Recently, much effort has been put into the fabrication of three-dimensional (3D) architectures (such as sponges, aerogels, etc.) from biocompatible nanomaterials and polymers due to their promising tissue engineering and drug delivery applications. However, the emerging approaches still lack sufficient control of macro- and microstructure of the 3D networks. In the present work, we demonstrate two simple fabrication routes for the synthesis of macroscopic networks with tunable porosity (20-96%) utilizing versatile, highly porous ceramic templates which are composed of interconnected, tetrapodal ZnO microparticles.
In the first approach, the sacrificial template is coated homogeneously with a nanomaterial dispersion or polymer solution using a wet chemical infiltration process. The following removal of the template results in free-standing, highly porous and lightweight 3D architectures consisting of interconnected hollow microtubes, being composed of individual nanomaterials (e.g. graphene oxide, GO) or biocompatible polymers, e.g. Poly(L-lactide-co-caprolactone) (PLCL). Initial cell experiments with co-cultures of mesenchymal stem cells (MSC) and outgrowth endothelial cells (OEC) on 3D GO and PLCL scaffolds revealed good cell attachment and the formation of vessel-like structures on GO scaffolds.
In the other method, the large accessible free volume within the ceramic template is filled with a two-component polymer mixture (e.g. poly(dimethylsiloxane) (PDMS). Wet chemical etching of the sacrificial template leads to a macroscopic network with interconnected microchannels. Due to the adjustable channel density and small channel diameter (< 3 µm), this structure can be used as a drug reservoir whose release mechanism is dominated by diffusion. Preliminary experiments demonstrated the prolonged release of alternative therapeutics for glioblastoma treatment (e.g. AT101) in artificial cerebrospinal fluid.