Preparation and characterization of silver sers nanotags

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Arts and Sciences, Department of Chemistry, Turkey

Approval Date: 2010




ABSTRACT PREPARATION AND CHARACTERIZATION OF SILVER SERS NANOTAGS Kibar, Seda M.S., Department of Chemistry Supervisor: Prof. Dr. Mürvet Volkan December 2010, 88 pages Tags are materials used for labeling substances and so make possible the qualitative and quantitative analysis both in macroscopic and microscopic world. Nowadays, surface enhanced Raman spectroscopy became the favored one among the optical based-tag detection systems. Progress in surface enhanced Raman detection and imaging technologies depends on the availability of Raman labels with strong light scattering characteristics. In this study various SERS nanotags were prepared. An ideal SERS nanotag consists of three parts, core nanoparticle for enhancement, Raman active molecule for signature and a shell for protection and further functionalization. As a core material, silver nanoparticles were prepared using the chemical reduction method with sodium citrate as reductant. SERS enhancement provided by Ag particles prepared was examined. For colloidal stabilization and further surface modifications, silica with a controlled thickness was deposited on Ag nanoparticles. Three single-dye doped nanotags, Ag-BCB@SiO2 Ag-CFV@SiO2 and Ag-CV@SiO2 were prepared using positively charged dyes, brilliant cresyl blue (BCB), cresyl fast violet (CFV) and cresyl violet (CV). The effects of silica thickness and dye concentration in the reaction medium were examined. Stability of prepared nanotags and repeatability of the method were investigated. Multi-dye doped nanotags were prepared using BCB and CFV solutions mixed at various concentration ratios. Resulting Raman spectra Ag-BCB-CFV@SiO2 nanotags successfully exhibited characteristic peaks of each dye with a good resolution. In addition, the molar ratio between dyes BCB and CFV was reflected on the related spectra. A linear correlation was observed between the molar ratio of the dyes and their Raman intensity ratio.