Polyaniline was exposed to glutaraldehyde under different experimental cond
itions and in all cases reduction of the polymer was observed. The reductio
n of polyaniline by glutaraldehyde in non-electrolytic, aqueous medium unde
r reflux, caused the polymer to become completely undoped and with high imp
ermeability to anions as evidenced by the displacement of the first anodic
voltammetric wave of polyaniline in acidic medium and by its dependence on
the kind of acid employed. The permeability and the normal electrochemical
behavior of the polymer could be restored after the first voltammetric cycl
e. Under simple exposure to glutaraldehyde in buffered solution (pH 8) the
reduction is not so extensive and changes in voltammetric behavior from cyc
le to cycle are related to the high pH of the medium. Some glutaraldehyde p
olymerizes inside the polyaniline matrix, causing the first voltammetric wa
ve of polyaniline to be slightly displaced to more anodic potentials. Enzym
e immobilization on polyaniline with glutaraldehyde seems to be related to
this polyglutaraldehyde produced in buffered solutions. (C) 1999 Elsevier S
cience Ltd. All rights reserved.