Amino-functionalized graphene quantum dots as a photoluminescent probe for in vitro cellular imaging of human lung cancer cell lines

Graphene-based fluorescent materials, particularly graphene quantum dots (GQDs), have emerged as a new class of biomedical agents. In the present study, functionalised GQDs have a better chance of being employed in a broader range of bioapplications because of their proven low toxicity, outstanding biocompatibility, and enhanced fluorescence properties. For this purpose, amino-functionalised GQDs (AF-GQDs) were synthesised via hydrothermal treatment by treating graphene oxide in ammonia with heat and water. The as-prepared AF-GQDs samples were characterised using a variety of techniques, including x-ray diffraction analysis (XRD), high-resolution transmission electron microscopy (HR-TEM), and photoluminescence (PL) spectroscopy. The results show that AF-GQDs are merely hexagonal, with an average size of about 8 nm. Also, AF-GQDs are highly soluble in water and display excellent luminescence behaviour. After 48 h of incubation, the MTT results showed that more than 63% of the cells were still alive, even at high concentrations (500 g ml−1) of AF-GQDs. In addition, the AO/EB staining results also showed that the AF-GQDs had the most robust green fluorescence (viable cells). This makes them a promising agent for biomedical imaging because they have good optical properties, are readily soluble in water, are biocompatible, and are not toxic.