Available online 13 September 2022, 127069

ZnO NPs were synthesized from cyanobacteria Gleocapsa gelatinosa extract.

Physicochemical characterization evidenced spherical particle with 31-35 nm in size.

ZnO NPs showed potent biofilm inhibition against multi-drug resistant bacteria pathogens.

ZnO NPs reduced the bacterial cell viability and eradicate the biofilms.

ZnO NPs targets cell membrane induced ROS generation as bactericidal mechanism.

Biofilms are microbial colonies that remain enclosed in an organic polymeric matrix substance on biotic and abiotic surfaces, allowing them to colonize medical equipments and involved in most device associated life intimidating infections. Due to their antimicrobial resistance there is an urgent need to discover novel biofilm preventive and therapeutic agents. Methods: ZnO NPs were synthesized using cyanobacteria Gleocapsa gelatinosa cell extract through green & cost-effective approach. Physiochemical characterization was done to determine their morphologies and size distribution. Antibiofilm and eradication activity of ZnO NPs was determined. Cell viability and internalization ability of ZnO NPs into biofilm was analyzed by flow cytometry. Confocal microscopy was done to visualize the disrupted biofilm morphology treated with ZnO NPs.

It was observed that ZnONPs were spherical in shape with 31–35 nm size and were moderately dispersed. ZnO NPs exhibited high antibiofilm activity against B. cereus and E. coli with minimum biofilm inhibitory concentration (MBIC) of ZnO NPs at 46.8 µg ml-1 and 93.7 µg ml-1. Flow cytometry analysis confirmed the reduced bacterial cell viability due to increased permeability, altered bacterial growth and enhanced production of intracellular ROS. Disruption of membrane integrity exhibited with reduced exopolysaccharides secretion and leakage of nucleic acids through UV-Vis spectroscopy. Results of confocal microscopy highlighted strong interaction of ZnO NPs with intracellular components leading to biofim destruction. Overall,

This study emphasizes the potential mechanisms underlying the selective bactericidal properties of ZnO NPs and highlighted the strong interaction of ZnO NPs with intracellular components leading to biofim destruction. Therefore, ZnO NPs could be considered as a promising antibiofilm agent and thus could expand the possibility to use as therapeutic agent.

Zinc oxide nanoparticles

Anti-biofilm

ROS generation

Flow cytometry

Confocal microscopy

Intracellular leakage

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