Abstract
The electrochemical determination of 7-methylguanine (7-mG) may result of interest because its presence can serve as probe of cytosine methylation of which is known as the most relevant epigenetic modification of DNA. This work explores the electrochemical response of 7-mG on different gold surfaces, both poly and single crystalline surfaces (Au (110), Au (111) and Au (100)). The results show that the adsorption-desorption process of the 7-mG is sensitive to the surface structure of the gold electrodes. Particularly, 7-mG adsorption-desorption profile on a Au (111) electrode exhibits some specific contributions which are found sensitive to the 7-mG concentration and, thereby could allow its quantification. These results may shed light on the future development of an electrochemical sensor for the diagnosis of the methylation degree in DNA.
Highlights
By using electrochemical methods, this adsorption desorption process has been described to be sensitive to the surface structure of the Au electrode, that is, to its specific atomic arrangement. Taking advantage of this surface structure sensitivity, our preliminary results have previously demonstrated that the adsorption-desorption properties of cytosine (C) and methylcytosine on Au surfaces are highly sensitive to the surface structure
The results clearly Figure out how sensitive the adsorptiondesorption of G to the surface structure of the Au electrode is and very distinct and characteristic voltammetric signals are recorded for each surface orientation
If these voltammetric profiles performed at gold single crystals are compared with that observed for a polyoriented surface, it is possible to make a reasonably good assignation of each one of the broad contributions observed on the polyoriented surface due to its corresponding surface structure
Summary
DNA methylation is one of the most important epigenetic processes, and there is a vast literature describing the strong evidences about the correlation between methylation of DNA and alterations of gene expression. Alterations in the methylation pattern were found to be related to different diseases such as human carcinomas [2], leukemia [3], lung [4], thyroid [4], pancreas [4] and prostate [5] tumours, to mention a few examples. Despite 7-methylguanine (7-mG) is considered as non-promutagenic with minimal biological relevance [6], the development of analytical methods for its determination is of relevance since its presence and level increase, as a consequence of the presence of methylating agents, can be correlated to pro-mutagenic and carcinogenic, such as O6-methylguanine and methyladenine [7].
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