A colorimetric biosensor for detection of attomolar microRNA with a functional nucleic acid-based amplification machine

• Published in: Talanta (Oxford) 2016-01, Vol.146, p.470-476
• Main Authors: Li, Dandan, Cheng, Wei, Yan, Yurong, Zhang, Ye, Yin, Yibing, Ju, Huangxian, Ding, Shijia
• Format: Article
• Language: English
• Subjects: Base Sequence; Biosensing Techniques - methods; Colorimetric biosensing; Colorimetry - methods; DNAzyme; Humans; Limit of Detection; MCF-7 Cells; MicroRNA; MicroRNAs - analysis; MicroRNAs - genetics; Nucleic Acid Amplification Techniques - methods; Oligonucleotide Probes - genetics; Signal amplification; Time Factors; Toehold initiated rolling circle amplification
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/j.talanta.2015.09.010

A functional nucleic acid-based amplification machine was designed for simple and label-free ultrasensitive colorimetric biosensing of microRNA (miRNA). The amplification machine was composed of a complex of trigger template and C-rich DNA modified molecular beacon (MB) and G-rich DNA (GDNA) as the probe, polymerase and nicking enzyme, and a dumbbell-shaped amplification template. The presence of target miRNA triggered MB mediated strand displacement to cyclically release nicking triggers, which led to a toehold initiated rolling circle amplification to produce large amounts of GDNAs. The formed GDNAs could stack with hemin to form G-quadruplex/hemin DNAzyme, a well-known horseradish peroxidase (HRP) mimic, for catalyzing a colorimetric reaction. The modified MB improved the stringent target recognition and reduced background signal. The proposed sensing strategy showed very high sensitivity and selectivity with a wide dynamic range from 10aM to 1.0nM, and enabled successful visual analysis of trace amount of miRNA in real sample by the naked eye. This rapid and highly efficient signal amplification strategy provided a simple and sensitive platform for miRNA detection. It would be a versatile and powerful tool for clinical molecular diagnostics. [Display omitted] •A functional nucleic acid-based amplification machine is designed for ultrasensitive biosensing of microRNA.•The machine integrates the advantages of enzymatic signal amplification and toehold initiated rolling circle amplification.•The modified molecular beacon improves the stringent target recognition and reduces background signal.•The machine leads to a mass of DNAzyme for one recognition event and thus an ultrasensitive colorimetric and visual method for detection of miRNAs.•The biosensing method shows attomolar-level detection limit, a detection range of 9 orders of magnitude for practical sample analysis.