The in situ coating of polymer substrate with polypyrrole, described herein with detailed know-how, represents a novel technique of surface functionalization. The choice of oxidizing agent and the polymerization time both affect the properties of the thin polypyrrole layer. The specific conductivity, free surface energy, thickness, topography, and FTIR spectra of polypyrrole layer were determined. The conductive coatings were further used to functionalize both isotropic and anisotropic electrospun polyurethane nanofibrous mats to show their applicability and study the bioactive effect of both the anisotropy and conductivity together. The morphology of composites was studied by means of atomic force microscopy and scanning electron microscopy. A complex cytocompatibility study was performed, including determining cytotoxicity by optical and fluorescence microscopy, the advanced qualification of cell morphology by cell-image analysis, and a study of stem cell behavior. The results clearly showed the significant impact of substrate modification on cells, especially on fibroblasts while the embryonic stem cells were less affected. This study shows not only the effective way to prepare a thin conducting layer based on polypyrrole but also demonstrates its importance for the fabrication of smart biomaterials.

• Keywords
• Anisotropy, Coating, Conductivity, Image analysis, Stem cells,
• Publication type
• Journal Article MeSH

Bio-inspired conductive scaffolds composed of sodium hyaluronate containing a colloidal dispersion of water-miscible polyaniline or polypyrrole particles (concentrations of 0.108, 0.054 and 0.036% w/w) were manufactured. For this purpose, either crosslinking with N-(3-dimethylaminopropyl-N-ethylcarbodiimide hydrochloride and N-hydroxysuccinimid or a freeze-thawing process in the presence of poly(vinylalcohol) was used. The scaffolds comprised interconnected pores with prevailing porosity values of ~ 30% and pore sizes enabling the accommodation of cells. A swelling capacity of 92-97% without any sign of disintegration was typical for all samples. The elasticity modulus depended on the composition of the scaffolds, with the highest value of ~ 50 kPa obtained for the sample containing the highest content of polypyrrole particles. The scaffolds did not possess cytotoxicity and allowed cell adhesion and growth on the surface. Using the in vivo-mimicking conditions in a bioreactor, cells were also able to grow into the structure of the scaffolds. The technique of scaffold preparation used here thus overcomes the limitations of conductive polymers (e.g. poor solubility in an aqueous environment, and limited miscibility with other hydrophilic polymer matrices) and moreover leads to the preparation of cytocompatible scaffolds with potentially cell-instructive properties, which may be of advantage in the healing of damaged electro-sensitive tissues.

• MeSH
• Biocompatible Materials chemistry   MeSH
• Hyaluronic Acid MeSH
• Polymers * chemistry   MeSH
• Porosity MeSH
• Pyrroles chemistry   MeSH
• Tissue Engineering * methods   MeSH
• Tissue Scaffolds chemistry   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biocompatible Materials MeSH
• Hyaluronic Acid MeSH
• Polymers * MeSH
• Pyrroles MeSH

The active role of biomaterials in the regeneration of tissues and their ability to modulate the behavior of stem cells in terms of their differentiation is highly advantageous. Here, polypyrrole, as a representantive of electro-conducting materials, is found to modulate the behavior of embryonic stem cells. Concretely, the aqueous extracts of polypyrrole induce neurogenesis within embryonic bodies formed from embryonic stem cells. This finding ledto an effort to determine the physiological cascade which is responsible for this effect. The polypyrrole modulates signaling pathways of Akt and ERK kinase through their phosphorylation. These effects are related to the presence of low-molecular-weight compounds present in aqueous polypyrrole extracts, determined by mass spectroscopy. The results show that consequences related to the modulation of stem cell differentiation must also be taken into account when polypyrrole is considered as a biomaterial.

• Keywords
• biocompatibility, conducting polymer, neurogenesis, polypyrrole, stem cells,
• MeSH
• Cell Differentiation drug effects   genetics   MeSH
• Cell Line MeSH
• Embryoid Bodies cytology   drug effects   MeSH
• Gene Expression drug effects   MeSH
• Molecular Structure MeSH
• Mouse Embryonic Stem Cells cytology   drug effects   metabolism   MeSH
• Mice MeSH
• Neural Stem Cells cytology   drug effects   metabolism   MeSH
• Neurogenesis drug effects   genetics   MeSH
• Reverse Transcriptase Polymerase Chain Reaction MeSH
• Polymers chemistry   pharmacology   MeSH
• Pyrroles chemistry   pharmacology   MeSH
• PAX6 Transcription Factor genetics   MeSH
• Basic Helix-Loop-Helix Transcription Factors genetics   MeSH
• SOXB1 Transcription Factors genetics   MeSH
• Animals MeSH
• Check Tag
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Ascl1 protein, mouse MeSH Browser
• Polymers MeSH
• polypyrrole MeSH Browser
• Pyrroles MeSH
• PAX6 Transcription Factor MeSH
• Basic Helix-Loop-Helix Transcription Factors MeSH
• SOXB1 Transcription Factors MeSH

Hemocompatibility is an essential prerequisite for the application of materials in the field of biomedicine and biosensing. In addition, mixed ionic and electronic conductivity of conducting polymers is an advantageous property for these applications. Heparin-like materials containing sulfate, sulfamic, and carboxylic groups may have an anticoagulation effect. Therefore, sodium dodecylbenzenesulfonate, 2-aminoethane-1-sulfonic acid and N-(2-acetamido)-2-aminoethanesulfonic acid were used for modification of the representative of conducting polymers, polyaniline, and the resulting products were studied in the context of interactions with human blood. The anticoagulation activity was then correlated to surface energy and conductivity of the materials. Results show that anticoagulation activity is highly affected by the presence of suitable functional groups originating from the used heparin-like substances, and by the properties of polyaniline polymer itself.

• Keywords
• conducting polymer, hemocompatibility, polyaniline, polymer conductivity,
• Publication type
• Journal Article MeSH