Incorporation
of a Clot-Binding Peptide into Polythiophene:
Properties of Composites for Biomedical Applications
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Abstract
Biocomposites
formed by a pentapeptide (CREKA), which recognizes
clotted plasma proteins, entrapped into the poly(3,4-ethylenedioxythiophene)
(PEDOT) matrix have been prepared using three very different procedures.
X-ray
photoelectron spectroscopy analyses indicate that PEDOT-CREKA films,
prepared by chronoamperometry in basic aqueous solution (pH = 10.3)
and deposited onto a PEDOT internal layer, present the higher concentration
of peptide: one CREKA molecule per six polymer repeat units. The surface
of this bilayered system shows numerous folds homogeneously distributed,
which have been exhaustively characterized by scanning electron microscopy
and atomic force microscopy. Indeed, the morphology and topography
of such bilayered films is completely different from those of biocomposite-prepared
acid aqueous and organic solutions as polymerization media. The impact
of the entrapped peptide molecules in the electrochemical properties
of the conducting polymer has been found to be practically negligible.
In contrast, biocompatibility assays with two different cellular lines
indicate that PEDOT-CREKA favors cellular proliferation, which has
been attributed to the binding
of the peptide to the fibrin molecules from the serum used as a supplement
in the culture medium. The latter assumption has been corroborated
examining the ability of PEDOT-CREKA to bind fibrin. The latter ability
has been also used to explore an alternative strategy based on the
treatment of PEDOT-CREKA with fibrin to promote cell attachment and
growth. Overall, the results suggest that PEDOT-CREKA is appropriated
for multiple biomedical applications combining the electrochemical
properties of conducting polymer and the ability of the peptide to
recognize and bind proteins
