Green Synthesis Of Carbon Dots Research Articles

Green synthesis of carbon dots (CDs) and their use for selective determination of Pb2+

Carbon dots were synthesized from fenugreek seeds through a single step hydrothermal method. The method is simple, fast, pleasant to the environment and cheaper. The CDs were characterized by Fourier Transform Infrared (FTIR), UV–visible spectrophotometer, X-ray diffraction (XRD), High Resolution Transmission electron microscopy (HR-TEM), and fluorescence. The CDs obtained were extremely fluorescent. The fluorescent carbon dots exhibited excitation-dependent behavior with the maximum excitation at 372 nm. The interaction of CDs was studied with different selected cations Al3+, Ca2+, Cd2+, Cr3+, Co2+, Cu2+, Cu+, Fe2+, Fe3+, K+, Sn4+, Na+, Ni2+, Pb2+, Mn2+, Zn2+, Sr2+, (NH4)6Mo7O24, 4H2O, Cr6+, Sb3+, Ba2+, Li+, and Mg2+. None of the ions studied showed any effect on its fluorescence intensity except Pb2+ which decreased its intensity. A direct relationship was found between Pb2+ concentrations and quenching of CDs intensity. Detection limit (DL) and quantification limits (QL) were determined as three and ten times of the standard deviation of the blank for ten number of measurements. DL and QL were found in the order 9.345 μM and 31.15 μM respectively. This linear behavior between quenching and Pb2+ concentration is useful for analytical purpose.

POE-Mediated Tunable Quantum Yield of Carbon Dots-Derived From Agapanthus Africanus (L.) Hoffmann Leaves.

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 2/3h. 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 ± 1.6nm, respectively. Their surface, devoid of chlorophyll, contains ─OH, ─C═O, and ─C(═O)OH groups and sylvite. Isolated CZ-300-3 emits at 400nm (excited at 260nm) 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 420/450nm (360nm), and QY values of 7 ± 1/16 ± 2% (400nm). The enhancement of the QY value of the bare CDs agrees withan 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.

Recent Trends and Advancements in Green Synthesis of Biomass-Derived Carbon Dots

The push for sustainability in nanomaterials has catalyzed significant advancements in the green synthesis of carbon dots (CDs) from renewable resources. This review uniquely explores recent innovations, including the integration of hybrid techniques, such as micro-wave-assisted and ultrasonic-assisted hydrothermal methods, as well as photocatalytic synthesis. These combined approaches represent a breakthrough, offering rapid production, precise control over CD properties, and enhanced environmental sustainability. In addition, the review emphasizes the growing use of green solvents and bio-based reducing agents, which further reduce the environmental footprint of CD production. This work also addresses key challenges, such as consistently controlling CD properties—size, shape, and surface characteristics—across different synthesis processes. Advanced characterization techniques and process optimizations are highlighted as essential strategies to overcome these hurdles. Furthermore, this review pioneers the integration of circular economy principles into CD production, proposing novel strategies for sustainable material use and waste reduction. By exploring innovative precursor materials, refining doping and surface engineering techniques, and advocating for comprehensive life cycle assessments, this work sets a new direction for future research. The insights provided here represent a significant contribution to the field, paving the way for more sustainable, efficient, and scalable CD production with diverse applications in optoelectronics, sensing, and environmental remediation.

Green synthesis of carbon dots from Hakka yellow wine lees: Characterization and applications for Fe3+ and NaFeEDTA sensing

In this study, Hakka yellow wine lees carbon dots (HYWL-CDs) with an average diameter of 1.75 nm are synthesized from Hakka yellow wine lees (HYWL) via a one-pot hydrothermal method. Results of X-ray photoelectron spectroscopy and FTIR reveal the presence of C=C and –OH in the HYWL-CDs. Additionally, the HYWL-CDs present excitation-wavelength dependence, with maximum excitation and emission wavelengths of 360 and 440 nm, respectively. The fluorescence of the HYWL-CDs can be quenched by Fe3+. The Fe3+ concentration is correlated linearly with the quenching rate over a linear range of 0.6–1.1 mg/mL, and the limit of detection is 0.18 μg/mL. And phenols have been shown to be present in HYWL-CDs, and the color reaction between phenols and FeCl3 is most likely the mechanism by which FeCl3 causes fluorescence burst in HYWL-CDs. Moreover, the HYWL-CDs demonstrate significant potential for detecting NaFeEDTA in iron-fortified soy sauces, the linear-fit equation was y = 185.38x + 1024.6 (R2 = 0.9995) The HYWL-CDs are loaded onto paper strips, iron-fortified straw mushroom dark soy sauce showed noticeable color changes, which allows one to differentiate normal soy sauce from iron-fortified soy sauce more conveniently and provides a new perspective for the high-value utilization of yellow wine lees.

