Morphology and Assembly Control of Nanostructures for Plasmonic Optical Amplification

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dc.description학위논문 (박사)-- 서울대학교 대학원 : 재료공학부, 2017. 2. 남기태.-
dc.description.abstractAbility to control the morphology and assembly of metal nanostructure is highly desirable as the geometry of particles is directly related with the properties of the nanoparticles. Different shape and assemblies provide wide variety of unique optical properties to nanostructures. The surface plasmon of the metal nanoparticle is the origin of unique optical properties and tailoring the structure allows one to modulate the surface plasmon mode. The surface plasmon which interact with visible range of light provides brilliant color with excellent stability and numerous physical color through morphological change of nanostructures. The confinement of a surface plasmon to a small volume results in localized electromagnetic field concentrating incident radiation to a subwavelength physical region and leads to strongly enhanced surface-enhanced Raman scattering signal. Due to these compelling optical properties and applications, there have been many efforts to control morphology and assembly of nanostructures. However, the number of methodologies and morphologies that can be achieved is quite limited. Through this research, we intended to push the boundary in the field of the nanostructure fabrication. In this thesis, we investigated new methodologies to fabricate plasmonic nanostructures with novel design, created unprecedented plasmonic nanostructures, and evaluated the optical properties of newly produced nanostructures.
By changing the ratio of cetyltrimethylammonium bromide (CTAB) and ascorbic acid (AA), we developed various shapes of gold nanoparticles. We chose the well-known ligand, CTAB and the reducing agent, AA and studied the role of them in shape control. The ratio of CTAB and AA is important to determine the relative growth of different crystallographic facet. Based upon the discoveries, we constructed the morphology diagram as a function of CTAB and AA concentration and successfully synthesized the rhombic dodecahedron and hexaoctahedron for the first time in CTAB and AA condition. This work can provide a useful guideline to control the morphology simply by controlling the relative ratio of CTAB and AA.
We developed a new system that can direct the growth of nanoparticle by changing the functional group in the organothiol called organothiol assisted growth. Generally the organothiol molecule is used for functionalization of nanoparticle, but in here we revisited the role of organothiol in shape control and developed unprecedented nanoparticle morphologies having compelling properties. The thiol group in organothiol strongly links the molecule to the metal surface and at the same time, functional groups in the molecule make characteristic attachment onto the surface thus change the direction of crystal growth. In this system, we rationally designed organothiol molecules and utilized it to induce crystal morphology appropriate for each function.
We identified benzenethiol system where the interaction energy between thiol and gold can be systematically varied and synthesized numerous high index nanoparticles. Especially, a new concave rhombic dodecahedron (RD) shape was fabricated using 4-aminothiophenol which has maximized binding energy due to electron donating amine. Sharp edges and multiple high index facets of concave RD generated strong electromagnetic field and exhibited superior catalytic performance.
Furthermore, we discovered peptide organothiol molecule which is capable of developing chiral morphologies. In this organothiol additive growth, continuous attachment of organothiol on gold surfaces during the evolution of particle mediates the crystallographic growth direction. During the growing process, gold atoms and peptides continuously provided onto the cube seed and the peptides make peptide-inorganic stereoselective recognition on gold surface which leads to modified growth direction on the surface changing in shape consequentially. By incorporating peptide-gold enantioselective interaction into particle growth, here, we demonstrated various novel chiral structures controlled at nanometer resolution with strong optical activity and achieved new advances in chiral morphology fabrication. The synthesized nanoparticle showed strong optical activity at visible light and rotated the angle of linear polarized horizontal light at a 28 degree. This organothiol assisted growth system holds great potential in developing the fabrication of nanoparticle. As there are myriad combinations of functional group in organothiol molecule, the system enables one to make numerous shape and establish nanostructure library. In addition, this will provide important insight for the rational design of nanoparticle.
Using genetically engineered M13 virus as assembling template, we fabricated closely aligned gold nanocube chain. Designing a surface-enhanced Raman scattering (SERS) nanoprobe with a controlled nanostructure and attachment of antibodies is an important issue in quantitative multiplexed detection. We have developed antibody containing SERS nanoprobe that is based on a genetically engineered, bifunctional M13 virus. At the end of the 1-µm-long filamentous virus, an antibody was expressed with high binding affinity against antigens. Along the length of the virus, gold nanocubes were closely aligned into chains through a gold-binding peptide sequence expressed on major coat proteins. These nanocube chains in a single virus amplified the Raman signals of various reporter molecules and thus served as a specific label to distinguish different antibodies. We successfully applied the virus-based platform to prostate specific antigen (PSA) detection and a quantitative immunoassay. Our results suggest a new possibility for the use of a multifunctional virus scaffold as a general SERS platform that can genetically carry various antibodies and templates for plasmonic nanostructures.
We believe that our newly developed methodologies, various fascinating shape and assembly in this research will pave the way to develop novel plasmonic nanostructures and bring about new opportunities for light manipulation.
dc.description.tableofcontentsChapter 1. Introduction 1
1.1 Morphology Dependent Properties of Nanostructures 1
1.2 Structure Control for Optical Amplification 7
1.3 Objective of Thesis 25
1.4 Bibliography 29
Chapter 2. Theoretical Background of Plasmonic Nanostructure Fabrication and Optical Properties 36
2.1 Metal Nanoparticle Synthesis 36
2.2 Metal Nanoparticle Assembly 46
2.3 Optical Properties of Metal Nanostructure 51
2.4 Bibliography 58
Chapter 3. Experimental Procedures 66
3.1 Synthesis of Nanoparticles 66
3.2 Fabrication of Assembled Nanostructure 68
3.3 Characterization of Nanostructure 70
3.4 Nanostructure Analysis for Applications 71
3.5 Bibliography 75

