title: Role of size and shape on biofilm eradication for nitric oxide-releasing silica nanoparticles.
abstract: 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.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.
authors.forename: Danielle L
authors.initials: DL
authors.lastname: Slomberg
authors.forename: Yuan
authors.initials: Y
authors.lastname: Lu
authors.forename: Angela D
authors.initials: AD
authors.lastname: Broadnax
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Hunter
authors.forename: Alexis W
authors.initials: AW
authors.lastname: Carpenter
authors.forename: Mark H
authors.initials: MH
authors.lastname: Schoenfisch
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D053758:Nanoparticles / Q000737:chemistry*; D009569:Nitric Oxide / Q000737:chemistry* / Q000494:pharmacology; D010316:Particle Size; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D012822:Silicon Dioxide / Q000737:chemistry / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D009569:Nitric Oxide; D012822:Silicon Dioxide