Abstract
Chitosan - the second most abundant polysaccharide on Earth has been known as a kind of non-toxic, environmentally friendly, biodegradable, antibacterial, and antifungal material. Compared with bulk chitosan-based materials, nanochitosan has superior properties in terms of permeability, solubility, and bioactivity. Nanochitosan is used as a carrier encapsulating various components via complexes with NH2 and OH groups of chitosan molecules to protect, stabilize, and deliver targeted bioactive compounds. For the first time, chitosan-zinc ion nanoparticles (CSZ NPs) have been successfully synthesized by ultrasound-assisted ionic gelation to produce much smaller particles with enhanced antibacterial and antifungal activities. The fabricated CSZ NPs have a diameter from 119.3 to 212.6 nm, polydispersity index ranging from 0.2 to 0.3, and zeta potential from 16.4 to 22.4 mV. The average size of the as-fabricated CSZ NPs is two times smaller than zinc ions loaded nanochitosan without ultrasonic treatment. The spherical shape of the nanochitosan particles is confirmed, along with a wide range of elemental distributions, including C (29.74 %), O (42.14 %), Na (15.80 %), and Zn (1.11 %). The antimicrobial activities of CSZ NPs are evaluated by using the agar well diffusion method with gram-negative bacteria (E. coli, P. aeruginosa), gram-positive (E. feacalis, S. aureus, S. aureus methicillin-resistant (MRSA)), and fungi (C. albicans, A. niger). The minimum inhibitory concentration of CSZ NPs is 14 µg/mL for bacteria and more than 58 µg/mL for fungi. CSZ NPs have potential antimicrobial applications in the food industry and agriculture.
