Surface plasmon resonance biosensor for highly sensitive detection of microRNA based on DNA super-sandwich assemblies and streptavidin signal amplification

• An enzyme-free and rapid SPR sensing strategy has been developed for miRNA detection.
• DNA super-sandwich assembly and streptavidin were used for dual signal amplification.
• The developed method showed high sensitivity and specificity for detection of miRNA.
• The biosensor performed well in analyzing extractions from MCF-7 cells.

MicroRNAs (miRNAs) play an important regulatory role in cells and dysregulation of miRNA has been associated with a variety of diseases, making them a promising biomarker. In this work, a novel biosensing strategy has been developed for label-free detection of miRNA using surface plasmon resonance (SPR) coupled with DNA super-sandwich assemblies and biotin–strepavidin based amplification. The target miRNA is selectively captured by surface-bound DNA probes. After hybridization, streptavidin is employed for signal amplification via binding with biotin on the long DNA super-sandwich assemblies, resulting in a large increase of the SPR signal. The method shows very high sensitivity, capable of detecting miRNA at the concentration down to 9 pM with a wide dynamic range of 6 orders of magnitude (from 1 × 10−11 M to 1 × 10−6 M) in 30 min, and excellent specificity with discriminating a single base mismatched miRNA sequence. This biosensor exhibits good reproducibility and precision, and has been successfully applied to the detection of miRNA in total RNA samples extracted from human breast adenocarcinoma MCF-7 cells. It, therefore, offers a highly effective alternative approach for miRNA detection in biomedical research and clinical diagnosis.

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