Development of a new detection method for DNA molecules

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