Biomedical Engineering Reference
In-Depth Information
Table 10.1
(Continued)
Materials
a
Structure
Ref.
78
Poly(LysMA)
d
n
4
y
3
n
g
|
7
a
Poly(CBAA) 5 poly(carboxybetaine acrylamide); poly(TM-SA) 5 poly([2-(Acryloyloxy)ethyl]
trimethyl ammonium chloride- carboxylic acid [2-carboxy ethyl acrylate]); poly(METMA-MES) 5
poly([2-(methacryloyloxy)
ethyl]trimethylammonium
chloride
-
-3-sulfopropyl
methacrylate
potassium
salt);
poly(MHist) 5 poly(N-Methacryloyl-L-histidine);
poly(SerMA) 5 poly(o-
methacryloyl-L-serine); poly(LysMA) 5 poly(e-methacryloyl L-lysine).
a physical and energetic barrier to prevent protein adsorption on the surface. This
is an intrinsic cause of the resistance of polymers. Recent results showed that 7-8
water molecules could tightly bind with one sulfobetaine (SB) unit while only y1
water molecule binds with one EG unit at a lower association constant than
with SB.
28
Simulations also reveal different structural and dynamic properties of
interfacial waters near the phosphorylcholine self-assembled monolayers (PC-
SAM) and oligo(ethylene glycol) self-assembled monolayer (OEG-SAM)
surfaces. First, interfacial water molecules near the zwitterionic PC-SAM surface
have longer residence times (stay longer) and smaller self-diffusion coefficients
(move slower) than those near the hydrophilic OEG-SAM surface, indicating that
the PC-SAM surface binds water molecules more strongly than the OEG-SAM
surface. Secondly, interfacial water molecules at the PC-SAM surface have much
larger reorientational dynamics than those at the OEG-SAM surface, indicating
that the PC-SAM binds water molecules via ionic solvation while the OEG-SAM
binds via hydrogen bonding.
14,27,29
After all, the bound water molecules on
zwitterionic polymers caused by strongly ionic solvation are more tightly bound
than ones on PEG through hydrogen bonding, The superior resistance to
nonspecific protein adsorption of zwitterionic polymers is rather unambiguous.
On the other hand, it is necessary to bear in mind the difference between
surface resistance and the intrinsic property of polymers to resist nonspecific
protein adsorption when unexpected protein adsorption on drug delivery
systems occurs. Surface packing (i.e. film thickness, packing density, and chain
conformation) could also affect the overall surface hydration. Chain flexibility
also plays an important role in protein resistance, especially for polymer brush-
coated surfaces. When a protein approaches the surface, the compression of
