Molecular Dynamics Study on the Water Mobility and Side-Chain Flexibility of Hydrated Poly(ω-methoxyalkyl acrylate)s

Abstract

Intermediate water (IW) is known to play an important role in the antifouling property of biocompatible polymers. However, how IW prevents protein adsorption is still unclear. To understand the role of IW in the antifouling mechanism, molecular dynamics simulation was used to investigate the dynamic properties of water and side-chains for hydrated poly­(ω-methoxyalkyl acrylate)­s (PMCxA, where x indicates the number of methylene carbons) with x = 1–6 and poly­(n-butyl acrylate) (PBA) in this study. Since the polymers uptake more water than their equilibrium water content (EWC) at the polymer/water interface, we analyzed the hydrated polymers at a water content higher than that of EWC. It was found that the water molecules interacting with one polymer oxygen atom (BW1), of which most are IW molecules, in PMC2A exhibit the lowest mobility, while those in PBA and PMC1A show a higher mobility. The result was consistent with the expectation that the biocompatible polymer with a long-resident hydration layer possesses good antifouling property. Through the detailed analysis of side-chain binding with three different types of BW1 molecules, we found that the amount of side-chains simultaneously interacting with two BW1 molecules, which exhibit the highest flexibility among the three kinds of side-chains, is the lowest for PMC1A. The high mobility of BW1 is thus suggested as the main factor for the poor protein adsorption resistance of PMC1A even though it possesses enough IW content and relatively flexible side-chains. Contrarily, a maximum amount of side-chains simultaneously interacting with two BW1 molecules was found in the hydrated PMC3A. The moderate side-chain length of PMC3A allows side-chains to simultaneously interact with two BW1 molecules and minimizes the hydrophobic part attractively interacting with a protein at the polymer/water interface. The unique structure of PMC3A may be the reason causing the best protein adsorption resistance among the PMCxAs.

Interactions between Acrylate/Methacrylate Biomaterials and Organic Foulants Evaluated by Molecular Dynamics Simulations of Simplified Binary Mixtures

“…MD simulations investigating the dynamic properties of water molecules and side chains of hydrated PMEA and its analogs indicated that polymer materials with a robust hydration layer showed better biocompatibility. 18 The thermodynamic properties of PMEA and PHEMA have also been explored. The free energy profiles of these materials were obtained using MD calculations to evaluate their protein resistances.…”

“…Another study, where MD simulations were performed to identify the structure of IW in hydrated PMEA and its analogs, suggested that IW molecules enhance the flexibility of the polymer side chains. MD simulations investigating the dynamic properties of water molecules and side chains of hydrated PMEA and its analogs indicated that polymer materials with a robust hydration layer showed better biocompatibility …”

Molecular Structure and Vibrational Spectra of Water Molecules Sorbed in Poly(2-methoxyethylacrylate) Revealed by Molecular Dynamics Simulation

“…In this study, we developed two kinds of PMEA models: one is a widely used force field model that has been employed in previous MD studies ,,− for the general purpose, for example, GAFF, OPLS, and so forth (model 1); the other is the model with the lone-pair VSs located on the carbonyl oxygen O 1 and the methoxy oxygen O 3 (model 2), as discussed in the Methods section. To determine the influences of the introduction of the VSs on the hydrated structure of the side chain of PMEA, we preliminarily carried out MD simulations consisting of one solute MEA in water, using model 1 and model 2, respectively, and calculated the RDFs between the MEA oxygens (O 1 , O 2 , and O 3 ) and water oxygen (O w ).…”

“…Molecular dynamics (MD) computer simulation is another powerful tool for investigating the H-bonding structure in an aqueous environment, and some characteristic interactions between water and PMEA have been discussed. − Vibrational spectroscopy calculations by MD simulations are also useful for interpreting experimentally observed vibrational spectra. , Recently, Kuo et al systematically examined the H-bonding states of water in PMEA and its analogue based on their classification of water mentioned above. − In particular, the velocity–velocity autocorrelation functions of water molecules sorbed into PMEA were calculated to discuss the vibrational spectra for the OH stretching region of water interacting with PMEA . However, the reproducibility of the calculated spectra may not be satisfactory, particularly at a low water content, because the spectra for the entire water-concentration range show a peak around 3400 cm –1 rather than around 3600 cm –1 , and no peak shift was observed in the MD simulation.…”

Effects of Side-Chain Spacing and Length on Hydration States of Poly(2-methoxyethyl acrylate) Analogues: A Molecular Dynamics Study

“…The theoretically evaluated BW1 content was found to negatively correlate with the experimentally measured amounts of adhered platelet and adsorbed fibrinogen on the PMC y A-coated surface ( y = 2–6). , Moreover, the flexibility of the side chains and the mobility of the bound water (BW) might have some influence on the protein adsorption . For example, the poor resistance of protein adsorption for PMC1A was ascribed to the highest mobility of BW1, whereas the best resistance of protein adsorption for PMC3A was attributed to the highest content of the side chain binding with two BW1 molecules …”