Preparation, characterization and analytical application of an electrochemical laccase biosensor towards low level determination of isoprenaline in human serum samples

Abstract

A novel electrochemical biosensor has been developed based on the immobilization of multiwalled carbon nanotubes (MWCNT) on to a glassy carbon electrode (GCE) and subsequent casting of silica sol–gel (SiSG) entrapped laccase (Lac) enzyme on to the MWCNT/GCE. The catalytic activity of laccase biosensor was found to be good enough for sensitive determination of isoprenaline (ISP) with the aid of voltammetric techniques and we have also demonstrated the detailed electrochemical redox mechanism of ISP. From the effect of the pH, we have optimized the optimum pH as 6.5, and from effect of scan rate we have evaluated the kinetic parameters, heterogeneous rate constant, charge transfer coefficient and diffusion coefficient values. Furthermore the limit of detection (LOD) and limit of quantification (LOQ) values were found to be 1.8 × 10⁻⁷ M and 6.0 × 10⁻⁷ M, respectively. The simultaneous determination of ISP in the presence of uric acid (UA) and ascorbic acid (AA) was successfully carried out. The surface nature of the biosensor was characterized by using electrochemical impedance spectroscopy. Finally the validation of the proposed method was verified by the recovery of injection (ISP) in serum samples and their recoveries were found to be in a satisfactory range. The proposed method was found to have good repeatability, reproducibility and stability with low relative standard deviation (RSD) values.