Patent ID: 6300141
Filing Date: 2001-10-09
Classification: G01N

Abstract:
A diagnostic card device for use in detecting or quantitating an analyte present in a liquid sample, comprising,a card substrate having formed therein a sample introduction region, a biosensor, and a sample-flow pathway communicating between said sample-introduction region and said biosensor,circuitry for generating an analyte-dependent electrical signal from the biosensor; and,a signal-responsive element for recording said signal,wherein said biosensor has a detection surface with surface-bound molecules of a first charged, coil-forming peptide for interacting with a second, oppositely charged coil-forming peptide to form a stable .alpha.-helical coiled-coil heterodimer, where the binding of the second peptide to the first peptide, to form said heterodimer, is effective to measurably alter a signal generated by the biosensor, and said sample-flow pathway contains (i) a conjugate of (ia) the second coil-forming peptide and (ib) the analyte or an analyte analog, and (ii) an analyte-binding agent immobilized within the pathway, wherein sample introduced in said sample introduction region is carried through the sample-flow pathway, where the analyte competes with said conjugate for binding to said analyte-binding agent, such that the presence of increasing amounts of analyte leads to increasing amounts of unbound conjugate which is then free to react with said first peptide in said biosensor to alter the signal generated by the biosensor in proportion to the amount of analyte present.