Catalytic and Antibacterial Activities with Molecular Docking Analysis of Chitosan and Polyethylene Glycol-NiO₂ Nanostructures

Toxic dyes and microbes in water have an alarming effect on the integrity of the environment and dairy industries. In this study, 2 and 4 wt.% of chitosan (CS) and 3% of polyethylene glycol (PEG) were incorporated to nickel oxide (NiO₂) nanostructures (NSs) to degrade dyes and to kill bacteria effectively, synthesized via the low-temperature co-precipitation technique. The motive of the research is to enhance catalytic and antimicrobial properties through surface modification and the generation of more active sites upon incorporation of dopants. X-ray crystallographic patterns confirm the hexagonal crystal structure of NiO₂ and a reduction in crystallite size with doping. The band gap energy of NiO₂ increases from 3.17 to 3.25 eV upon doping. TEM elucidates the formation of an interconnected network of nanorods and nanoparticles with reduced agglomeration upon PEG and CS addition. Doping controlled the morphology and charge recombination dynamics of NiO₂, which significantly boosts the catalytic and antibacterial potential. Particle size of the NiO₂ nanostructures decreases from 34.7 to 24.53 nm with the addition of dopants. Notably, the highly doped sample exhibited maximum RhB degradation of 92.3% in neutral medium and maximum inhibition zone of 5.25 ± 0.03 mm against gram-negative multiple drug-resistant Escherichia coli (MDR E. coli) (p < 0.05). The computational results correspond with observational data, providing compelling support for the microbial efficacy of CS/PEG-NiO₂ in suppressing DNA gyrase.