Effect of hydrophilic and hydrophobic microdomains on mode of interaction between block polymer and blood platelets

Abstract

ABA-type block copolymers composed of 2-hydroxyethyl methacrylate (HEMA), a hydrophilic monomer, and styrene (St), a hydrophobic monomer, were synthesized by the coupling reaction of telechelic oligomers used as prepolymers. These block copolymers may be represented as microphase-separated structures. It is therefore possible to change the balance between hydrophilicity and hydrophobicity in the level of an assembled order of macromolecules. In response to the relative composition of the copolymers, three typical morphological patterns were observed in electron microscopic photographs: dispersed domains of continuous St chains in the region of HEMA chains, alternate HEMA and St lamellae and finally, dispersed phases of continuous HEMA chains in the region of St chains. The effect of the hydrophilic and hydrophobic microdomains of the copolymers on the mode of interaction between polymers and platelets was studied by the microsphere column method. In the case of homopolymers and random copolymers, a significant degree of platelet adhesion and aggregation was observed. However, the degree of platelet adhesion and deformation was suppressed on the surfaces of the block copolymers containing 0.608 and 0.347 mole fractions of HEMA whose microdomains were hydrophilic-hydrophobic lamellae and isolated hydrophilic islands in hydrophobic areas, respectively. These results show that the microphase-separated structures were antithrombogenic and prevented platelet adhesion and deformation. On the basis of the results obtained, the interaction between platelets and polymer surfaces was described in terms of the effect of hydrophilic and hydrophobic microdomains.

Swelling behavior of poly (2-hydroxyethyl methacrylate) copolymer gels

“…Hydrogels of poly (2-hydroxyethyl methacrylate), henceforth designed as PHEMA, represent a system of low toxicity well accepted by body tissues and used as biomedical materials in various devices [14,15]. They are also known as implantable devices since fulfilling all the requirements of biocompatibility [16].…”

Novel segmented polyurethanes having galactitol analogous groups

“…The hydrophilicity-hydrophobicity of the surface of a biomaterial influences its biocompatibility [34,35]. The contact angles of water on the cast films of the synthesized SPUs at room temperature are summarized in Table 2.…”

Creation of a blood-compatible surface: A novel strategy for suppressing blood activation and coagulation using a nitroxide radical-containing polymer with reactive oxygen species scavenging activity

“…One of the most simple and important techniques is polymer coating using biocompatible polymers such as poly(ethylene glycol) [4], zwitterionic polymers [5][6][7], microphase-separated polymers [8,9], and poly(2-methoxyethyl acrylate) [10]. These approaches can drastically reduce the adsorption of serum proteins.…”

“…In the process, we have hypothesized that ROS-scavenging characteristics play a crucial role in blood activation and coagulation when blood comes in contact with material surfaces. To validate our hypothesis, we 8 have designed and developed a hydrophobic nitroxide radical-containing polymer (NRP) composed of hydrophobic poly(chloromethylstyrene) (PCMS) chains in which TEMPO moieties were conjugated via condensation reaction of the chloromethyl groups in PCMS with the sodium alkolate group of 4-hydroxy-TEMPO (TEMPOL) (see Figure 1b). In this paper, we describe the synthesis of the NRP homopolymer and its characterization in terms of blood compatibility.…”