Electrochemical Characterization of Guanine and Guanosine Based Biosensors Over Multi-Walled Carbon Nanotube Modified Graphite Electrode

Electroactive purine nucleobase, guanine and purine nucleoside, guanosine were immobilized over multi-walled carbon nanotubes (MWCNT) modified graphite electrode.The electrooxidation properties of purines were evaluated using differential pulse voltammetry.Mixtures of purine nucleobase and nucleoside in various concentrations were prepared and electrochemically immobilized over the working electrodes using positive potential difference.The anodic current at around 0.7 V was used as analytical signal for guanine.The influence of immobilization time, MWCNT concentration and purine concentration were evaluated and electrochemical mechanisms have been discussed.Special emphasis was given to study the stable recognition layer in a redox couple (0.1M NaCl containing 10/10 mM K 3 Fe(CN) 6 /K 4 Fe(CN) 6 ) using electrochemical impedance spectroscopy and cyclic voltammetry.Further, electrochemical interaction of immobilized purine structures over benzene substituted organic compounds were studied using DPV in 0.1M phosphate buffer, and CV and EIS in 0.1 M NaCl containing 10/10 mM K 3 Fe(CN) 6 /K 4 Fe(CN) 6 .The standardized and calibrated purine immobilized electrode could be potentially used as purine based biosensor for the electrochemical detection of benzene substituted organic compounds.