A convenient green method to synthesize luminescent carbon dots from edible carrot and its application in bioimaging and preparation of nanocatalyst

Microplasma-induced in situ rapid synthesis of CoSe nanosphere@N-doped polymeric carbon dots derived from ZIF-67 for highly sensitive dopamine detection

BACKGROUND

Designing a fast and sensitive electrochemical sensing platform to achieve selective quantitative detection of dopamine (DA) is a great challenge. Combining transition metal selenides (TMSs) with a variety of conductive carbonaceous materials is one of the effective strategies to improve the electrocatalytic activity of TMSs. However, most of the reported preparation methods of TMSs/carbon-based composite nanomaterials need to be annealed at a high temperature for a long time, which does not meet the requirements of sustainable development. Therefore, it is of great significance to explore an energy-efficient and fast method to prepare these compounds.

RESULTS

In this work, CoSe nanosphere@nitrogen-doped polymeric carbon dots are rapid prepared using ZIF precursor by simple dielectric barrier discharge (DBD) microplasma-induced on carbon cloth (CoSe NSs@N-PCDs/CC) for the first time. Owing to the fact that CoSe can promote rapid proton transfer, N-CDs has a high specific surface area, rich functional groups and electrical conductivity, this electrode exhibits highly sensitive non-enzymatic electrochemical sensing performance for DA detection. The linear range and detection limit are 0.1 μM-50 μM and 40.2 nM, respectively, and it have been successfully applied to the determination of DA levels in real human serum samples. Theoretical DFT calculations show that the most efficient interaction with DA on the surface of CoSe (101) can promote electrochemical reactions and catalyze DA oxidation.

SIGNIFICANCE

Using ZIF as precursor, CoSe NSs@N-PCDs/CC electrochemical electrode was synthesized in situ by simple and energy-saving DBD microplasma. CoSe NSs can effectively prevent the aggregation of function-rich N-PCDs and significantly improve the electrocatalytic activity of the composite. The mechanism of high selectivity of CoSe NSs@N-PCDs/CC electrode to DA was studied by DFT calculation. This work provides a new idea for the fast and green synthesis of transition metal and carbon-based nanomaterials by microplasma.

N-doped carbon quantum dots for the selective detection of OCl- ions, bioimaging, and the production of Fe3O4 nanoparticles utilized in the synthesis of substituted imidazole

Nitrogen-doped quantum dots (NCQD) were synthesized by solvothermal means using o-phenylenediamine and l-tartaric acid. The resultant NCQD produced a high quantum yield (40.3%) and a vivid green fluorescence. They were about 6 nm in size. The NCQD is useful in HeLa cell bioimaging investigations and is used for the fluorescence detection of OCl- ions. The quantum dots' Limit of Detection (LoD) was discovered to be 40 nM. Additionally, cytotoxicity testing was conducted, and we found out that HeLa cells safely endured up to 6.5 mg ml-1 of NCQD. Furthermore, NCQDs were employed to synthesize Fe3O4 nanoparticles, with the quantum dots acting as a reducing and stabilizing agent. The nanoparticles exhibited remarkable catalytic activity towards organic processes due to their size of 11 nm and surface area of 67.360 m2 g-1. Excellent yields of tri-substituted imidazole derivatives were produced using Fe3O4 nanoparticles as nanocatalysts in a solvent-free method.

Sensitive and rapid determination of tetracycline antibiotic by carrot juice-derived carbon dots as a fluorescent probe

The antibiotic tetracycline can be efficiently used as medicine for the deterrence of bacterial infections in humans, animals, and plants. However, the unprecedented use of tetracycline is of great concern owing to its low biodegradability, extensive usage, and adverse impacts on the environment and water quality. In this study, a sensitive spectrofluorometric method was proposed for the direct determination of tetracycline, based on biocompatible fluorescent carbon dots (CDs). The synthesis of CDs was performed by adopting a green hydrothermal procedure from carrot juice without requiring surface passivation or outflowing any environmentally hazardous waste. X-ray diffraction analysis and transmission electron microscopy revealed amorphous spherical-shaped CDs that exhibited blue emission under blue illumination. The fabricated fluorescent probe directly detected tetracycline in the concentration range of 4.00 × 10-6 to 1.55 × 10-5 mol L-1 with an LOD of 1.33 × 10-6 mol L-1. The performance of the probe was assessed in a tap water sample, with recovery values between 80.70 and 103.60%. The method's greenness was evaluated using the Analytical Green metric approach (AGREE) and confirmed to be within the green range. The developed method is facile, rapid, cost-effective, and offers a wide linear range and satisfactory selectivity, making it potentially suitable for determining tetracycline in water applications.

