Glucosamine functionalized copper nanoparticles: Preparation, characterization and enhancement of anti-bacterial activity by ultraviolet irradiation

Glucosamine functionalized copper nanoparticles (GlcN-Cu NPs) were synthesized for anti-bacterial function. Electron microscopic characterization revealed the hybrid morphology, selected-area electron diffraction pattern and elemental mapping of GlcN-Cu NPs. Average particle size distribution was 93 ± 8 nm. GlcN functionalization allowed significant shift in the ultraviolet (UV)-visible absorbance at 525 nm and fluorescent emission wavelength at approximately 353 nm for Cu NPs. Stretching and bending vibrations from Fourier transform-infrared and Raman analysis ensured GlcN functionalization on Cu NPs. We demonstrated the enhanced anti-bacterial property of GlcN-Cu NPs against two Gram-negative and Gram-positive bacterial strains by UV irradiation of prepared materials for 10 and 20 min. Minimum inhibitory concentration (MIC) determinations revealed that UV irradiated GlcN-Cu NPs possessed enhanced anti-bacterial activity than simple Cu NPs, Cu metal salt and standard anti-biotic kanamycin. MIC for GlcN-Cu NPs was 4 μg/mL for Escherichia coli and 8 μg/mL for Salmonella typhimurium, Enterococcus faecalis and Bacillus subtilis, confirming its potential as an anti-infective agent for the protection of medical instruments, water treatment and in food processing.

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► Glucosamine (biomolecule) functionalized copper nanoparticles (Cu NPs) were synthesized.
► Physico-chemical characterizations ensured the surface modification of nanoparticles.
► Bio-functionalization can retain the optical and crystalline properties of Cu NPs.
► UV irradiation enhanced the anti-bacterial effect of glucosamine-Cu NPs.