Cost-Effective Hydrothermal Synthesis of Luminescent Carbon Dots from Date Palm Midrib

Nanocarbon synthesis from diverse sources has garnered significant attention, with a particular focus on materials derived from biomass. Carbon dots (CDs), due to their water solubility, low toxicity, and biocompatibility, have emerged as promising candidates for a wide range of applications. In recent years, CDs have found utility in several applications such as bioimaging, drug delivery, and biosensors. In this study, we present an eco-friendly, straightforward, and cost-effective technique for the synthesis of carbon dots through a hydrothermal reaction, utilizing peeled date palm midribs as the source material. High-resolution transmission electron microscopy, X-ray diffraction, UV-visible absorption spectroscopy, photoluminescence analysis, Fourier-transform infrared spectroscopy, and zeta potential measurements services to investigate the synthesized carbon dots' morphology, crystal and structure, and optical properties. The results show that the carbon dots had a size distribution ranging from 2.5 to 6 nm, and a crystallographic interplanar distance of 0.23 nm corresponding to the graphitic structure. When excited at a wavelength of 340 nm, the synthesized dots exhibited a prominent bluish emission at 420 nm, highlighting their potential for use in optical and biological applications. This work underscores the feasibility of harnessing sustainable biomass sources, such as date palm midribs, for the green synthesis of carbon dots with desirable properties, opening up new avenues for their utilization in cutting-edge technologies.

Synthesis of Carbon Dots via Microwave-Assisted Process: Specific Sensing of Fe(III) and Antibacterial Activity.

Carbon dots synthesized from a renewable and sustainable source of biomass have greater attention in the nanomaterial research field. In the present study, we adopted a facile and green synthesis of carbon dots from bio waste of pumpkin seeds using a one-pot microwave-assisted carbonization method. The synthesized carbon dots exhibit excellent photoluminescence properties with a bright blue emission peak at 399nm and fluorescence quantum yield was about 9.5%. The optical properties and structure of carbon dots were examined using various spectroscopy techniques and the synthesized carbon practical size was about 4.37nm and possessed good solubility in water. Carbon dots were used for the detection of Ferric ions in the water bodies and the interaction between Fe3+ ions and carbon dots was evaluated by fluorescence spectroscopy techniques. This method is a simple and selective detection of Fe3+ in the aqueous medium. Interestingly carbon dots also show good antibacterial activity at a very low concentration (1mg/L) for effective control of E. coli 93% and Pseudomonas aeruginosa (81%), within 12h.

Green synthesis of carbon dots from mature green tea leaves for label-free fluorescence sensing of chromium(VI)

Hexavalent chromium (Cr(VI)) has been established as a highly carcinogenic and mutagenic entity. Therefore, there has been a persistent demand for affordable, sensitive, and quick sensors to monitor the presence of Cr(VI) in aqueous systems. A straightforward, cost-efficient, and eco-friendly approach has been reported in this work in terms of blue-fluorescent carbon dots (CDs, 5.2 nm) being realized in a single-step hydrothermal process. For this purpose, fully grown green tea leaves as the main carbon source were deployed due to being cheap, and environmentally sustainable and readily accessible sources. These CDs exhibit good water solubility, photo-stability and photo-emission (maximal emission at 438 nm for 360 nm excitation wavelength), anti-interference, and low cytotoxicity. The article demonstrates a straightforward fluorescent test for the precise detection and determination of Cr(VI). This was realized through the construction of a non-luminous complex which led to fluorescence quenching via the inner filter effect (IFE). Accordingly, the system can be employed as a label-free nanosensor. Under optimal condition (pH 4 and 5 min reaction time), the fluorescence quenching efficiency of CDs exhibited a well-defined linear correlation in the 0.01–8 mg/L concentration range of Cr(VI). A linear equation represents the system sensor as F0/F = 0.2101x + 1.0016 (R2 = 0.99). The limit of detection (LOD) has been as minimal as 0.004 mg/L (s/k = 3). These findings infer CDs as a potential cost-effective nanosensor for Cr(VI) identification in tap water specimens.

