Preparation and characterization of expanded graphite/metal oxides for antimicrobial application

摘要

Composite materials based on expanded graphite (EG) and metal oxide (MO) particles was prepared by an ex¬ plosive combustion and blending method. The objective of the study was to develop EG impregnated with metal oxide particulates (Ag20, CuO and ZnO) and evaluate the level of protection the materials conferred against biological agents. The physical properties of the EG/MO composites were examined using SEM, EDX and XRD spectroscopy, and the results indicated that the MO particles were incorporated into the EG matrix after impreg¬ nation. The antimicrobial activities of the EG/MO composites against Gram-positive bacteria, Gram-negative bac¬ teria and Bacillus anthracis were investigated using zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and plate-counting methods. EG/Ag20 exhibited a stronger antibac¬ terial activity than EG/CuO and EG/ZnO, with a MIC of 0.3 mg/mL and a MBC of 0.5 mg/mL. To the best of our knowledge, few studies have demonstrated that EG/MO composites can inhibit the growth of Bacillus anthracis-adhered cells, thus preventing the process of biofilm formation. Nanoscale metal oxides display en¬ hanced reactive properties toward bacteria due to their high surface area, large number of highly reactive edges, corner defect sites and high surface to volume ratio.