Bottom-up and green-synthesis route of amino functionalized graphene quantum dot as a novel biocompatible and label-free fluorescence probe for in vitro cellular imaging of human ACHN cell lines

In this study, bright green-luminescent probe (His-GQDs) were synthesized using a new one-pot "bottom-up" pyrolysis green-synthesis route, without consuming any water and chemical reagent. Citric acid as carbon source and Histidine as amino-functionalized agent, with optimized ratios, were used for fabricating His-GQDs as a novel, label-free, and selective probe. His-GQDs can be then used for cellular imaging of human ACHN cell lines that are composed of graphene sheets with the average size of 2.0 nm. Obtained His-GQDs probe has ultra-small size, low toxicity, chemical stability, biocompatibility, anti-photo bleaching and excellent optical properties with a rather high quantum yield of 62.8%. The detailed structural studies were confirmed by FT-IR, HR-TEM and powdered X-ray diffraction analysis respectively. In this project, the His-GQDs were utilized for cellular imaging of human ACHN cell lines for the first time. This probe indicated the presence desired biocompatibility of His-GQDs in human ACHN cell lines even at high their concentration (1800 mu g mL(-1)) at 24h post-treatment and their distribution in ACHN cell lines cytoplasm.