Conductive polymer blend based on polyaniline and galactomannan: Optical and electrical properties

Polyaniline (PAni) is a semiconductor polymer characterized by a wide conductivity range and can be used as a biosensor for glucose measurement via glucose oxidase (GOx) catalysis because PAni can immobilize GOx on its surface and allows charge transfer between GOx and its surface. However, PAni presents issues with enzyme leaching and high dielectric constant ( 10 4 - 10 5 ), which hinders its electrical response as a sensor. To solve both issues simultaneously, a blend of polyaniline and galactomannan (Gal) is presented. Gal is able to preserve the enzymatic activity and has insulating properties, making it suitable to enhance the immobilization of GOx on PAni and to improve the electrical response of the latter for biosensing. PAni was synthesized from the polymerization of aniline in HCl and ammonium persulfate and blended with a solution of Gal 2%, resulting in the polyaniline and galactomannan blend (PAni/Gal). Samples of Gal 2%, PAni and PAni/Gal were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and impedance spectroscopy (IS). The FTIR of the PAni/ AP blends detected the presence of the band associated to the deformation outside the binding plane (C-N) and the oxidizing agent responsible for the semiconducting property of PAni. The XRD patterns showed the crystalline structure of PAni and the amorphous structure of PAni/Gal. The IS showed that PAni/Gal exhibited a smaller dielectric constant and a higher loss tangent than PAni, indicating that PAni/Gal has better electrical behavior as a sensor compared to PAni and thus has solid potential for use in biosensors.