Electrochemical Detection of Insulin in Blood serum using Ppy/GF Nanocomposite Modified Pencil Graphite Electrode

In this study, pencil graphite electrode (PGE) was modified using conductive polypyrrole (Ppy) and graphene (GF) nanocomposite for electrochemical determination of insulin. Electrochemical behavior of insulin on PGE was evaluated using differential pulse voltammetric (DPV), cyclic voltammetric (CV) and chronoaprometry (CA) methods. Several effective variables including pH, concentration, and scan rate for electrochemical modification of electrode were investigated and optimal conditions were proposed. Kinetics of the oxidation reaction and diffusion coefficient of the sensor was studied. The performed steps allow the measurement of insulin with a linear repeatability curve and appropriate accuracy at a range of 0.225 to 1.235 μM. The limit of detection was obtained at 8.65nMfor insulin. The amount of electron transfer coefficient between modified electrode and insulin was obtained to 0.5 with 0.84~1 number of electrons exchanged during oxidation of insulin. The proposed nano biosensor was chosen for insulin measurements in human blood serum analysis.