Natural Biowaste Derived Fluorescent Carbon Quantum Dots: Synthesis, Characterization and Biocompatibility Study

In this present study, a straightforward and affordable method for the environmentally safe synthesis of carbon quantum dots (CQDs) by employing human hair as the carbon source without any need of chemicals was synthesized. CQDs obtained from human hair was further functionalized with Poly-L-Lysine to form PLLCQDs. The synthesized PLLCQDs was demonstrated numerous advantageous characteristics like strong fluorescence intensity, superior photostability, and outstanding water solubility. Various physicochemical characterization was employed to confirm successful formation of PLLCQDs including UV-vis Spectroscopy, Fluorescence Spectroscopy, Fourier Transform Infrared (FTIR) Spectroscopy, Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). The size of synthesized PLLCQDs is 3 nm. The resultant PLLCQDs exhibited strong blue emission with a quantum yield of 28%. Under UV light, the synthesized PLLCQDs emit blue (at 365nm) fluorescence. The optimization of synthesis parameters including synthesis method, effect of reaction temperature, effect of reaction time and effect of reaction concentration have a significant impact on the quality and quantity of synthesized PLLCQDs, as well as their properties and applications. The effect of pH and UV radiation on synthesized PLLCQDs exhibited excellent photo and chemical stability. The cytotoxicity of bulk system (Hair precursor) and PLLCQDs was evaluated using fibroblast cell line (L929). The cell viabilities of 99.47% was obtained from L929 cells using MTT assay and it can applicably function as agents for cell labelling as a good bioimaging probe.

Automated summary

In this study, a cost-effective and environmentally safe method was developed to synthesize carbon quantum dots (CQDs) using human hair as the carbon source without the need for chemicals. The synthesized CQDs were further functionalized with Poly-L-Lysine to form PLLCQDs, which exhibited strong fluorescence intensity, photostability, and water solubility. Various characterization techniques were used to confirm the successful formation of PLLCQDs, and their size was determined to be 3 nm. The optimized synthesis parameters, including method, temperature, time, and concentration, had a significant impact on the quality and quantity of PLLCQDs, as well as their properties and applications. The synthesized PLLCQDs demonstrated excellent photo and chemical stability under different pH and UV radiation conditions, and showed low cytotoxicity towards fibroblast cells.