Biomedical Engineering Reference
In-Depth Information
isalsoexplained.Afterreadingthischapter,thehighpotencyofMPC
polymers to regulate cell/material interfaces should beclarified.
19.2 Molecular Design and Fundamental
Property of MPC Polymers
Thecellmembranesurfaceisconsideredthebestsurfaceforsmooth
interaction with blood components such as proteins and cells. The
structure of the cell membrane, which is well known as the fluid-
mosaic model, was proposed by Singer and Nicolson.
3
According
to this model, amphiphilic phospholipids are arranged in a bilayer
structure and proteins are located in or upon it. The distribution
of these components is asymmetric. The phospholipids always flow
dynamically, and the cell membrane maintains its strength by the
supporting proteins. In all cells for which lipid compositional asym-
metryhasbeendescribed,negativelychargedphospholipidssuchas
phosphatidylserine are predominantly found on the inner, cytoplas-
mic side of the membrane, whereas the neutral, zwitterionic phos-
phorylcholine lipids such as phosphatidylcholines are located in the
outerleaflet.Thephosphatidylcholinesurfaceprovidesaninertsur-
face for the biological reactions of proteins and glycoproteins to
occur smoothly on the membrane. This fact provides very signif-
icant information for the development of novel blood compatible
polymers.
A new concept was proposed for making blood-compatible poly-
mermaterialsthathavegoodstability,processability,andapplicabil-
ity using a methacrylate monomer with a phosphorylcholine group,
MPC (Fig. 19.2).
4
The synthesis of MPC was di
cult. However, in
1987, Ishihara developed an improved synthetic route and purifica-
tion method for MPC and a su
cient amount of MPC with excellent
purity could be obtained.
5
Now, a Japanese chemical company pro-
duces MPC on an industrial scale and provides it worldwide. Thus,
it became possible to prepare MPC polymers with various other
methacrylates or styrene derivatives, and their blood compatibility
was carefully evaluated.
6
Theintroductionofothermonomerunitscouldchangetheprop-
ertiesoftheMPCpolymer.MPCcanbepolymerizedwithothervinyl
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