Lysine-doped polypyrrole/spider silk protein/poly(l-lactic) acid containing nerve growth factor composite fibers for neural application

Lysine-doped polypyrrole (PPy)/regenerated spider silk protein (RSSP)/poly(l-lactic) acid (PLLA)/nerve growth factor (NGF) (L-PRPN) composite scaffold was fabricated by co-axial electrospraying and electrospinning. This L-PRPN composite scaffold had a structure of microfibers with a core–shell structure as the stems and nanofibers as branches. Assessment in vitro demonstrated that the L-PRPN composite micro/nano-fibrous scaffold could maintain integrated structure for at least 4months and the pH value of PBS at about 7.28. It had good biocompatibility and cell adhesion and relatively stable conductivity. PC 12 cells cultured on this scaffold, anisotropic cell–neurite–cell–neurite or neurite–neurite sheets were formed after being cultured for 6days. Evaluations in vivo also showed that L-PRPN composite fibrous conduit was effective at bridging 2.0cm sciatic nerve gap in adult rat within 10months. This conduit and electrical stimulation (ES) through it promoted Schwann cell migration and axonal regrowth. [Display omitted] •Fabricated PPy/RSSP based composite fiber with a coaxial cable structure•Found the composite fibrous scaffold has good cell adhesion and stable conductivity•Found PC 12 cells cultured on the scaffold formed cell–neurite–cell–neurite sheet•Found the composite fibrous conduits bridged a 2.0cm sciatic nerve gap in adult rat