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Preparation, characterization and application of bacterial cellulose based functional nanocomposites : 박테리아 셀룰로오스 기반 기능성 나노복합체의 제조와 특성 및 응용 연구

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dc.contributor.advisor현진호-
dc.contributor.author박민성-
dc.date.accessioned2017-07-13T17:46:22Z-
dc.date.available2017-07-13T17:46:22Z-
dc.date.issued2016-08-
dc.identifier.other000000137222-
dc.identifier.urihttps://hdl.handle.net/10371/121122-
dc.description학위논문 (박사)-- 서울대학교 대학원 : 바이오시스템·소재학부 바이오소재전공, 2016. 8. 현진호.-
dc.description.abstract본 논문에서는 적합한 합성전략을 통해 박테리아 셀룰로오스에 무기나노입자와 바이오폴리머를 도입한 나노복합체를 제작하였고, 그 응용가능성을 평가해 보았다.
첫 번째로 자성나노입자, 실리콘나노입자, 금나노입자를 각각 박테리아 셀룰로오스와 복합화하였다. 자성 박테리아셀룰로오스 복합체는 자성나노입자가 함유된 배지에 박테리아를 배양하는 생합성 방법을 통하여 제조하였고, 아닐린 모노머를 도입하여 전도성 고분자인 폴리아닐린을 중합하였다. 전자기 차폐막으로의 응용가능성을 파악하기 위해 자성과 전기전도성 측정 실험을 수행하였고, 합성된 복합체는 전도성과 자성을 모두 가졌다. 실리콘나노입자가 함유된 박테리아 셀룰로오스 나노복합체는 안정적으로 분산된 실리콘나노입자 분산용액에 박테리아셀룰로오스를 담침시키는 방법으로 제조하였다. 실리콘 나노입자들은 셀룰로오스 나노섬유에 균일하게 도입되었다. 이 후, 폴리아닐린을 중합하여 복합체에 전도성을 부여하였다. 완성된 복합체는 반복적인 구부림 시험에서 일정한 전기 전도성을 나타내었다. 이를 통하여 유연성 전극으로 응용이 가능함을 확인하였다. 금나노입자-박테리아셀룰로오스 복합체는 in situ 합성법을 통해 제조되었다. 셀룰로오스 나노섬유는 합성 과정에서 지지체이자 환원제로서 역할을 하였다. 제조된 복합체의 구조적 변형을 통하여 분석물질의 표면 증강 라만 산란 신호를 크게 증가시킬 수 있었다.
두 번째로, TEMPO/NaBr/NaClO 산화 시스템을 통해 개질된 박테리아셀룰로오스와 바이오폴리머를 이용한 복합체를 제작하였다. 수용액에 잘 분산된 산화 박테리아셀룰로오스를 알지네이트와 섞고, 칼슘이온에 의한 이온가교를 유도하여 하이드로젤 형태로 제조하였다. 형성된 복합체는 기계적∙화학적 저항성이 증가하였고, 세포 담지체로서의 응용가능성이 평가되었다. 수용액상에서 양전하를 갖는 엘라스틴 유래 폴리펩타이드와 음전하를 갖는 산화 박테리아 셀룰로오스를 이용하여 온도민감성 하이드로젤 복합체를 제조하였다. 온도가 증가함에 따라 엘라스틴 유래 폴리펩타이드가 물리적 가교제로 작용을 하여 하이드로젤이 형성되고, 온도가 낮아짐에 따라 젤-졸 전이가 일어났다. 이 후 세포 실험을 통하여 하이드로젤 내부에서 세포를 안정적으로 성장시킬 수 있었다.
위와 같은 적합한 합성전략을 통한 다양한 박테리아셀룰로오스 기반 나노복합체 연구들은 소재로서의 박테리아 셀룰로오스에 대한 이해를 넓혀주고, 다양한 분야로의 응용 가능성을 높여 줄 수 있을 것으로 기대한다.
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dc.description.abstractBacterial cellulose (BC)-based nanocomposites incorporated with inorganic nanoparticles and biopolymers were fabricated by employing suitable synthesis strategies, and their potential applications were investigated. Firstly, a series of BC nanocomposites containing inorganic nanoparticles were synthesized using appropriate methods. BC magnetite nanocomposites (MNP-BC) were biosynthesized by incubating bacteria in a medium containing magnetic nanoparticles (MNPs). Subsequently, polyaniline (PANi) was synthesized on the MNPs-BC nanocomposites by carrying out oxidative polymerization of aniline. Magnetic and electrical measurements confirmed that the MNP-PANI-BC exhibited the potential to be used as an electromagnetic shielding material. Silicon nanoparticles (SiNPs)-BC nanocomposites were prepared by dipping BC in the SiNPs dispersion. SiNPs were uniformly attached to the BC pellicle surfaces along the nanofibers. The conductive PANi-Si-BC composite exhibited stable conductivity under repetitive bending stress, confirming its potential for flexible anode application. Gold nanoparticles (AuNPs)-BC nanocomposites were prepared by employing the in situ polymerization of AuNPs on the BC fibers, which could act as a template and an immobilized reducing agent. The surface-enhanced Raman scattering signals corresponding to molecules to be detected on the AuNPs-BC nanocomposite were significantly enhanced due to the spatial deformation of the composite. Secondly, a series of BC nanocomposites containing biopolymers were synthesized with TEMPO-oxidized bacterial cellulose (TOBC). TOBC fibers were obtained using a TEMPO/NaBr/NaClO system at pH 10 and room temperature. The fibrillated TOBCs mixed with alginate were cross-linked in the presence of Ca2+ solution to form hydrogel composites. Alginate/TOBC hydrogel composites exhibited improved mechanical and chemical resistance, indicating that the hydrogel could be used for cell encapsulation applications. Elastin-like polypeptide (ELP)-BC composites were synthesized, which could be used as a thermosensitive hydrogel for cell encapsulation applications. Positively charged ELP was used as a polymeric cross-linker for conjugating with negatively charged cellulose nanofibers. Hydrogel formation was triggered by increasing the temperature, and the hydrogel was converted to the liquid phase by decreasing the temperature.-
dc.description.tableofcontentsChapter 1. Introduction 1

