Human Hair Keratin-Based In Situ Forming Hydrogels ; Synthesis and Characterizations
초록/요약
In situ forming hydrogel systems have received a great attention in the biomedical research fields due to capability of minimally invasive injection, the structural similarity to the natural extracellular matrix of hydrogel, and multi-tunable properties. Up to date, various kinds of biomaterials have been utilized to create injectable hydrogel matrices for therapeutic implants and therapeutic vesicles. Among them, keratin, derived from hair, has emerged as a fascinating biomaterial due to high biocompatibility, biodegradability, cellular activity, low immune reaction, possibility of autologous implantation, and high rich-resource which is suitable for biomedical applications. While the natural polymer based in situ forming hydrogels have been widely investigated, there have been no report about in situ cross-linkable keratin based hydrogel systems so far and poor solubility of keratin in aqueous solutions is a limitation for use in a broad range of applications too. In this study, keratin based in situ forming hydrogel system was developed. First we designed a water soluble keratin by conjugating poly(ethylene glycol) (PEG) molecules and tethered with tyramine (TA) to exploit the horseradish peroxidase (HRP) mediated enzymatic reaction. We synthesized three different Keratin-PEG-TA (KPT) conjugates with different PEG portion and characterized their chemico-physical properties. The gelation times and mechanical properties can be varied by changing the concentration of HRP and H2O2 respectively and the surface morphologies of KPT hydrogels were porous which is suitable for transporting of nutrients and bioactive molecules to cultivate cells. Finally, in vitro cytotoxicity test was conducted, exhibiting excellent cytocompatibility. These results demonstrated that developed KPT hydrogels could be a suitable scaffold for f biomedical applications in tissue engineering
more목차
1. INTRODUCTION ………………………………………………………… 1
1.1 Biomaterials and tissue engineering ………………………..……………….. 1
1.2 Hydrogels as fascinating biomaterials ………………………………………. 4
1.2.1 The Origin of hydrogels ………………………………………………….. 5
1.2.2 In situ forming hydrogels …………………………………………………. 8
1.2.3 Various cross linking method for in situ forming hydrogels …….............. 10
1.2.4 Horseradish peroxidase catalyzed cross-linking reaction ………………... 12
1.3 Human hair keratin as new materials for biomedical applications ….…….... 13
1.3.1 Properties and characteristics of human hair keratin ……………………... 13
1.3.2 Previous studies and applications about human hair keratin based hydrogels
………….……..…………………………………………………………… 16
1.4 Objectives ……………………………………………………………………. 17
2. EXPERIMENTS ……………………………………………………..…... 20
2.1 Materials ……………………………………………………………………. 20
2.2 Synthesis of polymers ………………………………………………………. 20
2.2.1 Synthesis of NH2-PEG-TA conjugates …………………………….…..... 21
2.2.2 Synthesis of Keratin-PEG-TA (KPT) conjugates with various ratio …….. 22
2.3 The water solubility of KPT conjugates …………………………………..… 23
2.4 Characterization of chemical structure of KPT conjugates …………………. 23
2.5 Preparation of KPT hydrogels ………………………………………………. 24
2.6 Characterization of KPT hydrogels ………………………………………..... 24
2.6.1 Gelation time test ………………………………………………………... 24
2.6.2 Rheological study ………………………………………………………... 24
2.6.3 SEM images ……………………………………………………………... 25
2.7 In vitro cytotoxicity test ……………………………………………………... 25
3. RESULTS AND DISCUSSIONS ……………………………………… 27
3.1 Design of keratin-PEG-TA having enhanced water solubility …………….... 27
3.2 Chemical structure of keratin-PEG-TA (KPT) ………………………..….…. 29
3.3 Horseradish peroxidase-mediated hydrogel formation and their physicochemical properties ……………………………………………………..……...… 31
3.3.1 Preparation of KPT hydrogels ……………………………………….….. 31
3.3.2 The controllability of gelation time ……………………………………... 32
3.3.3 The variable mechanical properties of KPT hydrogels ……………….… 32
3.3.4 Surface morphologies ………………………………………………....… 35
3.4 High cell proliferative activities of human dermal fibroblasts ………….….... 35
4. CONCLUSION …………………………………………………………… 39
5. REFERENCE …………………………………………………………..…. 40