Green synthesis of carbon dots from Nigella sativa seeds for supercapacitor application

The synthesis of carbon dots (CDs) from sources such as coal and phenolic resins requires the use of chemicals that sometimes are hazardous to the environment. Several studies have highlighted the significance of using natural and biomass sources in ecologically friendly CDs synthesis. This strategy guarantees their accessibility, environmental friendliness and cost-effectiveness. In this work, we report the synthesis of CDs from Nigella sativa seeds for supercapacitor application. A hydrothermal technique was adopted for this experiment. The structural, size distribution, fluorescence, and electrochemical properties of the synthesized CDs were studied using an X-ray diffraction (XRD) spectroscope, Transition electron microscope (TEM), spectrofluorometer and potentiostat, respectively. The TEM revealed distinct scattered quasi-spherical dots on the surface and the estimated size distribution ranges from 6.08 to 9.91 nm. The fluorescence spectra revealed that CDs have green light emission, which redshifts as the excitation wavelength increases. The electrochemical measurement confirms that CDs exhibited an electrical double layer (EDL) capacitance behavior with an areal capacitance of 2.82 mF/cm2 at 5.21 μA/cm2 current density. To the best of our knowledge, this is the first report on the fabrication of supercapacitor from CD derived from Nigella sativa seeds.

Advancements in the green synthesis of carbon dots for sustainable development

The use of various biomass derivatives and wastes to produce carbon dots (CDs) represents a green synthesis approach that holds great potential for commercialization by offering economically viable, abundant, and sustainable resources. The process is reliable and reproducible by producing high-quality CDs with controllable size and surface structure, high photoluminescence (PL), and narrow emission. This review highlights the potential of biomass wastes and derivatives as a valuable resource for the production of CDs, showcasing their economic viability and environmental sustainability. The discussion is focusing on optimizing the green synthesis of CDs from different biomass precursors, including small molecules (e.g., sugars, polymers, amino acids, proteins, etc.) and biomass wastes (e.g., leaves, stem, root, flower, pollen, etc.), elucidating the underlying synthetic mechanisms, and exploring various modification techniques. The pursuit of high-quality CDs materials is also realized through innovative modification strategies, such as surface passivation, precise morphology and size control, and heteroatom doping, which enable tailoring the properties of CDs according to specific requirements while minimizing waste generation. The formation mechanism and tuning of optical properties were also discussed in detail, focusing on the comparison with CDs using other precursors. We further introduced the sustainable applications of these green CDs on renewable energies, such as photocatalysis, electrocatalysis, supercapacitors, lithium-ion batteries, and photovoltaics. Finally, this review provides a perspective on the challenges, potential advancements and future directions in the field of the green CDs.

Green synthesis of carbon dots from mangosteen peel for fluorescent cancer cells

Recently, carbon dots (CDs) have received significant attention owing to their outstanding optical properties, good solubility, and low toxicity. In this research, CDs were synthesized by a hydrothermal method based on an environmentally friendly and straightforward strategy, using only mangosteen peel and deionized water. The synthesized CDs had an average size of 3.09 ± 0.38 nm. The absorbance spectrum peak for the CDs was seen at 282 nm, and the central wavelength of fluorescence emission was observed at 433 nm under an excitation wavelength of 355 nm. An aqueous solution of CDs exhibited bright green fluorescence when observed with the naked eye under UV irradiation. Both Fourier transform infrared and X-ray photoelectron spectroscope measurements were taken to determine the elemental compositions of the organic substance functional groups on the surface of the CD, such as hydroxyl, carboxyl, and carbonyl groups. These functional groups originate the different emission centers leading to multicolor fluorescent emissions. Furthermore, the synthesized CDs were found to have good biocompatibility with organic and biological materials. The remarkable properties of CDs, including their nanoscale dimensions, strong multicolor fluorescent emissions, non-toxicity, and excellent cell compatibility, could effectively permeate the cell membrane, cytoplasm, and nucleus and provide fluorescence emission. This suggests a significant potential for CDs in fluorescent cell staining applications. Finally, the CDs were used as a fluorescent dye for human colon cancer cells, as they exhibited excellent fluorescence for cell staining.

Synthesis of Green Carbon Dots from Nephelium Lappaceum L. Seeds

In this study, rambutan (Nephelium Lappaceum L.) seeds were used to fabricate green carbon dots (gCDs) by employing a hydrothermal process. The synthesized CDs were evaluated using Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) for the structural properties as well as UV-Vis and fluorescence spectrophotometry for the optical properties. UV-Vis examination revealed that the produced gCDs showed emission-dependent photoluminescence excitation, with two absorption peaks at 265 nm and 330 nm. The presence of functional groups and chemical composition such as C=C, C=O, -COOH, and -OH on the surface of gCDs was confirmed by the results of FTIR and XPS spectra. Consequently, gCDs present several opportunities for exploration in a range of applications.

