| AVS 55th International Symposium & Exhibition | |
| Biological, Organic, and Soft Materials Focus Topic | Thursday Sessions |
| Session BO+EM+BI+NC-ThM |
| Session: | Semiconducting Biointerfaces and Sensors |
| Presenter: | W. Kulisch, European Commission Joint Research Center, Italy |
| Authors: | W. Kulisch, European Commission Joint Research Center, Italy D. Gilliland, European Commission Joint Research Center, Italy G. Ceccone, European Commission Joint Research Center, Italy L. Sirghi, European Commission Joint Research Center, Italy F. Rossi, European Commission Joint Research Center, Italy H. Rauscher, European Commission Joint Research Center, Italy |
| Correspondent: | Click to Email |
Optical waveguide biosensors frequently require the use high refractive index thin films such as tantalum pentoxide to act as both as a light guide and as a surface on which active biomolecules can be covalently immobilized. In this work, a process for the room temperature deposition of Ta2O5 films onto silicon/silica and thermoplast substrates by reactive ion beam sputtering from a tantalum target has been developed. The resultant high refractive index films have been chemically and optically characterized and methods examined for the wet chemical modification of the oxide film to produce either reactive amino groups or low protein fouling polyethylene glycol (PEG) layers. In both cases the first step toward the functionalization of the as-grown films used either an oxygen plasma or to an UV/O3 treatment to produce a clean and fully oxidized surface. Using these clean, active surfaces-NH2 terminated SAMs could be routinely produced using a conventional silanization process using 3-aminopropyl trimethoxysilane (APTMS). To produce high density, low protein binding (anti-fouling) layers a more sophisticated procedure based on surface initiated atom transfer radical polymerization (SI-ATRP) of poly(ethylenglycol)methacrylate (PEGMA) has been used. In this method the oxide surface is firstly modified using a combination of poly(glycidylmethacrylate) (PGMA) and α-bromoisobutyryl bromide (BIB) to produce a surface rich in tethered α-bromoisobutyryl groups. These BIB groups can then used as initiation sites for the growth of dense PEG films using the copper complex catalysed ATRP of PEGMA macromonomers. To characterize the final surfaces and to assist in the optimization of process, time-of-flight secondary ion mass spectrometry (TOF-SIMS), X-ray photoelectron spectroscopy (XPS), contact angle measurements and atomic force microscopy (AFM) have been applied to samples after each step of the different processes. The effectiveness of the two processes will be demonstrated and examples given of methods by which the two methods have been combined for the production of fouling/non-fouling micropatterned surfaces.