|Panos, Melisa -|
|Ahunbay, Goktug -|
Submitted to: Langmuir
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 27, 2012
Publication Date: August 2, 2012
Citation: Panos, M., Sen, T.Z., Ahunbay, G.M. 2012. Molecular simulation of fibronectin adsorption onto polyurethane surfaces. Langmuir. 28(34):12619-12628. Interpretive Summary: Polymers are widely used in biomedical applications and several factors need to be considered during the design stage of these polymers. For example, some polymers are subject to swelling when it is inserted into the human body or when it is in contact with an open wound. To control the swelling, castor oil is incorporated into the polymer matrix. However, castor oil may also increase protein adsorption, which will decrease the usefulness of polymers in biomedical applications. In the paper, the researchers applied computational methods to analyze protein (fibronectin) adsorption on polyurethane polymers with and without castor oil. It concludes that castor oil indeed increases protein adsorption, which needs to be taken into account when it is used for biomedical applications to improve human health.
Technical Abstract: Polyethylene glycol-based polyurethanes have been widely used in biomedical applications, however are prone to swelling. A natural polyol, castor oil can be incorporated into these polyurethanes to control the degree of the swelling, which alters mechanical properties and protein adsorption characteristic of the polymers. In this work, we modeled polyethylene glycol and castor oil copolymers of hexamethylene diisocyanate-based polyurethanes (PEG-HDI and CO-HDI respectively) and compared their mechanisms for fibronectin adsorption using molecular mechanics and molecular dynamics simulations. Results showed that the interplay between the hydrophobic residues concentrated at the head of the protein, the surface roughness, and the hydrophilicity of the polymer surface determine the overall protein adsorption affinity. Incorporating explicit water molecules in the simulations results in higher affinity for fibronectin adsorption to more hydrophobic surface of CO-HDI surfaces, emphasizing the role water molecules play during adsorption. We also observed that the strain energies that are indicative of flexibility and consequently entropy are significantly affected by the changes in the patterns of ß-sheet formation/breaking. Our study lends support to the view that while castor oil controls the degree of swelling, it increases the adsorption of fibronectin to a limited extent due to the interplay between its hydrophobicity and its surface roughness, which needs to be taken into account during the design of polyurethane-based biomaterials.