Green Carbon Dots: Synthesis, Characterization, Properties and Biomedical Applications

Abstract

Carbon dots (CDs) are a new category of crystalline, quasi-spherical fluorescence, “zero-dimensional” carbon nanomaterials with a spatial size between 1 nm to 10 nm and have gained widespread attention in recent years. Green CDs are carbon dots synthesised from renewable biomass such as agro-waste, plants or medicinal plants and other organic biomaterials. Plant-mediated synthesis of CDs is a green chemistry approach that connects nanotechnology with the green synthesis of CDs. Notably, CDs made with green technology are economical and far superior to those manufactured with physicochemical methods due to their exclusive benefits, such as being affordable, having high stability, having a simple protocol, and being safer and eco-benign. Green CDs can be synthesized by using ultrasonic strategy, chemical oxidation, carbonization, solvothermal and hydrothermal processes, and microwave irradiation using various plant-based organic resources. CDs made by green technology have diverse applications in biomedical fields such as bioimaging, biosensing and nanomedicine, which are ascribed to their unique properties, including excellent luminescence effect, strong stability and good biocompatibility. This review mainly focuses on green CDs synthesis, characterization techniques, beneficial properties of plant resource-based green CDs and their biomedical applications. This review article also looks at the research gaps and future research directions for the continuous deepening of the exploration of green CDs.

Facile one‐pot synthesis of PEG‐derived carbon dots with enhanced luminescence via L‐cysteine‐assisted S,N‐doping

“…This technique effectively disintegrates large carbon molecules into smaller ones, offering numerous exceptional advantages. Notably, this method is environmentally friendly, cost-effective, and exhibits remarkable penetration and uniformity in its effects [25,53,54]. Hence, we changed the synthesis method again, and this time we applied the hydrothermal method and modified the synthesis protocol by Kumar et al [23] to include ultrasonication for 5 min and the addition of 0.1 M NaOH to one of the samples prior to 6 h hydrothermal synthesis.…”

The Effect of Surface Treatments on Zirconia Bond Strength and Durability

“…Because each crystal possesses a unique pattern of X-ray diffraction (XRD), XRD is widely used to characterize crystalline structure and for phase identification and transformation [ 26 ]. Because each functional group of molecules has a specific vibrating spectrum when detected by Fourier transform infrared spectroscopy (FTIR) [ 27 ], attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) is used to analyze the chemical compositions and functional groups of material surfaces [ 28 ]. Since X-ray photoelectron spectroscopy (XPS) can analyze binding energies of elements, XPS is used to determine qualitative information on elemental compositions and the valence state of the elements on the material surfaces [ 29 ].…”

Carbon dots with tissue engineering and regenerative medicine applications

“…23 Green resources are favorable sources for synthesizing CDs due to their high contents of carbon, high affordability and availability, excellent stability, simple extraction protocol, safeness, eco-friendliness, etc. 11,25,26 The comparison between “top-down” and “bottom-up” approaches also showed that CDs obtained from these two methods had different photoluminescence characteristics and chemical states. 22 In this context, the synthesized CDs may have a different distribution of functional groups ( e.g.…”