A novel electrochemical approach for sensitive and simultaneous detection of 7,8-dihydro-8-oxoadenine and 2-hydroxyadenine based on a screen-printed carbon electrode modified with carbon-encapsulated Fe3O4.

Excessive reactive oxygen species attack DNA, resulting in the formation of oxidative guanine (oxoG) and oxidative adenine (oxoA) as significant types of oxidative DNA damage. Despite the similar carcinogenic potential and content levels of oxoA, there is still a lack of comprehensive studies and detection methodologies compared to oxoG. Herein, a novel electrochemical approach for sensitive and simultaneous detection of 7,8-dihydro-8-oxoadenine (8-oxoA) and 2-hydroxyadenine (2-oxoA) was first reported and designed using screen-printed carbon electrode (SPCE) modified with carbon-encapsulated Fe3O4 (Fe3O4@C). The SPCE modified with Fe3O4@C (Fe3O4@C/SPCE) exhibited excellent electrocatalytic performance for the simultaneous detection of 8-oxoA and 2-oxoA without requiring any enzymes. Although 8-oxoA and 2-oxoA are a pair of isomers, their oxidation peaks could be separated using differential pulse voltammetry. Under the optimal conditions, the corresponding limits of detection were 45.3 nM and 34.5 nM for 8-oxoA and 2-oxoA (S/N = 3), demonstrating high sensitivity and a wide linear range from 0.05 μM to 100 μM. The proposed electrochemical sensor was also applied to oxoA analysis in rat serum samples with satisfactory recovery values. Overall, Fe3O4@C/SPCE displayed a promising oxoA assay platform, which expands the choice of biomarkers in purine oxidation and contributes to describing DNA oxidative damage more comprehensively and accurately.