Electrosynthesis of Poly(thiophene-3-acetic Acid) Film in Ionic Liquids for Covalent Immobilization of Biologically Active Species

Poly(thiophene-3-acetic acid) (PTAA) film with good biocompatibility, low toxicity, and high conductivity was electrosynthesized in an ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate. Glutamate oxidase (GO), one of biologically active species, was covalently immobilized on the surface of PTAA film for the design and fabrication of the electrochemical biosensor. The impedance spectroscopy, infrared spectra, and scanning electron microscopy indicated that GO molecules were successfully immobilized on the surface of PTAA film. The oxidation current increased linearly with the concentration of L-glutamic acid in the range from 6 × 10−7 to 3 × 10−3 M with a regression coefficient of 0.998. The limit of detection was found to be 0. 23 µM, this method also provided a sensitivity of 87.1 mA M−1 cm−2, and a response time of less than 5 s. Moreover, the bioaffinity and operational and storage stability of the biosensor were also evaluated. Satisfactory results indicated that the resulting PTAA film is a promising candidate for the covalent immobilization of biologically active species.