Electron-Beam-Induced Grafting of Chitosan onto HDPE/ATZ Composites for Biomedical Applications.

Maria Giulia Faga,Donatella Duraccio,Giulio Malucelli,Christelle Kowandy,Mattia Di Maro,Xavier Coqueret,Federico Davide Mussano,Tullio Genova

doi:10.3390/polym13224016

Abstract

The surface functionalisation of high-density polyethylene (HDPE) and HDPE/alumina-toughened zirconia (ATZ) surfaces with chitosan via electron-beam (EB) irradiation technique was exploited for preparing materials suitable for biomedical purposes. ATR–FTIR analysis and wettability measurements were employed for monitoring the surface changes after both irradiation and chitosan grafting reaction. Interestingly, the presence of ATZ loadings beyond 2 wt% influenced both the EB irradiation process and the chitosan functionalisation reaction, decreasing the oxidation of the surface and the chitosan grafting. The EB irradiation induced an increase in Young’s modulus and a decrease in the elongation at the break of all analysed systems, whereas the tensile strength was not affected in a relevant way. Biological assays indicated that electrostatic interactions between the negative charges of the surface of cell membranes and the –NH3+ sites on chitosan chains promoted cell adhesion, while some oxidised species produced during the irradiation process are thought to cause a detrimental effect on the cell viability.

Highlights

Chitosan is the deacetylated polysaccharide from chitin, the natural biopolymer mainly found in shells of crustaceans, as well as in certain fungi cell walls and insects [1,2].As a natural multifunctional polysaccharide, it has been widely studied for biomedical, pharmaceutical, surgical, and tissue engineering applications [3]
To immobilise chitosan at the surface of high-density polyethylene (HDPE)-based materials, we selected a radiationinduced peroxidation method which seemed well adapted to the objective of producing, by simple and scalable procedures, surface-modified composites with enhanced properties for biomedical applications
Chitosan was grafted onto HDPE and HDPE/aluminatoughened zirconia (ATZ) composite surfaces after their activation via EB irradiation, with the aim to obtain biomaterials a new system the negative charges of the surface of cell membranes and the –NH3 + sites on chitosan chains, which first promote interaction, as already reported in the literature [11,47,48,49]

Summary

Introduction

Chitosan is the deacetylated polysaccharide from chitin, the natural biopolymer mainly found in shells of crustaceans, as well as in certain fungi cell walls and insects [1,2].As a natural multifunctional polysaccharide, it has been widely studied for biomedical, pharmaceutical, surgical, and tissue engineering applications [3]. After deacetylation, chitosan turns into a polycation, due to the protonation of the free amino groups of the Dglucosamine residues, which can interact with proteins, lipids, DNA, and, in general, with synthetic polymers negatively charged. This characteristic of chitosan contributes to an increase in solubility, biodegradability/biocompatibility, hemostasis, muco-adhesion, and antimicrobial properties. Chitosan can be considered a low-cost and eco-friendly biopolymer [4] In bone engineering, both in vitro and in vivo assays have demonstrated that chitosanbased biocomposite scaffolds may favour tissue regeneration [5]. Some clinical applications of chitosan in jawbone regeneration and alveolar bone have been reported, showing a reconstruction of critical size defects and an acceleration of dental implant osseointegration [8,9]

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