title: Uniform distribution of Ag particles upon imprinted polymer grating for Raman signal enhancement.
abstract: Surface Enhanced Raman Scattering (SERS) is gaining popularity among analytical methods in biosciences and sensor technology since it provides high specificity, non-destructiveness, and the unique fingerprint spectra of the molecules. Historically, glass has been the primary choice as a substrate for SERS, but polymers are attractive due to their plasticity, ease of handling, and their low cost. Herein, the performance of cyclo olefin polymer (COP) as a substrate with 1D subwavelength modulations combined with silver nanoparticles is studied for SERS measurements. These 1D grating structures on polymer are fabricated by hot embossing method followed by deposition of silver nanoparticles (AgNPs) using the drop-casting method. Spatial variations of the substrate surface have been reduced by providing a consistent distribution of hot-spots. We present an analysis of the surface uniformity related to the distribution of Ag particles. We achieve around 8-fold Raman signal enhancements with improved reproducibility in comparison to smooth, unmodulated surfaces with AgNPs. This method of fabrication of SERS substrates is simple and inexpensive compared to the thermal evaporation method (TEM) of metallic layer deposition. It also helps to control the tarnishing effect on metallic surfaces due to silver deposition prior to Raman measurements. This kind of polymer gratings combined with AgNPs have potential applications in medical, biological and chemical sensing, where Raman signal enhancement with high reproducibility is required.
authors.affiliation: Institute of Photonics, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland. Electronic address: salman.daniel@uef.fi.
authors.forename: Salman
authors.initials: S
authors.lastname: Daniel
authors.affiliation: Institute of Photonics, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Antti
authors.initials: A
authors.lastname: Matikainen
authors.affiliation: Institute of Photonics, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Jari
authors.initials: J
authors.lastname: Turunen
authors.affiliation: Institute of Photonics, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Pasi
authors.initials: P
authors.lastname: Vahimaa
authors.affiliation: Department of Biology, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland.
authors.forename: Tarmo
authors.initials: T
authors.lastname: Nuutinen
mesh_terms: D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry*; D012834:Silver / Q000737:chemistry*; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D011108:Polymers; D012834:Silver
keywords: Cyclo olefin polymer; Silver colloid; Subwavelength grating; Surface enhanced Raman scattering; Surface uniformity