Development of a new detection method for DNA molecules

Abstract

A highly sensitive analysis method for biological molecules isrequired because of recent developments in molecular biology. Conventional highly sensitivedetection methods are based on labelling techniques using fluorescent dyes orenzymes. However, since those techniques involved some problems with signalinstability, a new technology has been sought. Because the superconducting interference device (SQUID) is an extremely highlysensitive magnetic sensor, it can be applied to the highly sensitive detection ofDNA labelled with small magnetic particles. The signal from SQUID is stable incontrast to fluorescent dyes and enzymes, therefore it permitshighly sensitive measurement over long periods of time.Sample coverslips on which the small magnetic particles were anchored usingbiotin labelled DNA were prepared to demonstrate the availability of thismethod. Scanning the high-Tc SQUID sensor on the coverslip demonstratedthat the magnetic flux on the coverslip agreed well with the pattern of labelled DNAanchored on the coverslip. This result suggests that SQUID can be applied forthe specific detection of DNA molecules, especially for the detection of DNA chips.