Ultraviolet light and laser irradiation enhances the antibacterial activity of glucosamine-functionalized gold nanoparticles

Saravanan Govindaraju,^1,3 Mohankandhasamy Ramasamy,¹ Rengarajan Baskaran,² Sang Jung Ahn,^3,4 Kyusik Yun<sup>1

1</sup>Department of Bionanotechnology, Gachon University, Gyeonggi-do, ²College of Pharmacy, Gachon University, Incheon, ³Centre for Advanced Instrumentation, Korea Research Institute of Standard and Science, University of Science and Technology, Daejeon, Republic of Korea; ⁴Major of Nano Science, University of Science and Technology, Daejeon, Republic of Korea

Abstract: Here we report a novel method for the synthesis of glucosamine-functionalized gold nanoparticles (GlcN-AuNPs) using biocompatible and biodegradable glucosamine for antibacterial activity. GlcN-AuNPs were prepared using different concentrations of glucosamine. The synthesized AuNPs were characterized for surface plasmon resonance, surface morphology, fluorescence spectroscopy, and antibacterial activity. The minimum inhibitory concentrations (MICs) of the AuNPs, GlcN-AuNPs, and GlcN-AuNPs when irradiated by ultraviolet light and laser were investigated and compared with the MIC of standard kanamycin using Escherichia coli by the microdilution method. Laser-irradiated GlcN-AuNPs exhibited significant bactericidal activity against E. coli. Flow cytometry and fluorescence microscopic analysis supported the cell death mechanism in the presence of GlcN-AuNP-treated bacteria. Further, morphological changes in E. coli after laser treatment were investigated using atomic force microscopy and transmission electron microscopy. The overall results of this study suggest that the prepared nanoparticles have potential as a potent antibacterial agent for the treatment of a wide range of disease-causing bacteria.

Keywords: gold nanoparticles, glucosamine, light irradiation, antibacterial activity, bacterial morphology

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