Pulsed Vacuum Arc Deposition of Nitrogen-Doped Diamond-like Coatings for Long-Term Hydrophilicity of Electrospun Poly(epsilon-caprolactone) Scaffolds

The surface hydrophobicity of poly(epsilon-caprolactone) electrospun scaffolds prevents their interactions with cells and tissue integration. Although plasma treatment of scaffolds enhances their hydrophilicity, this effect is temporary, and the hydrophobicity of the scaffolds is restored in about 30 days. In this communication, we report a method for hydrophilization of poly(epsilon-caprolactone) electrospun scaffolds for more than 6 months. To that end, diamond-like coating was deposited on the surface of the scaffolds in a nitrogen atmosphere using pulsed vacuum arc deposition with sputtering of graphite target. This approach allows for a single-side hydrophilization of the scaffold (water contact angle of 22 +/- 3 degrees vs. 126 +/- 2 degrees for pristine PCL scaffold) and preserves its structure. With increased nitrogen pressure in the chamber, sp(3)-hybridized carbon content decreased twice (sp(2)/sp(3) ratio decreased from 1.06 to 0.52), which demonstrates the possibility of tailoring the content of carbon in sp(2) and sp(3) hybridization state. Nitrogen content in the deposited coatings was found at 16.1 +/- 0.9 at.%. In vitro tests with fibroblast cell culture did not reveal any cytotoxic compounds in sample extracts.