A novel surface plasmon resonance biosensor for enzyme-free and highly sensitive detection of microRNA based on multi component nucleic acid enzyme (MNAzyme)-mediated catalyzed hairpin assembly

MicroRNAs (miRNAs) are potentially useful biomarkers for early diagnosis of human diseases. Here, a simple surface plasmon resonance (SPR) biosensor has been developed for highly sensitive detection of miRNA by designing a new enzyme-free and isothermal amplification strategy, named multi component nucleic acid enzyme-mediated mismatched catalyzed hairpin assembly (MNAzyme-CHA). The partial MNAzymes co-recognized the target to form a stable active MNAzyme, which continued to digest multiple hairpin H0 substrates, concomitantly generating a lot of fragments. The H0 fragments could initiate the mismatched CHA cycles, resulting in the generation of massive hairpin H1-H2 complexes. As a result, the H1-H2 complexes and streptavidin were attached to the sensor surface, leading to a significantly amplified SPR signal readout. The established biosensor showed high sensitivity and selectivity with a wide dynamic range from 1 pM to 100 nM. It was also successfully applied to the determination of target miRNA spiked into human total RNA samples. Thus, this developed biosensing strategy presents a simple and stable platform toward sensitive and convenient miRNA detection, and has great potential in assays of many other nucleic acids analytes for biomedical research and early clinical diagnosis. (C) 2016 Elsevier B.V. All rights reserved.