Response surface methodology use in construction of polianiline-coated carbon paste electrode-based biosensor:...

In this study, the effect of amperometric glucose biosensor construction and using conditions on the current response was investigated in detail applying experimental design. Polyaniline (PANI) was synthesized on the carbon paste electrode (CPE) surface using the cyclic voltammetry technique in sodium oxalate (NaO_x ) electrolyte medium, and an amperometric biosensor was constructed by immobilizing glucose oxidase (GOD). Biosensor preparation (aniline, GOD and NaO_x concentrations, and scan rate) and operating conditions (pH and applied potential) were optimized by Box-Behnken and optimal designs, respectively, via State Ease Design Expert 7.0.1.1 software. ANOVA analyses showed that among the biosensor preparation parameters, the NaO_x concentration has the highest effect on the current measured in the presence of glucose, whereas in the optimization of pH and potential parameters applied in current measurement studies, it has been revealed that pH has a very high effect on the measured current. Several compounds, such as MWCNT, two different ionic liquids and two different organic molecules were added to carbon paste, and, among them, 2-cyanoethylpyrrole (CPy) enhanced the efficacy highly, most probably due to its polymerization in the paste and increasing the electron transfer rate of the CPE. Sucrose- and lactose-sensitive biosensors were also constructed by co-immobilizing GOD with invertase (INV) or β-galactosidase, respectively, onto modified CPE, and sensitivities to their substrates were shown by cyclic voltammetry and impedance analysis. CPy modification caused an increase in the current values, and also I_max /K_M values increased approximately 11.8, 7.83, and 2.56 times for glucose-, sucrose-, and lactose-sensitive CPEs, respectively.