Coupling of a DNA piezoelectric biosensor and polymerase chain reaction todetect apolipoprotein E polymorphisms

In this paper we report the coupling of the Polymerase Chain Reaction (PCR) with a piezoelectric biosensor to detect a point mutation in a human gene. Biotinylated 23-mer probes were immobilised on the streptavidin coated gol d surface of a quartz crystal; streptavidin was covalently bound to the thi ol/dextran modified gold surface. The hybridisation of the immobilised prob es with a short sequence (23 mer) complementary, non-complementary and mism atched DNA was investigated: the device was able to distinguish the differe nt synthetic oligonucleotides. Many cycles of measurements can be performed on the same crystal surface regenerating the single strand of DNA with 1 m M of HCl. The same hybridisation reaction was then performed using real sam ples of human DNA extracted from blood and amplified by PCR, following a st andard procedure for genetic detection of the polymorphism of the apolipopr otein E (apoE) gene. The procedure was able to distinguish the sequences pr esent in the different samples, which differ only in one base: in this way it was possible distinguish between different groups of genotypes with apoE typing. Experiments with 'blank' samples confirmed the absence of adsorpti on or non-specific effects on the quartz crystal treated with the reported procedure. (C) 2000 Elsevier Science S.A. All rights reserved.