Optical Molecular Imaging of Cancer Cells/Tissues Using Bioconjugated Metal Nano Probes

Abstract

Raman signal enhancement effect of pyridine that adsorbed on electrochemically roughened silver surface was observed by Martin Fleischman and coworkers in 1974.1 Jeanmaire and Van Duyne and Albrecht and Creighton proposed that principles of the Surface Enhanced Raman Scattering effect was came from a electromagnetic effect and charge-transfer effect.2, 3 The enhancement factor can be as much as 1014-1015, which allows the technique to be sensitive enough to detect single molecules.4 This striking discovery was denoted Surface-enhanced Raman Scattering (SERS) effect and immediately became the subject of intensive study. After its discovery more than 30 years ago, SERS was expected to have major impact as a sensitive analytical technique and tool for fundamental studies of surface molecules. Unfortunately, the lack of reliable and reproducible SERS signals limited its applicability. In recent years, the new techniques for nanofabrication, the design of substrates that maximize the electromagnetic enhancement, and the discovery of single-molecule SERS are raising a interest of biomedical application. In this dissertation, we presented SERS application of medical diagnostics using variety metal nanoparticles. For maximize the SERS enhancement and stability, Au and Ag nanoparticle was combined by core-shell type. Because of Au nanoparticle had stability and Ag nanoparticle had strong enhancement property. Next, hollow nanosphere with high reproducibility was used as nanoprobes. These particles show strong enhancement effects from individual particles because of their capability to localize the surface electromagnetic fields through the pinholes in the hollow particle structures. Lastly, combined with greater speed and wide FOV of fluorescent, Raman nanoprobes were used for multiple cancermarker detection. The abstracts for each chapter are as follows. Chapter 1. Highly Sensitive Cancer Cell Detection Using Goldcore-Silvershell Nanoprobes. Surface-enhanced Raman scattering (SERS) imaging has been used for the targeting and imaging of specific cancer markers in live cells. For this purpose, Au/Ag core-shell nanoparticles, conjugated with monoclonal antibodies, were prepared. The procedures to label live cells with those bimetallic nanoprobes have been developed and used for highly sensitive SERS imaging of live cells. In the present study, live HEK293 cells expressing PLCΥ1 have been used as the optical imaging target. Our results demonstrate the potential feasibility of SERS imaging technology for the highly sensitive imaging of cancer biomarkers in live cells. Chapter 2. SERS imaging of HER2 Cancer Markers in Single Cell using Hollow Gold Nanosphere (HGN). Antibody-conjugated hollow gold nanospheres (HGNs) have been used for the SERS imaging of HER2 cancer markers overexpressed in single MCF7 cells. SERS mapping images show that HGNs have much better homogeneous scattering properties than silver nanoparticles. The results demonstrate the potential feasibility of HGNs as highly sensitive and homogeneous sensing probes for biological imaging of cancer markers in live cells. Chapter 3. Fluorescence / Raman Dual Modal Nanoprobes for Multiple Marker Detection in Single Cancer Cell. Fluorescence microscopy is a well-known imaging technique which provides a specific protein distribution inside cells. However, most of currently available fluorescent organic dyes have relatively weak emission intensities and they are also photo-bleached quickly. In order to resolve this problem, more sensitive and stable probes are still needed. In the present work, dual modal nanoprobes, which can be used for both the SERS and fluorescence detections, have been developed. SERS detection is a powerful analytical technique that allows ultra-sensitive chemical or biochemical analysis in terms of unlimited multiplexing and single molecule sensitivity. Combining advantages of fluorescence and SERS allow these dual modal nanostructures to be used as powerful probes for a novel biomedical imaging.