Coupling hybridization chain reaction with catalytic hairpin assembly enables non-enzymatic and sensitive fluorescent detection of microRNA cancer biomarkers.

The identification and quantification of sequence-specific microRNAs (miRNAs) plays an important role in early diagnosis of different diseases. In this work, by integrating two independent signal amplification approaches, hybridization chain reaction and catalytic hairpin assembly, we report an enzyme-free and dual amplified approach for highly sensitive detection of a human prostate cancer biomarker, miR-141. The presence of miR-141 triggers the self-assembly of two hairpin DNAs into dsDNA polymers, which co-localize two split segments of ssDNA into proximity. Subsequently, these co-localized ssDNA sequences further act as triggers to initiate catalytic assembly of two fluorescently quenched hairpin DNAs to form numerous dsDNA strands, resulting in the recovery of the fluorescent emissions and remarkably amplified signals for highly sensitive detection of miR-141 down to 0.3 fM. In addition, this method is also selective for the target miRNA against other control sequences. With the advantages of high sensitivity and nanomaterial/enzyme-free detection format, the developed method can be a general sensing platform for the detection of trace amounts of sequence-specific nucleic acid targets.