Conductive Composite Fiber with Optimized Alignment Guides Neural Regeneration under Electrical Stimulation

Abstract

Conductivity and alignment of scaffolds are two primary factors influencing the efficacy of nerve repair. Herein, conductive composite fibers composed of poly(e-caprolactone) (PCL) and carbon nanotubes (CNTs) with different orientation degrees are prepared by electrospinning at various rotational speeds (0, 500, 1000, and 2000 rpm), and meanwhile the synergistic promotion mechanism of aligned topography and electrical stimulation on neural regeneration is fully demonstrated. Under an optimized rotational speed of 1000 rpm, the electrospun PCL fiber exhibits orientated structure at macroscopic (mean deviation angle = 2.78 degrees) or microscopic crystal scale (orientation degree = 0.73), decreased contact angle of 99.2 degrees +/- 4.9 degrees, and sufficient tensile strength in both perpendicular and parallel directions to fiber axis (1.13 +/- 0.15 and 5.06 +/- 0.98 MPa). CNTs are introduced into the aligned fiber for further improving conductivity (15.69-178.63 S m(-1)), which is beneficial to the oriented growth of neural cells in vitro as well as the regeneration of injured sciatic nerves in vivo. On the basis of robust cell induction behavior, optimum sciatic nerve function index, and enhanced remyelination/axonal regeneration, such conductive PCL/CNTs composite fiber with optimized fiber alignment may serve as instructive candidates for promoting the scaffold- and cell-based strategies for neural repair.