Intermolecular interactions of chitosan: Degree of acetylation and molecular weight

Chanoong Lim; Dong Soo Hwang; Dong Woog Lee

doi:10.1016/j.carbpol.2021.117782

Intermolecular interactions of chitosan: Degree of acetylation and molecular weight

Carbohydr Polym. 2021 May 1:259:117782. doi: 10.1016/j.carbpol.2021.117782. Epub 2021 Feb 9.

Authors

Chanoong Lim¹, Dong Soo Hwang², Dong Woog Lee³

Affiliations

¹ School of Energy & Chemical Engineering, UNIST (Ulsan National Institute of Science and Technology), Ulsan, 44919, Republic of Korea.
² School of Interdisciplinary Science and Engineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea; Division of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea. Electronic address: dshwang@postech.ac.kr.
³ School of Energy & Chemical Engineering, UNIST (Ulsan National Institute of Science and Technology), Ulsan, 44919, Republic of Korea. Electronic address: dongwoog.lee@unist.ac.kr.

PMID: 33674019
DOI: 10.1016/j.carbpol.2021.117782

Abstract

The degree of acetylation (DA), which determines as the molar proportion of N-acetyl-D-glucosamine units on chitosan, characterizes the physical, chemical, and biological properties of chitosan. Thus, DA can be a critical factor in the utilization of chitosan. Nevertheless, quantitative studies on the molecular interactions of chitosan as a function of DA are lacking. Here, we directly measured the molecular interaction (adhesion and cohesion) of molecularly thin chitosan films, dependent on the molecular weight and DA, using a surface forces apparatus. Using low molecular weight (LMW, ∼5 kDa) and high molecular weight (HMW, ∼135 kDa) chitosan, we obtained several DA ranges through a reacetylation method. The interactions of LMW chitosan were greatly influenced by the intrinsic charge of the chitosan units, whereas for HMW chitosan, chain flexibility was found to be the major factor affecting molecular interaction Taken together, our comprehensive data provides a holistic understanding of the interaction mechanism of chitosan.

Keywords: Biopolymer; Degree of acetylation; High molecular weight chitosan; Interaction forces; Low molecular weight chitosan; Surface forces apparatus.