A ratiometric fluorescent biosensor based on self-fluorescent MOF and target-triggered rolling circle amplification for sensitive detection of exosome-derived miRNA

• Published in: Analytica chimica acta 2022-08, Vol.1221, p.340136-340136, Article 340136
• Main Authors: Sun, Zhiwei, Li, Juan, Tong, Yao, Han, Hecheng, Yang, Yufei, Wang, Chuanxin, Li, Hui, Du, Lutao, Jiang, Yanyan
• Format: Article
• Language: English
• Subjects: Biosensor; Exosomal miRNAs; Metal-organic framework; Ratiometric fluorescence; Rolling circle amplification
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2022.340136

MicroRNAs (miRNAs) are considered as biomarkers and display great potential in the diagnosis of diseases. As a colorectal cancer (CRC)-associated miRNA biomarker, miR-92a-3p possesses higher concentration in exosomes than in serum, causing it more feasible to diagnose CRC by measuring the concentration of miR-92a-3p inside exosomes. Herein, a rationally-engineered ratiometric fluorescent biosensor is proposed to detect the concentration of exosomal miR-92a-3p. The metal-organic framework (MOF-525) with self-fluorescence serves as both a fluorescent reference and a quencher of the fluorescence of single-stranded reporter by adsorption. The presence of miR-92a-3p triggers the looping of 5P-template strand and the further periodic rolling circle amplification. The periodic long strands and the reporters can form double strands to prevent the reporters from being adsorbed by MOF-525. The concentration of miR-92a-3p is positively correlated with the Δreporter/MOF-525 fluorescence intensity ratio. The biosensor exhibits a detection range of 0.1–10 pM and can differentiate miR-92a-3p from mismatched RNA sequences. The accuracy and practicality of the proposed biosensor for exosomal miRNA detection were evaluated by comparing with the conventional RT-qPCR. The as-obtained results are close to those of the RT-qPCR. This ratiometric fluorescent biosensor holds the potential for the sensitive detection of exosomal miRNA. [Display omitted] •MOF-525 performs the dual functions of quencher and internal fluorescence reference.•Target-triggered rolling circle amplification was introduced for biosensing.•The biosensor exhibits high sensitivity for detecting clinical exosomal miRNA.