Enzyme-free signal amplification of analyte in a single closed tube by fluorescent hybridization chain reaction

Background: Hybridization chain reaction (HCR) is an attractive method to amplify the signal of targeted nucleic acids. Methods: Fluorescent HCR systems, including basic fluorescent HCR and real-time fluorescent HCR, were developed and evaluated in the present study. Results: Fluorescent HCR but not basic HCR could be performed by enzyme-free signal amplification in a single closed tube. In real-time fluorescent HCR, which was performed in only approximately 10 min, hybridization curves and hybridization logarithmic curves were developed to depict the hybridization thermodynamic kinetics of HCR. The results showed that the starting point of polymerization of fluorescent HCR was dependent on the concentration of initiator I. The low sensitivities of basic and fluorescent HCR (i.e., 0.05 μM) might be determined by the intrinsic features of monomer hairpins used in all of the above HCR systems. Although the sensitivities were not improved in fluorescent HCR compared to basic HCR, fluorescent HCR has a potential role in identification and analysis of amplified nucleic acid targets acting as initiators in HCR. Conclusions: Fluorescent HCR, including basic fluorescent HCR and real-time fluorescent HCR, is a fast, simple and robust method to identify various analytes in a single closed tube. Clin Chem Lab Med 2008;46:1384–7.