Immobilization of purine bases on a poly-4-aminophenol matrix

Conducting polymers or semi-conductors have various features that make them excellent materials for the immobilization of biomolecules and the rapid transfer of electrons necessary for the production of biosensors. Conducting electroactive polymers of poly-4-aminophenol have been developed as sensors to detect the purine bases (adenosine triphosphate, ATP and guanosine triphosphate, GTP) of DNA. The electrooxidation of 4-aminophenol onto a graphite electrode in the presence of perchloric acid yielded thin polymer films. The conductivity was studied by cyclic voltammetry and surface morphology by optical microscopy and interferometry. The immobilization and detection of ATP and GTP on a graphite electrode or modified electrode coated with poly-4-aminophenol was studied by cyclic voltammetry. Systematic variation of the experimental conditions that influenced the electrode reaction, particularly the pH of the electrolytic solution, showed that the oxidation potentials of the immobilized ATP or GTP in the modified electrodes decreased with increasing pH of the electrolyte. When these conditions were optimized based on voltammetric measurements, modified electrodes coated with poly-4-aminophenol were found to be efficient in immobilizing purine bases, and increased the amplitude of the ATP and GTP signals by ∼1.5 and ∼24 times, respectively, when compared with non-coated graphite surfaces.