Fabrication of Aligned Conducting PPy-PLLA Fiber Films and Their Electrically Controlled Guidance and Orientation for Neurites

Electrically conductive biomaterial scaffolds have great potential in a neural tissue regeneration. In this work, an aligned conductive fibrous scaffold was prepared by electrospinning PLLA on rotating collector and chemical oxidation polymerization of pyrrole (PPy) codoped with poly(glutamic acid)/dodecyl benzenesulfonic acid sodium. The characterization results of composition, structure and mechanics of fiber films show that the existence of weak polar van der Waals' force between PPy coating and PLLA fibers. The resistivity of aligned rough PPy-PLLA fiber film (about 800 nm of fiber diameter) at the perpendicular and parallel directions is 0.971 and 0.874 Omega m, respectively. Aligned rough PPy-PLLA fiber film could guide the extension of 68% PC12 neurites along the direction of fiber axis. Under electrostimulation (ES) of 100, 200, and 400 mV/cm, median neurite lengths of differentiated PC12 on aligned fiber-films are 128, 149, and 141 pm, respectively. Furthermore, under ES of 100, 200, and 400 mV/cm, the alignment rate of neurite along the electropotential direction (angle between neurite and electropotential direction <= 10 degrees) on random fibers film are 17, 23, and 28%, respectively, and the alignment rate of neurites along the fiber axis (angle between neurite and fiber axis <= 10 degrees) on aligned fibers film reach to 76, 83, and 79%, respectively, indicating that the combination of ES and rough conducting aligned structure could adjust the alignment of cellular neurites along the direction of the fiber axis or electropotential.