Effects of hydration water on bioresponsiveness of polymer interfaces revealed by analysis of linear and cyclic polymer-grafted substrates.

Given that the hydration water of polymer matrices may differ from that of outermost polymer surfaces, processes at biomaterial-biofluid interfaces and role of hydration water therein cannot be adequately examined using most conventional characterization methods. To bridge this gap, a gold substrate was herein modified with linear and cyclic poly(2-methoxyethyl acrylate) to prepare -PMEA and -PMEA surfaces, respectively, as models for the outermost surfaces of blood-contacting medical devices. Both surfaces suppressed the adhesion of human platelets but differed in the adhesion behaviors of normal and tumor cells despite having the same areal density of fixed-end units.

Role of intermediate water in alleviating postsurgical intrapericardial adhesion.

Purpose: Various polymers have been used as postsurgical antiadhesive materials; however, the mechanisms underlying their efficacy remain unclear. Intermediate water has been found to prevent the adhesion between polymer molecules and proteins or cells. The present study investigated the role of intermediate water retained in the polymer in alleviating postsurgical pericardial adhesion.

Characterization of Hydration Water Bound to Choline Phosphate-Containing Polymers.

Zwitterionic methacrylate polymers with either choline phosphate (CP) (poly(MCP)) or phosphorylcholine (PC) (poly(MPC)) side groups were analyzed to characterize the bound hydration water molecules as nonfreezing water (NFW), intermediate water (IW), or free water (FW). This characterization was carried out by differential scanning calorimetry (DSC) of polymer/water systems, and the enthalpy changes of cold crystallization and melting were determined. The electron pair orientation of CP is opposite to that of PC, and the former binds the alkyl terminal groups at the phosphate esters.

Spreading Dynamics of a Precursor Film of Ionic Liquid or Water on a Micropatterned Polyelectrolyte Brush Surface.

Time evolution of the microscopic wetting velocity of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI-TFSI) or water on a micrometer-scale line-patterned surface with a poly(3-sulfopropyl methacrylate) brush and a hydrophobic perfluoroalkyl monolayer was precisely measured by direct observation using optical microscopy and a selective dyeing method over a long period (178 days). When a liquid droplet was placed on the dyed line-patterned brush surface, the liquid penetrated and spread into the polymer brush layer, forming a precursor thin film that extended beyond the macroscopic contact line. The elongation proceeded in two stages by an adiabatic process followed by a diffusive process.

Time Evolution of Precursor Thin Film of Water on Polyelectrolyte Brush.

The microscopic wetting behavior of a water film on the line-patterned surface of a polyelectrolyte brush was directly visualized using an optical microscope by dyeing procedures. Surface line patterns of 5 and 5 μm width or 10 and 5 μm width for the polyelectrolyte brush and hydrophobic monolayer, respectively, were prepared by a photolithography process, chemical vapor adsorption method, and surface-initiated polymerization. A droplet of water containing dye was placed on the line-patterned surface.