Preconcentrated Gold Nanoparticle as a Surface Enhanced Raman Scattering Substrate in a Microfluidic Chip Kwang Bok Kim1, Ji-Hyung Han2, Hyoungseon Choi1, Taek Dong Chung2* and Hee Chan Kim3* 1Interdisciplinary Program, Bioengineering Major, Graduate School of Seoul National University, Seoul, Korea 2Department of Chemistry, Seoul National University, Seoul, Korea 3Department of Biomedical Engineering, College of Medicine and Institute of Medical & Biological Engineering , Medical Research Center, Seoul National University, Seoul, Korea B. Working principle (1) Anion preconcentration C. Experiments Surface-enhanced Raman Scattering (SERS) SERS on a Chip using preconcentrated gold nanoparticles Preconcentration Method : Electrokinetic trapping - Ion-depletion - Extract cations through the charge selective polymer (poly-2-acrylamido-2-methyl-1-propanesulfonic acid, pAMPSA) Samples (SERS analytes) - 4-aminobenzoic acid (4-ABA) - pyridine - 4-mercaptobenzoic acid (4-MBA) - Neurotransmitter (Histamine) SERS signal obtained every 10 seconds (a) Cation extraction (b) Ion depletion A. SERS on a Chip (c) Anion preconcentration (2) Anionic gold nanoparticle preconcentration and SERS analysis The gold nanoparticles have negative zeta potential at pH values over 5. The proposed system can also preconcentrate the anionic metal nanoparticles such as a gold nanoparticle. Optimum Power - V1 : 20 V - V2 : 5 V Reversible preconcentrator Not necessary to fabricate and clean the SERS- active nano structure. The preconcentrated gold nanoparticles can be uses as SERS-active substrate. Reduce the sample and reagent volume. This method may provide new approach that research about ‘hot-spot’ of SERS. Further research, SERS on a chip system will propose the small-sized SERS device. Glass to glass microfluidic chip - Width : 60 um , Height : 30 um Electrode : Platinum Laser : He-Ne 633 nm Raman spectroscopic system Power : DC-2 channel Gold nanoparticle - 20 nm (dia.) in 10 mM PB - PB (Phospate Buffer) *This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government(MEST) (No. 2005-2001287).