Exploiting the Versatility of Polydopamine-Coated Nanoparticles to Deliver Nitric Oxide and Combat Bacterial Biofilm

Abstract

In this study, an antimicrobial platform in the form of nitric oxide (NO) gasreleasing polydopamine (PDA)-coated iron oxide nanoparticles (IONPs) is developed for combating bacterial biofilms. NO is bound to the PDA-coated IONPs via the reaction between NO and the secondary amine moieties on PDA to form <i>N</i>-diazeniumdiolate (NONOate) functionality. To impart colloidal stability to the nanoparticles in aqueous solutions (e.g., phosphate buffered saline (PBS) and bacteria cell culture media M9), a polymer bearing hydrophilic and amine pendant groups, P(OEGMA)-<i>b</i>-P(ABA), is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization and is subsequently grafted onto the PDA-coated IONPs by employing the Schiff base/Michael addition reaction between <i>o</i>-quinone and a primary amine. These nanoparticles are able to effectively disperse <i>Pseudomonas aeruginosa</i> biofilms (up to 79% dispersal) at submicromolar NO concentrations. In addition, the nanoparticles demonstrate excellent bactericidal activity toward <i>P. aeruginosa</i> planktonic and biofilm cells (up to 5-log₁₀ reduction).