Exploration of the Potential Efficacy of Natural Resource Derived Blue Emitting Graphene Quantum Dots in Cancer Therapeutic Application

Coal is the most abundant natural resource being used worldwide and shows graphite-like clusters. Here, we report an innovative and cost effective oxidative functionalization approach followed by acid-free and oxone oxidant-assisted solvothermal synthesis of graphene quantum dots from coal for the first time. This oxidative functionalization method of coal has been performed through heat treatment of nitric acid followed by acid recovery process. Indeed, solvothermal method is entirely free from the utilization of strong acids; and involves a simple, eco-friendly, and salt free purification process with high production yield (~45%). Due to the synergistic synthesis technique, our developed GQDs are found to exhibit a strong blue photoluminescence (PL) characteristic with significantly high quantum yield (~14.42 %). High resolution Transmission electron microscopy (HRTEM) images indicate that nanocrystalline GQDs have uniform and narrow particle size distribution in the range of 2.5-5 nm. The anticancer efficacy of the synthesized GQDs nano material is validated through cellular morphological pattern analysis and DAPI stain images of neuroblastoma cell and breast cancer cell. Additionally, the alteration of mitochondrial membrane potential is scrutinized using JC1 micrographs. Interestingly, RITC tagged GQDs are showing cellular internalization within breast cancer cells. The robust functionality, luminescence stability, nanosecond lifetime, biocompatibility and low toxicity of our developed GQDs enable them to be promising probes for cancer therapeutic applications. This study unveils new opportunities for sustainable production of GQDs with novel attributing features because of the easily available of raw material, cost-effective productivity and fascinating photoluminescence property.