Nano- and Micro-sized Molecularly Imprinted Polymer Particles on Solid Surfaces

Sammanfattning: Molecularly imprinted polymers (MIPs) are artificial receptors made by imprinting template molecules in a polymer matrix followed by their removal through washing to obtain a specific and selective template cavities. This property of the MIPs have made them a very efficient material for diverse applications such as chromatography, purification, drug sensing, etc. Recently, zero-dimensional polymer materials, in the present case molecularly imprinted polymer nanoparticles (MIP nanoparticles), have been used widely for the fabrication of various functional materials. The large surface area of MIP nanoparticles leads to better and efficient template binding. Nanoparticles synthesized with a thin and uniform shell (core-shell MIP nanoparticles) have provided additional functional groups (amine, thiols) that can be advantageous for different analytical applications. In this thesis, the immobilization of both MIP and MIP core-shell nanoparticles on solid surfaces and the application of Surface-enhanced Raman scattering (SERS) on MIP-modified surfaces for the detection of an analyte (propranolol and nicotine) have been studied. In the first part of the thesis different covalent and electrostatic approaches for the immobilization of imprinted polymer nanoparticles on glass, silicon, and Au wafers are reported. The covalent approaches comprises photoconjugation, epoxide ring opening reactions, and carbodiimide chemistry. In the electrostatic approach a polymer interlayer has been used. The particles’ immobilized surfaces are characterized using different surface analytical techniques. The morphology and surface property of the particles’ surfaces are reported using scanning electron microscopy (SEM), atomic force microscopy (AFM), fluorescence microscopy, and water contact angle measurements. Further, the chemical analysis of the surfaces using x-ray photoelectron spectroscopy (XPS) confirms the functionalization of the solid surfaces before and after MIP immobilization. Finally, the template binding property (selectivity and specificity) of the immobilized particles are reported using autoradiography measurements. In the second part of the thesis I report the different surface morphologies for of the SERS detection of propranolol and nicotine sensing in imprinted nano- and micro sized polymer spheres. Nicotine-imprinted MIP spheres were immobilized on a Au wafer using surface thiols. After the confirmation of stable and dense particle attachment using SEM, the Au surfaces were made SERS active either using Au colloids or replacing Au with Raman-active Klarite surfaces. The propranolol-imprinted nanoparticles are attached to Klarite using a photoconjugation approach. Using SERS as the detection method I analyzed the binding capacity of the polymer sphere-coated transducer surface. The MIPs exhibit good specificity and selectivity in a complex biological sample.