Modulated Antimicrobial Activity and Drug-Protein Interaction Ability of Zinc Oxide and Cadmium Sulfide Nanoparticles: Effect of Doping with Few First-Row Transition Metals

ZnO and CdS nanoparticle (NP) doped with first row transition metal ions showed significant antibacterial activity towards Gram-negative as well as Gram-positive bacteria. While, the antibacterial activity of ZnO NPs was found to be significant in Gram-negative bacteria, the effect was comparatively less pronounced towards Gram-positive bacteria. The activity was found to increase with increasing concentration of the NPs. Doping of ZnO NP with Fe atom resulted in significant reduction in the efficacy its antimicrobial activity. In comparison, CdS quantum dot showed antibacterial activity both in Gram-negative and Gram-positive bacteria. While Co doped CdS particles did not show any modulated antibacterial activity; doping by Fe atom augments it with increasing the dopant concentration. The interaction of anti-diabetic drug chlorpropamide is significantly stronger with bovine serum albumin adsorbed on Fe-doped CdS in comparison with undoped NPs without significant alteration in the protein secondary structure. Present study reveals that the drug binding ability of proteins can be significantly modulated on judicious choice of NP system and also the dopant. The modulation in antimicrobial activity and the drug binding ability of the adsorbed protein was explained on the basis of structural parameters and different physicochemical properties of the doped NP systems.