Medical polyurethane fiber membrane after extraction with water, and then establish the determination of N, N dimethyl acetamide (DMAC) in Medical polyurethane fiber membrane by GC, and discuss the analysis and evaluation of other extracts of polyurethane fiber membrane for the determination of DMAC in the linear range of the average recovery rate was more than 90%, the RSD 1.51%-2.08% (n = 6). This method is simple, fast, sensitive and accurate, and may serve as a mass control method for DMAC in Medical polyurethane fiber membrane.
Acetamides ; chemistry ; Chromatography, Gas ; Membranes, Artificial ; Polyurethanes ; chemistry ; Water

Gastrointestinal (GI) cancers cause obstruction of the GI tract including biliary tree. In advanced GI cancer, endoscopic stent insertion is the treatment of choice. However, the current stent allows only mechanical palliation of obstructed GI tract and has no anti-tumor effect. The primary role of a drug eluting stent (DES) in gastrointestinal malignancy is that it decreases the tumor re-growth and sustains the stent patency. This might not be as impressive as the effect of a vascular DES which decreases the incidence of restenosis and thus increases the survival rate of the patient. However, in terms of improving the quality of life of the patient, maintaining the stent patency is one of the most important task of GI doctors. With an advanced technology in stent production, Korea would be able to play an active role in the field of DES especially with more advanced anti-tumor effect. Moreover, advances in this type of drug delivery system will enable the development of local treatment of GI malignancy using endoscopy.
*Drug-Eluting Stents ; Gastrointestinal Diseases/*drug therapy ; Humans ; Polyurethanes/*chemistry

A novel Cu-IUDs material, PU/PEG/Cu nanocomposite, was prepared by melt blending method with thermoplastic polyurethane (PU) as the matrix, with polyethylene glycol (PEG) as a hydrophilic modifier, and with nanometer particles of copper as active matter instead of copper wire or copper tube. The structure, morphology, mechanical properties, thermal stability and water absorption were investigated by using FT-IR, XRD, SEM and so on. The results indicated that the nanometer particles of copper were uniformly dispersed in the matrix in PU/PEG/ Cu nanocomposites. It can be seen that the water absorption ability of this nanocomposite was obviously improved while mechanical properties and thermal stability were at high levels. These results provided a good basis for the studies on the cupric ions release of the nanocomposites in future.
Biocompatible Materials ; chemistry ; Intrauterine Devices, Copper ; Nanocomposites ; chemistry ; Polyethylene Glycols ; chemistry ; Polyurethanes ; chemistry

Polyurethanes are popularly used in cardiovascular and other biomedical fields due to their good biocompatibility as well as mechanical properties. But they are subject to biodegradation in vivo for a long time, and cause inflammation, so improving the biocompatibility of medical polyurethanes is an important subject of biomaterials. Recent researches have focused on biological modelling of biomaterials for improving the biocompatibility of polyurethanes. This paper reviews two main methods for improving biocompatibility of polyurethanes-endothelial cells seeding and mimic biomembrane (phospholipid surface), and summarizes the main procedures and questions of these two methods.
Biocompatible Materials ; chemistry ; Endothelial Cells ; drug effects ; Humans ; Phospholipids ; chemistry ; Polyurethanes ; chemistry

BACKGROUNDPeople recently realized that it is important for artificial vascular biodegradable graft to bionically mimic the functions of the native vessel. In order to overcome the high risk of thrombosis and keep the patency in the clinical small-diameter vascular graft (SDVG) transplantation, a double-layer bionic scaffold, which can offer anticoagulation and mechanical strength simultaneously, was designed and fabricated via electrospinning technique.

METHODSHeparin-conjugated polycaprolactone (hPCL) and polyurethane (PU)-collagen type I composite was used as the inner and outer layers, respectively. The porosity and the burst pressure of SDVG were evaluated. Its biocompatibility was demonstrated by the 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyl-2H tetrazolium bromide (MTT) test in vitro and subcutaneous implants in vivo respectively. The grafts of diameter 2.5 mm and length 4.0 cm were implanted to replace the femoral artery in Beagle dog model. Then, angiography was performed in the Beagle dogs to investigate the patency and aneurysm of grafts at 2, 4, and 8 weeks post-transplantation. After angiography, the patent grafts were explanted for histological analysis.

RESULTSThe double-layer bionic SDVG meet the clinical mechanical demand. Its good biocompatibility was proven by cytotoxicity experiment (the cell's relative growth rates (RGR) of PU-collagen outer layer were 102.8%, 109.2% and 103.5%, while the RGR of hPCL inner layer were 99.0%, 100.0% and 98.0%, on days 1, 3, and 5, respectively) and the subdermal implants experiment in the Beagle dog. Arteriography showed that all the implanted SDVGs were patent without any aneurismal dilatation or obvious anastomotic stenosis at the 2nd, 4th, and 8th week after the operation, except one SDVG that failed at the 2nd week. Histological analysis and SEM showed that the inner layer was covered by new endothelial-like cells.

CONCLUSIONThe double-layer bionic SDVG is a promising candidate as a replacement of native small-diameter vascular graft.

