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Preparation of Zinc Oxide Nanoparticles and the Evaluation of their Antibacterial Effects
Published on: September 27, 2024
Correlation between defects in capped ZnO nanoparticles and their antibacterial activity.
Raj Kumar Dutta1, Bhavani P Nenavathu, Mahesh K Gangishetty
1Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247667, India. duttafcy@iitr.ernet.in
Journal of Photochemistry and Photobiology. B, Biology
|August 6, 2013
Summary
Surface modifications of zinc oxide nanoparticles (ZnO NPs) impact their antibacterial efficacy. Capping agents like mercaptoacetic acid (MAA) and polysorbate 80 (T-80) enhance ROS generation and antibacterial activity by minimizing oxygen vacancies.
Area of Science:
- Nanotechnology
- Materials Science
- Microbiology
Background:
- Antibacterial activity of zinc oxide nanoparticles (ZnO NPs) is primarily mediated by reactive oxygen species (ROS).
- The generation of ROS is influenced by the behavior of photoexcited charge carriers within the ZnO NPs.
- Surface capping agents can alter the electronic properties and defect sites of ZnO NPs, affecting their antibacterial mechanisms.
Purpose of the Study:
- To investigate the effect of different capping agents (polyethylene glycol, ascorbic acid, mercaptoacetic acid, polysorbate 80) on the antibacterial activity of ZnO NPs.
- To correlate the antibacterial efficacy with the presence of oxygen vacancies and ROS generation.
- To understand the role of photoexcited charge carrier dynamics in mediating the antibacterial properties of capped ZnO NPs.
Main Methods:
- Synthesis of 7-9nm ZnO NPs using the precipitation method.
- Capping of ZnO NPs with polyethylene glycol (PEG), ascorbic acid (AsA), mercaptoacetic acid (MAA), and polysorbate 80 (T-80).
- Assessment of ROS generation using the TBARS assay.
- Evaluation of antibacterial activity against E. coli.
- Characterization of oxygen vacancies through photoluminescence (green emission peak).
Main Results:
- PEG-capped and AsA-capped ZnO NPs showed weaker antibacterial activity, correlated with strong green emission indicating oxygen vacancies that trap photoexcited electrons, reducing ROS generation.
- MAA-capped and T-80-capped ZnO NPs exhibited significantly higher antibacterial activity (13% and 43% inhibition of E. coli growth, respectively).
- These effective NPs showed minimal green emission, suggesting fewer oxygen vacancies, which facilitates higher ROS generation due to efficient charge carrier utilization.
Conclusions:
- The antibacterial activity of ZnO NPs is strongly dependent on the surface capping agent and the resulting defect sites, particularly oxygen vacancies.
- Minimizing oxygen vacancies through appropriate capping (e.g., MAA, T-80) enhances charge carrier mobility, leading to increased ROS production and potent antibacterial effects.
- Surface engineering of ZnO NPs offers a promising strategy for developing effective antibacterial agents.
