Chitosan as a Biomaterial: Influence of Degree of Deacetylation on Its Physiochemical, Material and Biological Properties.

Leslie John Ray Foster,Monica Basuki,Sonia Ho,James Hook,Helder Marçal,Warren Batchelor

doi:10.1371/journal.pone.0135153

Abstract

Chitosan is a biomaterial with a range of current and potential biomedical applications. Manipulation of chitosan degree of deacetylation (DDA) to achieve specific properties appears feasible, but studies investigating its influence on properties are often contradictory. With a view to the potential of chitosan in the regeneration of nerve tissue, the influence of DDA on the growth and health of olfactory ensheathing cells (OECs) was investigated. There was a linear increase in OEC proliferation as the DDA increased from 72 to 85%. This correlated with linear increases in average surface roughness (0.62 to 0.78 μm) and crystallinity (4.3 to 10.1%) of the chitosan films. Mitochondrial activity and membrane integrity of OECs was significantly different for OECs cultivated on chitosan with DDAs below 75%, while those on films with DDAs up to 85% were similar to cells in asynchronous growth. Apoptotic indices and cell cycle analysis also suggested that chitosan films with DDAs below 75% were cytocompatible but induced cellular stress, while OECs grown on films fabricated from chitosan with DDAs above 75% showed no significant differences compared to those in asynchronous growth. Tensile strength and elongation to break varied with DDA from 32.3 to 45.3 MPa and 3.6 to 7.1% respectively. DDA had no significant influence on abiotic and biotic degradation profiles of the chitosan films which showed approximately 8 and 20% weight loss respectively. Finally, perceived patterns in property changes are subject to change based on potential variations in DDA analysis. NMR examination of the chitosan samples here revealed significant differences depending upon which peaks were selected for integration; 6 to 13% in DDA values within individual samples. Furthermore, differences between DDA values determined here and those reported by the commercial suppliers were significant and this may also be a source of concern when selecting commercial chitosans for biomaterial research.

Highlights

Chitosan as a biomaterial elicits a negligible immune response following implantation, injection, topical application or ingestion in mammalian systems [1]
The degree of deacetylation (DDA) values determined here using NMR differed significantly from those reported by the chitosan suppliers
While S2 and S3 purchased from Sigma Aldrich had DDA values within the ranges reported (75 to 85% for S2 and >75% for S3), a value of >75% for S1 was significantly less than the mean of 85% determined in this study

Summary

Introduction

Chitosan as a biomaterial elicits a negligible immune response following implantation, injection, topical application or ingestion in mammalian systems [1]. Chitosan has approval for application as a biomaterial by the Food and Drug Administration (FDA) in the USA and regulatory bodies of other countries, and is currently used in a number of commercial products from haemostatic bandages to dietary aides [6,7,8]. A copolymer of D-glucoasmine and N-acetyl-D-glucosamine, is commonly derived through the N-deacetylation of chitin found in crustacean and insect carapaces, (Fig 1) [5]. With approximately 1011 tons of chitin produced per year from waste crustacean carapaces, chitosan is a cost effective biomaterial [4]. The degree of deacetylation (DDA) exhibited by chitosan can be controlled during a relatively aggressive alkaline hydrolysis process applied to the chitin, through a combination of exposure duration and temperature [9]

Methods

Results

Conclusion