Polycrystalline bismuth oxide films for development of amperometric biosensor for phenolic compounds

An attractive biocomposite based on polycrystalline bismuth oxide (BiO_x) film and polyphenol oxidase (PPO) was proposed for the construction of a mediator-free amperometric biosensor for phenolic compounds in environmental water samples. The phenolic biosensor could be easily achieved by casting the biocomposite on the surface of glassy carbon electrode (GCE) via the cross-linking step by glutaraldehyde. The laboratory-prepared bismuth oxide semiconductor was polymorphism. Its hydrophilicity provided a favorable microenvironment for retaining the biological activity of the immobilized protein. The parameters of the fabrication process and the various experimental variables for the enzyme electrode were optimized. The proposed PPO/BiO_x biosensor provided a linear response to catechol over a concentration range of 4 × 10⁻⁹ M to 1.5 × 10⁻⁵ M with a dramatically developed sensitivity of 11.3 A M⁻¹ cm⁻² and a detection limit of 1 × 10⁻⁹ M based on S/N = 3. In addition, the PPO/BiO_x biocomposite was characterized by scanning electron microscope (SEM), Fourier transform infrared spectra (FTIR) and rotating disk electrode voltammetry.