Chitosan (Ch) was reacted with seven benzaldehyde analogs separately through reductive amination in which the corresponding imines were formed and followed by reduction to produce N-(benzyl) chitosan (NBCh) derivatives. 1H NMR spectroscopy was used to characterize the products. The nanoparticles (NPs) of Ch and NBCh derivatives were prepared according to the ionotropic gelation mechanism between Ch products and sodium tripolyphosphate, followed by high-energy ultrasonication. Scanning electron microscopy, particle size, polydispersity index, and zeta potential were applied for the NPs examination. The particle size was ranged from 235.17 to 686.90 nm and narrow size distribution (PDI <1). The zeta potential of NPs was varied between -1.26 and -27.50 mV. The antimicrobial activity was evaluated against bacteria (Erwinia carotovora subsp. atroseptica, Erwinia carotovora subsp. carotovora, and Ralstonia solanacearum), fungi (Aspergillus flavus and Aspergillus niger), and yeast (Candida albicans). The action of NBCh derivatives was significantly higher than Ch. The NPs had considerably higher than the Ch and NBCh derivatives. The activity was directly proportional to the chemical derivatization of Ch and the zeta potential of the NPs. The antimicrobial efficacy of these derivatives formulated in a greener approach could become an alternative to using traditional antimicrobial applications in an environmentally friendly manner.
Keywords: Antimicrobial activity; N-(benzyl) chitosans; NMR spectroscopy; Nanoparticles.
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