4.8 Article

Sensitive, Highly Stable, and Anti-Fouling Electrode with Hexanethiol and Poly-A Modification for Exosomal microRNA Detection

Journal

ANALYTICAL CHEMISTRY
Volume 94, Issue 13, Pages 5382-5391

Publisher

AMER CHEMICAL SOC
DOI: 10.1021/acs.analchem.2c00069

Keywords

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Funding

  1. National Natural Science Foundation of China [21874019]
  2. Fujian Science and Technology Innovation Joint Found Project [2019Y9008]
  3. Science and Technology Plan Guided Project of the Fujian Provincial Science and Technology Department [2020Y0022]
  4. Natural Science Foundation of Fujian Province [2019J01681, 2020J01545]
  5. United Fujian Provincial Health and Education Project for Tackling the Key Research, China [WKJ2016-2-30]

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This research proposes a self-assembled electrode that combines different materials to address the challenges of electrochemical biosensors in practical applications. By using hexanethiol for forming a self-assembled monolayer, cholesteryl-modified DNA for increasing assembly efficiency and uniformity, and poly-adenine for enhancing anti-fouling ability, a dual-signal amplification electrochemical biosensor is developed for the detection of exosomal microRNAs, showing great sensitivity and potential utility in cancer diagnosis.
It remains a huge challenge to integrate the sensitivity, stability, reproducibility, and anti-fouling ability of electrochemical biosensors for practical applications. Herein, we propose a self-assembled electrode combining hexanethiol (HT),poly-adenine (poly-A), and cholesteryl-modified DNA to meet this challenge. HT can tightly pack at the electrode interface to form a hydrophobic self-assembled monolayer (SAM), effectively improving the stability and signal-to-noise ratio (SNR) of electrochemical detection. Cholesteryl-modified DNA was immobilized at theelectrode through the hydrophobic interaction with HT to avoidthe competition between the SAM and the DNA probe on the goldsite. Thus, the assembly efficiency and uniformity of the DNAprobe as well as the detection reproducibility were increasedremarkedly. Poly-A was added on the HT assembled electrode to occupy the unreacted sites of gold to further enhance the anti-fouling ability. The combination of HT and poly-A allows the electrode to ensure favorable anti-fouling ability without sacrificing the detection performance. On this basis, we proposed a dual-signal amplification electrochemical biosensor for the detection of exosomal microRNAs, which showed excellent sensitivity with a detection limit down to 1.46 aM. Importantly, this method has been successfully applied to detect exosomal microRNA-21 in cells and human serum samples, proving its potential utility in cancer diagnosis.

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