1,4-Bis(2-hydroxyethyl)piperazine-derived water-dispersible and antibacterial polyurethane coatings for medical catheters†

Abstract

To prolong usage and mitigate infections associated with bacterial colonization on medical catheters, the development of water-dispersible polyurethane (PU) coatings with bactericidal properties is desirable. With this objective, we have formulated polyurethane coatings that exhibit both antibacterial activity and water dispersibility. A piperazine-based diol, 1,4-bis(2-hydroxyethyl)piperazine (HEPZ), was synthesized and used as a chain extender in PU synthesis. The PUs were prepared using hexamethylene diisocyanate (HDI), 4,4′-methylene diphenyl diisocyanate (MDI), polyethylene glycol (PEG₆₀₀), and polypropylene glycol (PPG₄₀₀), resulting in a series of polyurethanes (PU1–PU4). MDI-containing PUs showed superior tensile strength (3.2–3.6 MPa) and elongation (67–70%) attributable to their higher aromatic content. The PEG₆₀₀-containing PUs (PU1 and PU3) were alkylated using methyl iodide (MeI) to varying degrees whereby a significant reduction in contact angle from ∼82° to ∼62° was observed, indicating enhanced hydrophilicity. MPU3-D with 72.5% methylation demonstrated the most stable water dispersion with a particle size of ∼190.8 nm and a zeta potential of +49.0 mV. In vitro cytocompatibility studies further revealed that methylated PU3 exhibited higher compatibility (80–90%) compared to methylated PU1 (30–40%). The hemolysis test showed the non-hemolytic behavior of MPU3-D films with a % hemolysis of 0.4 ± (0.2)% making it suitable for coating on medical devices. Additionally, MPU3-D films also demonstrated antibacterial activity against Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria, with zones of inhibition measuring 7 mm and 8 mm, respectively. Also, water-dispersible MPU3-D-based coatings with a hardness of ∼75 A and a thickness of ∼17 μm (as observed through FESEM) showed strong adhesion to PVC catheters, exhibiting an adhesion strength of 4B rating. Our results suggest that water-dispersible polyurethane coatings with antibacterial properties are promising materials to reduce catheter-associated infections and enhance patient care.