Comparative Analysis of Aligned Conductive Electrospun Mats of PLGA-Polypyrrole for Neural Tissue Engineering: Encapsulation vs Coating

The electrical conductivity of aligned electrospun mats has shown promising results in neural tissue engineering due to its capacity to stimulate neural cell growth and cell differentiation. Herein, we compare two processing routes of conductive aligned electrospun mats to be used as a conduit in nerve regeneration. In the first route, polypyrrole (PPy) nanoparticles were encapsulated into poly lactic-<i>co</i>-glycolic acid (PLGA) fibers. In the second route, PLGA fibers were coated with PPy by in situ oxidative polymerization of pyrrole. Their microstructure, physicochemical, electrical, and biological properties were investigated and compared. The results showed that both routes achieved well aligned fiber structures, without bead defects and fiber diameters between 500 nm and 1 μm (after the coating). Regarding the first route, PPy-encapsulated fibers increased electrical conductivity by one magnitude order compared to neat PLGA fibers. This result derives from the shielding encapsulation effect caused by the polymer matrix. Nevertheless, PPy-encapsulated fibers presented higher mechanical properties and biocompatibility, compared to PPy-coated fibers. In the second route, PPy-coated fibers presented significantly higher responses in terms of wettability and electrical properties. However, these PPy-coated mats exhibited high cytotoxicity levels as evidenced by MTT assay, and proved to be difficult to roll into a conduit. In conclusion, the first route was considered more suitable for further studies, making them a promising material for the development of aligned electrospun fibers conduits for nerve regeneration.