DNA hybridization techniques are being used increasingly for detection of genetic defects and disease diagnostics. High specificity can be achieved through the use of complementary single-stranded DNA probes to form target/probe double-stranded DNA hybrids, but visualization of hybrid double strands poses some difficulty. Hybrids are usually detected using fluorescent or chemiluminescent markers, which either intercalate into the double helix between base pairs or are covalently attached to either the probe or the target strands. However, these markers require the derivitization of the probe or target strands, which can introduce multiple labeling and contamination problems. Also, tedious sample handling is required, which further enhances the risk of contamination and of false identifications.

To overcome these problems, University of California researchers have developed a flow-through capillary biosensor for detecting target/probe hybrids in an underivitized state. The UC method also has the added advantage that, lacking additional sample preparation steps, sample dilution or loss can be minimized to enable detection of target DNA in nanoliter-sized volumes. Hybridization takes place inside the capillary tube (where high probe loading capacities can be attained), and the hybrids can be subsequently eluted from the tube with flow directed through a very sensitive detection system. The capillary can accomodate multiple probes characterized by different hybrid elution times, so the UC method can be used for assaying multiple targets in a single sample.

File Number: 10110 

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