural properties with antioxidant and anti-inflammatory activities

Green synthesis of fluorescent carbon dots from Hongcaitai for selective detection of hypochlorite and mercuric ions and cell imaging

Facile synthesis of fluorescent carbon dots using watermelon peel as a carbon source

Carbon dots (CDs) have outstanding optical properties, biocompatibility, and photostability, making them attractive for imaging applications. A facile and green one-step hydrothermal synthesis method is proposed, which can be safely used in a wide range of applications such as chemical sensing, bioimaging, and optoelectronics. In this study, we report green synthesis of carbon dots from bitter orange juice (Citrus Aurantium) by hydrothermal treatment for the first time. We studied effects of time, temperature, and pH on fluorescence of CDs, characterized them using various spectroscopic and microscopic methods, and evaluated their toxicity to different cell lines. Identifying an optimum reaction condition of 180 ºC for 7 h heating gave CDs that showed pH-dependent fluorescence, with the largest fluorescence at a pH of 7.0. The CDs were 1-2 nm in size with a spherical morphology and negative surface charge. The CDs showed a high quantum yield of 19.9 %, reasonable photostability, excellent water solubility, and long fluorescence lifetime. A one step hydrothermal rout led to various hydrophilic functional groups on the surface of the CDs. Our results showed that the CDs were non-toxic over a large concentration range and effective for imaging of cells, indicating their potential as imaging probes in medical diagnostics and biosensor applications.

Industrial discharge of synthetic dyes, particularly thymol blue (TB), poses a major environmental concern due to their chemical nature and toxicity toward aquatic life and human health. TB, a sulfonephthalein dye extensively used in laboratory and textile sectors, demonstrates high resistance to conventional treatment methods. Carbon dots (CDs), synthesized through a green, biomass-derived route, exhibit dual fluorescence behavior with prominent green (λmax 521 nm) and orange emissions (λmax 665 nm), and have emerged as efficient catalysts for environmental remediation. Their ability to generate reactive oxygen species (ROS) enables the degradation of persistent organic pollutants. Herein, green-synthesized CDs from paddy straw are reported to demonstrate rapid catalytic degradation of TB in under 1 min. The process is driven by the generation of ROS, which effectively cleaves the TB molecules into less harmful byproducts. These results demonstrate that biomass-derived CDs provide a sustainable, cost-effective alternative to traditional wastewater treatments, significantly mitigating the environmental concern of dye pollution. Moreover, the green synthesis strategy minimizes hazardous byproduct formation, advancing sustainable chemistry principles and promoting the circular economy through the utilization of biomass waste into functional nanomaterials.

Facile, green and energy-efficient preparation of fluorescent carbon dots from processed traditional Chinese medicine and their applications for on-site semi-quantitative visual detection of Cr(VI)

ZnCl2 Enabled Synthesis of Highly Crystalline and Emissive Carbon Dots with Exceptional Capability to Generate O2⋅–

Green synthesis of fluorescent carbon dots from canon ball fruit for sensitive detection of Fe3+ and catalytic reduction of textile dyes

Carbon dots (CDs) synthesized from biological sources have attracted much interest in bioimaging and biomedical applications due to their excellent biocompatibility, and thus, a facile synthesis of CDs with high fluorescence quantum yield (QY) is requisite for practical applications. In this work, we report a simple, rapid, and green approach to synthesize photoluminescent CDs using eutrophic algal blooms as the carbon source. This method offers a possibility for large scale production of highly luminescent CDs (QY = 13%) with the average particle size ∼8 nm. These CDs are highly water-soluble and exhibit nanosecond fluorescence lifetime with high photostability, luminescence stability in different environments, low cytotoxicity, and excellent cell permeability. Laser scanning confocal microscopy shows the uptake of CDs by MCF-7 cells, and the destined application of these CDs as a potential biomarker is demonstrated.

