title: Amino acid-mediated synthesis of zinc oxide nanostructures and evaluation of their facet-dependent antimicrobial activity.
abstract: ZnO nanostructures (ZnO-NSs) of different morphologies are synthesized with the amino acids L-alanine, L-threonine, and L-glutamine as capping agents. X-ray diffraction (XRD) shows the formation of a crystalline wurtzite phase of ZnO-NSs. The surface modification of ZnO-NSs due to the capping agents is confirmed using Fourier transform infrared (FTIR) spectroscopy. Photoluminescence spectroscopy reveals that the concentration of surface defects correlates positively with the number of polar facets in ZnO-NSs. The antimicrobial activity of the ZnO-NSs has been tested against Escherichia coli and the common pathogens Staphylococcus aureus, Klebsiella pneumoniae, and Bacillus subtilis. Culture-based methods in rich medium show up to 90% growth inhibition, depending on the ZnO-NSs. Flow cytometry analyses indicate that the reactive oxygen species (ROS) generated by ZnO-NSs contribute mostly to the antibacterial activity. Control experiments in minimal medium show that amino acids and other reducing agents in Luria-Bertani (LB) medium quench ROS, thereby decreasing the antimicrobial activity of the ZnO-NSs.
authors.affiliation: Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur, Kancheepuram (D.t.), Chennai 603203, Tamil Nadu, India.
authors.forename: Meghana
authors.initials: M
authors.lastname: Ramani
authors.affiliation: Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur, Kancheepuram (D.t.), Chennai 603203, Tamil Nadu, India. Electronic address: suruponnus@gmail.com.
authors.forename: S
authors.initials: S
authors.lastname: Ponnusamy
authors.affiliation: Center for Materials Science and Nano Devices, Department of Physics, SRM University, Kattankulathur, Kancheepuram (D.t.), Chennai 603203, Tamil Nadu, India.
authors.forename: C
authors.initials: C
authors.lastname: Muthamizhchelvan
authors.affiliation: School of Biotechnology, Dublin City University, Collins Avenue, Dublin 9, Dublin, Ireland; Singapore Centre on Environmental Life Sciences Engineering (SCELSE), Nanyang Technological University, 60 Nanyang Drive, 637551 Singapore, Singapore. Electronic address: enrico.marsili@gmail.com.
authors.forename: Enrico
authors.initials: E
authors.lastname: Marsili
mesh_terms: D000362:Agar; D000596:Amino Acids / Q000737:chemistry*; D000890:Anti-Infective Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000254:growth & development; D004705:Endocytosis / Q000187:drug effects; D005434:Flow Cytometry; D005452:Fluoresceins / Q000378:metabolism; D007477:Ions; D008826:Microbial Sensitivity Tests; D049329:Nanostructures / Q000737:chemistry* / Q000633:toxicity / Q000648:ultrastructure; D017382:Reactive Oxygen Species / Q000378:metabolism; D015034:Zinc Oxide / Q000138:chemical synthesis* / Q000494:pharmacology* / Q000633:toxicity
chemical_list: C110400:2',7'-dichlorodihydrofluorescein diacetate; D000596:Amino Acids; D000890:Anti-Infective Agents; D005452:Fluoresceins; D007477:Ions; D017382:Reactive Oxygen Species; D000362:Agar; D015034:Zinc Oxide
keywords: Antimicrobial; Nanostructures; Reactive oxygen species; Zinc oxide