Journal
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY
Volume 126, Issue -, Pages 105-111Publisher
ELSEVIER SCIENCE SA
DOI: 10.1016/j.jphotobiol.2013.07.010
Keywords
ZnO NPs; Oxygen vacancies; Capping agents; Antibacterial activity; Reactive oxygen species; TBARS assay
Categories
Funding
- Ministry of Human Resource Development (MHRD), Govt of India
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Antibacterial activity of ZnO nanoparticles (NPs) triggered by generation of reactive oxygen species (ROS) depends on the fate of photoexcited charge carriers. Batches of wide band gap ZnO NPs of 7-9 nm sizes, capped with polyethylene glycol (PEG), ascorbic acid (AsA), mercaptoacetic acid (MAA) and polysorbate 80 (T-80) were synthesized by precipitation method. These capped ZnO NPs exhibited ROS induced antibacterial activity, where the ROS was measured by TBARS assay. The PEG capped and AsA capped ZnO NPs exhibited weaker antibacterial activity and were correlated with strong and broad green emission peak owing to oxygen vacancies. The oxygen vacancies were trap sites of photoexcited electrons which inhibited interaction between the photoexcited electrons and oxygen on the surface of the ZnO NPs and accounted for lesser ROS generation and subsequently weaker antibacterial activity. Contrastingly MAA capped and T-80 capped ZnO NPs did not exhibit significant green emission peak, but exhibited 13% and 43% inhibition of growth of E. coli, respectively. The lack of oxygen vacancy defects in MAA capped and T-80 capped ZnO NPs perhaps led to lesser trapping of charge carriers, which is favorable for higher ROS generation and consequently higher antibacterial activity. (c) 2013 Elsevier B.V. All rights reserved.
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