One‐Pot Approach Reduction of Graphene Oxide Through <i>Calendula officinalis</i> for Promising Biomedical Applications

ABSTRACT This work reports a one‐pot green synthesis of reduced graphene oxide (RGO) from graphene oxide (GO) using Calendula officinalis mother tincture as a natural reducing and stabilizing agent. Taken together, a bathochromic shift with a broad absorption band cantered near 305 nm in UV–Vis; attenuation of carbonyl and C–O bands and stronger sp 2 C = C features in FTIR; disappearance of the GO (001) low‐angle XRD peak at 11.9° and the emergence of a graphitic (002) peak at 26.4° for RGO; and increased ID/IG ratio from 0.832 to 1.08 and a shift of weak 2D features band from 2694 to 2678 cm − 1 in Raman for RGO implies partial restoration of the sp2 conjugated network and confirmed successful reduction. Furthermore, a smoother, compact, and restacked sheet‐like microstructure of RGO in FESEM and TEM analyses provides compelling evidence for the successful reduction of GO to RGO. Finally, in vitro biological performance of RGO was evaluated through antibacterial assays against Bacillus subtilis and Escherichia coli ; cytocompatibility, proliferation by using L929 cells; and hemocompatibility. Overall, C. officinalis acts as both a green reductant and functionalizing agent that can effectively produce hemocompatible, antimicrobial, and cytocompatible RGO with promising therapeutic potential.