Disulfide-Crosslinked PGA/HA Membrames for Biomedical Applications

• Main Authors: Chen-I Lee, 李蓁宜
• Other Authors: Ying-Jiin Wang
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/65207496226748129280

碩士 === 國立陽明大學 === 醫學工程研究所 === 98 === The purpose of this study is to develop a new, mild crosslinking process, to alleviate the toxicity caused by chemical crosslinking and to improve the mechanical property of the synthesized anti-adhesion membrane for surgical operation. In this work, both PGA and HA molecules were thiolated with cysteine and used as the base macromolecules for constructing three different anti-adhesion membranes (PGA-s-s-PGA, PGA-s-s-HA and HA-s-s-HA). The synthesized PGA-SH and HA-SH contain grafted cysteine of 770 μmol and 330 μmol per gram of polymer, respectively. After coupling with cysteine, thiolated PGA or HA could be crosslinked through disulfide bonds during casting and the membrane thus formed became water-insoluble membranes. Under a wet condition, films of PGA-s-s-PGA and PGA-s-s-HA could be easily manipulated for surgical operation. The three membranes (in the order of PGA-s-s-PGA, PGA-s-s-HA and HA-s-s-HA) have water contents of 43 %, 47 % and 72 %; gel contents of 92 %, 85 % and 81 %; and swelling ratios of 0.77, 0.89 and 2.63 with film thickness increased by 2.44, 1.73 and 2.51 fold, respectively. The results of in-vitro stability and degradation test show that these three films retain 75 % of their initial weight after rinsing in PBS and even treated with 10U of hyaluronidase for over 10 days. These demonstrate that crosslinking by disulfide bonding is an effective way to stabilize the membrane structure. The surfaces of these three films appear to be flat and compact. On the cross sectional area of film, PGA-s-s-PGA exhibits rough textures paralleling with its cross-section plane whereas HA-s-s-HA exhibits flat structure with part of irregular crack patterns, and PGA-s-s-HA displays characteristics of veins of both PGA-s-s-PGA and HA-s-s-HA. The applications of these three films as the carrier for drug delivery were demonstrated by using FITC-labeled BSA as a model compound. The BSA-release data were fitted by a series of models including zero-order, first-order, Higuchi model and the burst effect modification models. Of these, the burst effect modification model (Mt/M∞=Mb/M∞+kt^n) has the highest correlation R-squared value with n values of 0.59, 0.67 and 0.57, and k of 0.0014, 0.0006 and 0.0021, for PGA-s-s-PGA, PGA-s-s-HA and HA-s-s-HA, respectively. It appears that PGA-s-s-HA film has the smallest k value meaning it has the best controlled ability at the initial time to release drugs from the drug carrier. There were some drug retained in films even after incubating for 9 days, but these BSA molecules were not retained covalently by linking to PGA as demonstrated by GPC molecular weight analysis. In summary, we have synthesized PGA-cysteine/HA-cysteine molecules and successfully developed a thiolation crosslinking process for fabricating anti-adhesion membranes based on these two biopolymers. They can be used as an excellent carrier for drug delivery and have a great potential for clinical applications.