Water-soluble chitosan derivatives and pH-responsive hydrogels by selective C-6 oxidation mediated by TEMPO-laccase redox system

Suse Botelho da Silva*, Malgorzata Krolicka, Lambertus A.M. van den Broek, August E. Frissen, Carmen Gabriela Boeriu

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

22 Citations (Scopus)

Abstract

Chitosan is a polysaccharide with recognized antioxidant, antimicrobial and wound healing activities. However, this polymer is soluble only in dilute acidic solutions, which restricts much of its applications. A usual strategy for improving the functionality of polysaccharides is the selective oxidation mediated by 2,2,6,6-tetra-methyl-1-piperidinidyloxy (TEMPO) using laccase as a co-oxidant. In this work, the TEMPO-laccase redox system was used for the first time to selectively oxidize chitosan in order to produce tailored derivatives. The reaction was performed at pH 4.5 under continuous air supply and the oxidized products were characterized structurally and functionally. The TEMPO-laccase oxidation successfully added aldehyde and carboxylate groups to chitosan structure resulting in derivatives with oxidation between 4 and 7%. These derivatives showed increased solubility and decreased viscosity in solution. If chitosan is dissolved in diluted hydrochloric acid prior to TEMPO-laccase oxidation, a crosslinked chitosan derivative was produced, which was able to form a pH-responsive hydrogel.
Original languageEnglish
Pages (from-to)299-309
JournalCarbohydrate Polymers
Volume186
DOIs
Publication statusPublished - 15 Apr 2018

Keywords

  • 2,2,6,6-Tetramethylpiperidinoxyl radical (TEMPO)
  • Chitosan
  • Laccase
  • Oxidation
  • pH-responsive hydrogel
  • Soluble chitosan

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