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

Abstract

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 the electrode through the hydrophobic interaction with HT to avoid the competition between the SAM and the DNA probe on the gold site. Thus, the assembly efficiency and uniformity of the DNA probe as well as the detection reproducibility were increased remarkedly. Poly-A was added on the HT assembled electrode to occupy the unreacted sites of gold to further enhance the antifouling 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.

Base-Stacking-Driven Catalytic Hairpin Assembly: A Nucleic Acid Amplification Reaction Using Electrode Interface as a “Booster” for SARS-CoV-2 Point-of-Care Testing

“…The polished GE was scanned by cyclic voltammetry (CV) in 0.5 M H 2 SO 4 until the curves were stable. Considering the high performance of the HT self-assembly monolayer, the HT-assembled electrode was used for constructing the BDCHA electrochemical biosensor according to our previous work . The GE was immersed in 10 mM HT for 1 h at room temperature.…”

“…Other methods , used separation technology to separate the steps of “amplification” and “capture” in order to benefit from low consumption and portability of heterogeneous reactions and high reaction efficiency of homogeneous reactions. That is, electrochemical detection was performed after amplification in solution, which enhanced the reaction efficiency and detection sensitivity.…”

“…15 In terms of the amplification reaction efficiency, the negative effect of excessive intermediate products resulting from insufficient strand displacement should also be considered. 16 Other methods 17,18 used separation technology to separate the steps of "amplification" and "capture" in order to benefit from low consumption and portability of heterogeneous reactions and high reaction efficiency of homogeneous reactions. That is, electrochemical detection was performed after amplification in solution, which enhanced the reaction efficiency and detection sensitivity.…”

In situdetection of miRNA-21 in MCF-7 cell-derived extracellular vesicles using the red blood cell membrane vesicle strategy

“…Therefore, in situ detection of miRNAs in EVs holds great promise for the non-invasive and credible diagnosis of cancer. 10,11 MicroRNAs (miRNAs) are endogenous regulatory singlestranded RNAs, short strands of which contain approximately 19-23 nucleotides. Currently, tumour-associated miRNAs have been identified as a reliable biomarker for cancer diagnosis.…”

“…Therefore, in situ detection of miRNAs in EVs holds great promise for the non-invasive and credible diagnosis of cancer. 10,11…”