Patent ID: 7230092

Claim:
A unimolecular probe for hybridization to a molecule comprising a target nucleic acid sequence, the probe comprising: (i) a first nucleic acid sequence complementary to the target nuclic acid sequence and comprising a first portion and a second portion; (ii) a second nucleic acid sequence complementary to the first portion of the first nucleic acid sequence and capable of hybridization therewith to form a first intramolecular duplex comprising a first hairpin structure under a defined set of conditions, the first intramolecular duplex including a portion of the first nucleic acid sequence complementary to the target nucleic acid sequence; and (iii) third and fourth nucleic acid sequences, the third and fourth nucleic acid sequences being complementary to each other and linked to each other so as to hybridize to form a second intramolecular duplex comprising a second hairpin structure under said set of conditions, wherein the second portion of the first nucleic acid sequence comprises a single standed region covalently attached to the third nucleic acid sequence and is located between the first and second intramolecular duplexes, and under said set of conditions and in the presence of the target nucleic acid sequence, the single standed region acts as a nucleic acid sequence such that hybrization of the target nucleic acid sequence and first nucleic acid sequence disrupts the first intramolecular duplex to form an intermolecular duplex.