Spray Coating Oxidized Graphene-Based Materials Makes Polyurethane Surfaces Antibacterial and Biocompatible: A Promising Approach for Medical Devices

Preventing bacterial infections remains a primary concern for healthcare systems and patients. Polyurethane (PU) is widely used in various invasive medical devices, improving PU surfaces─particularly by reducing bacterial adhesion─a highly sought-after goal. This study explores the spray coating of PU-based medical devices with oxidized graphene-based materials (GBMox) as antibacterial agents, specifically oxidized graphene nanoplatelets (GNPox) and graphene oxide (GO). Different formulations, with and without PU as a coating binder, were investigated to assess the potential for tuning the coating based on the intended application. The resulting coatings were characterized in terms of morphology using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM), along with wettability and stability analysis. Antibacterial activity was evaluated against <i>Staphylococcus epidermidis</i>, with GNPox-containing coatings reducing bacterial adhesion by up to 82%, with no effect from blood plasma proteins. <i>In vitro</i> biocompatibility was confirmed across all surfaces: human fibroblasts adhered and spread on coatings without PU, while coatings combining GNPox and PU retained the low cell adhesiveness typical of PU. Overall, GBMox coatings on PU enhance antibacterial performance, preserve biocompatibility, and enable tuning of the cell adhesion behavior. These coatings offer a promising antibiotic-free strategy for PU-based biomedical applications, and the spray coating method provides a simple, reproducible, and industrially scalable approach.