Immobilization of heparin/poly-l-lysine microspheres on medical grade high nitrogen nickel-free austenitic stainless steel surface to improve the biocompatibility and suppress thrombosis

- We succeed in immobilizing Hep/PLL microspheres onto the surface of medical grade high nitrogen nickel-free austenitic stainless steel substrates via polydopamine as an intermediate layer.
- The layer of Hep/PLL microspheres on the surfaces improved the cytocompatibility of high nitrogen nickel-free austenitic stainless steel. In vitro cytocompatibility and blood compatibility tests demonstrated that HNS-PDA-Hep/PLL microsphere substrates exhibited excellent stability and anticoagulant activity.
- Further more, we found that HNS-PDA-Hep/PLL microsphere substrates efficiently accelerated endothelialization and anticoagulation. Consequently, this work has potential application for the design of coronary artery stent surfaces tailored for vascular cell behavior.

Thrombosis formation, restenosis, and delayed endothelium regeneration continue to be a challenge for coronary artery stent therapy. To improve the hemocompatibility of cardiovascular implants and to selectively direct vascular cell behavior, a novel heparin/poly-l-lysine microsphere was developed and immobilized on a dopamine-coated surface. We chose medical grade high nitrogen nickel-free austenitic stainless steel as the stent material since it has better biocompatibility. The stability and structural characteristics of the microspheres changed with the heparin: poly-l-lysine concentration ratio. Antithrombin III binding was significantly enhanced. Furthermore, for plasma coagulation tests, the activated partial thromboplastin time and thrombin time were prolonged and depended on the heparinfunction. The modified exhibited excellent stability and anticoagulant activity, and efficiently accelerated endothelialization and anticoagulation. This work has potential application for the design of coronary artery stent surfaces tailored for vascular cell behavior.