Colorimetric readout of hybridization chain reaction

A method of identifying an aggregated nucleic acid structure in a sample, the method comprising:

• a) providing a first nucleic acid construct comprising a duplex region, a first loop region, and an initiator complement region that is substantially complementary to an initiation region of an initiator nucleic acid;
• b) providing a second nucleic acid construct comprising a second duplex region, at least one second loop region, and a first nucleic acid complementary region that is substantially complementary to the initiator complement region of the first monomer, wherein upon binding of an initiator nucleic acid to the first nucleic acid construct, the first and second monomers aggregate to form an aggregated nucleic acid structure;
• c) providing a detection component comprising one or more nano-gold particles, and
• e) identifying the presence of the aggregated nucleic acid structure in the sample by observing a color change in the nano-gold particles.

An kit for the detection of an analyte in a sample, the kit comprising:

• a) a first metastable nucleic acid monomer comprising an initiator complement region;
• b) a second metastable nucleic acid monomer comprising a propagation region that is substantially complementary to a portion of the first nucleic acid;
• and
• c) a detection component comprising a nano-gold particle.