Active bayerite underpinned Ag2O/Ag: an efficient antibacterial nanohybrid combating microbial contamination

Active surfaces with bactericidal properties are of paramount importance in health care sector as a judicious approach to confront prevalent challenges presented by disastrous pathogenic infections and antibiotic-resistant microbes. Herein, we present Bayerite underpinned Ag2O/Ag (ALD), a nanohybrid with excellent antibacterial and antibiofilm functionalities against tested standard strains and clinical isolates. The multicomponent system coexists and complement each other with respect to phase and functionalities, demonstrated by XRD, XPS, and TEM analyses. In situ reduction of Ag+ ions to Ag-0 over Bayerite as a stable bound phase is favoured by pH of the reaction, yielding 60-80% bound Ag protruding outwards facilitating active surface for interaction with microbes. ALD has a minimum inhibitory concentration (MIC) of 0.068 mg/ml against clinical isolates: Pseudomonas aeruginosa RRLP1, RRLP2, Acinetobactor baumannii C78 and C80. Disc diffusion assay demonstrated excellent antibacterial activity against standard strains (positive control: standard antibiotic disc, Amikacin). ALD incorporated PMMA films (5 and 10 wt%; PALD-5 and PALD-10) exhibited significant contact killing (99.9%) of clinical isolates in drop-test besides strong antibacterial activity (disc diffusion assay) comparable to that of ALD. ALD exemplified a dose (0.034 and 0.017 mg/ml) dependent biofilm inhibition (P < 0.001) and significant eradication of pre-formed biofilms (P < 0.001) by clinical isolates. PALD 5 and PALD 10 significantly declined the number of viable biofilm associated bacteria (99.9%) compared to control. Both ALD and PALD samples are proposed as green antibacterial materials with antibiofilm properties. Results also present ample opportunity to explore PALD as antibacterial and/or antibiofilm coating formulations.