Multifunctional Conducting Polymer Composite Scaffolds for Human Stem Cell Cultures

Stem cell research has benefitted enormously from a variety of different materials used to create scaffolds to grow stem cells in 3D, however, only few studies report the development of structures that are able to recapitulate 3D tissue-like environments and exhibit multifunctional properties (i.e. electrical and optical). Three-dimensional organic bioelectronic devices proposed to bridge the dimensionality mismatch between 2D/static electronics and 3D/dynamic biology, comprising a versatile platform for hosting and monitoring cells. These devices take advantage of the soft mechanical properties, and mixed conduction properties of conjugated polymers (CPs) and enabled the realization of highly biomimetic, electro-active interfaces. Here we show the development of 3D, multifunctional polymer composite structures that exhibit good electrical conductivity, photo-sensitivity and mechanical properties compatible with human tissue. Water-based solution mixtures of PEDOT:PSS, polythiophene and a polyethylene glycol-based crosslinker are freeze dried and 3D scaffolds with an average pores size of 50 μm are realized. These structures exhibit lower Young’s modulus and higher water swelling capacity compared with pure PEDOT:PSS scaffolds cross-linked with GOPS. Scaffold slices with different thicknesses ranging between 100 μm - 400 μm are attached on flat ITO substrates and their (photo) electrochemical properties are evaluated with electrochemical impedance spectroscopy (EIS) and photo-amperometry. These multifunctional platforms are used to host 3D human adipose derived stem cells (hADCs) and to monitor their proliferation in situ with both EIS and fluorescence microscopy. Differentiation of the 3D hADCs cultures to both osteoblasts and neurons is attempted via chemical, electrical and light stimulation by leveraging the scaffold’s multifunctional properties.