| BACKGROUND: Injury of articular ligaments is very common in daily life, military training and sports activities. It has been a consensus that the injured ligaments should be reconstructed by the transplantation. Autoplastic tendons transplantation are still the gold standard of ligament transplant reconstruction, although there are some limitations in autografts, such as pain of donor area and insufficient strength. Artificial ligament transplantation is becoming more effective approaches to reconstruct ligament and restore joint function, following the rapid development of artificial materials. Poly(ethyleneterephthalate)(PET) material has fine biomechanical characteristics and is able to obtain biocompatibility through surface modification. It has been wildly used in artificial blood vessel and heart valve ring, also in field of artificial ligament. However, due to its lack of biological characeristics, PET has low biocompatibility degree and host cells grow poorly onto it. Therefore it is one of the current research focuses as how to improve the biocompatibility and cellular affinity of PET, in order to provide favorable biological interface for cell adhesion, proliferation and differentiation. Studies have indicated that connection of hydrophilic groups with"inactive"artificial ligament material, which will boost hydrophilicity, can effectively add cellular affinity towards artificial ligament. In this way cell growth and biology function of artificial ligament are favored.In this subject through a series of chemical and external modification carboxyl groups were successfully grafted onto the surface of PET knitted fiber. Then, the biological characteristics of the fiber were improved and biological PET fiber materials which own intellectual property rights were developed. Also, pertinent scientific analyses of chemicophysical behavior and biocompatibility as well as further research of cytological characteristics were conducted. There are yet no domestic or foreign reports on the approach in which hydrophilicity and biological characteristics of PET for artificial ligament use are improved by introducing carboxyl through index.Biological PET knitted fiber gained patent of utility model of China (ZL200920034762.8), which were carried out by three steps of chemical modification which included surface hydrolyzation, isocyanic acid reaction and hydroxyl introduction. Furthermore, we came up with an idea that stably paintcoating macromolecule onto the surface of PET knitted fiber. and applied for patent of invention, which is in proclamatory period (201010292173.7).1. Chemical preparation of PET fiber and its analysis of chemicophysical behaviorOBJECTIVE: Modify the biological characteristics of PET fiber material using surface modification technology and conduct research on the chemicophysical behavior after modification. METHOD: At particular temperatures in a given environment modification of biological characteristics were carried out by three steps which were surface hydrolyzation, isocyanic acid reaction and hydroxyl introduction. Technical approaches including fourier transform infrared spectroscopy (FT-IR), differential scan calorie (DSC) and performance test of single fiber elongation were employed to study the surface structure, melting point, crystal degree and fiber biomechanical characteristics of PET material before and after biological characteristic modification. RESULTS: FT-IR indicated significant enhancement of absorption peak of carboxyl and hydroxyl on the modified PET surface; DSC showed a slender reduce of melting point and crystal degree of the modified PET but there were no statistical significance(p>0.05); performance test of single fiber elongation suggested a smaller average initial modulus of the modified PET fiber and there were no statistical significance either(p>0.05). CONCLUSIONS: Surface-modified PET fiber has remarkably more hydrophilic groups on the surface whereas there is no significant change of internal structure and mechanical characteristics.2. Study on biocompatibility of biological PET fiber and cytologyOBJECTIVE: To evaluate the biocompatibility, apoptosis, cell cycle and vitro cell adhesion as well as growth of biological PET fiber. METHOD: With reference of related national standards, biological safety evaluation were conducted to the biological PET fiber, including vitro cell proliferation test, fluorescent staining observation of living/death cells, acute systemic toxicity test, hemolytic test, pyrogen test and sensitization test. Apoptosis and cell cycle were observed with flow cytometer. Cell adhesion to material surface and growth were observed with scanning electron microscope. RESULTS: Cell growth curve indicated that compared with the normal growth group, the unmodified group had inhibitive effects on L929 Cell proliferation. The biologically modified group showed no significance compared with the normal growth group which represents good cell compatibility. Compared with the normal growth grouop, the group of leaching solution of biological PET fiber showed no significance in terms of living/death cellular staining. In vivo biocompatibility test showed that there was no acute systemic toxicity reaction on biological PET fiber. In hemolytic test the hemolysis ratio was 0.07%<5% and in pyrogen test the temperature increase of each group showed no significance (p>0.05). Negative results were obtained in the sensitization test. Apoptosis and cell cycle suggested there were no significance (p>0.05) between the group of leaching solution of biological PET fiber and the normal growth group in terms of 2d and 4d cell proliferation rate (S+G2/M period) and apoptosis rate. Cell adhesion and growth on biological PET fiber were proved to be favorable by scanning electron microscope. CONCLUSIONS: Compared with the unmodified PET fiber, biological PET fiber has no cytotoxicity, eligible biocompatibility and fine cellular affinity, which can provide good biology support to in vivo cell proliferation and differentiation as artificial ligament woven material. |
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