Green synthesis of Zn2+ nanocarriers from Auricularia auricula fermentation broth with excellent antioxidant activity

Nanoparticles (NPs) possessing nanoscale dimensions and remarkable antioxidant activity were synthesized via a green hydrothermal method utilizing Auricularia auricula fermentation broth, referred to as AFNPs. The functional groups on the surface of the AFNPs significantly contributed to the formation of AFNPs-Zn2+. The AFNPs-Zn2+ appeared a zinc retention rate of 40.80 % after gastrointestinal digestion. When compared to typical zinc supplements, AFNPs-Zn2+ did not exhibit visible cytotoxicity or hemolysis. Furthermore, AFNPs-Zn2+ demonstrated the ability to mitigate cell damage resulting from zinc deficiency. In vivo experiments showed that AFNPs-Zn2+ were mainly observed in the stomach, intestine, kidney, and testis after oral administration. In vivo distribution experiments indicated predominant presence of AFNPs-Zn2+ in the stomach, intestine, kidney, and testis following oral administration. This study highlights the potential for Auricularia auricula NPs to serve as the efficient, stable, and safe nanocarriers for Zn2+.

A critical review on the environmental applications of carbon dots

The discovery of zero-dimensional carbonaceous nanostructures called carbon dots (CDs) and their unique properties associated with fluorescence, quantum confinement and size effects have intrigued researchers. There has been a substantial increase in the amount of research conducted on the lines of synthesis, characterization, modification, and enhancement of properties by doping or design of composite materials, and a diversification of their applications in sensing, catalysis, optoelectronics, photovoltaics, and imaging, among many others. CDs fulfill the need for inexpensive, simple, and continuous environmental monitoring, detection, and remediation of various contaminants such as metals, dyes, pesticides, antibiotics, and other chemicals. The principles of green chemistry have also prompted researchers to rethink novel modes of nanoparticle synthesis by incorporating naturally available carbon precursors or developing micro reactor-based techniques. Photocatalysis using CDs has introduced the possibility of utilizing light to accelerate redox chemical transformations. This comprehensive review aims to provide the reader with a broader perspective of carbon dots by encapsulating the concepts of synthesis, characterization, applications in contaminant detection and photocatalysis, demerits and research gaps, and potential areas of improvement.

High reactive oxygen species produced from fluorescence carbon dots for anticancer and photodynamic therapies: A review

High-photoluminescence carbon dots (CDs) were synthesized from various sources and various methods using two approaches, namely bottom up and top down, with emission-dependent excitation wavelength. Electronic transition from the higher-occupied molecular orbital (HOMO) state to the lowest-unoccupied molecular orbital(LUMO) state, surface defect states, wider excitation spectrum, higher quantum yield, efficient energy transfer, and element doping affected the fluorescence properties of CDs. Using 102 references listed in this review, the authors studied the relationship between fluorescence mechanism and reactive oxygen species (ROS) produced for photodynamic therapy (PDT) and materials anticancer applications. We described how the radical atom or ROS work as anticancer therapy and PDT and described the chemical reaction of high-resolution fluorescence CDs. We summarized experimental techniques that are used for producing CDs and discussed their characteristics. Finally, conclusions and future prospects in this field are also discussed. The important characteristics of CD-based design for high ROS may usher in new prospects and challenges for high efficiency and stability of PDT and anticancer therapy. In conclusion, we have provided perspectives and challenges of the future development of CD s.

Recent advances in green carbon dots (2015-2022): synthesis, metal ion sensing, and biological applications

Carbon dots (CDs) show extensive potential in various fields such as sensing, bioimaging, catalysis, medicine, optoelectronics, and drug delivery due to their unique properties, that is, low cytotoxicity, cytocompatibility, water-solubility, multicolor wavelength tuned emission, photo-stability, easy modification, strong chemical inertness, etc. This review article especially focuses on the recent advancement (2015-2022) in the green synthesis of CDs, their application in metal ions sensing and microbial bioimaging, detection, and viability studies as well as their applications in pathogenic control and plant growth promotion.

Heavy metal ion detection using green precursor derived carbon dots

The discovery of carbon dots (CDs) for environmental remediation has gained awareness because of the diverse economically viable and environmental friendly green precursors generated from biowastes and biomass compared to the toxic inorganic quantum dots and CDs prepared from chemical precursors. This review presents the recent progress in green CDs, including their synthesis methods and sensing applications for the detection of heavy metal ions such as Iron (III), Mercury (II), Copper (II), Chromium (VI), Lead (II), Arsenic (III), Cobalt (II), Aluminum (III), Silver (I), and Gold (III) which are prominent environmental pollutants. The comparison based on selectivity, sensitivity, quantum yield, detection limit, linear concentration range, and sensing mechanisms are also reported. This review also covers the performance of doped green CDs using heteroatoms, toward the detection of heavy metal ions. Apart from the future perspectives, this review provides a general guide to use such environmental friendly CDs to detect harmful pollutants.

