Study on Electrochemical Biosensor for Polycyclic Organic Compounds Based on DNA-Toluidine Blue Bio-polyion Complex Membrane

Based on the interaction between DNA and small molecules, a DNA/chitosan (CTS) bio-polyion complex membrane was used for immobilization of DNA binding electro-activators. A DNA-toluidine blue (TB)/CTS bio-polyion complex membrane modified electrode was developed for a reagent-less DNA electrochemical biosensor of polycyclic organic compounds (POCs), which based on the specific and competitive binding between POCs and dye molecules to DNA. Using tetracycline (TC) as a model analyte of polycyclic organic compounds, the electrochemical characteristic of the modified electrode and the response to the TC were studied by cyclic voltammetry and square wave voltammetry. It was found that DNA and TB were successfully co-immobilized on the electrode, and the embedded TB maintained its electro-active properties. The mechanism by which the modified electrode responded to TC was investigated by using UV-vis spectrophotometry. Linearity range of the biosensor found was 2.5-100 μmol·L-1.