Elastin-like polymer coating on CoCr surfaces for cardiovascular applications

Abstract

Cardiovascular diseases have emerged as a major concern since they are the first cause of death in developed countries. The advent of percutaneous transluminal coronary angioplasty consisted in an alternative to invasive surgery. Especially the introduction of cardiovascular stents has significantly meliorated the potential of angioplasty, e.g. with the use of drug eluting and bioadsorbable stents. Still, restenosis remains a major implant-related complication and can imply re intervention. Therefore, research has focused on limiting and/r avoided restenosis by investigating the field of surface treatments and drug delivery material. The rapidly developing field of material technology and engineering has enable design of molecular-specific surfaces for a new generation of vascular devices. This project has been focused on how to promote endothelialization on a bare metal CoCr alloy stent still widely used nowadays. The knowledge about biological response and interactions between extra cellular matrix proteins and cellular agents has lead to explore the potential of genetically engineered protein based polymers such as elastin-like polymers which mimic properties of the human elastin. This project has for general goal to promote endothelialization on CoCr-alloy by functionalizing the surfaces with REDV elastin-like biopolymer which contains a specific domain for endothelial cell adhesion. For that purpose different surface treatments have been performed on CoCr in order to enhance the biopolymer adhesion. First surfaces have been activated by means of O2 plasma, acid HNO3 and NaOH basic etching. Afterwards, a series has been CPTES silanized previous to biopolymer adsorption. Finally, REDV elastin-like biopolymer has been physically and/or chemically attached to the different treated surfaces. All treatments have been thoroughly physic-chemically characterized before and after all treatments steps. Finally special attention has been paid to the study of biopolymer coating stability after some thermal and/or mechanical treatments in order to determine the best surface treatment conditions of adhesion and the efficiency of previous surface treatments. REDV elastin-like biopolymer was successfully adsorbed on CoCr ASTM F-90 alloy surfaces. It was biofunctionalized CoCr ASTM F-90 alloy surfaces through CPTES silane. Silanization increased biopolymer adsorption but the efficiency was low. NaOH activated samples presented a higher CPTES silane attachment and biopolymer adhesion as observed by an increase of adhered HUVEC cells compared to other treatments. REDV elastin-like biopolymer is more sensitive to mechanical and thermal treatments probably due to a detachment and/or denaturation of the biomolecule. The increase of silanization efficiency on treated CoCr surfaces could enhance biopolymer stability as observed for NaOH treated surfaces.Incomin