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Synthesis and Application of Silica-Armored Conjugated Supramolecules and Nanostructures

  • Jinkyu Roh (대학원 화공생명공학과 화공생명공학전공)

초록/요약

The goals of this thesis are to synthesize functional armor on the surface of polydiacetylene (PDA) supramolecules and nanostructures using a modified layer-by-layer assembly, and to apply the armor as a protective layer to provide size-selective permeation, enhanced surface modifications, and a replica-synthesis template. The detailed results for each research topic are discussed as follows. In Chapter 2, super-stable diacetylene (DA) vesicles were developed that adopt an outer armor to maintain their functions for six months. The dense silica armors can be directly grown as ~5-nm spherical nanoparticles on an amine linker layer that is deposited on the vesicles by a modified Stöber reaction in pure water. Once formed, the stability of the DA vesicles dramatically increases and remains stable, even as a dried powder that could be stored for long periods; thus, an unprecedented shelf life for the DA vesicles is demonstrated. Furthermore, their sensing capability is maintained, even after approximately six months, which we believe is a phenomenal result that has never been achieved before. Thus, the silica armor serves only to protect the 10,12-tricosadiynoic acid (TCDA) vesicles and does not change their functions. This result is expected to have a large impact on DA-based materials for improving their technological values. In Chapter 3, silica-armor membrane on PDA vesicles were firstly presented to self-screen stimuli with molecular and structural sizes. Using electrostatic interactions and the direct hydrolysis of silica, the silica-armor membrane composed of silica nanoparticles (NPs) can be continuously formed on the PDA vesicles. The permeability of the membrane depends on its thickness, and we observe a size-selective response for the PDA vesicles. Consequently, the PDA vesicle in a silica-armor membrane can self-screen stimuli of size ~60 nm, which cause size-selective responses for the PDA vesicles. We expect these results to have large effects in the chemo- and bio-sensor fields that use membrane technologies. In Chapter 4, the silica-armored DA vesicles were described to immobilize on a substrate using silica armor and the layer-by-layer method for the patterned sensor. Silica NPs are densely formed on the surface of a DA vesicle by surface modifications and electrostatic forces, in which dense silica NPs act as armor on the surface, enhancing the surface activity of the vesicles. This silica-armored DA vesicle can be continuously immobilized on rigid and flexible substrates. In addition, we can achieve literature patterning for visible and fluorescent sensors from a substrate using photo-polymerization on a photo-mask. Using this sensor, we can directly recognize chemical stimuli within 5 sec using the naked eye and photoluminescence. These patternization methods can be extended toward using PDA-based sensing materials in industrial on-site sensors. In Chapter 5, a tailored silica cage was applied to prepare a shape-controlled nanoparticle. The advantage of this method is that we can change the shape of the replicated NPs based on the initial selection of the particle shape, largely without limits. The greatly large number of micro/nanopores in the silica and its high physicochemical stability allow various small materials to diffuse through it. The materials that diffuse through the silica can react with the contents at the core. With the investigation of this process, shape-persistent replicas of bimetallic nanoplates can be prepared in a tailored silica cage. In Chapter 6, the raspberry silica structures was developed by the adsorption of HPTS/silica (HPTS= 8-hydroxypyrene-1,3,6-trisulfonic acid) NPs on RBTIC/silica (RBTIC= rhodamine B isothiocyanate) NPs for ratiometric fluorescence-based pH sensing. To overcome the well-known problem of dye leaching that occurs during encapsulation of anionic HPTS dye in silica NPs, we utilized polyelectrolyte-assisted incorporation of the anionic HPTS. Morphological and optical characterizations were performed for the as-synthesized dye-doped NPs and the resulting nanohybrids. The pH-sensitive dye, HPTS, incorporated in the HPTS-doped silica NPs provides a pH-dependent fluorescence response, while the RBITC-doped silica provides a reference signal for ratiometric sensing. We evaluated the effectiveness of the nanohybrids for pH sensing; the ratio of the fluorescence emission intensity at 510 nm and 583 nm at excitation wavelengths of 454 nm and 555 nm, respectively. The results show a dynamic response in the acidic pH range. With this approach, nanohybrids containing different dyes or receptors could be developed for multifunctioning and multiplexing applications. Finally, in Chapter 7, the PDA-based nanobio-complex was presented to use a probe of immunochromatographic assays (ICAs) for detecting hepatitis B virus (HBV). ICAs using nitrocellulose (NC) membranes offer several advantages. ICAs are faster and simpler than other immunoassays. PDA vesicles have unique optical properties that simultaneously show a red color and red fluorescence. In this system, PDA vesicles are used as fluorescent dyes and as a surface for the immobilized hepatitis B surface antibody (HBsAb). PDA has a better stability than other fluorescent dyes. In this study, the most suitable PDA/HBsAb nanobio-complex is introduced for detecting the hepatitis B surface antigen (HBsAg). Then, the PDA/HBsAb nanobio-complex-affixed antibody is attached to an NC membrane, which has two lines to confirm the detection of HBsAg. The main advantage of this system is that HBsAg detection can be observed in visible and fluorescent images because of the optical properties of PDA. The detection of HBsAg is observed up to 0.1 ng/mL by fluorescence analysis and by the confirmed red line on the NC membrane up to 1 ng/mL (HBsAg) by the naked eye. Consequently, these results show that the PDA/HBsAb nanobio-complex was successfully applied to the ICA for diagnosing hepatitis B.

