Additional amplifications of SERS via an optofluidic CD-based platform.

In this paper, signal amplifications of surface-enhanced Raman scattering (SERS) are realized by an optofluidic compact disc (CD)-based preconcentration method for effective label-free environmental and biomolecular detections. The preconcentration of target molecules is accomplished through the accumulation of adsorbed molecules on SERS-active sites by repeating a 'filling-drying' cycle of the assay solution in the optofluidic CD platform. After 30 cycles, the clear and high SERS signal of rhodamine 6G of 1 nM is readily detected. In addition to the preconcentration-based signal amplification by the optofluidic SERS system on the CD platform, we introduce a controlled precipitation of gold nanoparticles by CuSO4 for SERS substrates. This method provides high-throughput, high-sensitive and large-area uniform SERS substrates on the optofluidic CD platform. The uniform SERS signals from different positions in spots of 3 mm2 on the different CDs gives us confidence in the reliability and stability of our SERS substrates.

[1]  Luke P. Lee,et al.  Nanophotonic crescent moon structures with sharp edge for ultrasensitive biomolecular detection by local electromagnetic field enhancement effect. , 2005, Nano letters.

[2]  R. Dasari,et al.  Ultrasensitive chemical analysis by Raman spectroscopy. , 1999, Chemical reviews.

[3]  Luke P. Lee,et al.  Magnetic Nanocrescents as Controllable Surface‐Enhanced Raman Scattering Nanoprobes for Biomolecular Imaging , 2005 .

[4]  Jürgen Popp,et al.  A reproducible surface-enhanced raman spectroscopy approach. Online SERS measurements in a segmented microfluidic system. , 2007, Analytical chemistry.

[5]  R. Dasari,et al.  Single Molecule Detection Using Surface-Enhanced Raman Scattering (SERS) , 1997 .

[6]  A. Wei,et al.  Tunable surface-enhanced Raman scattering from large gold nanoparticle arrays. , 2001, Chemphyschem : a European journal of chemical physics and physical chemistry.

[7]  Luke P. Lee,et al.  Nanowell surface enhanced Raman scattering arrays fabricated by soft-lithography for label-free biomolecular detections in integrated microfluidics , 2005 .

[8]  Igor Nabiev,et al.  Applications of Raman and surface‐enhanced Raman scattering spectroscopy in medicine , 1994 .

[9]  Shr-Bin Wu,et al.  Highly Raman‐Enhancing Substrates Based on Silver Nanoparticle Arrays with Tunable Sub‐10 nm Gaps , 2006 .

[10]  R. G. Freeman,et al.  Ag-Clad Au Nanoparticles: Novel Aggregation, Optical, and Surface-Enhanced Raman Scattering Properties , 1996 .

[11]  Hongxing Xu,et al.  Spectroscopy of Single Hemoglobin Molecules by Surface Enhanced Raman Scattering , 1999 .

[12]  M. Natan,et al.  Self-Assembled Metal Colloid Monolayers: An Approach to SERS Substrates , 1995, Science.

[13]  S. Bell,et al.  Surface-enhanced Raman spectroscopy (SERS) for sub-micromolar detection of DNA/RNA mononucleotides. , 2006, Journal of the American Chemical Society.

[14]  Luke P. Lee,et al.  High-density silver nanoparticle film with temperature-controllable interparticle spacing for a tunable surface enhanced Raman scattering substrate. , 2005, Nano letters.

[15]  D. L. Jeanmaire,et al.  Surface raman spectroelectrochemistry: Part I. Heterocyclic, aromatic, and aliphatic amines adsorbed on the anodized silver electrode , 1977 .

[16]  P. Hildebrandt,et al.  Surface-enhanced resonance Raman spectroscopy of Rhodamine 6G adsorbed on colloidal silver , 1984 .

[17]  H. Fabian,et al.  New developments in Raman spectroscopy of biological systems , 1993 .

[18]  Jun Kameoka,et al.  An optofluidic device for surface enhanced Raman spectroscopy. , 2007, Lab on a chip.

[19]  N J Halas,et al.  Surface-enhanced Raman scattering on tunable plasmonic nanoparticle substrates , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[20]  H. Beier,et al.  Nanofluidic biosensing for beta-amyloid detection using surface enhanced Raman spectroscopy. , 2008, Nano letters.

[21]  J. Kraut,et al.  pH-dependent conformational changes in Escherichia coli dihydrofolate reductase revealed by Raman difference spectroscopy. , 1997, Biophysical journal.

[22]  Steven R. Emory,et al.  Probing Single Molecules and Single Nanoparticles by Surface-Enhanced Raman Scattering , 1997, Science.

[23]  Duncan Graham,et al.  Bead-based DNA diagnostic assay for chlamydia using nanoparticle-mediated surface-enhanced resonance Raman scattering detection within a lab-on-a-chip format. , 2007, Analytical chemistry.

[24]  Luke P. Lee,et al.  Surface‐Enhanced Raman Scattering of Small Molecules from Silver‐Coated Silicon Nanopores , 2003 .

[25]  K. S. Krishnan,et al.  A New Type of Secondary Radiation , 1928, Nature.

[26]  D. Weitz,et al.  Fractal structures formed by kinetic aggregation of aqueous gold colloids , 1984 .