Synthesis of terbium and silica modified graphene quantum dots for targeted bioimaging of breast cancer cells using folate receptors

The overexpression of folate receptors (FR) on the surface Michigan Cancer Foundation 7 (MCF-7) cancer cells offers a strategic target for enhancing cancer imaging and diagnostic accuracy due to their high affinity toward folic acid (FA). Graphene quantum dots (GQDs) were synthesized via thermal pyrolysis and chelated with terbium (Tb) ions. These Tb-GQDs were then coated with a silica layer and functionalized with FA, resulting in a fluorescent nanoprobe specifically designed for targeted bioimaging of FR-positive cells. The synthesized Tb-GQDs-SiO₂-APTES-NH₂-FA nanoprobe demonstrated intense fluorescence emission at 425 nm upon excitation at 310 nm. Characterization of the nanoprobe revealed a high quantum yield (QY) of 29%, along with excellent photostability and favourable optical properties, establishing its efficacy as a tool for specifically targeting FR on MCF-7 cancer cells. Qualitative analysis via fluorescence microscopy confirmed the successful and specific uptake of Tb-GQDs-SiO₂-APTES-NH₂-FA by MCF-7 cells, which was evaluated across varying incubation times and concentrations. Cytotoxicity assays further confirmed the biocompatibility of the nanoprobe at concentrations up to 1000 µg/mL, with cell viability remaining above 90%. These findings collectively suggest that Tb-GQDs-SiO₂-APTES-NH₂-FA holds significant potential for future in vivo cancer cell imaging applications. In conclusion, the Tb-GQDs-SiO₂-APTES-NH₂-FA nanoprobe represents a promising and biocompatible platform for the targeted bioimaging of cancer cells, with strong implications for improving diagnostic precision in breast cancer.