Surface modification of polyurethane films by plasma and ultraviolet light to improve haemocompatibility for artificial heart valves.
Prosthetic cardiac valves implantation is a common procedure used to treat heart valve diseases. Although there are different prostheses already available in the market (either mechanical or bioprosthetic), their use presents several problems, specifically concerning thrombogenicity and structural failure. Recently, some progresses have been achieved in developing heart valves based on synthetic materials with special emphasis in polymers. Among them, polyurethanes are one of the most commonly used for the production of these devices. Herein, Elastollan(®)1180A50, a thermoplastic polyurethane (TPU), was used to formulate films whose surfaces were modified by grafting 2-hydroxyethylmethacrylate (HEMA) either by ultra-violet (UV) or by plasma treatment. All films were analyzed before and after grafting. X-ray photoelectron spectroscopy (XPS) measurements were used to evaluate TPU surfaces functionalization. HEMA grafting was confirmed by the increase of the hydroxyl (OH) groups' concentration at the surface of the films. Atomic force microscopy (AFM) analysis was done to evaluate the surface topography of the biomaterials. Results showed that the roughness of the surface decreased when HEMA was grafted, especially for plasma treated samples. After grafting the films' hydrophilicity was improved, as well as the polar component of the surface energy, by 15-30%. Hydrophobic recovery studies using milli Q water or PBS were also performed to characterize the stability of the modified surface, showing that the films maintained their surface properties along time. Furthermore, blood-contact tests were performed to evaluate haemolytic and thrombogenic potential. The results obtained for HEMA grafted surfaces, using plasma treatment, confirmed biomaterials biocompatibility and low thrombogenicity. Finally, the cytotoxicity and antibacterial activity of the materials was assessed through in vitro assays for both modified films. The obtained results showed enhanced bactericidal activity, especially for the films modified with plasma.
CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra, Portugal. Electronic address: palves@eq.uc.pt.
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Alves
CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra, Portugal.
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Cardoso
CICS-UBI, Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde, Universidade da Beira Interior, 6200-506 Covilhã, Portugal.
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Correia
CICS-UBI, Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde, Universidade da Beira Interior, 6200-506 Covilhã, Portugal.
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Antunes
CICS-UBI, Centro de Investigação em Ciências da Saúde, Faculdade de Ciências da Saúde, Universidade da Beira Interior, 6200-506 Covilhã, Portugal.
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Correia
CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra, Portugal; IBB, Instituto de Biotecnologia e Bioengenharia, Instituto Superior Técnico, Universidade Técnica de Lisboa, 1049-001 Lisboa, Portugal. Electronic address: pferreira@eq.uc.pt.
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Ferreira
D020099:Coated Materials, Biocompatible / Q000009:adverse effects*; D006350:Heart Valve Prosthesis; D018625:Microscopy, Atomic Force; D056951:Photoelectron Spectroscopy; D011140:Polyurethanes / Q000737:chemistry*; D014466:Ultraviolet Rays
D020099:Coated Materials, Biocompatible; D011140:Polyurethanes
Biocompatibility; Heart valves; Plasma and UV activation; Polyurethanes; Surface modification