Chapter 2. Literature survey 7
2.1. Cellulose nanofibers 8
2.1.1. Cellulose 8
2.1.2. Processes of cellulose nanofibers preparation 12
2.1.3. Three types of cellulose nanofibers 12
2.1.4. Surface modification of cellulose nanofibers 20
2.2. Bacterial cellulose (BC) 23
2.2.1. General information of BC 23
2.2.2. Biosynthesis process of BC 25
2.2.3. Factors affecting the production capacity of BC 28
2.2.4. Productivity of BC 30
2.2.5. Characteristic differences between the plant cellulose and BC 34
2.2.6. Applications of BC 38

Chapter 3. Electromagnetic BC nanocomposite using magnetite nanoclusters and polyaniline 44
3.1. Introduction 45
3.2. Materials and method 48
3.2.1. Preparation of highly dispersive magnetite nanoparticles (MNPs) 48
3.2.2. Biosynthesis of MNP-incorporated BC (MNP-BC) nanocomposites 49
3.2.3. Polymerization of polyaniline (PANi) on the MNP-BC (PANi-MNP-BC) nanocomposites 49
3.2.4. Characterizations of nanocomposites 50
3.3. Results and discussion 51
3.3.1. Enhancement of the colloidal stability of MNP solutions 51
3.3.2. Biosynthesis of MNP-BC nanocomposites 54
3.3.3. Synthesis of PANi-MNP-BC nanocomposites 58
3.3.4. Electromagnetic properties of nanocomposites 64
3.4. Summary 66

