Immobilization of Tyrosinase in Poly(2-thiophen-3-yl-alkyl ester) Derivatives

Abstract

In this study, construction of novel biosensors for the determination of phenolic compound was performed via immobilization of tyrosinase during the electrochemical synthesis of conducting block copolymers of 2-thiophen-3-yl-alkyl ester derivatives with 3,4-ethylenedioxythiophene and synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT). The resultant biosensors were characterized in terms of their maximum reaction rates, Michaelis–Menten constants (K_m), temperature and pH stabilities. All the copolymer matrices represented higher reaction rates and higher K_m values in comparison to both polypyrrole and PEDOT matrices and a relation between the morphology of the matrice and the kinetic parameters was observed. Biosensors maintained their activity even at temperatures as high as 80°C and could be used at pHs higher than 8 with high precision. The amount of phenolics in actual samples (red wines) was investigated using electrodes, and results were compared with those found from Folin–Ciocalteau method. Hence, the present study has proven the suitability of these copolymers to be used as polymer matrices for enzyme immobilization.

Keywords:

• Tyrosinase
• immobilization
• phenolic compounds
• electrochemistry
• conducting polymer
• copolymer
• biosensor

Acknowledgments

The authors gratefully thank the DPT-2005K120580, METU and Akdeniz University Research Funds and TUBA Grants.

Notes

^a (13)

^b Average of four experiments

^a (13)

^b values ±50 mg/L