Ultra sensitive probes for detection of nucleic acid

A composition comprising:

• a) a target probe capable of hybridizing to a target nucleic acid, said target probe comprising a pre-bridge region having a tail palindromic sequence;
• b) at least one bridge probe, wherein the bridge probe comprises sequentially
• (i) a first region having a head palindromic sequence;
• (ii) a second region having a gap sequence;
• (iii) a third region having the tail palindromic sequence;
• and
• c) a label probe capable of hybridizing to the bridge probe, said label probe comprising a label.

A method of detecting a target nucleic acid in a sample, said method comprising:

• a) contacting a target probe to the target nucleic acid, wherein the target probe is capable of hybridizing to the target nucleic acid and comprises a pre-bridge region having a tail nucleotide sequence;
• b) associating a first bridge probe, a second bridge probe and a label probe with the target probe, wherein:
• the first bridge probe comprises sequentially
• (i) a first head region having a first head nucleotide sequence;
• (ii) a first gap region having a gap nucleotide sequence;
• and
• (iii) a first tail region having the tail nucleotide sequence;
• the second bridge probe comprises sequentially
• (i) a second head region having a second head nucleotide sequence complementary to the first head nucleotide sequence;
• (ii) a second gap region having the gap nucleotide sequence;
• (iii) a second tail region having a second tail nucleotide sequence complementary to the first tail nucleotide sequence;
• the label probe capable of hybridizing to the bridge probe, said label probe comprising a label;
• and
• c) detecting the presence, absence, or amount of the label probe associated with the target molecule.