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

Area of Science:

• Nanotechnology
• Materials Science
• Microbiology

Background:

• The mechanism of biocidal action for single-element noble metal anisotropic nanoparticles remains unclear.
• Understanding nanoparticle shape and reactive oxygen species (ROS) interactions is crucial for developing effective antimicrobial agents.

Purpose of the Study:

• To investigate the photogenerated ROS production kinetics of anisotropic silver nanoparticles (AgNPs).
• To determine the direct impact of individual ROS species on Gram-negative and Gram-positive bacteria.
• To correlate nanoparticle morphology with bactericidal efficacy.

Main Methods:

• Fabrication of triangular, cube, and rod-shaped AgNPs via plasmon-mediated synthesis.
• Quantification of ROS species (O2•−, •OH, 1O2) production kinetics.
• Assessment of bactericidal activity against bacteria using varying NP concentrations and exposure times.
• Scanning Electron Microscopy (SEM) for analyzing NP-bacteria interactions.

Main Results:

• Triangular AgNPs (Ag-Tri) demonstrated superior bactericidal capacity, achieving complete bacterial inactivation at 18 μg mL−1 within 180 min.
• Ag-Tri significantly outperformed cube (Ag-Cub) and rod (Ag-Rod) shaped NPs in terms of efficacy and required concentration.
• Superoxide radical (O2•−) was the dominant ROS species, but not the sole determinant of antimicrobial activity; physical cell damage by Ag-Tri's morphology was critical.

Conclusions:

• Nanoparticle shape, particularly the sharp-tip morphology of triangular AgNPs, is paramount for potent antibacterial activity.
• The {111} facets of triangular AgNPs contribute to physical deterioration of bacterial cells.
• The combined effects of physical damage and ROS generation by triangular AgNPs lead to superior and multifaceted antibacterial performance.