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931.
932.
Electrospinning fabrication and characterization of poly(vinyl alcohol)/montmorillonite/silver hybrid nanofibers for antibacterial applications 总被引:1,自引:0,他引:1
Jae Hyeung Park Mohammad Rezaul Karim In Kyo Kim In Woo Cheong Jong Won Kim Do Gyu Bae Jin Won Cho Jeong Hyun Yeum 《Colloid and polymer science》2010,288(1):115-121
Poly(vinyl alcohol) (PVA)/montmorillonite clay (MMT)/silver (Ag) nanoparticles have been electrospun for fabricating PVA/MMT/Ag
nanofiber in aqueous solutions. Since PVA is a water-soluble and biocompatible polymer, it is one of the best materials for
preparation of antibacterial nanofiber. MMT has been used as an inorganic filler to enhance properties of homopolymeric nanofiber.
The PVA/MMT/Ag nanofiber diameter increases with increasing contents of MMT clay and Ag nanoparticles. In preservation test,
the PVA/MMT/Ag nanofiber confirms an excellent antibacterial performance, elucidating for practical uses as a new preservative.
Moreover, the PVA/MMT/Ag nanofiber shows improved thermal properties. 相似文献
933.
In order to prevent restenosis after angioplasty or stenting, one of the most popular targets is suppression of the abnormal growth and excess migration of vascular smooth muscle cells (VSMCs) with drugs. However, the drugs also adversely affect vascular endothelial cells (VECs), leading to the induction of late thrombosis. We have investigated the effect of epigallocatechin-3-gallate (EGCG) on the proliferation and migration of VECs and VSMCs. Both cells showed dose-dependent decrease of viability in response to EGCG while they have different IC(50) values of EGCG (VECs, 150 mM and VSMCs, 1050 mM). Incubating both cells with EGCG resulted in significant reduction in cell proliferation irrespective of cell type. The proliferation of VECs were greater affected than that of VSMCs at the same concentrations of EGCG. EGCG exerted differential migration-inhibitory activity in VECs vs. VSMCs. The migration of VECs was not attenuated by 200 mM EGCG, but that of VSMCs was significantly inhibited at the same concentration of EGCG. It is suggested that that EGCG can be effectively used as an efficient drug for vascular diseases or stents due to its selective activity, completely suppressing the proliferation and migration of VSMCs, but not adversely affecting VECs migration in blood vessels. 相似文献
934.
In the present study, we prepared new Li-ion batteries with inorganic membrane-coated electrodes fabricated by the direct
coating of a 400-nm-sized Al2O3 particles onto the anodes and studied their charge–discharge characteristics for the first time. Being made of 94 wt.% Al2O3 powder and 6 wt.% polymeric binder, the membranes on the anodes showed excellent wettability with the liquid electrolytes,
due to their high porosity and capillarity. The Li-ion batteries prepared by the assembly of the inorganic membrane-coated
electrodes showed excellent charge–discharge behavior compared to conventional Li-ion batteries with a polymeric separator.
However, their high-rate performance was affected by the binder contents in the inorganic membranes. The thermal properties
of the Li-ion battery with the inorganic membrane-coated electrodes were compared with those of a conventional one with a
polymeric separator. 相似文献
935.
936.
We report a diagnostic method for Anaplasma phagocytophilum (A. phagocytophilum) infection in cattle using a nested PCR and microchip electrophoresis (ME). A. phagocytophilum causes human granulocytic anaplasmosis and granulocytic ehrlichiosis, which are emerging tick‐borne zoonotic diseases. Nested PCR was used to amplify genomic DNA samples extracted from cattle blood. The amplified PCR products were analyzed under a sieving gel matrix of 0.7% poly(ethyleneoxide) (Mr=8 000 000) in a conventional glass microchip. In the ME assay, A. phagocytophilum was analyzed within 35 s with a relative standard deviation of 1.30% (n=5) using a programmed field strength gradient (PFSG) as follows: 615.3 V/cm for 0–24 s, 66.7 V/cm for 24–34 s, 615.3 V/cm for 34–100 s. The ME‐PFSG assay was clinically validated by comparing the 16S rRNA gene levels obtained by this method with those measured using conventional slab gel electrophoresis performed with ten cattle blood samples suspected of A. phagocytophilum infection. In contrast to slab gel electrophoresis, the proposed ME‐PFSG methodology had increased sensitivity (200–450 pg/μL), a faster analysis time (<35 s), and required a smaller sample volume (~162 fL). 相似文献
937.
