Effects of Heteroatom Doping of Carbon Dots from Sugar on Optical Properties, Phenolic Content, Antioxidant Activity, Photostability, and Cytotoxicity

Quercetin-derived carbon dots promote proliferation and migration of Schwann cells and enhance neurite outgrowth

Quercetin, a flavonoid known for its antioxidant properties, has recently garnered attention as a potential neuroprotective agent for treatment of the injured nervous system. The repair of peripheral nerve injuries hinges on the proliferation and migration of Schwann cells, which play a crucial role in supporting axonal growth and myelination. In this study we synthesized Quercetin-derived carbon dots (QCDs) and investigated their effects on cultured Schwann cells and the NG108-15 cell line. QCDs was obtained by solvothermal synthesis and characterized via UV-vis absorption spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The particles demonstrated significant dose-dependent free radical scavenging activity in DPPH and ABTS radical scavenging assays, supported in vitro proliferation and migration of Schwann cells, expression of neurotrophic and angiogenic growth factors, and stimulated neurite outgrowth from NG108-15 cells. Thus, QCDs could serve as a potential novel treatment strategy to promote regeneration in the injured peripheral nervous system.

Gamma Irradiation Synthesis of Sugar-Derived Carbon-Dot-Functionalized Glutathione for Hg2+ Detection and Antioxidant Activity

Mercury, a particularly toxic heavy metal from industrial processes, poses significant risks to both people and the environment when it accumulates to dangerous levels, damaging the liver, kidneys, and nervous system. Therefore, fluorescent organic carbon dots (CDs) were developed for detecting Hg2+ ions. These CDs were easily synthesized, chemically stable, biocompatible, low in toxicity, and environmentally friendly. In this work, glutathione-functionalized CDs (CDs-GSH) were produced from sugar using the EDC/NHS coupling method. Gamma irradiation induced the chemical reactions necessary to produce fluorescent CDs. CDs-GSH demonstrated significant selectivity for Hg2+ with an 83% reduction in fluorescence intensity. Additionally, they exhibited a phenolic content of 19.1 μg/mg GAE and strong antioxidant characteristics, with DPPH radical scavenging activity of 63% at 1.0 mg/mL. Due to their stability, selectivity, and antioxidant qualities, high-value CDs can be produced from table sugar using an environmentally friendly synthesis process, offering potential applications in sensing and antioxidant activity.

Advances in the study of the biological activity of polysaccharide-based carbon dots: A review

Carbon dots have attracted worldwide interest due to their customizable nature, luminescent properties, and exceptional biocompatibility. In particular, biomass-derived carbon dots have attracted attention for their environmentally friendly and cost-effective synthesis. Recent research looks into how polysaccharides can be used to make carbon dots. Using them as starting materials for nanomaterials has benefits in terms of structure, morphology, and doping elements. Although research has extensively examined the optical properties of carbon dots, their potential biological applications have not been thoroughly investigated. This review mainly summarises the cytotoxicity and biological functions of polysaccharide-based carbon dots (e.g. agar, alginate, cellulose, carrageenan, chitosan, chitosan, starch, gelatin, etc.), such as antioxidant, antibacterial and anti-tumor functions, highlighting the different scenarios of the methods of preparation of carbon dots. The applications of carbon dots in food, biomedical sciences, soil fertilization, and power generation are highlighted by reviewing the low toxicity of carbon dots with safety and biocompatibility in human contact. Finally, the importance and challenges of polysaccharide-based carbon dots and the prospects and research directions of polysaccharide-based carbon dots are explained by comparing them with other nanomaterials.

Water Soluble PMPC-Derived Bright Fluorescent Nitrogen/Phosphorous-Doped Carbon Dots for Fluorescent Ink (Anti-Counterfeiting) and Cellular Multicolor Imaging

Here, a simple one-step hydrothermal-assisted carbonization process was adopted for the preparation of nitrogen/phosphorous-doped carbon dots from a water-soluble polymer, poly 2-(methacryloyloxy)ethyl phosphorylcholine (PMPC). By the free-radical polymerization method, PMPC was synthesized using 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) and 4,4′-azobis (4-cyanovaleric acid). The water-soluble polymers, PMPC, that have nitrogen/phosphorus moieties are used to prepare carbon dots (P-CDs). The resulting P-CDs were thoroughly characterized by various analytical techniques such as field emission-scanning electron microscopy (FESEM) with energy-dispersive X-ray spectroscopy (EDS), high-resolution transmittance electron microscopy (HRTEM), X-ray diffraction (XRD), Raman spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) spectroscopy and fluorescence spectroscopy to determine their structural and optical properties. The synthesized P-CDs displayed bright/durable fluorescence, were stable for long periods, and confirmed the enrichment of functionalities including oxygen, phosphorus, and nitrogen heteroatoms in the carbon matrix. Since the synthesized P-CDs showed bright fluorescence with excellent photostability, excitation-dependent fluorescence emission, and excellent quantum yield (23%), it has been explored as a fluorescent (security) ink for drawing and writing (anti-counterfeiting). Further, cytotoxicity study results advised for biocompatibility and thus were used for cellular multicolor imaging in nematodes. This work not only demonstrated the preparation of CDs from polymers that can be used as advanced fluorescence ink, a bioimaging agent for anti-counterfeiting, and cellular multicolor imaging candidate, but additionally prominently opened a new perspective on the bulk preparation of CDs simply and efficiently for various applications.

Diverse Applications of Biomass-Derived 5-Hydroxymethylfurfural and Derivatives as Renewable Starting Materials

This Review summarizes recent efforts to capitalize on 5-hydroxymethylfurfural (HMF) and related furans as emerging building blocks for the synthesis of fine chemicals and materials, with a focus on advanced applications within medicinal and polymer chemistry, as well as nanomaterials. As with all chemical industries, these fields have historically relied heavily on petroleum-derived starting materials, an unsustainable and polluting feedstock. Encouragingly, the emergent chemical versatility of biomass-derived furans has been shown to facilitate derivatization towards valuable targets. Continued work on the synthetic manipulation of HMF, and related derivatives, for access to a wide range of target compounds and materials is crucial for further development. Increasingly, biomass-derived furans are being utilized for a wide range of chemical applications, the continuation of which is paramount to accelerate the paradigm shift towards a sustainable chemical industry.