Enhanced degradation of chitosan by applying plasma treatment in combination with oxidizing agents for potential use as an anticancer agent

•Plasma treatment in combination with H2O2 effectively reduced molecular weight of chitosan.•Plasma treatment not only reduced the use of H2O2 but also accomplished fast reaction rate.•By this method, chitosan (ca. 400kDa) was degraded to be water-soluble chitosan (≤6.5kDa).•Chitooligosaccharide (COS), up to 9-mers, was produced up to 40% of the degraded products.•The obtained COS had anticancer activity against cervix cancer cell line (HeLa cell). Solution plasma (SP) treatment in combination with oxidizing agents, i.e., hydrogen peroxide (H2O2), potassium persulfate (K2S2O8) and sodium nitrite (NaNO2) were adopted to chitosan degradation in order to achieve fast degradation rate, low chemicals used and high yield of low-molecular-weight chitosan and chitooligosaccharide (COS). Among the studied oxidizing agents, H2O2 was found to be the best choice in terms of appreciable molecular weight reduction without major change in chemical structure of the degraded products of chitosan. By the combination with SP treatment, dilute solution of H2O2 (4–60mM) was required for effective degradation of chitosan. The combination of SP treatment and dilute solution of H2O2 (60mM) resulted in the great reduction of molecular weight of chitosan and water-soluble chitosan was obtained as a major product. The resulting water-soluble chitosan was precipitated to obtain COS. An inhibitory effect against cervical cancer cell line (HeLa cells) of COS was also examined.