Animals ; Bionics ; Blood Vessel Prosthesis ; Cell Line ; Collagen ; Dogs ; Heparin ; chemistry ; Mice ; Polyesters ; chemistry ; Polyurethanes ; chemistry

Acrylic Resins ; chemistry ; Composite Resins ; chemistry ; Dental Research ; Dental Stress Analysis ; Polymerization ; Polyurethanes ; chemistry

A series of bio-based thermosetting polyurethanes (Bio-PUs) were synthesized by the crosslinking reaction of polylactide and its copolymers diols with hexamethylene diisocyanate (HDI) trimer. The obtained Bio-PUs were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), universal tensile testing machine and cytotoxicity test. Results indicate that the PLA copolymer (P(LA-co-CL)) diols reduced the glass transition temperature (Tg) of Bio-PUs and improved their thermal stability, compared with PLA diols. The Bio-PUs synthesized from P (LA-co-CL) diols exhibit better mechanical performance and shape memory properties. Especially, Young modulus and elongation at break of the obtained Bio-PUs were 277.7 MPa and 230% respectively; the shape recovery time of the obtained Bio-PUs at body temperature was only 93 s. Furthermore, alamar blue assay results showed that the obtained Bio-PUs had no cell toxicity.
Biocompatible Materials ; chemistry ; Materials Testing ; Polyesters ; chemistry ; Polymers ; Polyurethanes ; chemistry ; Spectroscopy, Fourier Transform Infrared ; Temperature

The progress of research of the physical and chemical modification methods to improve the antithrombogenic property of biomedical polyurethane (PU) in the past five years is reviewed in this paper. The physical modification method includes physical blending, physical vapor deposition (PVD) and replication molding technique. Meanwhile, chemical modification method is focused on the covalent bonding to immobilized special molecular. Moreover, the covalent bonding method covered functionalizing the PU surface with tailor-made groups in the bulk and the activation of the surface to form unstable active sites for further reactions.
Animals ; Biocompatible Materials ; chemistry ; pharmacology ; Chemical Phenomena ; Fibrinolytic Agents ; chemistry ; pharmacology ; Humans ; Polyurethanes ; chemistry ; pharmacology

OBJECTIVETo analyze the color parameters and translucency of four frequently-used veneer materials.

METHODSForty disc specimens[(1.00±0.01) mm in thickness, 10 mm in diameter] were fabricated according to the manufacturer's instructions with IPS Empress(®) CAD[A2, high translucency (HT)], IPS e.max(®) Press(A2, HT), IPS e.max(®) CAD (A2, HT) and VITABLOCS(®) Mark II (A2) respectively and were divided into Groups A, B, C, D. All of the specimens were ground and polished on a grinding machine. Then color parameters (L*, a*, b*) and transmittance (τ) were measured using spectrocolorimeter and transmissivity testing device. The color parameters of the specimens were compared to the color parameters of A2 shade of Ivoclar Vivadent A-D shade guide. The data were analyzed with one-way analysis of variance (ANOVA), and mean values were compared by the Tukey's test (α = 0.05).

RESULTSThere was no statistical difference between the color parameters L*, a*, b* and C*ab of Group A and Group D (P > 0.05). But the color parameters of those two ceramic materials were statistically different from the color parameters of Group B and Group C (P < 0.05). There was no statistical difference between color parameters b* and C*ab of Group B and Group C(P > 0.05). However, the color parameters L* and a* of the two materials were statistically different(P < 0.05). The color differences (ΔE) between Group A, B, C, D and standard A2 were 6.05±0.12, 5.11±0.27, 3.73±0.27, 6.30±0.38 respectively. The transmittances of Group A, B, C, D were (29.69±0.31)%, (25.83±0.36) %, (28.92±0.47)% and (26.94±0.33)% respectively.

CONCLUSIONSThe color parameters of these four materials are different. Their transmittance are relatively high but statistically different. The color difference (ΔE) between IPS e.max(®) CAD (A2, HT) and standard A2 is lowest among all the groups.

Acrylic Resins ; chemistry ; Ceramics ; chemistry ; Color ; Composite Resins ; chemistry ; Dental Porcelain ; chemistry ; Dental Veneers ; Optical Phenomena ; Polyurethanes ; chemistry

The radical compliance of small diameter artificial vascular grafts was measured by a device made of laser micrometer, pressure transducer, A/D card, micro computer and pulsed circulation loop, the volumetric compliance was measured by a device made of micro-syringe and pressure transducer; the longitudinal compliance was calculated from volumetric compliance and radical compliance. The research results showed that the radical compliance, volumetric compliance and longitudinal compliance would rise not only with the increase in polyurethane (PU) elasticity and salt/polymer ratio (or porosity), but also with the decrease in dipping layers (or wall thickness). Circumferential moduli E zeta and longitudinal moduli E theta could be calculated from volumetric compliance and longitudinal compliance respectively; E theta and E zeta would decrease with the increase in PU elasticity and salt/polymer ratio, but was independent on number of dipping layers. Small diameter PU artificial vascular grafts with compliance close to natural vein or artery can be prepared by choosing of more elastic PU materials (Chro or PCU1500), optimization of salt/polymer ratio (6:1), and the number of dipping layers (4-6 layers).
Biocompatible Materials ; chemistry ; Blood Vessel Prosthesis ; Compliance ; Elasticity ; Humans ; Polyurethanes ; chemistry