Gold Catalyst Anchored to Pre-Reduced Co3O4 Nanorods for the Hydrodeoxygenation of Vanillin Using Alcohols as Hydrogen Donors

The preparation of highly dispersed metal catalysts with strong electronic metal-support interactions (EMSIs) is of great significance. In this study, oxygen vacancies (OVs) were generated on the surfaces of Co₃O₄ nanorods (NRs) through NaBH₄ treatment, and then the generated surface OVs were used to anchor gold clusters. The resulting catalyst was used for the hydrodeoxygenation (HDO) of vanillin based on transfer hydrogenation with alcohol donors. The conversion of vanillin and the selectivity to 2-methoxy-4-methylphenol (MMP) both reached 99% under the optimized reaction conditions, and these values were significantly higher than those obtained for the gold catalyst supported on the untreated Co₃O₄ NRs. The obtained results were verified by theoretical calculations and experimental data and confirmed the existence of strong EMSIs between the OV-enriched Co₃O₄ NRs (Co₃O₄ NRs-OVs) and the gold clusters, which allows electron transfer from the Co₃O₄ NRs to gold. Increasing the number of electrons on the gold surface can promote the catalytic hydrogen transfer of alcohol, in addition to selectively adsorbing the C═O group in vanillin to improve the selectivity toward MMP. This strategy based on the OV-anchoring of metals onto the surface of a support can be extended to other metals, thereby providing a promising method for the design of advanced and highly efficient metal catalysts.

Research progress in synthesis and biological application of quantum dots

Quantum dots are an excellent choice for biomedical applications due to their special optical properties and quantum confinement effects. This paper reviews the research and application progress of several quantum...

Biomass-Based Carbon Dots: Current Development and Future Perspectives

Carbon dots have been considered as a solution to the challenges that semiconductor quantum dots have encountered because they are more biocompatible and can be synthesized from abundant and nontoxic materials such as biomass. This review will highlight the advantages of these biomass-based carbon dots in terms of synthesis, properties, and applications in the biomedical field. Furthermore, future applications especially in the biomedical field of biomass-based carbon dots as well as the challenges of semiconductor quantum dots such as biocompatibility, photobleaching, environmental challenges, toxicity, and poor solubility will be discussed in detail. Biomass-derived quantum dots, a subsection of carbon dots that are the most desirable for future research, will be focused upon including from synthesis to applications. Finally, the future development of biomass derived quantum dots in the biomedical field will be discussed and evaluated to unlock the potential for their applications.

Facile synthesis of a carbon dots and silver nanoparticles (CDs/AgNPs) composite for antibacterial application

Bacterial infections can seriously harm human health, and the overuse of traditional antibiotics and antibacterial agents will increase the resistance of bacteria. Therefore, it is necessary to prepare a new kind of antibacterial material. In this work, a carbon dots and silver nanoparticles (CDs/AgNPs) composite has been synthesized in a one-step facile method without the introduction of toxic chemicals, wherein CDs could serve as a reducing and stabilizing agent. The CDs/AgNPs composite was characterized by UV-vis spectrophotometry, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM), which demonstrate that the silver nanoparticles were successfully synthesized in the composite. The zeta potential of the CDs/AgNPs composite was −15.3 mV, indicating that the composite possesses high stability. Furthermore, the composite also exhibited biocidal effects for both Gram-negative E. coli bacteria and Gram-positive S. aureus bacteria. Thus, the composite is considered to be of great potential in bactericidal and biomedical applications.

One-step facile synthesis of a carbon dots and silver nanoparticles (CDs/AgNPs) composite without the introduction of toxic chemicals.

