Photocrosslinkable Tissue Adhesive Based On Dextran

Bioadhesives are one kind of novel potential wound closure methods to replace the traditional sutures, in the fields of trauma, plastic and emergency medicine. They represent a fast and less traumatic closure method that includes less pain and for that reason does not require anaesthesia and also eliminate the problem of suture removal and scar of wound. Especially, they present the potential to serve the irregular wound. In this paper, dextran, biocompatible natural polymer, was modified by introduction of urethane groups and photosensitive methacrylate groups. A dextran derivative with excellent performance which is (methacryloyloxy) ethyl urethane dextran (Dex-U) was obtained. Bioadhesives were prepared by photopolymerization technique. The main contents and conclusions are described as follows.Photosensitive dextran derivative was synthesized by urethane reaction. The structure, crystallinity and degree of substitution of derivative were characterized by FTIR, NMR spectroscopy and XRD. The affected factor of crystallinity and dissolution performance of Dex-U on degree of substitution also were evaluated. Photocrosslinkable dextran gels based on Dex-U and hydrogels based on Dex-U copolymerized with 2-Hydroxyethyl methacrylate were prepared. The characterization was studied by RTIR, surface tension, viscosity, swelling test, adhesion strength, burst pressure test, SEM, cytotoxicity and cellular compatibility.The results indicated as follow:1. According to adjustment of weight ratio of dextran and isocuanate ethyl methacrylatethe, Degree of substitution (DS) of Dex-U varied from 0.1 to 3.0. Crystallinity of dextran was destroyed and transferred to amorphous structure. With the further increase of DS, the new crystal structure occurred. The obtained Dex-U could dissolve in many kinds of solvent such as methanol, acetone, methylene dichloride, etc.2. The Dex-U gels with 2wt% photoinitiator 2959 could polymerize in 5min under UV light intensity of 30mW/cm. The eventual conversion of double bond could reach to about 80%. With increase of DS, the conversion rate was improved, and the eventual conversion slightly decreased. The adhesion strength was firstly raised. But, after reached to a maximal value of 2.99MPa, it began to drop. The highest burst pressure is 35mmHg. In vitro cytotoxicity test indicated that the highest cell relative proliferation could reach to 96% after 72h culture.3. The Dex-U/HEMA hydrogels with 2wt% photoinitiator 2959 could completely polymerize in 8min under UV light intensity of 30mW/cm2. The eventual conversion of double bond could reach to about 100%. With increase of weight ratio of Dex-U and HEMA, the conversion rate deceased, and the eventual conversion of pure HEMA only was about 50%. The adhesion strength was firstly raised With increase of weight ratio of Dex-U and HEMA. But, after reached to a maximal value of 3MPa, it began to drop.