A new diol with a phosphatidylcholine polar headgroup,
[bis(2-hydroxymethyl)]propane-2-(trimethylammonio)ethyl phosphate (BTEP), was synthesized and
characterized. The
BTEP, together with 1,4-butanediol (BD) as a chain extender, was used
to synthesize
segmented polyurethanes (SPUs) based on diphenylmethane diisocyanate
(MDI) and various
types of soft segments such as polycarbonate, polyether, polyester, and
hydrocarbon diols.
The bulk characteristics of the resulting SPUs were investigated
by infrared (IR) spectroscopy, viscosity, and gel-permeation chromatography (GPC) measurements.
Good mechanical
properties of the typical SPU containing poly(butadiene) glycol
(PBD) were indicated by
dynamic viscoelasticity and tensile measurements. The
phosphatidylcholine polar groups
were oriented on the surface of these materials as revealed by
attenuated total reflectance−Fourier transform infrared spectroscopy (ATR−FTIR), electron
spectroscopy for chemical
analysis (ESCA), and contact angle measurements. The
hemocompatibilities of the new
polymers were evaluated by platelet-rich plasma (PRP) contact studies
and viewed by
scanning electron microscopy (SEM) using medical BioSpan as a
reference. The new
materials have good surfaces in terms of platelet adhesion, and the
morphology of adhered
platelets undergoes a relatively low degree of variation. Suitably
increasing percentages of
phosphatidylcholine polar groups in the polymers and higher molecular
weights of the soft
segments of the polymers may further improve
hemocompatibility.
The mechanism of alumina formation from tri-methyl aluminum (TMA) and oxygen (O 2 ) using catalytic-chemical vapor deposition (Cat-CVD) with an iridium catalyzer was investigated by quadrupole mass spectrometry (QMS). Above 600 -C, TMA decomposed into Al and CH 3 . Aluminum in the presence of O 2 caused a decrease in O 2 and the creation of alumina on Si crystals. These results imply that O 2 and Al produced AlO as expected. The iridium catalyzer was resistant to oxidation. MIS diodes with 17-nm-thick alumina gates were produced with a hysteresis shift voltage of 0.01 mV and a fixed charge density of 6.7 Â 10 11 cm À 2 .
We reported herein that 2-(methacrylorloxy)ethyl-2-(trimethylammonium)ethyl phosphate (MTP) was successfully grafted onto a segmented polyurethane (SPU) cast film surface. We found MTP orientated onto a film surface had excellent hemocompatibility, and the addition of the cross-linking agent N,N′-methylenebisacrylamide (MBAA) further increased MTP orientation on the surface and lead to better hemocompatibility. 1,4-Butanediol (BD) as a chain extender was used to synthesize the SPU which was based on diphenylmethane diisocyanate (MDI), vinyl group-containing poly(butadiene) diol (PBD), and hydrogenated poly(butadiene) diol (HPBD). To obtain an alcohol-orientated surface of SPU, glycidyl methacrylate (GMA) was copolymerized with the SPU using R,R′-azobis(isobutyronitrile) (AIBN) as a radical initiator, and diethanolamine (DEA) was used to open the epoxy group leading to hydroxylated SPU. Furthermore, MTP and the cross-linking agent MBAA were grafted onto the cast film surface of hydroxylated SPU by using diammonium cerium(IV) nitrate as a catalyst. The bulk characteristics of the resulting polymers were investigated by infrared spectroscopy (IR) measurements. We found that both polymerization time and MBAA concentration accelerated grafting. The phosphatidylcholine groups of MTP orientated on the surface and the addition of MBAA accelerated MTP grafting as revealed by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and electron spectroscopy for chemical analysis (ESCA) measurements. The hemocompatibility in vitro was evaluated with rabbit platelet-rich plasma (PRP) contact tests and viewed by scanning electron microscopy (SEM) using commercially available BioSpan and nongrafted SPU (NG-SPU) as references. We found that fewer platelets adhered to the MTP grafted surfaces and that they showed less shape variation than the references. Platelet adhesion to MTP-grafted polymers was inhibited 50-84% compared with NG-SPU. The relative clotting time of the cast films in contact with cow PRP was 2.74, 2.28, 1.79, and 1.00 for MTP grafted-SPU, NG-SPU, BioSpan, and glass, respectively.
New segmented polyurethanes (SPUs) grafted phospholipid analogous vinyl monomers and polyfunctional monomers were synthesized. The soft segments used in this study were poly(butadiene). The hard segments of these polyurethanes were 4,49-methylenediphenyl diisocyanate and 1,4-butanediol. The blood compatibilities of the new polymers were evaluated by platelet rich plasma (PRP) contact studies and viewed by scanning electron microscopy (SEM) using medical grade BioSpan and non-phospholipid polyurethane as a reference. The clotting times of the materials in contact with platelet poor plasma (PPP) were also measured. These results of two evaluations suggest that these grafted polymers may be regarded as hopeful biomaterials.
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