Abstract
Nanoporous Au exhibits high antibacterial activity (AA) without releasing reactive oxygen species or metal ions, instead its AA depends on the work function (WF) because cell walls are affected by peculiar electronic states at the surface. Based on this mechanism, a flat surface without nanostructure should show high AA if the WF of the surface is suitably tuned. To verify this, ultrathin Pt islands with high WF was fabricated on flat Au by underpotential deposition (UPD) of copper and subsequent redox replacement with Pt, and the AA of the Pt/Au substrate on Escherichia coli was evaluated. The Pt/Au substrate showed higher AA than Pt and Au surfaces, and a positive relationship between AA and WF was demonstrated. In addition, first principles calculations were performed to investigate the mechanism for the high WF of the Pt/Au substrate. The findings suggest that the high WF of the Pt/Au substrate is at least partly due to charge transfer from Au to Pt.
Highlights
Nanoporous Au exhibits high antibacterial activity (AA) without releasing reactive oxygen species or metal ions, instead its AA depends on the work function (WF) because cell walls are affected by peculiar electronic states at the surface
It was reported that nanoporous Au, which is typical of nanostructured surfaces, showed high AA against Escherichia coli (E. coli) and Staphylococcus epidermidis[14]
The AA of a Pt/Au substrate having ultrathin Pt islands on flat Au with high WF was investigated to verify that flat substrates without nanostructure can exhibit high AA if the WF of the surface is suitably tuned
Summary
Nanoporous Au exhibits high antibacterial activity (AA) without releasing reactive oxygen species or metal ions, instead its AA depends on the work function (WF) because cell walls are affected by peculiar electronic states at the surface Based on this mechanism, a flat surface without nanostructure should show high AA if the WF of the surface is suitably tuned. The work function (WF) is related to the electric double layer at the surface[18,19], the AA of npAu has a positive correlation with the WF because the WF is increased by the enhanced hyperpolarization of cell walls[20] According to this mechanism, a flat surface without nanostructures should show high AA if the WF of the surface is suitably tuned. First principles calculations were performed to reveal the mechanism for the high WF of the Pt/Au surface
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