Surface-enhanced Raman scattering (SERS) is used for the characterization of six yeast species and six isolates. The sample for SERS analysis is prepared by mixing the yeast cells with a four times concentrated silver colloidal suspension. The scanning electron microscopy (SEM) images show that the strength of the interaction between silver nanoparticles and the yeast cells depends on the biochemical structure of the cell wall. The SERS spectra are used to identify the biochemical structures on the yeast cell wall. It is found that the density of -SH and -NH2 groups might be higher on certain yeast cell walls. Finally, the obtained SERS spectra from yeast is used for the classification of the yeast.

Surface-enhanced Raman scattering (SERS) is a powerful technique used for obtaining chemical information about the moleculesand molecular structures in the vicinity of surfaces of noble metal nanostructures. The chemical information acquired through SERS can be used for not only characterization but also detection and identification. In a clinical setting, rapid and accurate identification of micro-organisms is critical. The biochemical information collected through the SERS spectra can be used for quick identification of micro-organisms. The concentrated silver colloidal nanoparticles (AgNPs) are simply mixed with micro-organisms after culturing, and their SERS spectra acquired. Since the nanoparticles are in contact with the cell wall of the micro-organism, the biochemical information obtained is mostly assumed as originating from the cell wall which the AgNPs are in contact with, and is considered as the 'fingerprint' of the micro-organism, which can be used for the identification. Since a SERS spectrum can be acquired only in seconds, the obtained spectrum can be used for fast micro-organism identification. The reproducibility of the spectra obtained from micro-organisms is first tested, and then the obtained spectra are used for the goal. The identification of micro-organisms in mixtures is also attempted in model mixtures. It is demonstrated that the SERS can be used for fast and accurate identification of micro-organisms such as bacteria and yeast, even in their mixtures. Four bacteria, i.e. Shigella sonnei, Erwinia amylovara, Proteus vulgaris and DH5α (E. coli strain), and three yeast cells, i.e. Hyphopichia burtonii, Candida parapsilosis and Filobasidiella neoformans are used as model micro-organisms in the study.

The development of an assay for the detection of gene mutations has been attempted based on surface-enhanced Raman scattering (SERS). Using multiplexing property and high sensitivity of SERS technique, the detection of all mutation possibilities on one given spot is achievable. To test the feasibility of approach, SNPs and other types of mutations such as insertion and deletion are investigated. The PCR amplified and isolated genomic DNA without PCR amplification is immobilized on poly-L/D-lysine coated glass surface after denaturing with heating. The SERS probes are prepared by simultaneous attachment of oligonucleotides complementary to the target mutation regions and Raman active dyes to 13 nm gold nanoparticles (GNPs). After the hybridization of SERS probes on the poly-L/D-lysine surfaces, it was stained with silver colloidal nanoparticles for further enhancement of Raman scattering. In the second approach, Raman active dyes are chemically attached on gold nanoparticles and a thin layer of silver film is deposited on top of it to prepare coreshell nanoparticles. The complementary oligonucleotides to the target regions of the gene are chemically attached to silver surfaces of the nanoparticles. The promising results indicate that it is possible to detect certain mutation types without PCR amplification using the approach.