Eco-friendly and biocompatible synthesis of reduced graphene oxide via antioxidant-assisted reduction using Momordica charantia

Abstract

Reduced graphene oxide (rGO) is a versatile nanomaterial with applications in energy storage, electronic devices, biomedical fields, and environmental technologies owing to its enhanced electrical conductivity, lightweight structure, large surface area, and mechanical strength. However, the chemical reduction of graphene oxide (GO) commonly involves toxic agents such as hydrazine, raising environmental and health concerns. As a safer alternative, renewable resources, including plant extracts, have gained attention as eco-friendly and biocompatible reducing agents, particularly for biological applications. In this study, we evaluated the antioxidant capacities of various Momordica charantia (bitter melon) extracts and, for the first time, used water (MCW) and ethanol (MCE) extracts derived from fresh fruit pulp for the green synthesis and characterization of rGO. These were compared with chemically reduced counterparts, namely ascorbic acid (AA_rGO) and hydrazine (H_rGO). UV-vis spectroscopy confirmed rGO formation via decreases in the optical band gap, while Raman spectroscopy indicated a significant reduction in the intensity of the D+G band for MCW_rGO and MCE_rGO, with MCW_rGO exhibiting an I-D/I-G ratio similar to hydrazine-reduced rGO. SEM analysis showed densely wrinkled surface morphologies in both MCW_rGO and MCE_rGO, consistent with the typical rGO structure. Cytotoxicity assays in L929 cells indicated that both plant-based rGOs, particularly MCW_rGO, exhibited lower toxicity than GO and AA_rGO at lower concentrations. These findings demonstrate that Momordica charantia extracts serve as highly effective, eco-friendly, and economical bioreducing agent, offering a sustainable approach for the development of biocompatible materials.