Trace and Label-Free MicroRNA Detection Using Oligonucleotide Encapsulated Silver Nanoclusters as Probes

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• 作者：Haifeng Dong ; Shi Jin ; Huangxian Ju ; Kaihong Hao ; Li-Ping Xu ; Huiting Lu ; Xueji Zhang
• 刊名：Analytical Chemistry
• 出版年：2012
• 出版时间：October 16, 2012
• 年：2012
• 卷：84
• 期：20
• 页码：8670-8674
• 全文大小：302K
• 年卷期：v.84,no.20(October 16, 2012)
• ISSN：1520-6882

文摘

A simple, sensitive, and label-free method for microRNA (miRNA) biosensing was described using oligonucleotide encapsulated silver nanoclusters (Ag-NCs) as effective electrochemical probes. The functional oligonucleotide probe integrates both recognition sequence for hybridization and template sequence for in situ synthesis of Ag-NCs, which appears to possess exceptional metal mimic enzyme properties for catalyzing H₂O₂ reduction. The miRNA assay employs gold electrodes to immobilize the molecular beacon (MB) probe. After the MB probe subsequently hybridizes with the target and functional probe, the oligonucleotide encapsulated Ag-NCs are brought to the electrode surface and produce a detection signal, in response to H₂O₂ reduction. An electrochemical miRNA biosensor down to 67 fM with a linear range of 5 orders of magnitude was obtained. Meanwhile, the MB probe allows the biosensor to detect the target with high selectivity. The Ag-NCs-based approach provides a novel avenue to detect miRNA with high sensitivity and selectivity while avoiding laborious label and signal amplification. It is convinced that rational introduction of signal amplification strategy to the Ag-NCs-based bioanalysis can further improve the sensitivity. To our best knowledge, this is the first application of the electrocatalytic activity of Ag-NCs in bioanalysis, which would be attractive for genetic analysis and clinic biomedical application.