# Polycatecholamine nanocoatings on stainless steel: the effect on attachment of human fibroblasts and platelets

## TL;DR

This study explores how different nanocoatings on stainless steel affect cell attachment, finding that PTYR coatings reduce platelet adhesion and improve biocompatibility.

## Contribution

The novel in situ oxidation process for creating PTYR nanocoatings and their hemocompatible properties are newly demonstrated.

## Key findings

- PTYR nanocoatings reduced platelet adhesion and activation compared to PDA coatings.
- Fibroblast attachment was influenced by coating roughness with a specific threshold effect.
- PTYR coatings showed higher stability and nanoparticulate morphology under physiological conditions.

## Abstract

Polydopamine (PDA) is widely used to functionalize materials and enhance cell attachment. At the same time, the potential of the dopamine precursor tyrosine in its polymerized form (polytyrosine, PTYR) remains underexplored despite its biological activity. In this study, we developed nanostructured PDA and PTYR layers on stainless steel 316L via a novel in situ oxidation process and evaluated their physicochemical properties and cellular interactions at the nano/microscale. Surface characterization revealed that the polymeric coatings formed a homogenous layer with distinct topographical features and thickness in the nanometer range for PTYR and in the micrometer range in case of PDA. Compared to PDA, PTYR coatings exhibited a nanoparticulate surface morphology and higher stability under physiological conditions. Wettability, roughness, and amine group density were systematically analyzed to determine their influence on interactions with fibroblasts and platelets. Our results show that PTYR nanocoatings significantly reduced platelet adhesion and activation, whereas PDA coatings, due to their higher primary amine content, could in some cases enhance platelet adhesion. Furthermore, fibroblast attachment was primarily influenced by coating roughness, with a specific threshold beyond which adhesion did not increase or was negatively impacted. These findings highlight the potential of engineered PTYR nanocoatings for developing advanced hemocompatible surfaces for biomedical implants.