Eco-Friendly One Pot Synthesis of Zinc Oxide Nanoparticles Using Catkin Extract of <i>Piper longum</i>: In Vitro Antibacterial, Antioxidant and Antibiofilm Potential against Multi Drug Resistant Enteroaggregative <i>E. coli</i> 

Abstract

Enteroaggregative Escherichia coli (EAEC) is a neglected, though emerging, bacterial pathogen associated with gastrointestinal illnesses worldwide. Recently, a surprising surge in the multi-drug resistance pattern among EAEC strains has been observed on a global scale; hence, emphasis has been given to adjuvant therapies to combat this nagging public health threat. This study assessed the antibacterial efficacy of ZnO NPs synthesised using the aqueous extract of Piper longum catkin against multi-drug resistant (MDR) strains of EAEC. Initially, the synthesis of ZnO NPs was confirmed via UV-Vis spectroscopy and Fourier transform infra-red spectroscopy (FTIR) analysis. The thermal stability of ZnO NPs was evidenced by TGA/DTA, while PXRD analysis revealed a hexagonal wurtzite crystalline structure, which was then confirmed by electron microscopy. The minimum inhibitory concentration and minimum bactericidal concentration of the bio-fabricated ZnO NPs, determined via microbroth dilution technique against MDR-EAEC (n = 3) strains, was revealed to be 125 μg/mL and 250 μg/mL, respectively. In addition, the ZnO NPs were found to be variably stable and safe. The green synthesised ZnO NPs exhibited a concentration-dependent antioxidant activity and inhibited the biofilm forming ability of the tested MDR-EAEC strains. Overall, this study revealed an eco-friendly one-pot synthesis of ZnO NPs, which could be used as a fruitful antimicrobial substitute against MDR-EAEC strains.

Keywords

• antimicrobial resistance
• enteroaggregative <i>Escherichia coli</i>
• green synthesis
• nanoparticle
• zinc oxide