Crack prevention of biodegradable polymer coating on metal facilitated by a nano-coupled interlayer

Abstract

Crack prevention of biodegradable polymer coatings on drug-eluting stents was investigated by introducing a nano-coupled layer at the interface between the metal surface and the polymer coating layer using surface-initiated ring-opening polymerization of ε-caprolactone. Poly(d,l-lactide-co-glycolide) coating on cobalt-chromium control and ricinoleic acid-poly(caprolactone)–grafted cobalt-chromium was carried out using electrospraying. The cracking of the biodegradable polymer coating on drug-eluting stents during ballooning was addressed by introducing a nano-coupled interlayer on the cobalt-chromium surface. The ricinoleic acid-poly(caprolactone) nano-coupled interlayer and poly(d,l-lactide-co-glycolide)-coated top layer were characterized using attenuated total reflection Fourier transform infrared, contact angle, ellipsometry, X-ray photoelectron spectroscopy, and atomic force microscopy. Based on scratch tests, the nano-coupled samples had stronger interfacial adhesion compared to the control sample without the nano-coupled layer. Scanning electron microscope images indicated that the cracking on the poly(d,l-lactide-co-glycolide) coating was addressed. Introducing a nano-coupling interlayer may be an important strategy to preventing polymer coating cracking on drug-eluting stents.