Advanced Hollow Cathode Discharge Plasma Treatment of Novel Bi-Layered Fibrous Guidance Conduits for Enhanced Peripheral Nerve Regeneration

In the tissue engineering field, the surface modification of hydrophobic nanofibers (NFs) to introduce cell-interactive chemical functionalities remains a challenge. Therefore, this study explores a novel three-step plasma based-method to synthesize coatings with a higher chemical selectivity in comparison to conventional plasma polymers. First, hexamethyldisiloxane (HMDSO) plasma polymerization was performed on NFs (blend of poly-ε-caprolactone and poly(D,L-lactide-co-glycolide), after which the samples were exposed to a helium plasma. Both steps were performed in a medium-pressure dielectric barrier discharge. Scanning electron microscopy (SEM) showed that the plasma-based steps did not damage the NFs, while X-ray photoelectron spectroscopy (XPS) and water contact angle measurements showed that a hydrophilic silanol-rich layer was formed. This layer was used in the final step, in which (3-aminopropyl) triethoxysilane (APTES) was grafted on the plasma polymer to introduce primary amine groups onto the surface, which was confirmed by XPS. This APTES-based layer could be partially removed, but the remaining stable layer enhanced Schwann cell responses in live/dead, The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT), immunofluorescent, and adhesion assays in comparison to the untreated and HMDSO-based coated NFs. As such, the fabricated coatings with selective functionality on PCL/PLGA NFs are a promising candidate to use in the tissue engineering field