Cellular Responses to Hydrophobic Polyelectrolyte/Wax Coatings for Biomedical Use

Polyelectrolyte multilayer (PEM) coatings represent a promising strategy for the biofunctionalization of biomaterials. Incorporating nonpolymeric components into the polymer matrix is a strategy to modulate PEM properties, enabling the development of new, application-specific functionalities. For example, integrating nano-thick wax layers both within and atop the PEM matrix creates hydrophobic waterproof barrier coatings that show great potential for use on bioresorbable magnesium implants. These coatings hinder contact between the implant and surrounding tissue and bodily fluids, thereby slowing down implants' degradation. However, the hydrophobic nature of such coatings raises concerns regarding their cell compatibility and overall biocompatibility. This study investigates and compares the viability of fibroblasts (3T3 cells) and human umbilical vein endothelial cells (HUVECs) on three different hydrophilic PEM coatings and their corresponding composite hydrophobic PEM/Wax counterparts. Our results show that some aspects of cellular behavior are cell-type-specific, while others are commonly influenced by the chemical composition of the coatings. Although hydrophobic, all three PEM/Wax coatings supported fibroblast adhesion and growth, surpassing their hydrophilic PEM counterparts, whereas the more surface- and environment-sensitive HUVECs showed reduced adhesion and viability on the hydrophobic coatings compared with the hydrophilic PEMs. Cytotoxicity testing, conducted in accordance with ISO 10993-5, confirmed that all coatings are noncytotoxic, supporting their suitability for use in medical devices.