Role of Size and Shape on Biofilm Eradication for Nitric Oxide-Releasing Silica Nanoparticles.

ACS applied materials & interfaces

PubMedID: 24006838

Slomberg DL, Lu Y, Broadnax AD, Hunter RA, Carpenter AW, Schoenfisch MH. Role of Size and Shape on Biofilm Eradication for Nitric Oxide-Releasing Silica Nanoparticles. ACS Appl Mater Interfaces. 2013;.
Nitric oxide (NO), a reactive free radical, has proven effective in eradicating bacterial biofilms with reduced risk of fostering antibacterial resistance. Herein, we evaluated the efficacy of NO-releasing silica nanoparticles against Gram-negative Pseudomonas aeruginosa and Gram-positive Staphylococcus aureus biofilms as a function of particle size and shape. Three sizes of NO-releasing silica nanoparticles (i.e., 14, 50, and 150 nm) with identical total NO release (~0.3 µmol/mg) were utilized to study antibiofilm eradication as a function of size. To observe the role of particle shape on biofilm killing, we varied the aspect ratio of the NO-releasing silica particles from 1 to 8 while maintaining constant particle volume (~0.02 µm(3)) and NO-release totals (~0.7 µmol/mg). Nitric oxide-releasing particles with decreased size and increased aspect ratio were more effective against both P. aeruginosa and S. aureus biofilms, with the Gram-negative species exhibiting the greatest susceptibility to NO. To further understand the influence of these nanoparticle properties on NO-mediated antibacterial activity, we visualized intracellular NO concentrations and cell death with confocal microscopy. Smaller NO-releasing particles (14 nm) exhibited better NO delivery and enhanced bacteria killing compared to the larger (50 and 150 nm) particles. Likewise, the rod-like NO-releasing particles proved more effective than spherical particles in delivering NO and inducing greater antibacterial action throughout the biofilm.