Carbon Dots (CDs) were synthesized using laser ablation by focusing the laser beam on carbon (Tea) material in colloid (CH3) for 3 hours. UV-Vis spectroscopic and fluorometric characterization showed absorption of the wavelength peaks caused by the control treatment and after laser ablation and coating using Poly Ethylene Glycol (PEG400). The excitation and emission energies are formulations of CDs absorbance wavelength and fluorescence intensity. The absorbance coefficient is obtained based on the absorbance value of the cuvette thickness. The transmittance value (T) is obtained based on the absorption coefficient multiplied by 100%. CD fluorescence wavelength based on control parameters was 489 nm. After laser ablation was 496 nm, and after coating was 511 nm. CDs morphology and size characteristics are 4 nm to 10 nm based on TEM measurements. Fluorescence analysis for bioimaging applications on the luminescence intensity value of internalized blue CDs in zebrafish eye organs. The average intensity of CDs in the eye organs, gill, intestinal, dorsal, and tail injection points was 88.15 %, 91.58 %, 92.76 %, and 0.00 %.

Formation of N, S-codoped fluorescent carbon dots from biomass and their application for the selective detection of mercury and iron ion

We report here the fast fabrication of fluorescent carbon dots (CDs) within several minutes by magnetic hyperthermia. This method offers an alternative platform to prepare excitation-dependent fluorescent CDs without any surface modification from various kinds of precursors varying from polymers like poly(vinyl alcohol) (PVA) and polyethylene glycol (PEG) to small organic molecules and salts like amino acid, glucose, EDTA, citrate acid–urea, sodium citrate, zinc stearate, and ammonium citrate. As an example, the magnetic hyperthermia synthesis, characterization, optical properties, and in vitro cytotoxicity of CDs obtained from ammonium citrate are thoroughly investigated. The excitation-dependent fluorescence mechanism is discussed based on the UV–vis absorption, excitation, and emission spectra as well as the photoluminescence (PL) response to metal ions and pH. These CDs are further used as ink for inkjet printing to produce fluorescent patterns with uniform and stable PL useful for anticounterfeit and optoelectronic applications. This magnetic hyperthermia method allows the rapid fabrication of versatile CDs from a wide range of carbon sources in a simple, low-cost, and easy-to-perform way.

Fluorescent carbon dots have the advantages of good chemical stability, low toxicity, and surface functionalization, which has caused concern. In recent years, polymer carbon dots synthesize by polymer polysaccharides have become a new research hotspot. In this paper, a chitosan-based fluorescent polymer carbon dot material is synthesized by hydrothermal method and used for drug-loading research. We choose chitosan-graft-polyethylene glycol monomethyl ether and citric acid derivatives as the carbon sources for the carbon dots, because chitosan and polyethylene glycol are both a carbon source for carbon dots and a passivation reagent for carbon dots. Then the quantum yield of the polymeric carbon dots is increased. Polymer carbon dots can also retain the molecular structure of polyethylene glycol and chitosan, providing favorable conditions for its application in drug loading. The structural characterization is performed on P(CS-g-mPEG-CA)CDs by IR, UV, X-ray diffraction, photoelectron spectroscopy, transmission electron microscopy and photoluminescence spectra and pH stability test is carried out. The results show that the synthesized P(CS-g-mPEG-CA)CDs has higher fluorescence quantum yield(66.81%), longer fluorescence lifetime(15.247 ns), and better pH stability. Using Doxorubicin as a model drug, a load study was conducted using this polymer carbon dot. The results show that if the degree of substitution of mPEG is 11.9%, the maximum loading rate of polymer carbon dots is 51.3% and the maximum drug release rate is 28.7%. In addition, we also found that drug loading and release could be controlled by the grafting rate of mPEG. In addition, the cytotoxicity of polymer carbon dots on nasopharyngeal carcinoma cells(CNE-2) is evaluated using an MTT assay. The study shows that there is no obvious cytotoxicity of blank P(CS-g-mPEG-CA)CDs, and that the survival rate of CNE-2 cells decreases with the increase of drug-loaded micelles. The results show that the P(CS-g-mPEG-CA)CDs have a certain application prospect in the aspects of fluorescence labeling, drug delivery, fluorescent tracer system and controlled release.

Smartphone-based portable device for rapid and sensitive pH detection by fluorescent carbon dots