Effects of degree of deacetylation on enzyme immobilization in hydrophobically modified chitosan

• Published in: Carbohydrate polymers Vol. 77; no. 2; pp. 420 - 424
• Main Authors: Sjoholm, Kyle H., Cooney, Michael, Minteer, Shelley D.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2009; Elsevier
• Subjects: Applied sciences; Chitosan; Deacetylation; Enzyme immobilization; Exact sciences and technology; Micellar polymers; Natural polymers; Physicochemistry of polymers; Reductive amination; Starch and polysaccharides; Reductive amination; Micellar polymers; Enzyme immobilization; Chitosan; Deacetylation; Structure effect; Glucose oxidase; Condensation reaction; Support; Enzyme; Immobilization; Butanal; Experimental study; Lateral group; Chemical modification; Enzymatic activity; Chitosan derivatives; Preparation; Oside polymer; Hydrophobic group; Basic medium; Oxidoreductases; Immobilized enzyme; Heterogeneous reaction
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2009.02.006

Chitosan is a deacetylated form of the polysaccharide chitin. Over the last decade, researchers have employed reductive amination to hydrophobically modify chitosan to induce a micellar structure. These micellar polymers have been used for a variety of purposes including drug delivery and enzyme immobilization and stabilization. However, commercial sources of chitosan vary in their degree of deacetylation and there remains a paucity of information regarding how this can impact the modified polymer’s functionality for enzyme immobilization. This paper, therefore, evaluates the effect that the degree of deacetylation has on the hydrophobic modification of medium molecular weight chitosan via reductive amination with long chain aldehydes and the resulting changes in enzyme activity after the immobilization of glucose oxidase in the micellar polymeric structure. The chitosan was deacetylated to differing degrees via autoclaving in 40–45% NaOH solutions and characterized using NMR, viscosity measurements, and differential scan calorimetry. Results suggest that a high degree of deacetylation provides optimal enzyme immobilization properties (i.e. high activity), but that the deacetylation method begins to significantly decrease the polymer molecular weight after a 20 min autoclave treatment, which negatively affects immobilized enzyme activity.