Molecular aspects of core-shell intrinsic defect induced enhanced antibacterial activity of ZnO nanocrystals.

Aim: To investigate molecular aspects of the antibacterial effect of size-dependent core-shell intrinsic defects of nanocrystalline ZnO synthesized through high energy ball milling technique.

Materials & Methods: Mechanically synthesized and characterized 7, 10 and 15 h milled ZnO nanoparticles were evaluated for antibacterial activity with molecular investigation by computational molecular docking.

Results: Synthesized ZnO nanoparticles displayed shrinkage of core and increase of shell with reduction in size of bulk ZnO particles from 250 to 80, 40 and 20 nm and increase in zeta potential up to -19 mV in 7, 10 and 15 h nano ZnO. Antibacterial activity was found increased with decrease in size due to increased reactive oxygen species and membrane damage in bacteria.

Conclusion: Synthesized nano ZnO exhibit size-dependent antibacterial action as consequences of interactions with cell membrane proteins via hydrogen bond interaction with amino acid residues followed by internalization, membrane depolarization and induction of reactive oxygen species generation.