Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion.
Double stranded calf thymus deoxyribonucleic acid (DNA) was physisorbed onto polypyrrole-polyvinyl sulphonate (PPY-PVS) films electrochemically deposited onto indium-tin-oxide (ITO) coated glass plates. These DNA immobilized PPY-PVS films optimized for various conditions, such as polymerization potential, pH of buffer, DNA concentration and scan rate were characterized using Fourier-transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM) and cyclic voltammetry (CV) techniques, respectively. The amperometric response studies of these DNA/PPY-PVS electrodes were carried out as a function of 2-aminoantharcene (2-AA, 0.01-20 ppm) and o-chlorophenol (OCP, 0.1-30 ppm) concentration, respectively at 25 degrees C. The observed amperometric current arising due to oxidation of guanine in the DNA/PPY-PVS films decreased linearly with the increase in the concentration of 2-AA and OCP. It has been revealed that 10 ppm of 2-AA is sufficient to reduce the observed guanine oxidation peak current by approximately -95+/-10% as compared to the reported values. A 25 ppm of OCP was capable enough to reduce the guanine oxidation current to zero. These DNA/PPY-PVS electrodes were found to have a shelf life of about 4 months when stored at 25 degrees C.