Antibacterial Activity of Partially Oxidized Ag/Au Nanoparticles against the Oral Pathogen Porphyromonas gingivalis W83

Figure 7

Representative atomic force microscopy height images of P. gingivalis W83 exposed to aerobically prepared Ag/Au nanoparticles. (a) Cells dividing in the exponential growth phase with undamaged membranes and typical dimensions (~1 × 1 μm²). (b) P. gingivalis W83 exposed to 0.5 mM AgNO₃ for ≈3 hours (corresponding to OD ≈ 0.5 in W83 control growth phase) revealed significant bacterial lysis and membrane disruption. (c) P. gingivalis W83 exposed to 0.25 mM H₂O₂ showing bacterial lysis. (d) P. gingivalis W83 exposed to glutathione capped Ag/Au nanoparticles for ≈10 min is similar to untreated bacteria and displays no signs of structural damage. (e) When P. gingivalis W83 is exposed to glutathione capped Ag/Au nanoparticles for ≈5 hours the majority of the bacterial membranes are completely disrupted with intracellular material leaking out. (f) P. gingivalis W83 exposed to glutathione capped Ag/Au nanoparticles in the presence of 0.25 mM H₂O₂.

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