Low molecular weight (LMW) chitosan has been a great attention in bio-molecular chemistry, medicine, and drug delivery system in particular. Depolymerization of high molecular weight (HMW) chitosan to LMW chitosan was achieved by solution plasma process (SPP) without affecting its chemical structures. Chitosan in solution was depolymerized by discharging plasma at 800 V with 35 kHz for various times (15-120 min). Gel permeation chromatography analysis revealed that molecular weight of chitosan decreased from 3.0 × 105 Da to 7.8 × 103 Da in 30 min plasma treatment, and further to 4.6 × 103 Da in 90 min. Dynamic light scattering and zeta potential studies confirmed formation of chitosan nano-aggregates. Interestingly, the LMW chitosan samples showed antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Candida albicans with minimal inhibitory concentration of 80-1200 μg·mL-1. They also exhibited an excellent antioxidant activity (58-75%) and swelling ratio of 0.2-2.0 mg·mg-1. LMW chitosan was likely to have potential for sustainable usage as carrier molecules, biomaterials, and biomedical applications.
Keywords: Antimicrobial activity; Antioxidant activity; Biomaterials; Low molecular weight chitosan; Solution plasma.
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