Biogenic silver and silver oxide hybrid nanoparticles: a potential antimicrobial against multi drug-resistant Pseudomonas aeruginosa

Abstract

There is an undying need for inexpensive, energy efficient and eco-friendly protocols to produce biocompatible nanoparticles to be used in the field of medicine. To address this issue, exploratory research was performed to produce silver nanoparticles (AgNPs) using a novel strain of Kitasatospora albolonga isolated during the course of the study. The objective was to test their antimicrobial activity against Multi Drug Resistant (MDR) Pseudomonas aeruginosa. UV-visible spectroscopy, dynamic light scattering (DLS), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) confirmed the presence of hybrid AgNPs. UV-visible spectroscopy showed a localized surface plasmon resonance (LSPR) absorption peak at approximately 420 nm. The DLS and SEM micrographs showed spherical particles ranging between 10 and 50 nm in size. XRD indicated a highly frustrated system comprising silver (cubic, Fmm) and silver oxide (cubic, pnm: 1) phases as identified from the diffraction peaks. The crystallite sizes of silver (Ag) were smaller than those of silver oxide (Ag₂O), indicating a possible core shell structure, also corroborated by the SEM and TEM studies. The Ag/Ag₂O hybrid nanoparticles (NPs) exhibited antimicrobial activity against MDR P. aeruginosa. The NP impregnated discs were compared with various commercially available antibiotic discs. Most of the antibiotic discs did not inhibit the growth of the MDR strain alone or in combination with the NPs. However, a synergistic action between Ag/Ag₂O NPs and carbenicillin (CN) drug was observed through the checkerboard assay against the MDR hospital isolate. The efficacy of this combination proved to be a lethal and viable option against MDR P. aeruginosa.