Part I : Nanostructure Fabrication 76
Chapter 4. Morphology Diagram from Rod to Rhombic Dodecahedron: Interplay between CTAB and Ascorbic acid 77
4.1 Introduction 77
4.2 Synthesis of Rhombic Dodecahedral Gold Nanoparticles 80
4.3 Morphology Diagram 83
4.4 Comparison of Synthesis Condition- Morphology Diagram for Generality 88
4.5 Extending Morphology Diagram - Two Step Growth 95
4.6 Conclusion 97
4.7 Bibliography 98
Chapter 5. Organothiol as a New Class of Shape Directing Additive 106
5.1 Introduction 106
5.2 Organothiol Assisted Growth – Giant Leap in Morphology Control 108
5.3 Effect of Benzenethiol as a Nanoparticle Shape Modifier and Stabilizer 111
5.4 Effect of Organothiol Structure on Nanoparticle Shape 116
5.5 Effect of Other Constituents on the Growth Solution 118
5.6 Proposed Growth Mechanism 123
5.7 Cysteine Assisted Growth for Chiral Nanostructure 126
5.8 Conclusion 131
5.9 Bibliography 132
Chapter 6. Virus Templated Gold Nanocube Chain 136
6.1 Introduction 136
6.2 Fabrication of Virus based Nanocube Chain 139
6.3 Analysis of Structural Integrity of Virus based Nanocube Chain 146
6.4 Conclusion 149
6.5 Bibliography 150

Part II. Optical Properties and Applications of Nanostructures 156
Chapter 7. Tuning Plasmonic Resonance by Structural Adjustment of Nanostructures 157
7.1 Introduction 157
7.2 Extinction Spectrum of Concave Rhombic Dodecahedron - Tunable Structural Color 170
7.3 Scattering Spectrum of Concave Rhombic Dodecahedron 172
7.4 Conclusion 176
7.5 Bibliography 177
Chapter 8. Surface-Enhanced Raman Scattering of Nanostructures 182
8.1 Introduction 182
8.2 SERS Measurement of Concave RD 188
8.3 SERS Measurement of Virus based Nanocube Chain 192
8.4 Immunoassay using Virus based SERS Nanoprobe 195
8.5 Conclusion 198
8.6 Bibliography 200
Chapter 9. Tailoring Optical Activity of Chiral Plasmonic Nanoparticle 204
9.1 Introduction 204
9.2 Synthesis of Diverse Chiral Nanomorphologies 210
9.3 Effect of Enantiomer in Chiral Morphology 212
9.4 Effect of Peptide on Chiral Formation 215
9.5 Effect of Synthesis Condition on Geometrical Chirality 220
9.6 Rotatory Optical Activity in Chiral Nanoparticle 224
9.7 Conclusion 226
9.8 Bibliography 227
Chapter 10. Other Application of Concave Rhombic Dodecahedron 229
10.1 Introduction 229
10.2 Surface Facet Crystallographic Analysis 231
10.3 Electrocatalytic Performance for CO2 Reduction 234
10.4 Conclusion 240
10.5 Bibliography 241
Chapter 11. Concluding Remarks 245
초록 249
dc.format.extent7641874 bytes-
dc.publisher서울대학교 대학원-
dc.subjectMetal nanostructure-
dc.subjectHigh index nanoparticle-
dc.subjectChiral nanoparticle-
dc.titleMorphology and Assembly Control of Nanostructures for Plasmonic Optical Amplification-
dc.contributor.affiliation공과대학 재료공학부-
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College of Engineering/Engineering Practice School (공과대학/대학원)Dept. of Material Science and Engineering (재료공학부) Theses (Ph.D. / Sc.D._재료공학부)
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