Colloidal Au is reported for enhancement the immobilization capacity and ultimately detection limit of DNA using quartz crystal microbalance (QCM). Immobilization of similar to 12 nm-diameter colloidal Au on to an An-coated QCM resulted in an easier attachment of oligonucleotide, with a mercaptohexyl group at the 5'-phosphate end and an increased capacity for nucleic acid detection, DNA immobilization and hybridization was monitored from QCM frequency changes, Hybridization was induced by exposure of the DNA-containing films to complementary DNA in solution, A much higher sensitivity was obtained for the analyte. The Au nanoparticle films on the Au plate provide a novel means for the fabrication of DNA sensor,