Protein detection on plasmonic nanodomes based on surface-enhanced raman scattering

Surface-enhanced Raman scattering (SERS) is a powerful technique used today for the detection and characterization of chemical and biological molecules and structures. Rapid, sensitive and accurate detection of proteins is significant in both clinical and industrial applications. In this thesis, SERS-based protein detection on plasmonic nanodomes is investigated. For this purpose, plasmonic silver nanodomes (AgNDs) are first obtained. To prepare AgNDs, 1600 nm latex particles are first deposited uniformly on a glass slide using convective-assembly method. Polydimethylsiloxane (PDMS) is poured onto prepared latex particles film and polymerized by temperature. The polymerized PDMS is removed from the surface of the film to obtain nanovoids on the PDMS. The obtained PDMS nanovoids are used as molds to prepare AgNDs. The PDMS nanovoids are filled with Ag by electrochemical coating to obtain AgNDs. The obtained AgNDs are characterized by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The prepared AgNDs are used as SERS substrates for the protein detection. Model proteins are used to test the performance of AgNDs in protein detection. For this purpose, SERS spectra are obtained by dropping the proteins at different concentrations on AgNDs. It is determined that the reproducibility of the obtained SERS spectra is good. SERS spectra are obtained by dropping protein solutions in decreasing concentrations on AgNDs to determine the lowest detection concentration. The results demonstrate that, a detection limit down to 0.05 μg/mL of proteins could be detected regardless of the protein type and size.