Polydopamine/carboxylic graphene oxide-composited polypyrrole films for promoting adhesion and alignment of Schwann cells

Polydopamine (PDA)- and carboxylic graphene oxide (CGO)-composited polypyrrole (PPy) films were prepared via electrospinning of poly-l-lactic acid (PLLA), electrodeposition of PPy blended with CGO and polymerization of dopamine (PDA/CGO/PPy-PLLA), and its surface conductivity and elastic modulus reached to similar to 17.3 S/cm and similar to 260 MPa, respectively. PDA composition could maintain the higher conduction and elastic modulus of this film after the immersion of 3 w, due to the stronger force between PDA molecule and CGO sheets or PPy particles. The results of cell experiments indicated the better adhesion and higher expression of neural proteins in rat Schwann cells (RSCs) on PDA/CGO/PPy-PLLA films, because the composition of PDA provided more absorption and immobilization site for proteins and the regular coating of PDA particles on the CGO sheets reduced the potential damage of Graphene derivatives on the cell membrane integrity. Electrical stimulation (ES) could facilitate similar to 31 % of RSCs to align along the current direction on PDA/CGO/PPy-PLLA films, significantly higher than those on PPy-PLLA and CGO/PPy-PLLA films. A mechanism about the cell alignment on films with ES was proposed: the movement of the cytomembrane proteins under ES and their linkage with serum proteins immobilized by PDA facilitated the extension of growth cone along the ES direction.