Green synthesis of agro-waste–derived potassium-doped graphene oxide for antimicrobial activity

Abstract

Graphene oxide (GO) has been unlocked as a potential bactericidal agent with multifaceted applications for a high degree of abundance of oxidizing functional groups over its structure. The potassium doping of GO (K-GO) enhances its biocompatibility and antimicrobial efficacy. Herein we present a one-step synthesis of K-GO using Quercus ilex (oak fruit) as a sustainable precursor. Characterization via Raman spectroscopy, UV-Vis spectroscopy, TEM, FT-IR, and TGA confirmed the successful synthesis of K-GO. The screening of antimicrobial activity of K-GO was undertaken against Gram-positive (E. faecalis and S. aureus), Gram-negative bacteria (E. coli and P. aeruginosa), and selected fungus (C. albicans and T. asperellum) using the disc diffusion assay. The midpoint inhibitory concentration (IC₅₀) of K-GO against E. coli and S. aureus was found to be 109.64 µg/mL and 38.90 µg/mL, respectively. Employing our green synthesis method using oak seeds as a precursor showcases both cost-effectiveness and sustainability. The aforementioned results suggest that K-GO nano-sheet possesses significant antimicrobial activity, thus may evolve as future antimicrobial nanomaterials.