Design and production of molecularly imprinted polymeric materials for optical biosensing applications

In this study, molecularly imprinted polymers (MIP), which are highly promising in sensor applications, were produced on the surface of 100 nm silica nanoparticles to be tested in Surface Plasmon Spectroscopy. After the nanoparticle production was carried out by the Stöber method, the surface was prepared by 3-aminopropyl triethoxysilane (APTES) coating for further modification steps. After modifying the nanoparticle surface by initiator layer of 4,4´-azobiscyanopentanoic acid (ACPA), methacrylic acid (MAA) and ethylene glycol dimethacrylate (EDMA) monomers were polymerized under UV light in presence of 2-phenylprop 2-yl dithiobenzoate (CDB) as RAFT agent via reversible addition-dissociation chain transfer polymerization (RAFT) which provides an efficient control of solution propagation and grafting process. Nanoparticles obtained by 2 hours of polymerization using L-Boc-phenylalanine anilide as template were fixed on gold substrate for use in SPR system. After each modification step, the nanoparticles were characterized by X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), atomic force microscopy (AFM), Dynamic Light Scattering (DLS) and Thermogravimetric Analysis (TGA) for chemical structure and surface topography analysis. Performances of the particles were followed by surface plasmon resonance spectroscopy (SPR) after coating the final product on gold deposited glass substrate against three different analogous of analyte molecules: L-Boc- tyrosine, L-Boc-tryptophan and L-Boc-phenylalanine. SPR spectroscopy is a primary method and it allows real time imaging of sensing even at very low template concentrations. These characterizations indicated that copolymer coated silica particles do contain binding sites for L-phenylalanine anilide, and Limit of Detection (LOD) were calculates as 7 μM. In another part of this thesis, polyethylene imine coated silica particles (MS-PEI) were used for anionic dye removal. Desorption and reusability tests were performed after determining the appropriate pH, temperature, contact time parameters of monolayer (MS-APTES) and polymer coated particles. The dye removal performance of the polymer coated silica particles was found to be higher as they contained more active ends compared to monolayer containing surfaces. It has been shown that the particles tested for water remediation performance can be prepared for conventional SPR system and used for both application and detection purposes.