Investigation of surface endothelialization on nitinol: Effects of composite hydrogel coatings

Due to high metal coverage and high mesh density，flow diverters (FD) are widely used for endovascular reconstruction of cerebrovascular disease. However, incomplete endothelialization, restenosis, and thrombosis hamper the long term clinical success. Thus, an effective coating to accelerate the endothelialization of the cerebrovascular FD raw materials and reduce the incidence of thrombosis and restenosis is needed. A novel composite hydrogel composed of matrigel and sodium alginate (SA) with different blending ratios, which was cross-linked with calcium chloride, was successfully prepared. The hydrophilicity of the coating surface was detected by measurement of the contact angle, and the surface morphology of the nitinol (NiTi) before and after modification was characterized by scanning electron microscopy (SEM). The elastic modulus was utilized to verify the mechanical properties and plasticity of the coating, and the release experiment was conducted to characterize the composite hydraulic coagulation. Additionally, biocompatibility was tested by in vitro cellular experiments. The SEM observations showed that when the concentrations of matrigel and SA were 5 and 3 mg/ml, respectively, cross-linking with 40 mg/ml calcium chloride solution was resulted in formation of the uniform M/SA composite hydrogel coating. The contact angle of M/SA-NiTi was only (32.28 ± 1.55°) (P < 0.0001), indicating a strong hydrophilicity of M/SA-NiTi. The 48 h coating release rate is 61.5%. In addition, M/SA-NiTi exhibited to have better biocompatibility and plasticity than B-NiTi and M-NiTi. Matrigel/sodium alginate composite hydrogel coating has good biocompatibility and low thrombosis characteristics, and strong drug-carrying capacity, which is expected to accelerate the endothelialization after FD implantation. It has also a great potential application value in the surface modification of biological materials.