An electro-spun tri-component polymer biomaterial with optoelectronic properties for neuronal differentiation

Optoelectronic biomaterials have recently emerged as a potential treatment option for neurodegenerative diseases, such as optic macular degeneration. Though initial works in the field have involved bulk heterojunctions mimicking solar panels with photovoltaics (PVs) and conductive polymers (CPs), recent developments have considered abandoning CPs in such systems. Here, we developed a simple antioxidant, biocompatible, and fibrous membrane heterojunction composed of photoactive polymer poly(3-hexylthiophene) (P3HT), polycaprolactone (PCL) and polypyrrole (PPY), to facilitate neurogenesis of PC-12 cells when photo-stimulated in vitro. The photoactive prototype, referred to as PCL-P3HT/PPY, was fabricated via polymerization of pyrrole on electro-spun PCL-P3HT nanofibers to form a membrane. Four experimental groups, namely PCL alone, PCL/PPY, PCL-P3HT and PCL-P3HT/PPY, were tested. In the absence of the CP, PCL-P3HT demonstrated lower cell survival due to increased intracellular reactive oxygen/nitrogen species production. PCL-P3HT/PPY rescued these cells by virtue of scavenging radicals, where the CP, PPY, acted as an antioxidant. Apart from having lower impedance, the material also enhanced neurogenesis of PC-12 cells when photo-stimulated, compared to the traditional PCL-P3HT. Lastly, the in vitro system with PC-12 was used to demonstrate the practicality of the material for potential use as a cellular patch in optic and nerve regeneration. This work demonstrated the importance of maintaining PV-CP heterojunctions while simultaneously providing an optoelectrical platform for neural and optical tissue engineering. STATEMENT OF SIGNIFICANCE: Regeneration and repair of injured nervous systems have always been a major clinical challenge. Stem cell therapy is a promising approach for nerve regeneration, and opto-electrical stimulation, which converts light into an electrical signal, has been shown to efficiently regulate stem cell behaviors with enhanced neurogenesis. We developed a micro-fibrous membrane, composed of photoactive polymer, P3HT, scaffold material PCL and conductive polymer PPY. Our heterojunction system improved cell survival via PPY quenching PCL-P3HT-generated cell-damaging reactive oxygen species. PPY also conducted electrons produced from light-stimulated P3HT to promote neurogenesis. This photoactive microfiber biomaterial has great potential as a highly biocompatible and efficient platform to wirelessly promote neurogenesis and survival. Our approach thus showed possibilities with respect to optical tissue engineering.