Natural carbon-based quantum dots and their applications in drug delivery: A review

Natural carbon based quantum dots (NCDs) are an emerging class of nanomaterials in the carbon family. NCDs have gained immense acclamation among researchers because of their abundance, eco-friendly nature, aqueous solubility, the diverse functionality and biocompatibility when compared to other conventional carbon quantum dots (CDs).The presence of different functional groups on the surface of NCDs such as thiol, carboxyl, hydroxyl, etc., provides improved quantum yield, physicochemical and optical properties which promote bioimaging, sensing, and drug delivery. This review provides comprehensive knowledge about NCDs for drug delivery applications by outlining the source and rationale behind NCDs, different routes of synthesis of NCDs and the merits of adopting each method. Detailed information regarding the mechanism behind the optical properties, toxicological profile including biosafety and biodistribution of NCDs that are favourable for drug delivery are discussed. The drug delivery applications of NCDs particularly as sensing and real-time tracing probe, antimicrobial, anticancer, neurodegenerative agents are reviewed. The clinical aspects of NCDs are also reviewed as an initiative to strengthen the case of NCDs as potent drug delivery agents.

A facile synthesis of CDs from quinoa for nanosensors and bio-imagining

Carbon dots (CDs) with strong fluorescence were synthesized by a facial and green hydrothermal method using biomass quinoa as the carbon source. The as-prepared carbon dots (CDs) aqueous solution shows bright blue photoluminescence under the irradiation of UV lamp with a quantum yield of 14% and considerable luminescence stability and excellent strong photobleaching resistance. The as-prepared CDs was nontoxic for in vitro and in vivo applications. In addition, not only the as-prepared CDs were used for HeLa cells imaging, but also detect Fe3+ ions in cells, and the ideal imaging pictures were obtained under excitation of 405 nm. The as-prepared carbon dots possessed excellent responsive properties towards Fe3+. The quenching phenomenon can be used to detect the Fe3+ ions within a linear range of 0–300 μmol l−1 with a limit of detection of 50 nmol l−1.

Electrochemical Sodium Ion Sensor Based on Silver Nanoparticles/Graphene Oxide Nanocomposite for Food Application

High sodium ion (Na+) consumption leads to high blood pressure which causes many health issues. Real-time determination of Na+ content in food is still important to limit Na+ intake and control the taste of food. In this work, we have developed an electrochemical sensor based on agglomeration of silver nanoparticles (AgNPs) and graphene oxide (GO) modified on a screen-printed silver electrode (SPE) for Na+ detection at room temperature by using cyclic voltammetry (CV). The AgNPs were synthesized through a simple green route using Pistia stratiotes extract as a reducing agent under blue light illumination and mixed with the GO to be a Na+ selective sensing nanocomposite. The AgNPs/GO/SPE sensor showed high sensitivity (0.269 mA/mM/cm2), high selectivity, linear relationship (0–100 mM), good stability, and excellent reproducibility to Na+ detection as well as low limit of detection (9.344 mM) for food application. The interfering species such as K+, Zn2+, Na+, Mg2+, glucose, and ascorbic acid did not have any influence on the Na+ determination. The AgNPs/GO/SPE sensor was successfully applied to determine Na+ in real samples such as fish sauce and seasoning powder of instant noodle.

Recent advancements in the applications of carbon nanodots: exploring the rising star of nanotechnology

Nanoparticles possess fascinating properties and applications, and there has been increasing critical consideration of their use. Because carbon is a component with immaterial cytotoxicity and extensive biocompatibility with different components, carbon nanomaterials have a wide scope of potential uses. Carbon nanodots are a type of carbon nanoparticle that is increasingly being researched because of their astounding properties such as extraordinary luminescence, simplicity of amalgamation and surface functionalization, and biocompatibility. Because of these properties, carbon nanodots can be used as material sensors, as indicators in fluorescent tests, and as nanomaterials for biomedical applications. In this review, we report on the ongoing and noteworthy utilization of carbon quantum dots such as bioimaging tests and photocatalytic applications. In addition, the extension and future components of these materials, which can be investigated for new potential applications, are discussed.

Multifaceted applications of green carbon dots synthesized from renewable sources

Fluorescent carbon dots (CDs) are an emerging class of nanomaterials in the carbon family. There are various inexpensive and renewable resources that can be used to synthesize green CDs, which have received immense attention from researchers because of their improved aqueous solubility, high biocompatibility, and eco-friendly nature compared with chemically derived CDs. Additional surface passivation is not required, as heteroatoms are present on the surface of green CDs in the form of amine, hydroxyl, carboxyl, or thiol functional groups, which can improve their physicochemical properties, quantum yield, and the probability of visible light absorption. Green CDs have potential applications in the fields of bioimaging, drug/gene delivery systems, catalysis, and sensing. Since their discovery, there have been several review articles that describe the synthesis of green CDs and some of their applications. However, there are no review articles describing the synthesis and complete applications of green CDs. Here, we provide detailed information regarding their synthesis and applications based on the available literature. In addition, we discuss some of the less explored applications of green CDs and the challenges that remain to be overcome.