Immobilization of acid phosphatase on a polyaniline/poly(acrylic acid) composite film for use as the anode of a fuel cell driven with L-ascorbic acid 2-phosphate

Abstract

An enzyme electrode was prepared by covalent immobilization of acid phosphatase (ACP) on a polyaniline/poly(acrylic acid) composite film (PANI/PAA film) deposited on an Au electrode and used as the anode of a fuel cell driven with L-ascorbic acid 2-phosphate (ASA2P). Biochemical and electrochemical properties of the enzyme electrode were compared with those of the one fabricated without the PANI/PAA film by enzyme immobilization on an Au electrode bearing a self-assembled monolayer formed with 3-mercaptopropionic acid. The former electrode was found superior to the latter in the quantity of immobilized ACP, the function to scavenge ascorbic acid (ASA), resulting from dephosphorylation of ASA2P by ACP and the electrochemical ability to oxidize ASA. The ASA2P fuel cells were constructed by use of the enzyme electrodes as anodes. The fuel cell using the enzyme electrode fabricated with the PANI/PAA film gave a maximum power output of 6.0 μW cm−2-anode, which was 70 times as large as that obtained with the cell using the electrode fabricated without the PANI/PAA film, and thus the power output was dependent on the performance of the enzyme electrode. An enzyme electrode was fabricated by covalent immobilization of acid phosphatase (ACP) on a polyaniline/poly(acrylic acid) composite film for use as the anode of a fuel cell driven with L-ascorbic acid 2-phosphate (ASA2P). The enzyme electrode showed an activity in biochemical dephosphorylation of ASA2P to ascorbic acid (ASA), and succeeded in electrochemical oxidation of ASA. The ASA2P fuel cell equipped with the enzyme electrode gave a maximum power output of 6.0 μW cm−2-anode, reflecting the bioelectrochemical activity of the electrode.