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

Abstract

Electrically conductive biomaterial scaffolds have great potential in 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 Ω 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 μm, 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°) 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°) 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.

Topographical and Electrical Stimulation of Neuronal Cells through Microwrinkled Conducting Polymer Biointerfaces

“…Effects of anisotropic topographies in guiding and promoting the neurite growth are consistent with results observed for SH‐SY5Y cells grown onto aligned fibers and ridges . Nevertheless, the combined effect of electrical and guidance cues was reported to enhance the neurite outgrowth in neuron‐like PC12 cells, stimulated through polypyrrole‐coated aligned sub‐micrometric fibers . In particular, enhancements in terms of fraction of neurite‐bearing cells (124%) and of neurite length (66% and 129%) were reported with respect to nonstimulated cells onto randomly oriented fibers.…”

“…Nevertheless, the combined effect of electrical and guidance cues was reported to enhance the neurite outgrowth in neuron‐like PC12 cells, stimulated through polypyrrole‐coated aligned sub‐micrometric fibers . In particular, enhancements in terms of fraction of neurite‐bearing cells (124%) and of neurite length (66% and 129%) were reported with respect to nonstimulated cells onto randomly oriented fibers. Results are not directly comparable since they were obtained for a different neuronal model and under different experimental conditions, in terms of stimulation protocols and electrical waveforms.…”

“…In particular, topographies presenting anisotropic cues have a role in influencing the behavior of cells, by inducing directional cell migration, or by impacting on cell differentiation and promoting the development of oriented cytoskeleton structures. [3][4][5] In the case of differentiating neuronal cells, interfaces with micro/sub-microscale aligned fibers [6][7][8] or ridges [9][10][11] were found to promote axonal guidance, by guiding and stimulating the neurite growth.With the aim to develop multifunctional smart biointerfaces, conducting polymers (CPs) are the materials of choice, because of their peculiar combination of both electronic and ionic conductivity. CPs are suitable for actively interfacing living tissues with electronic devices, allowing for efficient delivery and recording of electrical signals as well as for converting electronic signals into ionic currents and vice versa.…”

Roles of electrical stimulation in promoting osteogenic differentiation of BMSCs on conductive fibers

“…In the case of POP fibrous meshes being studied, however, mineral deposition was apparently accelerated under ES. Some studies have reported the applied ES could enrich the electric charge densities at the protruding cusps on rough-surfaced conductive PPY layer, 43,44 which was able to further enhance protein absorption, as confirmed by results shown in Figure 5. For the same reason, ES may improve ionic adsorption for electric charge on POP fibers.…”

Incorporation of Conductive Materials into Hydrogels for Tissue Engineering Applications

“…As the most studied conductive polymer, PPy has been synthesized by chemical oxidation using a radical initiator with an appropriate electrolyte solution [59,60] or by electrochemical oxidation of pyrrole with an electrolyte solution on a platinum-coated electrode [61]. PPy has been reported to offer focal adhesion and the growth of various cell types associated with endothelial cells [62,63], neurons, supporting cells (DRG) [64][65][66], and rat pheochromocytoma (PC12) cells [66][67][68][69]. Yang et al devised conductive hydrogels of hyaluronic acid and PPy that enhanced mechanical and conductive properties [70] (Figure 4).…”