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Direct Electrochemistry of Hemoglobin in Polyacrylamide Hydrogel Films on Pyrolytic Graphite Electrodes
Author(s) -
Sun Hong,
Hu Naifei,
Ma Hongyan
Publication year - 2000
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/1521-4109(200009)12:13<1064::aid-elan1064>3.0.co;2-f
Subject(s) - pyrolytic carbon , electrochemistry , electron transfer , redox , chemistry , polyacrylamide , cyclic voltammetry , electrode , catalysis , electrocatalyst , inorganic chemistry , photochemistry , polymer chemistry , organic chemistry , pyrolysis
Abstract Stable thin films made from amphiphilic polymer polyacrylamide (PAM) on pyrolytic graphite (PG) electrodes demonstrated direct electrochemistry for the incorporated redox protein hemoglobin (Hb). Cyclic voltammetry of Hb‐PAM films showed a pair of well‐defined and nearly reversible peaks for Hb Fe(III)/Fe(II) redox couple at about –0.27 V (vs. SCE) in pH 5.5 buffers. Compared to bare PG in Hb solutions, the electron transfer between Hb and PG electrodes was greatly facilitated in the microenvironment of PAM hydrogel films. Positions of Soret absorption band suggest that Hb keeps its secondary structure similar to its native state in the films at medium pH. The formal potential of the Hb Fe(III)/Fe(II) couple in PAM films shifted linearly between pH 4.5 and 11 with a slope of –47 mV pH –1 , suggesting that one proton transfer is coupled to each electron transfer in the electrochemical reaction. Hb can act as an enzyme‐like catalyst in PAM films as demonstrated by catalytic reduction of trichloroacetic acid (TCA) with significant decreases in the electrode potential required, showing the possible future application of the films for biosensors and biocatalysis.