Lw. Wang et Nf. Hu, Direct electrochemistry of hemoglobin in layer-by-layer films with poly(vinyl sulfonate) grown on pyrolytic graphite electrodes, BIOELECTRO, 53(2), 2001, pp. 205-212
Stable layer-by-layer electroactive films were grown on pyrolytic graphite
(PG) electrodes by alternate adsorption of layers of polyanionic poly(vinyl
sulfonate) (PVS) and positively charged hemoglobin (Hb) from their aqueous
solutions. Cyclic voltammetry (CV) of {PVS/Hb}(n) films showed a pair of w
ell-defined and nearly reversible peaks at about - 0.28 V vs. SCE at pH 5.5
, characteristic of Hb heme Fe(III)/Fe(II) redox couple. The process of {PV
S/Hb} bilayer growth was monitored and confirmed by CV, X-ray photoelectron
spectroscopy (XPS) and UV-Vis spectroscopy. While the amount of Hb adsorbe
d in each bilayer was the same, the amount of electroactive Hb in each bila
yer decreased dramatically with increase of the number of bilayer, and elec
troactivity was just extended to 8 {PVS/Hb} bilayers. CVs of {PVS/Hb}(8) fi
lms maintained stable in buffers containing no Hb. Positions of Soret band
of Hb in {PVS/Hb}(n) films grown on transparent glass slides suggest that H
b in the films keeps its secondary structure similar to its native state in
a wide pH range. Trichloroacetic acid and nitrite were catalytically reduc
ed by (PVS/Hb), films with significant lowering of the electrode potential
required. (C) 2001 Elsevier Science B.V. All rights reserved.