Exploring the antibacterial and antibiofilm potential of graphene nanosheets synthesized from candlenut shell waste

The rising threat of antibiotic-resistant pathogens necessitates the development of novel antimicrobial agents, and graphene nanomaterials have emerged as a promising alternative due to their unique physicochemical properties. This study evaluated the antibacterial and antibiofilm efficacy of graphene nanosheets synthesized from candlenut shell waste (GNSsCSW) against Staphylococcus aureus and Salmonella enteritidis, addressing the unexplored potential of agro-waste-derived graphene nanomaterials in combating bacterial infections. The GNSsCSW exhibited potent antibacterial activity, with a minimum inhibitory concentration (MIC) of 12.5 μg/mL against S. aureus and 6.25 μg/mL against S. enteritidis. The minimum bactericidal concentration (MBC) values were 25 μg/mL and 12.5 μg/mL against S. aureus and S. enteritidis, respectively. Cell leakage assays revealed a significant release of nucleic acids and proteins, confirming membrane disruption. Time-kill kinetics showed complete elimination of S. aureus within 16 h at 25 μg/mL and rapid eradication of S. enteritidis within 8 h at 25 μg/mL. Biofilm assays demonstrated a significant (p < 0.05) reduction in both biomass and viability of biofilms. Fourier-transform infrared (FTIR) spectroscopy revealed alterations in the biofilm matrix composition, suggesting interference with extracellular polymeric substances. These results confirm that GNSsCSW has potent antibacterial and antibiofilm effects, offering a sustainable strategy to combat pathogenic bacteria with implications for both biomedical and environmental applications.