Detection of point mutations in DNA by PNA-based quartz-crystal biosensor

Currently there is an extensive search for biosensors for detecting genetic defects by hybridisation to immobilised oligonucleotides. A concept able t o detect a single mismatch in a 15mer single-strand target of the p53 tumor suppresser gene is presented (a mutation found in many types of cancer cel ls). In this method, the unique hybridisation properties of the DNA mimic p eptide nucleic acid (PNA) are combined with electronically detected mass an d shear dissipation at the surface of a quartz crystal. Cysteine-labeled PN A efficiently immobilises on crystal-gold surface at 20 degrees C. At 60 de grees C, addition of complementary DNA results in a signal response corresp onding to hybridisation between DNA and the PNA-covered surface, whereas ad dition of DNA differing in only one of the 15 bases gives no response at al l. (C) 2000 Elsevier Science B.V. All rights reserved.