Engineering Nano-to-Micron-Patterned Polymer Coatings on Bioresorbable Magnesium for Controlling Human Endothelial Cell Adhesion and Morphology

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Surface patterning is an attractive approach to modify the surface of biomaterials for modulating cell activities and enhancing the performance of medical implants without involving typical chemical changes to the implants such as adding growth factors, antibiotics, and drugs. In this study, nano-to-micron patterns were engineered on thermoplastic and thermoset polymer coatings on bioresorbable magnesium (Mg) substrates to control the cellular responses and material degradation for vascular applications. Capillary force lithography (CFL) was modified and integrated with spray coating to fabricate well-aligned nano-to-micron patterns on the thermoplastic poly(lactic-co-glycolic acid) (PLGA) and thermoset poly(glycerol sebacate) (PGS) coatings on Mg substrates. Specifically, a new process of molding-curing CFL was revised from the conventional CFL to successfully create nano-to-submicron patterns on thermoset PGS for the first time. The nano-to-micron-patterned polymer coatings of PLGA and PGS on Mg were carefully characterized, and their effects on cell adhesion and morphology were investigated through direct culture with human umbilical vein endothelial cells (HUVECs) in vitro. The results showed that the 3000 nm parallel grooves could effectively elongate the HUVECs, while the 740 nm parallel grooves tended to reduce the spreading of HUVECs. The PLGA coatings reduced the degradation of Mg substrates more than that of the PGS coatings in the direct culture with HUVECs in vitro. CFL-based methods coupled with spray coating should be further studied as a nonchemical approach for creating nano-to-micron-patterned polymer coatings on Mg-based substrates of various sizes and shapes, which may present a new direction for improving the performance of Mg-based bioresorbable vascular devices toward potential clinical translation.