pH-dependent interactions of serum albumins with green-synthesized partially reduced graphene oxide nanosheets

Graphene oxide (GO) and its partially reduced derivatives have attracted considerable attention because of their tunable physicochemical properties and potential applications in sensing and biomedicine. However, the pH-dependent interactions of phytochemical-assisted partially reduced GO with serum proteins remain less explored. In the present study, a simple and environmentally benign one-step hydrothermal approach was employed to synthesize partially reduced GO nanosheets using lentil extract as a natural phytochemical source. The synthesized material was characterized using complementary structural, morphological, and spectroscopic techniques, confirming the formation of partially reduced, structurally heterogeneous GO nanosheets containing oxygenated and partially restored sp²‑carbon domains. The interactions of the synthesized partially reduced GO with serum albumins were systematically investigated at different pH conditions using UV-visible absorption spectroscopy, steady-state fluorescence spectroscopy, and time-resolved fluorescence lifetime measurements. The results demonstrated pronounced pH-dependent fluorescence quenching and changes binding behavior, indicating that the physicochemical state of the nanomaterial and the ionization state of the proteins strongly influence their interactions. These findings provide molecular-level insights into the interaction of phytochemical-derived partially reduced GO with serum albumins and improve our understanding of the behavior of graphene-based nanomaterials in protein-rich biological environments. The study may contribute to the rational development of graphene-based materials for biosensing, drug delivery, and other nano biomedical applications.