3D Printing of Conductive Tissue Engineering Scaffolds Containing Polypyrrole Nanoparticles with Different Morphologies and Concentrations

Inspired by electrically active tissues, conductive materials have been extensively developed for electrically active tissue engineering scaffolds. In addition to excellent conductivity, nanocomposite conductive materials can also provide nanoscale structure similar to the natural extracellular microenvironment. Recently, the combination of three-dimensional (3D) printing and nanotechnology has opened up a new era of conductive tissue engineering scaffolds exhibiting optimized properties and multifunctionality. Furthermore, in the case of two-dimensional (2D) conductive film scaffolds such as periosteum, nerve membrane, skin repair, etc., the traditional preparation process, such as solvent casting, produces 2D films with defects of unequal bubbles and thickness frequently. In this study, poly-l-lactide (PLLA) conductive scaffolds incorporated with polypyrrole (PPy) nanoparticles, which have multiscale structure similar to natural tissue, were prepared by combining extrusion-based low-temperature deposition 3D printing with freeze-drying. Furthermore, we creatively integrated the advantages of 3D printing and solvent casting and successfully developed a 2D conductive film scaffold with no bubbles, uniform thickness, and good structural stability. Subsequently, the effects of concentration and morphology of PPy nanoparticles on electrical properties and mechanical properties of 3D conductive scaffolds and 2D conductive films scaffolds have been studied, which provided a new idea for the design of both 2D and 3D electroactive tissue engineering scaffolds.