DNA-point mutation detection based on DNA ligase reaction and nano-Au amplification: A piezoelectric approach

A novel piezoelectric method for DNA point mutation detection based on DNA ligase reaction and nano-Au-amplified DNA probes is proposed. A capture probe was designed with the potential point mutation site located at the 3 ' end and a thiol group at the 5 ' end to be immobilized on the gold electrode surface of quartz crystal microbalance (QCM). Successive hybridization with the target DNA and detection probe of nano-Au-labeled DNA forms a double-strand DNA (dsDNA). After the DNA ligase reaction and denaturing at an elevated temperature, the QCM frequency would revert to the original value for the target with single-base mismatch, whereas a reduced frequency response would be obtained for the case of the perfect match target. In this way, the purpose of point mutation discrimination could be achieved. The current approach is demonstrated with the identification of a single-base mutation in artificial codon CD 17 of the beta-thalassemia gene, and the wild type and mutant type were discriminated successfully. The scanning electron microscope (SEM) image showing that plenty of gold natioparticles remained on the electrode surface demonstrated that the nano-Au label served as an efficient signal amplification agent in QCM assay. A detection limit of 2.6 x 10(-9) mol/L of oligonucleotides was achieved. Owing to its ease of operation and low detection limit.. it is expected that the proposed procedure may hold great promise in both research-based and clinical genomic assays. (c) 2006 Published by Elsevier Inc.