Nanomateriales

Bioanalytical Application of SERS Immunoassay

Bull. Korean Chem. Soc. 2010, Vol. 31, No. 5 1215 DOI 10.5012/bkcs.2010.31.5.1215

Bioanalytical Application of SERS Immunoassay for Detection of Prostate-Specific Antigen
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Kyung Jin Yoon,a Hyeong Kuyn Seo,a Hoon Hwang, Dongjin Pyo, In-Yong Eom,† Jong Hoon Hahn,‡ and Young Mee Jung* Department of Chemistry, Institute for Molecular Scienceand Fusion Technology, Kangwon National University, Chunchon 200-701, Korea. *E-mail: ymjung@kangwon.ac.kr † Department of Life Chemistry, Catholic University of Daegu, Gyeongsan 712-702, Korea ‡ Department of Chemistry, BK School of Molecular Science, POSTECH, Pohang 790-784, Korea Received February 18, 2010, Accepted March 2, 2010
We demonstrate the possible application of the sandwich typesurface-enhanced Raman scattering (SERS) immunoassay using antigen-antibody binding for detection of prostate-specific antigen (PSA) in cancer cells. In this sandwich type of SERS immunoassay, to capture antigens onto the immobilized layer of antibodies on the gold substrate we prepared the monolayer of gold nanoparticles on the APTMS-derivatized surface of a glass slide by using the SAM technique.This sandwich type of SERS immunoassay in which antigens on the substrate specifically capture antibodies on a Raman reporter (DSNB coated gold nanoparticles with R6G) could successfully detect PSA at low levels. A strong SERS spectrum of Raman reporter was observed only with a substrate in which PSA is present.

Key Words: Surface-enhanced Raman scattering (SERS), Immunoassay, Prostate-specificantigen (PSA), Raman reporter, Gold nanopaticles Introduction Surface-enhanced Raman scattering (SERS) spectroscopy has recently received much attention due to its considerable potential in highly selective and sensitive detection of molecules 1-30 of interest even in single-molecule detection. SERS in which the scattering cross-sections are dramatically enhanced for molecules adsorbed on metallicnanostructure has been a promising candidate for various applications in nanoscience and nanotechnology. Particular interest has thus been focused on applications of molecular sensors operating via SERS for biochemical 28 studies, clinical diagnoses, and environmental monitoring. Especially, SERS immunoassays based on antigen-antibody binding have been reported for biomarkers for early cancerdia12-18,21-24,26,30 For successful application of SERS immunognosis. assays for biological sensors, people usually used novel metal nanoparticles modified to integrate bioselective species (e.g., antibodies) with molecular labels for the generation of intense, biolyte-selective SERS responses in immunoassays and other bioanalytical applications. Immunoassays, with high selectivity and affinity ofantibody molecules to their corresponding antigens, have been widely exploited for analytical purposes in the field of clinical dia31-36 Immunoassay readout methods have been based on gnoses. fluorescence, electrochemistry, chemiluminescence, Rayleigh scattering, and Raman scattering. Fluorescence spectroscopy has been one of the most widely used readout methods due to its high sensitivity. Ramanspectroscopy has inherent problems such as extremely low sensitivity as an immunoassay readout method. However, immunoassay based on SERS provides a high sensitivity which is comparable to that of fluorescence spectroscopy. Prostate-specific antigen (PSA), which is a glycoprotein cona

sisting of one polypeptide chain, has been used as a serologic marker for detecting prostate cancer. Some types ofimmunoassay for PSA have been reported, such as fluorescence microscopy, surface plasmon resonance technology, lateral flow immunoassay, enzyme-linked immunosorbent assay (ELISA), radioimmunoassay, immunochromatographic assay system, and SERS based on immunoassays.15-17,26,37-44 In this study, we applied a sandwich type SERS immunoassay for the detection of PSA with high sensitivity. It shows...