Effects of Gentamicin-Loaded Chitosan-ZnO Nanocomposite on Quorum-Sensing Regulation of Pseudomonas Aeruginosa

Abstract

Cell density-based intercellular signaling mechanism is known as Quorum sensing (QS); it serves a significant role in regulating the pathogenic factors. The objective of the present study was to assess the influence of chitosan-zinc oxide nanocomposite (CH-ZnO nanocomposite), alone and in combination with gentamicin, on the sensitivity to hydrogen peroxide (H₂O₂), the production of pathogenic factors and QS-regulated genes of Pseudomonas aeruginosa. The efficacy of the minimum inhibitory concentration (MIC) and 1/4 MIC of the CH-ZnO nanocomposite, alone and in combination with gentamicin, on the sensitivity to H₂O₂, pyocyanin secretion, swarming and twitching motilities was evaluated. In addition, the expression of some QS-regulated genes including rhlI, rhlR, lasI and lasR genes was measured by Real-time quantitative PCR (RT-qPCR) following exposure to the nanocomposite. The results demonstrated that at MIC concentrations, the gentamicin-loaded CH-ZnO nanocomposite significantly inhibited QS-regulated phenotypes such as pyocyanin secretion (82.4%), swarming (76%) and twitching (73.6%) motilities; further it increased the inhibition growth zone (134.5%), as well as, at 1/4 MIC concentration decreased the expression of lasI (72%), lasR (78%), rhlI (76%) and rhlR (82%) genes; as compared to untreated P. aeruginosa PAO1 (P < 0.05). Our results also demonstrated that the CH-ZnO nanocomposite combined with gentamicin could be a potential innovative candidate, which could be broadly applied in the treatment of P. aeruginosa infections.

Keywords: Chitosan-ZnO nanocomposite; Pseudomonas aeruginosa; Quorum sensing; Virulence factors.