In Jin Ha Young Wan Ha Minseok Kang Jongsung Lee Deokhoon Park Yeong Shik Kim 《Journal of separation science》2010,33(13):1916-1922
Platycosides, the saponins found in the roots of Platycodon grandiflorum (Platycodi Radix), are typically composed of oleanane triterpenes with two side chains. In platycosides, platycodin D, a glucose unit at C‐3, is a major component, which has several pharmacological activities. Because of the high demand for this compound, we attempted to enzymatically convert platycodin D3 and platycoside E, having two and three glucose units at C‐3, respectively, into platycodin D. In this study, we tested the ability of several glycosidases to transform platycosides, or more specifically, the ability to transform platycoside E and platycodin D3 into platycodin D. To obtain pure platycodin D on a preparative scale, high‐speed countercurrent chromatography with a solvent system of ethyl acetate/n‐butanol/water (1.2:1:2, v/v/v) was used for the separation of the enzymatically transformed product. Approximately 39.4 mg of platycodin D (99.8% purity) was obtained from 200 mg of the product in a one‐step separation. The results strongly support the advantage of enzymatic transformation of the platycosides for the efficient enrichment of platycodin D in the complicated extract of the medicinal plant. 相似文献
938.
An analytical method of CE-MS and CE with an online preconcentration technique induced by a dynamic pH junction, addition of organic solvent and large volume injection was developed for sensitive determination of peptides in biological samples. Leucine enkephalin, methionine enkephalin, dynorphin A, β-endorphin and angiotensin II were used as model peptides. The optimal online preconcentration conditions were obtained at a sample matrix consisting of 100?mM borate buffer (pH 10.0) with 50% v/v acetonitrile and a BGE containing 1?M formic acid at pH 2.0, along with a 25-cm injection length. Under the optimized conditions, a 4.0×10(3)-1.1×10(4)-fold increase in peak intensity was achieved without degrading the peak shape. This online preconcentration method was applied to analyze the intracellular angiotensin II within the peptides extracted from HL1 cells and approximately increase of 1×10(4)-fold sensitivity was achieved compared to normal condition. Thus, the developed method could be applied to the analysis of various peptides for peptidomics study in biological samples. 相似文献
939.
Karamzadeh B Kumar D Sastry GN de Visser SP 《The journal of physical chemistry. A》2010,114(50):13234-13243
Prolyl-4-hydroxylase is an important nonheme iron-containing dioxygenase in humans involved in the regioselective hydroxylation of a proline residue in a peptide chain on the C(4) position. In biosystems this process is important to create collagen cross-linking and cellular responses to hypoxia. We have performed a series of density functional theory (DFT) studies into the origin of the regioselectivity of proline hydroxylation by P4H enzymes using a minimal active site model (where substrate is unhindered in the binding site) and a larger active site model that incorporates steric hindrance of the substrate by several secondary sphere aromatic residues. Our studies show that thermodynamically the most favorable hydrogen atom abstraction position of proline is from the C(5) position; hence, the small model gives a low reaction barrier and large exothermicity for this process. However, stereochemical repulsions of the substrate with aromatic residues of Tyr(140) and Trp(243) in the second coordination sphere prevent C(5) hydroxylation and make C(4) hydroxylation the dominant mechanism, despite a lesser driving force for the reaction. These studies explain the remarkable regioselectivity of proline hydroxylation by P4H enzymes and show that the regioselectivity is kinetically controlled but not thermodynamically. In addition, we calculated spectroscopic parameters and found good agreement with experimental data. 相似文献
940.
Mi-Young Song Gil-Saeng Jeong Kang-Beom Kwon Sun-O Ka Hyun-Young Jang Jin-Woo Park Youn-Chul Kim Byung-Hyun Park 《Experimental & molecular medicine》2010,42(9):628-638
NF-κB activation has been implicated as a key signaling mechanism for pancreatic β-cell damage. Sulfuretin is one of the main flavonoids produced by Rhus verniciflua, which is reported to inhibit the inflammatory response by suppressing the NF-κB pathway. Therefore, we isolated sulfuretin from Rhus verniciflua and evaluated if sulfuretin could inhibit cytokine- or streptozotocin-induced β-cell damage. Rat insulinoma RINm5F cells and isolated rat islets were treated with IL-1β and IFN-γ to induce cytotoxicity. Incubation of cells and islets with sulfuretin resulted in a significant reduction of cytokine-induced NF-κB activation and its downstream events, iNOS expression, and nitric oxide production. The cytotoxic effects of cytokines were completely abolished when cells or islets were pretreated with sulfuretin. The protective effect of sulfuretin was further demonstrated by normal insulin secretion of cytokine-treated islets in response to glucose. Treatment of mice with streptozotocin resulted in hyperglycemia and hypoinsulinemia, which was further evidenced by immunohistochemical staining of islets. However, the diabetogenic effects of streptozotocin were completely prevented when mice were pretreated with sulfuretin. The anti-diabetogenic effects of sulfuretin were also mediated by suppression of NF-κB activation. Collectively, these results indicate that sulfuretin may have therapeutic value in preventing β-cell damage. 相似文献