의생명 및 조직공학용 나노셀룰로오스 기반의 온도감응 주사형 하이드로젤 및 그 복합체 연구 = Injectable nanocellulose thermoresponsive hydrogel and composite for biomedical and tissue engineering

다국어 초록 (Multilingual Abstract)

TEMPO–oxidized cellulose nanofiber (TOCNF) and cellulose nanocrystals (CNC) are natural material extracted from cellulose with many promising properties, including biocompatibility and degradability. In this thesis, we used both types of nanocellulose (TOCNF and CNC) in fabricating of injectable thermosensitive hydrogel and composite for biomedical and tissue engineering, especially bone healing application. In the first study, we integrated TOCNF at different concentrations (0.2, 0.4, 0.6, 0.8% w/v) with chitosan (CS) and created a thermosensitive injectable hydrogel intended for biomedical applications. These hydrogels can undergo sol-gel transition at body temperature through interactions between chitosan and β-glycerophosphate. The addition of TOCNF resulted in faster gelation time and increased porosity. These hydrogels with TOCNF showed improved biocompatibility both in vitro and in vivo compared to CS hydrogel. Both MC3T3-E1 pre-osteoblast cells and L929 fibroblast cells showed biocompatibility towards CS/ TOCNF 0.4. After 7 days of implantation, initial inflammatory response to CS/TOCNF 0.4 was found. Such response was significantly subsided within 14 days. Cell infiltration within the hydrogel was also prominent, showing anti-inflammatory or wound healing (M2) macrophage at 14 days after implantation. These results showed that the addition of TOCNF could significantly improve the biocompatibility of CS hydrogel as a biomaterial for biomedical application. Based on result of the first study, we developed CS/TOCNF hydrogels as drug delivery system for bone defect healing in the second study. CS/TOCNF was loaded FK506 to support faster bone formation and was added NaHCO3 in gel agent to enhance gelation properties. The result indicated that higher content of NaHCO3 resulted in faster sol/gel transition and slower degradation of CS/TOCNF hydrogel suitably for bone treatment. FK506 low concentration 5nM is suitable to load in CS/TOCNF hydrogel for development and differentiation of pre-osteoblast MC3T3-E1 cells in vitro (2D culture). Also, CS/TOCNF hydrogel showed success in injection to bone defects in vivo. The last study focused on fabrication of novel brushite cement for bone treatment and evaluate effect of cellulose nanocrystals incorporation in brushite cement. Brushite cement can inject easily within setting time and harden overtime. Addition of cellulose nanocrystal in brushite cement resulted in faster rate of final setting time, increasing size of formed brushite crystals, and quicker degradation. Moreover, like TOCNF, CNC also enhances biological activity brushite cement in vitro with reduction of toxic and good cell adhesion support.

목차 (Table of Contents)

• Table of contents
• Acknowledgement i
• Dedication ii
• List of figures v
• Abstract ix
• Chapter1 Introduction 1
• 1.1. Introduction about cellulose 1
• 1.2. Objective of this thesis 4
• 1.3. References 4
• Chapter2 In vitro and in vivo acute response towards injectable thermosensitive chitosan/TEMPO-oxidized cellulose nanofiber hydrogel 11
• 2.1. Introduction 11
• 2.2. Materials and Methods 13
• 2.3. Results 20
• 2.4. Discussion 31
• 2.5. Conclusion 36
• References 36
• Chapter3 Injectable chitosan/TEMPO-oxidized cellulose nanofiber hydrogel loaded with FK506 for enhancing bone regeneration 44
• 3.1. Introduction 44
• 3.2. Materials and methods 47
• 3.3. Results and discussion 53
• 3.4. Conclusion 62
• References 63
• Chapter4 Evaluating effects of cellulose nanocrystal in brushite for bone regeneration 69
• 4.1. Introduction 71
• 4.2. Materials and methods 71
• 4.3. Results and discussion 74
• 4.4. Conclusion 75
• References 83
• Chapter5 General conclusion 86
• Research achievements 87