Design of a piezoelectric gene-sensor using base-specific drug-functionalized nano-microspheres as amplifying probes

A gene sensor was designed using actinomycin D-functionalized magnetic nano-microspheres, which can interact with double-stranded DNAs (dsDNAs) anchored on the gold film electrode of an electrochemical quartz crystal microbalance (EQCM). Actinomycin D acts as a guide that leads heavy microspheres onto the dsDNAs at the EQCM film. A magnetic separation shelf could separate unreacted microspheres conveniently. The modification and DNA hybridization at EQCM electrodes were examined by microgravimetric and electrochemical methods so that an outstanding change in frequency decrease has been detected owing to the mass increase on the EQCM electrodes. The limit for the determination of target DNA could be improved from 6.2/spl times/10/sup -8/ to 2.0/spl times/ 10/sup -12/ mol l/sup -1/ by the amplifying technique.