Co-assembling bioactive short peptide nanofibers coated silk scaffolds induce neurite outgrowth of PC12 cells

Controlling biomolecular-cell interactions is crucial for the design of scaffolds for tissue engineering (TE). Regenerated silk fibroin (RSF) has been extensively used as TE scaffolds, however, RSF showed poor attachment of neuronal cells, such as rat pheochromocytoma (PC12) cells. In this work, amphiphilic peptides containing a hydrophobic isoleucine tail (I3) and laminin or fibronectin derived peptides (IKVAV, PDSGR, YIGSR, RGDS and PHSRN) were designed for promoting scaffold-cell interaction. Three of them (I3KVAV, I3RGDS and I3YIGSR) can self-assemble into nanofibers, therefore, were used to enhance the application of RSF in neuron TE. Live / dead assays revealed that the peptides exhibited negligible cytotoxicity against PC12 cells. The specific interaction between PC12 cells and the peptides were investigate using atomic force microscopy (AFM). The results indicated a synergistic effect in the designed peptides, promoting cellular attachment, proliferation and morphology changes. In addition, AFM results showed that co-assembling peptides I3KVAV and I3YIGSR possesses the best regulation of proliferation and attachment of PC12 cells, consistent with immunofluorescence staining results. Moreover, cell culture with hydrogels revealed that a mixture of peptides I3KVAV and I3YIGSR can also promote 3D neurites outgrowth. The approach of combining two different self-assembling peptides shows great potential for nerve regeneration applications.