Abstract

An electrochemical sensor was developed for guanine and adenine detection using multiwall carbon nanotubes (MWCNTs) decorated with NiFe₂O₄ magnetic nanoparticles on a glassy carbon electrode. Incorporation of MWCNT/NiFe₂O₄ nanohybrid on the surface of the electrode significantly increases oxidation the peaks currents but reduces the peaks potential of guanine and adenine. The modified electrode was employed for detecting purine bases using linear sweep voltammetry and hydrodynamic amperometry. With hydrodynamic amperometry, the peaks current of both guanine and adenine showed linear dependence on their concentrations in the range of 3.0–45.0 μmol L^–1 for guanine and 3.0–40.0 μmol L^–1 for adenine. When linear sweep voltammetry was used, the peak currents exhibited linear dependence on guanine in the concentration range of 0.05–3.0 μmol L^–1 and on adenine in the concentration range of 0.1–4.0 μmol L^–1. The limit of detection (S/N = 3) was found to be 0.006 and 0.01 μmol L^–1 for guanine and adenine, respectively. Linear sweep voltammetry was also used for simultaneous determination of adenine and guanine. Finally, the proposed electrochemical sensor was employed to determine guanine and adenine in single-strand deoxyribonucleic acid (ssDNA) samples with satisfactory results.