ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 7, pp. 1175!1177. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + E.I. Kulish, R.R. Fatkullina, V.P. Volodina, S.V. Kolesov, Yu.B. Monakov, 2007, published in Zhurnal Prikladnoi Khimii, 2007,
Vol. 80, No. 7, pp. 1206!1208.
AND POLYMERIC MATERIALS
Degradation of Enzyme-Containing Chitosan Films
E. I. Kulish, R. R. Fatkullina, V. P. Volodina, S. V. Kolesov, and Yu. B. Monakov
Bashkir State University, Ufa, Bashkortostan, Russia
Institute of Organic Chemistry, Ufa Scientific Center, Russian Academy of Sciences, Ufa,
Received September 19, 2006; in final form, May 2007
Abstract-The features of degradation of the chitosan films prepared from acetic acid solutions using
Collagenase KK enzyme preparation were studied.
The use of chitosan (CH) as a drug seems rather
promising [1, 2]. Incorporation of proteolytic enzymes
into CH can improve its pharmaceutical properties. It
is believed that, in the absence of chemical bonding
with the polymer, the enzymes will be released owing
to the diffusion of the protein macromolecules from
the polymer matrix into the environment and owing to
the enzymatic degradation of chitosan.
In this work we simulated biodegradation of chito-
san films containing a proteolytic enzyme.
In this study we used chitosan [TU (Technical
Specifications) 6-09-05-296376, Khimmed Company,
Russia] prepared by alkaline deacetylation of the crab
chitin (75% degree of deacetylation, M
Collagenase KK proteolytic enzyme preparation
from hepatopancreas of commercial crab species (Im-
munopreparat State Unitary Enterprise, Ufa, Bashkor-
tostan, Russia). CH films were prepared by casting
a polymer solution onto the glass surface. The weight
concentration of CH in the initial solution was 2 g dl
in 1% acetic acid. In all the experiments the film
thickness was constant, 0.1 mm. The enzyme prepara-
tion preliminarily dissolved in a small amount of
water was added into the CH solution just before
casting. The content of the enzyme in the film was
varied from 0.5 to 10 wt% with respect to CH weight.
Biodegradation of chitosan under the effect of
the enzyme added into the film was studied by vis-
cometric method in a buffer solution containing 0.3 M
acetic acid and 0.2 M sodium acetate according to
the standard procedure . The experimental error
was no more than 5%. To simulate the enzymolysis,
the chitosan film was placed on a support wetted with
a solution of the enzyme preparation and kept at 35oC
for a certain period (up to 1 h). The concentration
of the enzyme preparation in the solution being in
contact with the chitosan film was varied from 0.1 to
50 wt %. The degradation kinetics was evaluated from
the viscometric data. The enzymolysis of chitosan
with the enzyme preliminarily added into the films
was also studied by viscometric procedure.
Addition of the Collagenase KK enzyme into the
CH solution in the stage of the film preparation leads
to the following results. As seen from Fig. 1a, with
increasing content of collagenase in the film, the
intrinsic viscosity of CH gradually decreases, which
suggests that the molecular weight of chitosan de-
creases owing to biodegradation under the effect of
the enzyme added.
Using viscometric data and Mark3Kuhn equation
for CH solutions  in acetate buffer ([h] = 1.38 0
), we can evaluate a relative decrease in
the intrinsic viscosity and in the molecular weight of
CH (see table).
A similar decrease in the intrinsic viscosity is also
observed in the case when the chitosan film prepared
without enzyme in placed on a support wetted with
a collagenase solution (Figs. 1b and 2a). The follow-
ing trends are observed.
(1) Sharp decrease in the intrinsic viscosity is ob-
served only in the first 10315 min of the film contact
with the enzyme solution (Fig. 2a). Longer enzymoly-
sis does not noticeably affect the intrinsic viscosity
of the CH solutions.