Reactive oxygen species may damage DNA by oxidizing guanine (G) to 8-hydroxyguanine (8-OH-G), a compound which has been implicated in Alzheimer’s disease, Parkinson’s disease, as well as some cancers. A recent study suggests that 8-OH-G detected in saliva can be a biomarker for oxidative stress in workers. Although several analytical methods such as gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatography (HPLC), exist for the detection of G and 8-OH-G, these methods are expensive, lack portability, and require highly trained technicians. Therefore, the detection of 8-OH-G and G is imperative since the accurate detection and measurement of these metabolites may prove useful for the early detection of these diseases.<br/>In this study inspired by similar electrodes developed by Gooding et al., gold nanoparticles (AuNPs) were immobilized on glassy carbon electrode (GCE) surfaces using a surface-anchored diazonium salt of 4-aminothiophenol (GCE-Ph-S-AuNPs). X-ray photoelectron spectroscopy (XPS) results confirmed the attachment of the AuNPs via 4-thiophenol onto the surface of the modified electrode. Differential pulse voltammetry (DPV) was performed for the simultaneous determination of guanine (G) and 8-hydroxyguanine (8-OH-G). The calibration curves were linear up to 140 µM and 60 µM with a detection of limit of 0.020 µM and 0.021 µM for G and 8-OH-G, respectively. Moreover, chronoamperometric studies were carried out for the determination of diffusion coefficients of 8-OH-G and G. The GCE-Ph-S-AuNPs was also applied for the determination of G and 8-OH-G in genomic DNA-spiked samples with recovery rates between 98.5% and 103.3%. This novel electrochemical sensor provided a potential point-of-care platform for sensitive detection of 8-OH-G related to the oxidative stress-induced DNA damage in cancer research.

Modification of gold nanoparticles on 4-thiophenol functionalized carbon surfaces for the simultaneous detection of 8-hydroxyguanine and guanine

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ACS Fall 2022

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