Insight into single-element nobel metal anisotropic silver nanoparticle shape-dependent selective ROS generation and quantification

The biocidal action mechanism of single element noble metal anisotropic nanoparticles has remained a perplexing challenge. Herein, we investigated the photogenerated anisotropic AgNP ROS production kinetics and each ROS species' direct impact on Gram-negative and Gram-positive bacteria. Three shapes (Triangular, Cubes, Rods) of AgNP with excellent morphology were fabricated via plasmon mediated synthesis. The results demonstrated a distinct bactericidal capacity of each NP shape where Ag-Tri outperformed Ag-Cub and Ag-Rod by displaying complete bacterial mutilation at a very low dose of 18 mu g mL(-1) for the shortest exposure time of 180 min. In contrast, Ag-Cub needed 66.6% higher NP concentration, while Ag-Rod was unable to achieve complete bacterial mutilation. In contrast to O-2(-), (Ag-Tri 69 +/- 3.2, Ag-Cub 72 +/- 2.9, Ag-Rod 68.5 +/- 3.7 mu M), the amount of OH production was considerably lower (Ag-Tri 11 +/- 1.6, Ag-Cub 10.4 +/- 1.9, Ag-Rod 11.3 +/- 2.2 mu M), while O-1(2) remained undetected for all NP shapes. Moreover, antimicrobial activity of selective ROS species revealed O-2(-) as a dominant species among ROS. However, O-2(-) was not found as a decisive factor in microbial mutilation. SEM images affirmed the significance of the specific geometrical shape and its resultant attachment to bacterial surface to be of paramount significance. The sharp-tip morphology with high-atom density active {111} facets played a pivotal role in physically deteriorating bacterial cells. Ag-Tri morphology in synchronization with ROS species assisted its wedging into the bacterial cell, translating into superior and multifaceted antibacterial performance.