Surface Plasmon Resonance Influence on the Antibacterial Effect of a Nanostructured Gold Surface

The present paper deals with experimental and theoretical studies of the antibacterial action of the nanostructured gold surface against Staphylococcus aureus ATCC 6538 (S. aureus). The primary purpose here is to answer whether the enhancement of the antibacterial effect of a nanostructured gold surface under the conditions of plasmon resonance takes place. For the reliability of our investigations, we use four identical samples of bacteria suspensions. They are the control sample which is reserved at room temperature in the darkness, the pumped sample, and the samples for the experiments when the suspension contacts the gold surface under and without surface plasmon (SP) resonance conditions. We use two experimental approaches. The bacterial suspension circulated along the metal surface is studied. Also, the case of bacteria slowly settling onto the gold surface under gravity is considered. Experiments in the case of suspension circulation discover the near-double enhancement of the antibacterial action of the gold surface against S. aureus under SP resonance conditions. The enhancement results from the increased interaction between the bacteria and the gold surface under these conditions. The adsorption potential is increased up to ten times when the SP is excited along the surface. As a result, the local-field enhancement effect is increased, which leads to an increase in the area of strong gradients of a local field and, thus, an increase in the act of ponderomotive forces. These forces are the reason for bacterial membrane damage.