Investigation on Surface interaction between Graphene Nanobuds and Cerium(III) via Fluorescence excimer, Theoretical, Real water sample, and Bioimaging studies

Abstract Graphene nanobud (GNBs) with an average size of ca. 35-40 nm was utilized to determine the micromolar concentration of Ce3+ via chelation-induced fluorescence excimer formation (CHEF) at 475 nm (λex: 328 nm). UV-visible and fluorescence spectroscopy findings on the interaction of GNB with Ce3+ confirm the binding stoichiometry as 1:1 (Ka= 4.85 × 10‒3 and 2.22 ×10‒2 M, respectively) with a LoD ca. 35.0 μM (S/N=3). The fluorescence decay profile experiment reveals the formation of a ground-state complex, GNB∙Ce3+, with an increase in lifetime (τ 7.02 → 27.01 ns), and fluorescence quantum yield (ФF 53.6 → 85.0%). Interference of other metal ions (M1+/2+/3+), the effect of solvent polarity, and the effect of time on the selective determination of Ce3+, and reversibility and the stability of GNB∙Ce3+ complex were examined. Theoretical calculation (TD-DFT) on the effect of molecular orbital energy levels of GNBs upon interaction with Ce3+ was investigated. Detection of Ce3+ in relevant water samples enriches the real-world application of GNBs which brings the futuristic application to sense Ce3+ in living cell lines. To accentuate, bioimaging of Ce3+ in living human breast cancer and human epithelial cells, and cytotoxicity test was successfully demonstrated. Confocal Raman microscopy images and corresponding spectrum articulated the practicability of GNBs in biological systems.