Radical adducts formation mechanism of CH3CO2∙ and CH3CO3∙ realized decomposition of chitosan by plasma catalyzed peracetic acid

Yue Liu; Dongrui Li; Mengna Chen; Qingyuan Sun; Ying Zhang; Jian Zhou; Tiecheng Wang

doi:10.1016/j.carbpol.2023.121121

Radical adducts formation mechanism of CH₃CO₂∙ and CH₃CO₃∙ realized decomposition of chitosan by plasma catalyzed peracetic acid

Carbohydr Polym. 2023 Oct 15:318:121121. doi: 10.1016/j.carbpol.2023.121121. Epub 2023 Jun 15.

Authors

Yue Liu¹, Dongrui Li¹, Mengna Chen¹, Qingyuan Sun¹, Ying Zhang², Jian Zhou¹, Tiecheng Wang³

Affiliations

¹ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, PR China.
² College of Information Science and Technology, Nanjing Forestry University, Nanjing 210037, PR China.
³ College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi Province 712100, PR China; Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China, Ministry of Agriculture, Yangling, Shaanxi 712100, PR China. Electronic address: wangtiecheng2008@126.com.

PMID: 37479454
DOI: 10.1016/j.carbpol.2023.121121

Abstract

High-molecular-weight chitosan has limited applications due to unsatisfactory solubility and hydrophilicity. Discharge plasma coupled with peracetic acid (PAA) oxidation ("plasma+PAA") realized fast depolymerization of high-molecular-weight chitosan in this study. The molecular weight of chitosan rapidly declined to 81.1 kDa from initial 682.5 kDa within 60 s of "plasma+PAA" treatment, and its reaction rate constant was 12-fold higher than single plasma oxidation. Compared with ¹O₂, ∙CH₃, CH₃O₂·, and O₂∙^-, CH₃CO₂∙ and CH₃CO₃∙ played decisive roles in the chitosan depolymerization in the plasma+PAA system through mechanisms of radical adduct formation. The attacks of CH₃CO₂∙ and CH₃CO₃∙ destroyed the β-(1,4) glycosidic bonds and hydrogen bonds of chitosan, leading to generation of low-molecular-weight chitosan; the main chain structure of chitosan was not changed during the depolymerization process. Furthermore, the generated low-molecular-weight chitosan exhibited greater antioxidant activities than original chitosan. Overall, this study revealed the radical adduct formation mechanisms of CH₃CO₂∙ and CH₃CO₃∙ for chitosan decomposition, providing an alternative for fast depolymerization of high-molecular-weight chitosan.

Keywords: Antioxidant activity; Chitosan; Cold plasma; Depolymerization; Peracetic acid.