Hydrosilylation reactions for a silicon cantilever-based biosensor

COLL 526

Joseph W. Tringe1, Bradley R. Hart, and Brandon L Weeks2. (1) Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, P.O. Box 808, L-232, Livermore, CA 94551-9900, (2) Biosecurity Support Laboratory, Lawrence Livermore National Laboratory, Chemistry and Materials Science Division, Livermore, CA 94551
Silicon micromachined cantilevers, chemically functionalized on one side, are extremely sensitive to surface stresses induced by small concentrations of pathogens and biologically active molecules in liquids. Cantilever-based sensors are therefore promising as in-situ monitors of environmental conditions and in pharmaceutical development. We report here on cantilevers that have been electrically isolated with silicon dioxide or silicon nitride to allow for piezoresistive sensing in liquid. For robust surface functionalization, a thin film of silicon was subsequently physically vapor-deposited on one side of the cantilever only. The silicon surface was then modified with a linker molecule via a hydrosilylation reaction. The linker molecule was designed to allow one end to react with the silicon surface; the opposite end contains an electrophilic group allowing for specific reactions. For this work, cantilevers were exposed to 3¢-amino modified single-stranded DNA. The sensitivity of the cantilevers to the hybridization of complementary single-stranded DNA is reported.