Relationship between blood compatibility and water structure—Comparative study between 2‐methoxyethylacrylate‐ and 2‐methoxyethylmethacrylate‐based random copolymers

Abstract

We have proposed that the excellent blood compatibility of poly(2-methoxyethylacrylate (MEA)) is caused by freezing bound water contained in it on the basis of results on platelet activation (Tanaka and Mochizuki, J Biomed Mater Res A 2004; 68:684-695). To clarify the applicability of this mechanism to other indexes for blood compatibility, the relationship between complement activation and water structure was investigated by using two copolymers, poly(MEA-2-hydroxyethylmethacrylate (HEMA)) and poly(2-methoxyethylmethacrylate (MEMA)-HEMA), where HEMA content was varied from 25 to 90 mol %. ESCA analysis revealed that the surface compositions of these copolymers (dry state) agreed with the compositions determined by (1)H NMR. However, analysis by water contact angle (wet state) showed that their surfaces were quite different. The contact angle of poly(MEMA-HEMA) depended on the monomer composition, whereas the angle of poly(MEA-HEMA) was close to that of polyHEMA regardless of the monomer composition. The effect of HEMA content in the copolymers on complement activation (production of C3a) was investigated in an in vitro test. The activation by poly(MEMA-HEMA) was enhanced according to the HEMA content, while the activation by poly(MEA-HEMA) with 0-40 mol % of HEMA was weak and did not depend on the HEMA content. These properties are discussed from the viewpoints of the water structure observed by DSC and the surface structure.

Water Structure and Blood Compatibility of Poly(tetrahydrofurfuryl acrylate)

“…We have proposed that freezing bound water plays a very important role in blood compatibility on the basis of the results obtained from comparisons of PMEA, MEA-HEMA co-polymers and various poly(meth)acrylates [6,7]. In particular, we pointed out that the amount of freezing bound water would affect blood compatibility based on a study of poly(MEA-r-HEMA) [17]. From these previous studies, it is easily predicted that the amount of freezing bound water in PTHFA is not sufficient to depress the activation of biocomponents in blood.…”

Comparative study on water structures in polyHEMA and polyMEA by XRD‐DSC simultaneous measurement

“…Some researchers suggest that the water structure on a material surface is one of the most important factors determining blood compatibility 6–10. According to this implication, we focused our attention on the water structure in polyMEA and found, by using DSC, that hydrated polyMEA has unique thermal behavior 11–13. That is, the DSC heating curve for hydrated polyMEA shows an exothermic peak at around −45°C and an endothermic peak at around 0°C.…”

Study on the Water Structure and Blood Compatibility of Poly(acryloylmorpholine-r-butyl methacrylate)

“…As mentioned in the Introduction, we proposed that water in a polymer plays an important role in determining its blood compatibility, and we evaluated many hydrated polymers [14][15][16][17]. Through these works, we categorized the water in polymers into three types using DSC, i.e., free water, freezing bound water (= coldcrystallizable water) and non-freezing water, and proposed that cold-crystallizable water is the key factor in determining blood compatibility.…”

“…In addition to these factors, the contribution of water on the material surface to blood compatibility has been suggested [9][10][11][12][13]. We have already disclosed the excellent blood compatibility of poly(2-methoxyethyl acrylate) (polyMEA) and have been investigating the rationale for this phenomenon by focusing our attention on the water structure in polyMEA [14][15][16][17]. Through these works we found that polyMEA has very unique water compared to other poly(meth)acrylates.…”