▎ 摘　　要

The manifold usage of fluorescent materials and their pliable association with optical imaging techniques have made great strides in unfolding the incredible potential of biotechnological research, particularly in cancer treatment, from point-of-care assay to clinical applications. Enlarged nuclei or numerous counts often indicate tumor growth activity, and these expressions can be visualized with the aid of fluorescence imaging. Therefore, developing highly fluorescent, biocompatible, and sustainable biomarkers for imaging is a vital necessity for their extensive application in cancer diagnosis and therapy. In this work, we have demonstrated the 'cradle-to-gate' transformation of abundant and cheap fossil fuel coke into a fluorescent probe for bioimaging. Herein, for the first time, a facile strategy for modulating the emission characteristics of coke-derived graphene system via doping of heteroatoms has been reported. It is found that the doping of nitrogen atoms could strongly influence photophysical properties, giving rise to increased quantum yield (16%), extended fluorescence lifetime (8.51 ns), and higher photostability (92%). Moreover, the as-synthesized nitrogen-doped graphene derivative is used as a potential labelling agent for the cellular imaging of cancerous cells, as well as normal cells, at concentrations ranging from 0 to 100 mu g/mL. For 24h incubation, the cells cultured with a concentration of 25 mu g/mL were observed to have an appreciable fluorescence accompanied by significant biocompatibility, with a viability value of >= 85%. Considering the heteroatom-induced emission characteristics and bioanalytical acuities, it is pro-spective that the coke-derived graphene system can be further explored to elucidate its significance in biomedical applications, without compromising on economic and environmental sustainability.