The Influence of Physical properties on the Antibacterial Activity of Lysine Conjugated Chitosan Functionalized Silver Nanoparticles

Abstract

The antibacterial activity of chitosan/lysine/silver (Cht/lys/Ag) on pathogens was influenced by physical properties and morphology to a higher degree compared with that of chitosan/silver (Cht/Ag). The antibacterial activity of Cht/Ag and Cht/lys/Ag were evaluated against pathogens Gram negative (E. coli and P. aeruginosa) and Gram positive bacteria (S. aureus and B. subtilis) by Kirby Bauer disk diffusion assay method. Crystallite size values of the synthesized system was calculated from XRD analysis to study their dependency on antibacterial activity. The FTIR spectral analysis shows the presence of -OH and COO- groups of Cht and lys and the variation in intensities confirmed the interaction with Ag nanoparticles which are stabilized. Moreover, UV–Vis results show that the Cht/lys/Ag composition enhanced the stability and induced the symmetry of Ag nanoparticles which were observed from surface plasmon resonance (SPR) effect of Cht/lys/Ag. In addition, the induced higher symmetry, low hydrodynamic diameter and higher diffusion coefficient from dynamic light scattering (DLS) measurement of Cht/lys/Ag were found to yield maximum bacterial inhibition than Cht/Ag which were due to lysine interaction. Obviously surface morphological changes in the composites are due to Ag and lysine interaction as seen from SEM micrographs. The synthesized NCs exhibit efficient antipathogens against Gram negative bacteria and are promising candidates in diverse applications in biomedical industries.