Electrochemical polymerization of functionalized thiophene derivatives for the immobilization of proteins

The hydroxy group of 3‐(2‐hydroxyethyl)thiophene was protected as methyl ether 1 and as dimethyl tert‐butyl silyl ether 5 before anodic polymerization. The poly[3‐(2‐methoxyethyl)thiophene] 2 was prepared by electrochemical homopolymerization of 1 . Ether cleavage was carried out in the polymer film 2 and the resulting poly [3‐(2‐hydroxyethyl)thiophene] ( 3 ) was activated with cyanogen bromide to immobilize alcohol dehydrogenase. Silylether 5 did not undergo homopolymerization but copolymerization of 5 with 3‐methylthiophene ( 4 ) was successful. After cleavage of the protecting group the resulting copolymer 7 was activated by cyanuric chloride, and chymotrypsin was immobilized. Electrocopolymerization of thiophene‐3‐acetic acid ( 8 ) and 3‐methylthiophene ( 4 ) under various conditions produces copolymer 9 . By activation of the carboxylic groups with N,N'‐dicyclohexylcarbodiimide (DCC) lactate oxidase (LOD) was bond to the surface of the electrode to form a lactate sensor.