Electrochemical, electrochemiluminescent and photoelectrochemical bioanalysis of epigenetic modifiers: A comprehensive review

Epigenetic modifications mainly includes nucleic modifications and histone modifications, which play crucial role in biological processes, such as gene and microRNA expression, DNA-protein interactions, suppression of transposable element mobility, etc. The abnormal expression of epigenetic modifiers is related to various diseases. Thus, the quantitative analysis of epigenetic modifiers is crucial to early diagnosis of disease, drug screening, prognosis of disease treatment, discovery of new biological function. Up to now, various methods have been developed for epigenetic modifier detection, including thin layer chromatography, northern blotting, microarray, chromatography-based technology, fluorescence, colorimetry, surface plasmon resonance, surface enhanced Raman spectroscopy, electrochemistry, etc. Among them, electrochemical-based techniques have received widespread attentions due to the merits of simple operation, fast response, radioactive labeling-free, low-dose reagent, inexpensive and portable instrument, high sensitivity. Therefore, in this paper, the application of electrochemical techniques for determining epigenetic biomarkers in last ten years are reviewed, in which the electrochemical techniques include electrochemistry, photoelectrochemistry and electrochemiluminescence, and the epigenetic modifiers contain DNA methylation (5-methylcytosine and 7-methylguanine), DNA hydroxymethylation (5-hydroxymethylcytosine), DNA formylation (5-formylcytosine), RNA methylation (N6-methyladenosine), protein phosphorylation and protein acetylation. In addition, application of these techniques for the determination of the relative enzymes is also reviewed. Moreover, the research trends and challenges in the development of electrochemical-based methods for monitoring epigenetic biomarkers were discussed.