Rapid green synthesis of carbon dots from Cleome viscosa seeds for the catalytic reduction of methylene blue and rhodamine B dyes

Rapid green synthesis of carbon dots from Cleome viscosa seeds for the catalytic reduction of methylene blue and rhodamine B dyes

Facile cost-effective green synthesis of carbon dots: selective detection of biologically relevant metal ions and synergetic efficiency for treatment of cancer

A facile cost-effective green synthesis approach has been used to synthesize carbon-dot (CDs) from the Kernel part of the Azadirachta Indica seeds and investigated their fluorescent and metal ions sensing capability and also used for the delivery of drugs. Metallic ions such as Ca2+, K+, Na+, Fe3+, and Zn2+ which are biologically important for many reactions and are selectively detected through the novel CDs. The resultant dot size of CDs (∼4 nm) is useful to eliminate the ‘Achilles heel’ problems, which is associated with the Zn2+ in the body and its detection is a very challenging task. It is found that the sensitivity of CDs for the detection of Zn2+ can be regulated by using different solvents. These CDs can also be used as a sensing probe for the selective detection of Fe3+ at a very low concentration of solution (∼5 μM). The synthesis method of CDs reported here is cost-effective, very fast and it is highly selective towards Fe3+ and Zn2+. Due to the fast response capability of these CDs, logic gate operation is achieved and it provides a new understanding to construct potential next-generation molecular devices for the detection of different biomolecules with high selectivity. Additionally, these CDs are biocompatible against normal healthy cells, capable of loading small biomolecules and drugs due to their porous nature, and exhibited potential impact for breast cancer therapy. It is observed that a significant synergic therapeutic effect of CDs loaded with doxorubicin against breast cancer cells is very promising. Thus, the CDs reported herein in this work have been synthesized through a green synthesis approach and can be used as a molecular probe for the detection of metal ions as well as for drug delivery applications.

Recent advances in green synthesis of carbon dots for heavy metal ion sensing

In recent years, the field of green synthesis for carbon dots has seen significant advancements in the development of materials for heavy metal ion sensing applications. A variety of eco-friendly and sustainable approaches have been explored to synthesize carbon dots (CDs) with enhanced sensing properties. These materials have shown great promise in detecting heavy metal ions due to their high sensitivity, selectivity, and low detection limits One of the key advancements in this area is the utilization of natural sources such as biomass, organic waste, and plant extracts as precursors for the synthesis of CDs. These green precursors not only contribute to the sustainable nature of the synthesis process but also result in the production of carbon dots with unique surface chemistry and optical properties. In addition to the synthesis and functionalization strategies, the understanding of the underlying mechanisms governing the interaction between CDs and heavy metal ions has advanced significantly. This improved understanding has facilitated the design of CDs with tailored sensing capabilities and improved overall performance. Overall, the recent progress in the green synthesis of CDs for heavy metal ion sensing holds great promise for the development of cost-effective, environmentally friendly, and high-performance sensing platforms with potential applications in environmental monitoring, industrial safety, and healthcare diagnostics.

Green synthesis of carbon dots from fish scales for selective turn off-on detection of glutathione.

Carbon dots as fluorescent probes were fabricated using readily available grass carp fish scales as the carbon source via one-step synthesis based on a pyrolytic reaction. The as-prepared grass carp fish scale carbon dots (GF-CDs) exhibited good biocompatibility and excellent optical properties with a high fluorescence quantum yield of 23.8%. Glutathione (GSH) is an essential small tri-peptide molecule present in every body cell and plays a crucial role in vivo and performs a wide range of biological functions. Ag+ can effectively quench the fluorescence of GF-CDs because of the electron transfer between GF-CDs and Ag+; however, the addition of GSH can significantly increase GF-CD-Ag+ fluorescence. Because of their combination with Ag+ and GSH, GF-CDs show selective fluorescence recovery. GF-CDs can serve as fluorescent probes for GSH detection. This detection method covered a wide linear range (1.6-36.0 μg mL-1) with the lowest detection limit of 0.77 μg mL-1 and manifested great advantages such as a short analysis time, good stability, repeatability, and ease of operation.

