Covalent immobilization of phenylalanine dehydrogenase on glutaraldehydemodified poly (3,4-ethylenedioxy) thiophene: Poly(styrenesulfonate)/ polyvinyl alcohol conducting polymer composite films for electrochemical detection of L-phenylalanine

Abstract

A new strategy was developed to investigate conducting polymer poly(3,4- ethylenedioxy)thiophene:poly(styrenesulfonate) (PEDOT:PSS) properties and potential for enzymatic electrochemical detection of l-phenylalanine. PEDOT:PSS was blended with polyvinyl alcohol (PVA) and further treated with glutaraldehyde (GA) to produce new conducting polymer composite films of PEDOT:PSS/PVA-GA on indium(tin) oxide (ITO)- coated glass slides. Phenylalanine dehydrogenase (PheDH) was covalently immobilized on the glutaraldehyde modified conducting polymer composite films to produce PEDOT:PSS/PVA-GA-PheDH films. Using this strategy, PEDOT:PSS remained chemically unmodified and its electrical properties was maintained in a matrix containing glutaraldehyde modified polyvinyl alcohol. Electrochemical behavior of the conducting polymer composite films, before and after enzyme immobilization, was investigated using a potentiostat/galvanostat. Cyclic voltammograms showed an oxidation peak of about 0.63 V for PEDOT:PSS/PVA-GA (PEDOT:PSS to PVA ratio=1/1) and about 0.73 V for PEDOT:PSS/PVA-GA-PheDH in different concentrations of L-phenylalanine in Glycine/KCl/KOH buffer solution (100 mM, pH=10.4). The redox properties of PEDOT:PSS/PVA-GA films which is attributed to oxidation of PEDOT seems to contribute to electron transfer to the electrode during enzymatic reaction. Results showed that the system is suitable for determination of L-Phe in human urine for people with phenylketonuria. é 2013 by CEE.