Detection of microRNA using a polydopamine mediated bimetallic SERS substrate and a re-circulated enzymatic amplification system
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A surface-enhanced Raman scattering (SERS) method is described for the determination of microRNA that is associated with various forms of cancer. The substrate consists of functionalized gold-silver bimetallic structure, and the sensitivity is strongly enhanced by making use of a re-circulated enzymatic amplification system (REAS). Poly-dopamine acts as both a reductant and a protective of the substrates. It was employed to link the gold core and silver satellite. The unique “hot spots” consisting of a Au@PDA@Ag nanocomposite improve the Raman signal and sensitivity. The reductive feature of PDA can prevent the susceptible oxidation of metallic silver to maintain the high Raman activity. To improve the sensitivity of the assays, a re-circulated enzymatic amplification system was developed in which the nicking endonuclease triggers the nucleic acid reaction system to enter an amplified cycle. By integrating the bimetallic nanosubstrate and magnetic separation into the REAS, microRNA can be detected by SERS (best at the Raman band of 1586 cm−1) with a limit of detection as low as 0.2 fM. In our perception, the assay provides an exciting new avenue to study the expression of tumor genes. Thus, it holds vast promise in cancer diagnosis.
KeywordsPolydopamine Bimetallic substrate Re-circulated enzymatic amplification Magnetic nanoparticles Nanocomposite
This research has been supported by National Natural Science Foundation of China (NSFC) (Grant nos. 21273083 and U1732146) and the Project under Scientific and Technological Planning Grant nos. 201805010002 by Guangzhou City.
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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