Fast biosensor-based system for measuring total DNA in protein solutions

We report the quantitation of picogram levels of DNA, with a fast, reproducible, and non-isotopic assay system. Two DNA binding proteins are used, one to link DNA in the sample to a membrane and the other to label DNA with an enzyme. Enzyme levels are quantitated with very high sensitivity, by monitoring surface potential changes with a proprietary biosensor, as the enzyme changes its local pH. With this configuration, the assay is generic, detecting the presence of any DNA in the sample; that is, there is no specific hybridization probe involved. The prototype system involves instrumentation, software, plastic disposables, and reagents. With a simple protocol, it allows the user to determine the DNA levels, in the range of 2 to 100 pg, concurrently in multiple samples, with standards, with a total processing time of less than one hour, after sample pretreatment. Representative data will be shown. Essentially the same material presented here appeared in a poster session at the 2nd Annual Symposium on Analytical Biotechnology, Baltimore, Maryland, May 1988.