Title Page
Contents
LIST OF ABBREVIATIONS 11
ABSTRACT 12
Ⅰ. INTRODUCTION 14
Ⅱ. MATARIALS AND METHODS 20
2.1. Biodegradable pH-Responsive Materials 20
2.2. Materials 23
2.3. Preparation of Hydrogels 24
2.3.1. Synthesis of Alginate/Gelatin/AAc Pre-gel 24
2.3.2. Preparation and UV curing of Passive gel 26
2.3.3. Ionic Crosslinking 26
2.4. Methods for 3D printing 28
2.4.1. Direct Ink Writing 3D printing 28
2.4.2. Infill density and pattern of 3D printing 31
2.4.3. Rheological Characterization 33
2.4.4. 3D Printability 36
2.5. Stimuli for Actuation and Biodegradation 39
2.5.1. pH-Responsiveness 39
2.5.2. Enzymatic Biodegradability 42
Ⅲ. RESULTS 43
3.1. pH-Responsive shape deformation of Hydrogel 43
3.2. Biocompatibility of Hydrogel 46
3.3. Biodegradation of Hydrogel 49
3.4. Application 53
3.4.1. pH-Responsive Bilayer Soft Actuator 53
3.4.2. pH-Responsive Bilayer Soft Gripper 56
Ⅳ. DISCUSSION 59
4.1. Future work for improved pH-Responsive Actuation 59
4.2. Future work for Complete Biodegradation 60
Ⅴ. CONCLUSION 61
Ⅵ. REFERENCES 63
ABSTRACT IN KOREAN 73
Table 1. Recipe for the preparation of Alginate/Gelatin/AAc Pre-gel 25
Table 2. Diameter of Nozzle tips. 37
Figure 1. Direct Ink Writing 3D Bio-printing 30
Figure 2. 3D printing patterns and Infill densities 32
Figure 3. Rheological characterization of Alginate/Gelatin/AAc ink with different AAc concentrations. 35
Figure 4. 3D Printability of Alginate/Gelatin/AAc ink. 38
Figure 5. pH-Responsiveness of Alginate/Gelatin/AAc. 41
Figure 6. pH-Responsive shape deformation of Alginate/Gelatin/AAc hydrogel. 45
Figure 7. Cytotoxicity test of Alginate/Gelatin/AAc and Bilayer hydrogels. 48
Figure 8. Degradation of Alginate/Gelatin/AAc hydrogel with Collagenase enzyme. 51
Figure 9. Degradation of Alginate/Gelatin/AAc hydrogel with Collagenase and Alginate lyase enzymes. 52
Figure 10. pH-Responsive actuation of the bilayer soft actuator. 55
Figure 11. pH-Responsive actuation of the bilayer soft gripper. 58