Authors:

Avery Martin

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About Paper:

The rapid rise of antimicrobial resistance (AMR) threatens the effectiveness of conventional antibiotics and necessitates alternative antimicrobial strategies. Silver nanomaterials (AgNPs) have emerged as promising candidates due to their broad-spectrum antimicrobial activity and multi-target mechanisms, which reduce the likelihood of resistance development. However, the role of nanoparticle physicochemical properties, especially particle shape, in modulating antimicrobial efficacy remains insufficiently understood. This study investigates how silver nanoparticle morphology influences antimicrobial activity against both Gram-negative and Gram-positive bacterial strains. Spherical, rod-shaped, and cubic silver nanoparticles were evaluated for their minimum inhibitory concentrations (MICs) using standard broth microdilution assays. Representative strains included Escherichia coli, Enterobacter cloacae, and Klebsiella pneumoniae (Gram-negative), as well as Staphylococcus aureus (Gram-positive). Nanoparticle suspensions were characterized for size distribution and concentration prior to biological testing to ensure consistent dosing across treatments. Preliminary results indicate that nanoparticle shape influences antimicrobial potency. Cubic and rod-shaped nanoparticles demonstrated lower MIC values than spherical nanoparticles in Gram-negative species, suggesting enhanced antimicrobial activity. Notably, exposure to 55 nm PVP-capped cubic AgNPs revealed species-specific susceptibility patterns: S. aureus and K. pneumoniae consistently exhibited greater susceptibility, whereas E. coli and E. cloacae displayed more variable responses. These differences may reflect variations in cell envelope architecture and nanoparticle-cell surface interactions. Overall, this work highlights the importance of nanoparticle morphology in shaping antimicrobial performance and contributes to ongoing efforts to address antimicrobial resistance through materials-based strategies.

Source:

University of Illinois Chicago

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Co-authors:

Avery Martin