Antimicrobial activity of graphite oxide doped with silver against Bacillus subtilis, Candida albicans, Escherichia coli, and Staphylococcus aureus by agar well diffusion test: Synthesis and characterization

In the present study, graphite oxide, graphite oxide doped with 0.8 g AgNO₃ named GrO-0.5Ag, and graphite oxide doped with 1.25 g AgNO₃ named GrO-1.0Ag (silver-doped graphitic materials) were synthesized by the modified Hummers and chemical doping methods. Subsequently, its antimicrobial activity against Bacillus subtilis, Candida albicans, Escherichia coli, and Staphylococcus aureus microorganisms was evaluated by agar well diffusion test with 1 and 2 mg·ml^-1 of material concentrations. The silver-doped graphitic materials were characterized by X-Ray Diffraction, Fourier-Transform Infrared, Raman, X-Ray Photoelectron spectroscopies, and Scanning Electron Microscopy. The GrO-0.5Ag material showed a percentage of inhibition effect of 86, 82, 48, and 45% with respect to the positive control for Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Candida albicans microorganisms, respectively. Otherwise, the GrO-1.0Ag material showed a percentage of inhibition effect of 54% with respect to the positive control for Bacillus subtilis and less than 50% for the other microorganisms. The material concentrations showed a slight change in the percentage of inhibition effect for all microorganisms. Graphite oxide functional groups, small crystal size, free silver ions, and silver carbonate formation in silver-doped graphitic materials presented a viable alternative to inhibit bacterial growth.