Title Page
Contents
ABSTRACT 11
Ⅰ. Introduction 13
1.1. Background 13
1.1.1. Introduction about succinoglycan (SG) 13
1.1.2. Hydrogel application of SG 14
1.2. Summary 15
Ⅱ. Physiochemical and rheological properties of succinoglycan overproduced by Sinorhizobium meliloti 1021 mutant 16
2.1. Introduction 16
2.2. Materials and Methods 18
2.2.1. Materials 18
2.2.2. Isolation of succinoglycan (SG) 18
2.2.3. N-methyl-N'nitro-N-nitrosoguanidine (NTG) mutagenesis 18
2.2.4. Fourier transform infrared (FT-IR) spectroscopy 19
2.2.5. 1H Nuclear magnetic resonance (NMR) spectroscopy 19
2.2.6. Differential scanning calorimetry (DSC) 20
2.2.7. Thermal gravimetric analysis (TGA) 20
2.2.8. Molecular weight by gel permeation chromatography (GPC) 20
2.2.9. Rheological measurements 20
2.2.10. Gelation test by metal cations 20
2.2.11. Antibacterial test 21
2.3. Results and Discussion 22
2.3.1. Optimization of SG yield 22
2.3.2. Characterization of SG 23
2.3.3. Rheological test of SG 26
2.3.4. Application capabilities through gelation and antibacterial test 31
2.4. Conclusions 34
Ⅲ. A pH-sensitive drug delivery using biodegradable succinoglycan/chitosan hydrogels with synergistic antibacterial activity 35
3.1. Introduction 35
3.2. Materials and Methods 38
3.2.1. Materials 38
3.2.2. Preparation of SG 38
3.2.3. Synthesis of SG/CS hydrogel 38
3.2.4. Fourier transform infrared (FTIR) spectroscopy 39
3.2.5. X-ray diffraction (XRD) 39
3.2.6. Rheological measurements 39
3.2.7. Compressive and tensile tests 40
3.2.8. Differential scanning calorimetry (DSC) 40
3.2.9. Thermal gravimetric analysis (TGA) 40
3.2.10. Field emission scanning electron microscopy (FE-SEM) 41
3.2.11. Equilibrium swelling ratio 41
3.2.12. Controlled drug release tests 41
3.2.13. In vitro degradation of hydrogel 42
3.2.14. Antibacterial test 42
3.2.15. In vitro cytotoxicity tests for cell proliferation 43
3.3. Results and Discussion 44
3.3.1. Characterization of SG/CS hydrogel 44
3.3.2. Rheological properties of SG/CS hydrogel 46
3.3.3. Morphologies of SG/CS hydrogel 48
3.3.4. Swelling behavior and controlled drug release of SG/CS hydrogel 49
3.3.5. In vitro degradation of hydrogel 51
3.3.6. Antibacterial test 52
3.3.7. In vitro cytotoxicity of SG/CS hydrogel 54
3.4. Conclusions 56
Ⅳ. Conclusion 57
References 58
Abstract (in Korean) 70
〈Table 1-1〉 FT-IR peak ratio analysis 25
〈Table 1-2〉 ¹H NMR peak ratio analysis 25
〈Table 1-3〉 Mn, Mw, and polydispersity of SG and SMC1-SG[이미지참조] 26
〈Table 2-1〉 The composition of SG/CS hydrogel 39
〈Figure 1-1〉 NTG mutagenesis protocol 19
〈Figure 1-2〉 Yield of succinoglycan produced by SMC1 according to mannitol content in media 22
〈Figure 1-3〉 Structure of succinoglycan 23
〈Figure 1-4〉 (a) FT-IR and (b) ¹H NMR of SG and SMC1-SG 24
〈Figure 1-5〉 (a) DSC and (b) TGA curves of SG and SMC1-SG 26
〈Figure 1-6〉 Rheological measurements for (a) angular frequency and (b) oscillation strain. 27
〈Figure 1-7〉 Viscosity of (a) SG and (b) SMC1-SG according to concentration 28
〈Figure 1-8〉 Viscosity of (a) SG and (b) SMC1-SG according to temperature 29
〈Figure 1-9〉 Rheological measurements of (a) SG and (b) SMC1-SG during heating and cooling, and (c) tan δ 30
〈Figure 1-10〉 Viscosity of (a) SG and (b) SMC1-SG in various pH condition 31
〈Figure 1-11〉 Viscosity of (a) SG and (b) SMC1-SG in various salt condition 31
〈Figure 1-12〉 Gelation of SMC1-SG by Fe³⁺ and Cr³⁺ 32
〈Figure 1-13〉 (a) Inhibition areas of SG and SMC1-SG against E. coli and S. aureus observed on agar plates. Evaluation of the antibacterial activity of against... 33
〈Figure 2-1〉 Preparation schematic of SG/CS hydrogel. 39
〈Figure 2-2〉 (a) FTIR and (b) XRD of SG, CS, and SG/CS hydrogel. (c) TGA, and (d) DSC of SG/CS hydrogel 46
〈Figure 2-3〉 G' and G'' versus (a) angular frequency and (b) oscillation strain R in the measurement of rheology of SG/CS hydrogel. (c) Compressive test... 48
〈Figure 2-4〉 FE-SEM images of SG/CS hydrogel 49
〈Figure 2-5〉 Swelling ratio of SG/CS hydrogel in PBS buffers of (a) pH 2.0, (b) pH 5.0, and (c) pH 7.4 at 37 ℃. (d) Cumulative amount (%) of 5-fluorouracil... 51
〈Figure 2-6〉 Time-dependent remaining weight (%) of SG/CS hydrogel in PBS buffers of pH 7.4, 5.0, and 2.0 at 37 ℃ 52
〈Figure 2-7〉 Evaluation of the resistance of SG/CS hydrogel to bacterial clones. Images of surviving (a) S. aureus and (b) E. coli on agar according to... 54
〈Figure 2-8〉 WST-8 assays for cell viability and of HEK 293 cells cultured on SG/CS 55