Abstract
In this study, Escherichia coli (E. coli) and Staphyllococcous aureus (S. aureus) were cultured with and without surface modified (amine adsorbed/functionalized) zinc oxide nanoparticles (ZnO-NPs) to control metabolic oxidative stress during normal bacterial culture in liquid media. Surface modification was done with different amines like isopropylamine (IPA), diethylamine (DEA) and triethylamine (TEA) via sol-gel method. Morphological observations using FESEM showed spherical particles of less than 10 nm size with fairly uniform shape and size distribution of crystalline nature. Material composition of the synthesized powder and functionalization of amine on ZnO-NPs was analyzed using FTIR and UV-Visible studies. It is observed that in the presence of DEA adsorbed ZnO-NPs, bacterial cells increased notably which acted as more anti-oxidative than the IPA and TEA adsorbed ZnO-NPs in both the bacterial types. A dose dependent study and the dose-response relationship were determined to obtain MIC value by obtaining growth curves. It was observed that the bacterial cells grew more than the positive control at lower concentrations between 0.5-2 mM in DEA and TEA adsorbed ZnO-NPs supplemented medium in both strains. Such behavior is correlated to the different amine concentrations on ZnO surface and resultant variation in generation of reactive oxygen species (ROS). Based on chemical and bacterial culture experiments, reaction mechanism for the oxidative stress management is proposed.