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

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.

Influence of freezing temperature and deacetylation degree on the performance of freeze-dried chitosan scaffolds towards cartilage tissue engineering

“…Chou et al [48] also observe an influence of chitosan DD on cell proliferation, attributing it to an effect on surface roughness and stiffness, which are affected by changes in DD. Foster et al [49] made similar observations with olfactory ensheathing cells cultured onto chitosan membranes with increasing DD. Interestingly, by assessing cells metabolic activity using the MTS assay, one could observe that the adhered cells became metabolically more active from day 7 to day 28 days.…”

“…The present work adds to the state-of-the-art showing the relevance of squid chitosan as an alternative to the commercially available crab and shrimp chitosans for biomedical applications [32], calling the attention to the pivotal role of DD and polymer Mw on the performance of this biopolymer. In fact, when comparing results from different works, these features should always be considered, namely, when commercially available extracts are used, which face significant variation from batch to batch and sometimes the values provided by the manufacturer do not meet the ones determined by the researchers [32,49]. Adding the great difference in purity found between different chitosan providers and batches, particular care should be taken when a new sample needs to be selected for further use [50].…”

Bioavailability of nutraceuticals: Role of the food matrix, processing conditions, the gastrointestinal tract, and nanodelivery systems

“…These properties depend on the deacetylation degree. Therefore, a high deacetylation degree (>80%) increases the solubility, mucoadhesivity, and bactericidal effect of chitosan (Foster, Ho, Hook, Basuki, & Marçal, 2015; Takahashi, Imai, Suzuki, & &Sawa, 2008). Chitosan is soluble at pH < 6 due to protonation of amino groups (p K a ∼ 6.5).…”

Modulating antioxidant activity and the controlled release capability of laccase mediated catechin grafting of chitosan

“…The NH stretching at 3300-3500 cm −1 become broader due to an increase of aromatic and non-aromatic stretching hydroxyl groups of phenols which result from a Michael addition reaction [11,13,14]. In wound dressing materials, the efficiency of fluid absorbance is an important factor to be considered to provide and maintain a moisturizing environment over the wound bed [43]. Moreover, swelling and erosion properties are important mechanisms to be considered as critical factors for drug release from hydrophilic matrices [42].…”