Chapter 4. Flexible conductive BC combined with silicon nanoparticles and polyaniline 67
4.1. Introduction 68
4.2. Materials and method 71
4.2.1. Preparation of the silicon nanoparticle-embedded BC (Si-BC) nanocomposites 71
4.2.2. Polyaniline (PANi) polymerization with BC (PANi-BC) and Si-BC nanocomposites (PANi-Si-BC) 71
4.2.3. Characterization of nanocomposites 72
4.3. Results and discussion 74
4.3.1. Preparation of the Si-BC nanocomposites 74
4.3.2. Synthesis of PANi-Si-BC nanocomposites 80
4.3.3. Conductivity of nanocomposite under bending stress 92
4.4. Summary 94

Chapter 5. Surface-enhanced Raman scattering sensor based on a BC hydrogel 95
5.1. Introduction 96
5.2. Materials and method 99
5.2.1. In situ synthesis of gold nanoparticles (AuNPs)-BC 99
5.2.2. Characterization of AuNPs-BC nanocomposites 99
5.2.3. SERS experiments 100
5.3. Results and discussion 100
5.3.1. In situ synthesis of AuNPs-BC hydrogel 100
5.3.2. SERS measurement using undeformed AuNPs-BC 105
5.3.3. SERS measurement using deformed AuNPs-BC 110
5.3.4. Detection of molecules with weak affinity to Au surfaces 114
5.4. Summary 116

Chapter 6. Oxidized BC/alginate hydrogel for cell encapsulation 117
6.1. Introduction 118
6.2. Materials and method 121
6.2.1. Preparation of TEMPO-mediated oxidized BC (TOBC) 121
6.2.2. Preparation of alginate/TOBC beads 121
6.2.3. Characterization of alginate/TOBC beads 122
6.2.4. Viability and proliferation of encapsulated cells 123
6.3. Results and discussion 123
6.3.1. Preparation of alginate/TOBC beads 123
6.3.2. Mechanical and chemical stability of alginate/TOBC 131
6.3.3. Permeability of alginate/TOBC beads 135
6.3.4. Viability and proliferation of encapsulated cells 139
6.4. Summary 142

Chapter 7. Thermoresponsive hybrid hydrogel of oxidized BC using a elastin like polypeptide 143
7.1. Introduction 144
7.2. Materials and method 147
7.2.1. Elastin like polypeptide (ELP) synthesis 147
7.2.2. Sol-gel transition 147
7.2.3. Characterization of ELP/TOBC 147
7.2.4. Cell viability and proliferation 149
7.3. Results and discussion 151
7.3.1. Gel formation of ELP/TOBC 151
7.3.2. Rheological analysis of ELP/TOBC hydrogel 154
7.3.3. Morphological analysis of ELP/TOBC hydrogel 157
7.3.4. Mechanism of TOBC/ELP hydrogel formation 160
7.3.5. Viability and proliferation of cells 166
7.4. Summary 168

Chapter 8. Conclusions 169

References 173

초록 204
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dc.formatapplication/pdf-
dc.format.extent6340418 bytes-
dc.format.mediumapplication/pdf-
dc.language.isoen-
dc.publisher서울대학교 대학원-
dc.subject박테리아 셀룰로오스 복합체-
dc.subject무기나노입자-
dc.subject자성나노입자-
dc.subject실리콘나노입자-
dc.subject금 나노입자-
dc.subject바이오폴리머-
dc.subject알지네이트-
dc.subject엘라스틴 유래 폴리펩타이드-
dc.subject.ddc660-
dc.titlePreparation, characterization and application of bacterial cellulose based functional nanocomposites-
dc.title.alternative박테리아 셀룰로오스 기반 기능성 나노복합체의 제조와 특성 및 응용 연구-
dc.typeThesis-
dc.contributor.AlternativeAuthorPark, Minsung-
dc.description.degreeDoctor-
dc.citation.pages206-
dc.contributor.affiliation농업생명과학대학 바이오시스템·소재학부-
dc.date.awarded2016-08-
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