Patent ID: 7195867

Claim:
A method for sequentially detecting multiple target nucleic acid fragments in a test sample comprises the steps of: (a) adding a test sample containing single strand target nucleic acid fragments into a test column, said column having a plurality of snares which are spaced apart along a longitudinal axis of said column and separated one from another by an intervening air space; at least one of said snares being a test snare having thereon at least two different single strand target capture DNA sequences, a first target capture DNA sequence being specific to a first target nucleic acid fragment in said test sample and a second target capture DNA sequence being specific to a second target nucleic acid fragment in said test sample; and wherein said first target nucleic acid fragment binds to said first target capture DNA sequence on said snare by forming a double strand target nucleic acid segment at a capture binding site of said first target nucleic acid fragment and said second target nucleic acid fragment binds to said second target capture DNA sequence on said snare by forming a double strand target nucleic acid segment at a capture binding site of said second target nucleic acid fragment; (b) washing said test column to remove unbound nucleic acid fragments; (c) adding a first single strand DNA probe to attach specifically to a probe binding site of said first target nucleic acid fragment, said first probe having thereon a first chemical label; (d) washing said test column to remove unbound first probe; (e) adding a first triggering solution to trigger said first chemical label; (f) detecting signals generated by said first chemical label on said test snare for determining the presence of said first target nucleic acid fragment; (g) washing said test column to remove said first triggering solution; (h) adding a second single strand DNA probe to attach specifically to a probe binding site of said second target nucleic acid fragment, said second probe having thereon a second chemical label; (i) washing said test column to remove unbound second probe; (j) adding a second triggering solution to trigger said second chemical label; and (k) detecting signals generated by said second chemical label on said test snare for determining the presence of said second target nucleic acid fragment.