Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.6 (thromboplastin)
 13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Magnesium based alloys are attracting tremendous interests as the novel biodegradable metallic biomaterials. However, the rapid in vivo degradation and the limited surface biocompatibility restrict their clinical applications. Surface modification represents one of the important approaches to control the corrosion rate of Mg based alloys and to enhance the biocompatibility. In the present study, in order to improve the corrosion resistance and surface biocompatibility, magnesium alloy (AZ31B) was modified by the alkali heating treatment followed by the self-assembly of 3-phosphonopropionic acid, 3-aminopropyltrimethoxysilane (APTMS) and dopamine, respectively. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectra (XPS) indicated that the molecules were successfully immobilized on the magnesium alloy surface by the self-assembly. An excellent hydrophilic surface was obtained after the alkali heating treatment and the water contact angle increased to some degree after the self-assembly of dopamine, APTMS and 3-phosphonopropionic acid, however, the hydrophilicity of the modified samples was better than that of the pristine magnesium substrate. Due to the formation of the passivation layer after the alkali heating treatment, the corrosion resistance of the magnesium alloy was obviously improved. The corrosion rate further decreased to varying degrees after the self-assembly surface modification. The blood compatibility of the pristine magnesium was significantly improved after the surface modification. The hemolysis rate was reduced from 56% of the blank magnesium alloy to 18% of the alkali heating treated sample and the values were further reduced to about 10% of dopamine-modified sample and 7% of APTMS-modified sample. The hemolysis rate was below 5% for the 3-phosphonopropionic acid modified sample. As compared to the pristine magnesium alloy, fewer platelets were attached and activated on the modified surfaces and the activated partial thromboplastin times (APTT) were prolonged to some degree. Furthermore, the modified samples showed good cytocompatibility. Endothelial cells exhibited the improved proliferative profiles in terms of CCK-8 assay as compared to those on the pristine magnesium alloy. The modified samples showed better endothelial cell adhesion and spreading than the pristine magnesium alloy. Taking all these results into consideration, the method of this study can be used to modify the magnesium alloy surface to improve the corrosion resistance and biocompatibility simultaneously.
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PMID:Effects of self-assembly of 3-phosphonopropionic acid, 3-aminopropyltrimethoxysilane and dopamine on the corrosion behaviors and biocompatibility of a magnesium alloy. 2728 7

In this study, poly(ethylene glycol) (PEG) and heparin were sequentially immobilized on a titanium surface by the carbodiimide covalent coupling method with the aim to improve the blood compatibility of titanium and enhance endothelial cell adhesion and proliferation. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that PEG and heparin were successfully immobilized on the titanium surface. Compared to the pristine titanium, a highly hydrophilic layer was achieved after the immobilization, and the resulting heparin-PEG layer can significantly prevent human plasma fibrinogen adsorption. Analysis of platelet attachment to the modified surfaces, via scanning electron microscopy (SEM), showed strikingly fewer platelets attached to the PEG and heparin modified surfaces, compared to the control. The immobilized PEG and heparin effectively prolonged the activated partial thromboplastin time (APTT) and inhibit platelet activation significantly. Furthermore, the modified samples showed good cytocompatibility. Endothelial cells exhibited improved proliferative profiles in terms of a CCK-8 assay, as compared to those on the pristine titanium. The modified samples showed a better endothelial cell adhesion and spreading, than the pristine titanium. Therefore, the blood compatibility and cytocompatibility of the titanium surface can be enhanced by PEG immobilization and further, by subsequent heparin grafting. It could be concluded that the negatively charged heparin-PEG layer with excellent hydrophilicity could obviously improve the blood compatibility and enhance the endothelial cell adhesion and proliferation, and the approach of the present study is considered as an effective method to improve the hemocompatibility and cytocompatibility of biomaterials.
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PMID:Blood compatibility and interaction with endothelial cells of titanium modified by sequential immobilization of poly (ethylene glycol) and heparin. 3226 21