In current study, tyrosinase enzyme was immobilized on chitosan support enhanced by magnetite nanoparticles. Electrochemical biosensor was constructed by coating this bionanocomposite film on 5mm diameter of working electrode. All electrochemical measurements were performed with a model PGSTAT 128N (AUTOLAB Instruments) having three electrode system (working electrode: tyrosinase–magnetite-chitosan modified glassy carbon, reference electrode: Ag/AgCl, auxiliary electrode: platinum wire). The interaction between the sensor component and their structure were characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Electrochemical characterizations were also performed by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The performance of electrochemical tyrosinase biosensor was tested by amperometric method in magnetically stirred PBS, followed by the addition of catechol solution as a phenolic compound.
The binding of tyrosinase enzyme to the bionanocomposite support was confirmed by FTIR and SEM analysis. According to the CV measurements, the reduction peak was observed attributed to the direct reduction of quinone on the electrode surface. EIS results showed decrease in mass transfer resistance indicate conducting properties of magnetite nanoparticles. Electrochemical sensing characteristics and analytical performance of developed sensor was also evaluated by amperometric detection of catechol. The designed sensor depicted wide linear range of catechol concentration with high correlation coefficient, high sensitivity, low detection limit and Kmvalue.
This study was supported financially by the Scientific and Technological Research Council of Turkey (TUBITAK Grant Number 114Z417).
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