Nanomaterials, especially formed by protein molecules, have received great attention for various biolog-ical applications. Protein-based metal nanomaterials exhibit unique biological or physical properties those allied with biocompatibility and high solubility in aqueous solutions have prompted the development of biosensing platforms. A better understanding of the bioconjugation with biomolecules and metal nanostructures are crucial for developing more effective synthetic approaches of nanomaterials, and thus it can increase the advantages of electronic, optical and catalytic properties of nanomaterials. In chapter 1, I presented the use of noble metal nanoparticles for biosensing strategies and synthetic approaches of these nanoparticles by using protein tem-plates.
Chapter 2 represent the first example of controlled embedment of a functional protein in silver nanostructures and its applications. I demonstrated the facile method to embed (antibody binding) protein G on gold/silver core shell nanoparticles. A linearly structured peptide linker was introduced for uniform pep-tide/protein layer formation on gold nanoparticle surfaces and successful protein-embedded silver shell deposi-tion. Gold/silver structures with stably embedded protein G were applied for naked-eye detection of surface-bound antigens. Compared to conventional antibody-adsorbed gold nanoparticles, nearly 10-fold higher sensi-tivity was obtained. In addition, the protein embedded silver shells were investigated as active SERS substrates. Protein-functionalized SERS probes were consistently prepared and showed greatly enhanced SERS signals for various dye molecules. The present strategy provides a simple but efficient way to conjugate antibodies to na-nosilver surfaces, which will greatly facilitate wider use of the superior optical properties of silver nanostructures in biological applications
Chapter 3 represent protein-templated fluorescent silver nanoclusters (NCs) with retained structures and functions of template proteins including fused binding proteins. I demonstrated facile synthesis of fluorescent and highly stable silver NCs in a mild aqueous buffer solution by employing recombinant human ferritin as a stabilizing and also interfacing ligand. The unique metal binding property of ferritin and optimized silver ion reduction allowed us to produce highly stable fluorescent silver NCs that are steadily assembled in native as well as genetically engineered ferritin proteins. These ferritin-templated silver NCs (Ft-Ag NCs) showed Cu2+ specific fluorescence quenching. The robust, and fluorescent Ft-Ag NCs were effectively encapsulated in highly porous hydrogels, leading to a highly stable hydrogel sensor chip for rapid Cu2+ detection.
In chapter 4, I described nanostructure assembly using proteins as a cross-linker. Driven by specific recognition property of proteins, nanoparticles are combined to form larger materials with ordered structures. This approach will facilitate use of new properties of assemble metal structures as biological tools and scaffolds for nanotechnology.
나노미터 크기의 미세 영역에서 새로운 물리현상과 향상된 물질 특성을 나타내는 연구들이 보고 되고, 이를 기반으로 나노 기술과 바이오 기술을 융합하여 질병 진단 및 치료, 바이오센서, 의약품 개발 등 생명과학 연구에 응용되면서 나노 기술에 대한 관심이 집중되고 있다. 금속 나노 입자는 표면 성분의 증가와 양자 효과 등에 의하여 크기와 모양에 의존하는 광학적, 전기적, 자기적 특성을 가진다. 본 논문에서는 생체분자의 상호작용을 분석하고 나노 물질을 이용한 바이오센서 개발에 사용될 수 있는 원천기술을 확보하기 위하여 단백질을 이용하여 입자의 크기와 모양이 조절된 금속 나노 입자를 합성하였다. 또한 나노 입자의 성질 이외의 기능성을 부여하고, 다양한 나노 입자를 활용한 다차원 구조물을 개발하기 위하여 나노 수준의 고정화 기술, 나노 패턴 기술, 형광 신호발생 기술을 기반으로 기능성 생체물질의 활성 유지, 방향성 제어 및 집적도 향상 문제를 해결함과 동시에 합성된 나노 입자들을 배열하고 개질 하는 연구를 진행하였다.