Kilian Höning

Electrically conductive polymers like polypyrrole (Ppy) offer a great opportunity to create scaffolds in which embedded cells can be electrically stimulated to enhance cell growth or to activate the release of specific drugs encapsulated inside the scaffold [1]. The key to providing an electrical conductivity alongside the polymer backbone is the process of doping. By this process, a charge carrier is introduced in the polymer network by removing or adding electrons from/to the system [2]. Crucial for the conductivity of such polymers are the type and quantity of the dopant. Polypyrrole, in particular, is one of the most investigated conductive polymers due to its great properties concerning synthesis because it can be fabricated at room temperature in large quantities in most solvents and moreover due to its good in vitro and in vivo biocompatibility [3]. Conductivities of up to 7.5 x 103 S.cm-1 have been reported for polypyrrole which is limited by defect sites in the backbone. These can increase by exposure to oxygen or water which cause oxidation and hence create less conductive states in the polymer chain [1]. Therefore, the aim of this work is to investigate novel potential doping substances to achieve highly conductive and biocompatible  polypyrrole. These materials will be characterized and compared in terms of electrical conductivity, morphology, chemical composition and biocompatibility. In addition, the new materials shall be investigated whether they are suitable for the integration in 3D printing processes to produce conductive, 3D printable polymer hydrogels for biofabrication.

[1] R. Balint et al., “Conductive polymers: Towards a smart biomaterial for tissue engineering”, Acta Biomaterialia 10, 2014, pp. 2341-2353.

[2] Y. Shi et al., “Nanostructured conductive polymers for advanced energy storage”, Royal Society of Chemistry Reviews 44, 2015, pp. 6685-6696.

[3] X. Wang et al., “Evaluation of biocompatibility of polypyrrole in vitro and in vivo”, Journal of Biomedical Materials Research Part A, 68A, 2003, pp. 411-422.