Electrochemical sensing and simultaneous determination of guanine and adenine based on covalent organic frameworks/NH2-rG/MoS2 modified glassy carbon electrode

Alteration in the concentrations of guanine (G) and adenine (A) leads to various abnormalities in the metabolic process which causes various diseases. Therefore, it still remains a challenge to establish an accurate, simple and accurate method for simultaneous detection of guanine and adenine. In this paper, using covalent organic frameworks (COFs) as a carrier and the amino functionalized reduced graphene oxide as charge transfer accelerator, layer molybdenum disulfide (MoS2) nanosheets are deposited on glassy carbon electrode (GCE) by simple physical stacking to fabricate a dual-signal amplification biosensor for simultaneous detection of adenine and guanine. Under optimized conditions, the electrochemical behaviors of guanine and adenine on the COFS/NH2-rG/MoS2 modified electrode were studied by cyclic voltammetry and differential pulse voltammetry. The sensor performs well in determining G and A at the same time with wide linear ranges of 0.5–150.0 μM and 1.0–280 μM and low detection limits of 0.51 μM(S/N = 3) and 0.44 μM(S/N = 3), respectively. The sensor was successfully used to assay G and A in thermally denatured herring sperm DNA, and the G/A ratio was calculated to be 0.79. The biosensor has the advantages of simplicity, speed, high sensitivity, good reproducibility, and long-term stability.