# Cellular Responses to Hydrophobic Polyelectrolyte/Wax Coatings for Biomedical Use

## TL;DR

This study explores how hydrophobic coatings made with polyelectrolytes and wax affect cell behavior, finding that they support fibroblast growth but may hinder endothelial cells.

## Contribution

The study introduces and evaluates hydrophobic PEM/Wax coatings for biomedical use, revealing their cell-type-specific biocompatibility.

## Key findings

- Hydrophobic PEM/Wax coatings supported fibroblast adhesion and growth better than hydrophilic PEMs.
- Endothelial cells showed reduced adhesion and viability on hydrophobic coatings compared to hydrophilic ones.
- All tested coatings passed cytotoxicity tests, confirming their safety for medical applications.

## Abstract

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.