Patent ID: 6833242
Filing Date: 2004-12-21
Classification: B01L,C12Q,G01N

Abstract:
A method for detecting a particular nucleic acid in a sample, which particular nucleic acid has at least one restriction site, and which method comprises:(a) contacting the sample with (i.) a primer that hybridizes to the particular nucleic acid a predetermined distance from the restriction site, (ii.) a polymerase and (iii.) a plurality of nucleotides, so that a complementary nucleic acid is synthesized from the primer at least to the restriction site; (b) contacting the complementary nucleic acid with a restriction enzyme under conditions capable of cutting the complementary nucleic acid at the restriction site; and (c) detecting a nucleic acid fragment having a particular length equal to the fixed distance by a method that comprises: (i) sorting polynucleotide molecules in the sample according to size in a device for processing a flow of polynucleotide molecules, which device comprises a substrate and an analysis unit, wherein the analysis unit comprises: a main channel having a polynucleotide sample inlet, a detection region downstream of the sample inlet and a branch point discrimination region adjacent to and downstream of the detection region, wherein on average one polynucleotide molecule at a time is placed within the detection region; at least two branch channels originating at the branch point discrimination region and in communication with the main channel; a detector sensitive to polynucleotide molecules passing through the detection region; and a flow control responsive to the detector and acting to direct polynucleotide molecules at the discrimination region into a selected branch channel; and (ii) identifying a polynucleotide having the particular length, wherein the presence of the nucleic acid fragment in the sample indicates that the particular nucleic acid is present in the sample.