Pluronic-coated silver nanoprisms: Synthesis, characterization and their antibacterial activity

The aim of this study is to investigate the antibacterial efficiency of pluronic-coated silver nanoparticles when, instead of commonly explored spherical nanoparticles, anisotropic nanoparticles (nanoprisms) enveloped in a biocompatible polymer are used. In the first step we successfully synthesized silver nanoprisms with edge length between 30 and 50 nm and thickness between 4 and 6 nm exhibiting well-resolved localized surface plasmon resonances (LSPR) at 615, 443 and 335 nm. To endow with colloidal and morphological stability required in biological environment, the as-prepared silver nanoprisms were coated with pluronic F-127—a synthetic triblock copolymer consisting of PEO (poly(ethylene oxide))–PPO (poly(propylene oxide))–PEO (poly(ethylene oxide)) chains. The bactericidal effects of pluronic-coated silver nanoprisms were evaluated against two methicillin-resistant Staphylococcus aureus (MRSA) strains (UCLA 8076 and 1190R) by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC). The strong antibacterial activity we found can be explained by considering that triangular nanoprisms exhibit crystalline facets of higher reactivity and, presumably, a higher rate of ions release from their tips and edges compared to other shapes of nanoparticles.