Green synthesis of carbon dots for sensing of heavy metal ions: Bibliometric analysis from 2003-2024

The release of heavy metals into the environment has surged, due to rapid industrialization and urbanization globally, which causes. contamination of air, water, and soil. These persistent and bioaccumulative metals (lead, mercury, cadmium, and arsenic) pose major risks to both human health and the ecological balance. Therefore, heavy metal pollution emerges as a daunting challenge in contemporary times, Carbon dots (CDs) have attracted significant attention in recent years due to their potential applications in sensing heavy metal ions. Many conventional chemical methods have been used for the synthesis of CDs, however, these methods possess many shortcomings such as noxious byproducts, harsh chemicals, high cost, etc. To diminish these shortcomings, green chemistry plays a significant role in the preparation of CDs. Thus, it is very imperative to explore the green synthesis methodologies for the preparation of CDs over conventional ones. The article delves into a comprehensive bibliometric analysis of the green synthesis methods CDs for heavy metal ion sensing applications in the period between 2003-2024. Additionally, we have also provided an overview of the mechanism behind the green synthesis of CDs by exploring the role of phytoconstitutes present in natural resources. Furthermore, the sensing mechanism of CDs toward heavy metal ions is also explored. This review compiles the bibliometric analysis and synthesis process with various materials used for the detection of heavy metals.

Green Synthesis of Carbon Dots for Rapid Selective Detection and Photoreduction of Cr(VI) under Sunlight

Green Synthesis of Carbon Dots for Rapid Selective Detection and Photoreduction of Cr(VI) under Sunlight

Green synthesis of carbon dots from cordyceps militaris and versatile applications in alcohol detection and waterproof fluorescent ink

Carbon dots (CDs) are a class of highly efficient and low-toxicity fluorescent nanomaterials. In this study, using cordyceps militaris as a carbon source, we prepared green-emitting CDs with excellent properties, such as good photobleaching resistance, salt resistance and chemical stability, as well as high quantum yield. Further exploration of the versatile applications of G-CDs in chemical detection and information anti-counterfeiting fields revealed that G-CDs can not only be used as detection agent for analyzing alcohol content in alcoholic beverages but also serve as waterproof fluorescent ink for painting and writing due to their water-resistant property. This work is based on natural biomass as the main precursor to prepare fluorescent CDs with excellent luminescent characteristics and stable physicochemical properties. It is significant for reducing reliance on chemical reagents, lowering the cost of synthesizing CDs, and expanding the application range of CDs.

Self-exothermic reaction assisted green synthesis of carbon dots for the detection of para-nitrophenol and β-glucosidase activity

A rapid, green synthesis strategy assisted by a self-exothermic reaction was designed to prepare highly luminescent carbon dots (CDs) from Ganpu tea infusion (G-CDs) within 5 min using H2O2 and diethylenetriamine (DETA) as the exothermic reactants. G-CDs were successfully obtained through a self-exothermic reaction The prepared G-CDs exhibited clear excitation-dependent characteristics and displayed a strong ultraviolet fluorescence emission (385 nm) at the excitation wavelength of 320 nm. The fluorescence of G-CDs was quantitatively quenched by para-nitrophenol (p-NP) with a concentration range of 0.05–50 µM through inner filter effect (IFE). Since p-NP is one of the hydrolysates of the substrate pNPG under the action of Beta-glucosidase (β-Glu), a new fluorescence assay was developed for the indirect determination of β-Glu activity. The detection limits of G-CDs based fluorescence assays are 14.6 nM for p-NP and 0.074 U·L-1 for β-Glu activity, respectively. The developed fluorescence assays were successfully applied to the detection of p-NP in water and human urine samples and β-Glu activity in fruit samples with satisfactory results.

Facile and Green Synthesis of Carbon Dots from Melia Azedarach Leaves for pH Sensing and Cell Imaging.

Carbon dots (CDs) have preeminent application prospects as a new star in the nanomaterials field. In this work, a green and facile method to synthesize the blue-emitting CDs was proposed with Melia azedarach leaves as the carbon precursors. Using nature materials without other expensive reagents and instruments, the processes were simple and environmental-friendly. The CDs had high fluorescence quantum yield (11.8%) and excellent luminescence properties. The size of them were among 1.5-2.5nm and the emission spectrum exhibited a strong peak at 460nm when excited at 380nm. Additionally, the CDs were stable in most ions but sensitive to different pH values. As a result, a pH sensor was established for the detection of pH with a linear range of 3-10 pH. Moreover, it was demonstrated that the synthesized CDs had extremely low cytotoxicity. Due to their low toxicity and good biocompatibility, they entered into the A549 cells successfully for cell imaging.