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효소 촉매 반응 효소 고정화 방법을 이용한 In situ 형성 하이드로젤의 제조 및 특성 평가
- Alternative Title
- Bae Young Kim
- Author(s)
- Kim Bae Young
- Alternative Author(s)
- Bae Young Kim
- Advisor
- 박기동
- Department
- 일반대학원 분자과학기술학과
- Publisher
- The Graduate School, Ajou University
- Publication Year
- 2015-02
- Language
- eng
- Keyword
- 하이드로젤
- Alternative Abstract
- Injectable hydrogel systems have received much attention due to their versatile and tunable characteristics based on a minimal invasive technique. In a free flow state, hydrogel precursor solutions can fill up a tissue defect or target site while containing bioactive molecules, and then act as a localized therapeutic depot after physical or chemical cross-linking. A horseradish peroxidase (HRP)-catalyzed cross-linking reaction has recently received much attention as a promising approach to developing in situ forming hydrogels. For the reaction, HRP and hydrogen peroxide (H2O2) are both considered as essential prerequisites for controlling the degree and rate of cross-linking. However, the inevitable incorporation of HRP and H2O2 during cross-linking may limit more extensive use of the system. Although HRP appears to be non-toxic, it may cause immune response resulted from its plant-derived origin. In addition, H2O2 is known to cause DNA damage and cell death at a high concentration. Therefore, there is an increasing demand for an alternative to the conventional HRP-catalyzed cross- linking method. The main objective of this dissertation is to develop and evaluate in situ forming enzymatically cross-linked hydrogels for injectable biomedical applications, which is based on enzyme immobilization and H2O2-generating enzyme. The first work of the thesis was to prepare and characterize an in situ forming gelatin hydrogel via HRP- and GOx-catalyzed cross-linking. The gelatin hydrogels were prepared from a gelatin solution above 5 wt% in the presence of HRP, GOx and Glucose. Their mechanical properties such as gelation time, swelling ratio and degradation time were evaluated at different HRP, GOx and glucose concentrations. In addition, it was clearly observed that gelatin hydrogels prepared via HRP- and GOx-mediated reaction were not cytotoxic under all given conditions, suggesting that the GOx-triggered cross-linking system enables us not only to minimize cellular damage by excess H2O2, but also maintain the catalytic activity of HRP. To improve unavoidable incorporation of enzymes into hydrogels, in situ forming enzyme-free hydrogels via ferromagnetic microbead- assisted enzymatic cross-linking were developed and characterized. We showed that the iron content in microbeads contributes greatly to the HRP- and GOx- catalyzed gelation process. The hydrogel was formed rapidly using HRP- and GOx immobilized beads with polymer solution containing glucose. The mechanical properties could be controlled from 400 Pa to over 7500 Pa by changing the bead-contact time. Furthermore, an in vitro 3D cell studies revealed that the enzyme-free GPT hydrogels could serve as a bioactive injectable matrix for cell delivery. Therefore, we expect that the interfacial in situ enzymatic cross- linking system using enzyme immobilized beads can be used as a certain alternative to the conventional method that has been widely used to prepare enzymatically cross-linked hydrogels.
- Fulltext
- Appears in Collections:
- Graduate School of Ajou University > Department of Molecular Science and Technology > 4. Theses(Ph.D)
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