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목차

Chapter 1. Introduction 1
1.1. Polydiacetylene Supramolecules 2
1.2. Silica-Based Nanostructures 5
1.3. Nucleation and Growth Mechanism 7
1.3.1. LaMer mechanism 7
1.3.2. Ostwald and digestive ripening 7
1.3.3. Finke-Watzky mechanism 8
1.4. Surface Functionalization 11
1.4.1. Self-assembled monolayers 11
1.4.2. Layer-by-layer assembly 13
1.5. Objective and Outline of the Thesis 15
1.6. References 18

Chapter 2. Super-Stable Diacetylene Vesicles with Silica-Armor 21
2.1. Scope of Research 22
2.2. Experimental Section 25
2.2.1. Synthesis of the TCDA vesicles 25
2.2.2. Formation of silica-armor on the TCDA vesicles 25
2.2.3. Confirmation of redispersibility 25
2.2.4. Reactivity tests due to thermal and chemical stimuli 26
2.2.5. Characterization 26
2.3. Results and Discussion 27
2.3.1. Direct growth of the silica-armor on TCDA vesicles 27
2.3.2. Characterization of the TCDA/silica 30
2.3.3. Stability of the TCDA vesicle after the surface modification 39
2.3.4. Dispersion stability of the TCDA/silica in water 44
2.3.5. Redispersibility of the TCDA vesicle with encapsulation 46
2.3.6. Powderization of the TCDA/silica and its reactivity 51
2.4. Summary 57
2.5. References 58

Chapter 3. Size-Selective Detection by Polydiacetylene Vesicles with Silica-Armor Membranes 61
3.1. Scope of Research 62
3.2. Experimental Section 64
3.2.1. Synthesis of the TCDA vesicles 64
3.2.2. Formation of silica-armor membranes on the TCDA vesicles 64
3.2.3. Size-selective response of TCDA vesicles in silica-armor membranes 65
3.2.4. Characterization 65
3.3. Results and Discussion 66
3.3.1. Formation of the silica-armor membrane on TCDA vesicles 66
3.3.2. Characterization of the silica-armor membrane on TCDA vesicles 68
3.3.3. Porosity analysis of the silica-armor membrane 73
3.3.4. Size-selective responses of the TCDA vesicles in the membrane 75
3.4. Summary 82
3.5. References 83

Chapter 4. Patterned Sensors Using Immobilized Silica-Armored Diacetylene Vesicles 86
4.1. Scope of Research 87
4.2. Experimental Section 89
4.2.1. Synthesis of the TCDA vesicles 89
4.2.2. Formation of silica-armor on the TCDA vesicles 89
4.2.3. Immobilization of the TCDA/silica on the glass 89
4.2.4. Sensitivity test of the patterned TCDA/silica on the glass 90
4.2.5. Characterization 90
4.3. Results and Discussion 91
4.3.1. Immobilization of the TCDA/silica on substrate by LbL method 91
4.3.2. Immobilization efficiency of the TCDA/silica on substrate 93
4.3.3. Morphological and optical properties of the TCDA/silica on glass 96
4.3.4. Patternization of the TCDA/silica on glass 100
4.3.5. Chemochromic responses of the patterned TCDA/silica on glass 103
4.4. Summary 105
4.5. References 106

Chapter 5. Replica Synthesis of Bimetallic Nanoplates Using Tailored Silica Cage 108
5.1. Scope of Research 109
5.2. Experimental Section 112
5.2.1. Synthesis of the Ag nanoplates 112
5.2.2. Synthesis of the silica cage on Ag nanoplates 112
5.2.3. Synthesis of the Au/Ag bimetallic nanoplates using the silica cage 113
5.2.4. Characterization 113
5.3. Results and Discussion 114
5.3.1. Mechanism of the Au/Ag bimetallic nanoplates by replica synthesis 114
5.3.2. Morphological property with the step of replica synthesis 117
5.3.3. Atomic structure of the Au/Ag bimetallic nanoplates 125
5.3.4. Effect of the tailored silica cage for the synthesis 132
5.4. Summary 137
5.5. References 138

Chapter 6. Dual-Fluorescent Raspberry Nanohybrids for Ratiometric pH Sensing 142
6.1. Scope of Research 143
6.2. Experimental Section 147
6.2.1. Materials 147
6.2.2. Synthesis of RBITC/silica nanoparticles 147
6.2.3. Synthesis of HPTS/silica nanoparticles 148
6.2.4. Preparation of raspberry nanohybrids 148
6.2.5. Characterization 149
6.3. Results and Discussion 150
6.3.1. Raspberry nanohybrids for ratiometric sensor 150
6.3.2. Optical characterization of the raspberry nanohybrids 156
6.3.3. Ratiometric pH sensing properties of the raspberry nanohybrids 160
6.4. Summary 166
6.5. References 167

Chapter 7. Polydiacetylene/HBsAb Nanobio-Complexes for Visible and Fluorescent Detection of HBsAg on Nitrocellulose Membrane 171
7.1. Scope of Research 172
7.2. Experimental Section 175
7.2.1. Materials 175
7.2.2. Preparation of polydiacetylene vesicles 175
7.2.3. Preparation of PDA/HBsAb nanobio-complexes 176
7.2.4. Application of the PDA/HBsAb nanobio-complexes in the assay 117
7.2.5. Application of the PDA/HBsAb nanobio-complexes based assay to the commercial kit 177
7.2.6. Characterization 177
7.3. Results and Discussion 178
7.3.1. PDA/HBsAb nanobio-complexes based chromatographic assay 178
7.3.2. Optimization of the assay conditions 182
7.3.3. Morphology of PDA/HBsAb nanobio-complexes 186
7.3.4. Visible responses of the PDA/HBsAb nanobio-complexes based assay 188
7.3.5. Fluorescence responses of the PDA/HBsAb nanobio-complexes based assay 192
7.3.6. Applicability of the PDA/HBsAb nanobio-complexes based assay for the commercial kit 196
7.4. Summary 198
7.5. References 199

Chapter 8. Conclusion and Perspective 202

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