Preparation of polymer brush-nanoparticle hybrid systems and their biosensor applications

In the first part of this study, temperature sensitive poly((2-methoxyethoxy)ethyl) methacrylate [P(MEO2-MA)] brushes with sulfıdryl end group on silicon (100) disc surface were synthesized via reversible addition-fragmentation chain transfer polymerization. The structural characterizations of P(MEO2-MA) brushes were carried out by X-ray photoelectron spectroscopy (XPS) and grazin angle Fourier transform infrared spectroscopy (GA-FTIR). Their hydrophilic/hydrophobic characters and surface morphologies were conducted by water contact angle measurements and atomic force microscopy (AFM), respectively. As the results of ellipsometry characterization, thickness, grafting density and distance of two adjacent macromolecules were found to be 27 nnm, 0.7 chain/nm2 and 1.35 nm, respectively. The P(MEO2-MA) brushes had a phase transition temperature at 34 ?C determined by temperature controlled water contact angle measurements. Polymer brush-nanoparticle hybrid systems were prepared after immobilization of gold nanoparticles with an avagare diameter of 15 nm on polymer brushes. The gold nanoparticle density on the hybrid system by AFM was calculated as 185 particles/nm2. ?Sandwich type? DNA hybridizations were done on the hybrid system for Hepatit B detection and based on surface enhanced Raman spectroscopy (SERS). The limit of detection for Hepatit B was found to be as 0.44 fM and 0.13 fM at room temperature and above phase transition temperature, respectively. Moreover, detailed analysis of the hybrid systems showed that they can be potentially used in clinical applications. In the second part of this study, silica nanoparticles with an avarege diameter of 62 nm were first prepared and then poly(glycidyl methacrylate) PGMA brushes with an average thickness of 7 nm were synthesized via reversible chain transfer catalyzed polymerization (RCTP) on the silica nanoparticles after the modification with 3-iodotrimethoxysilane (IPTS). Anti-carsinio embryogenic antigen (anti-CEA) and embryogenic antigen (CEA) molecules were bound on the polymer brushes. Meanwhile, magnetic silver nanoparticles were also synthesized and modified with Raman reporter molecules and anti-CEA to be based on SERS of the prepared hybrid system. Finaly, ?Sandwich complexes? were produced between CEA coated silica nanoparticles and anti-CEA coated magnetic silver nanoparticles.The detection limit of the hybrid system was found to be 0.08 ng/mL without an external magnetic field and 1 pg/mL with an external magnetic field. The results of these studies also indicated that the hybrid system can be potentially used in clinical applications such as lung cancer detection.