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51.
We show that cantilever array sensors can sense the formation of supported phospholipid bilayers on their surface and that they can monitor changes in mechanical properties of lipid bilayers. Supported lipid bilayers were formed on top of microfabricated cantilevers by vesicle fusion. The formation of bilayers led to a bending of the cantilevers of 70-590 nm comparable to a surface stress of 27-224 mN/m. Physisorption of bilayers of DOPC and other bilayers on the silicon oxide surface of cantilevers led to a tensile bending of about 70 nm whereas formation of chemisorbed bilayers of mixed thiolated (DPPTE) and non-thiolated lipids (DOPC) on the gold side of cantilevers led to a compressive bending of nearly 600 nm which depended on the ratio of DPPTE to DOPC. First results on bending of bilayer-covered cantilevers due to their interaction with the pore-forming peptide melittin are shown. The results demonstrate that cantilever sensors with immobilized bilayers can be used as model systems to investigate mechanical properties of cellular membranes and may be used for screening of membrane processes involving modification, lateral expansion, or contraction of membranes. 相似文献
52.
53.
Kenneth I. Ozoemena Raluca‐Ioana Stefan‐van Staden Tebello Nyokong 《Electroanalysis》2009,21(14):1651-1654
Novel electrochemical sensors based on carbon paste impregnated with metallopthalocyanine (MPc, M=Co, Fe) complexes, have been constructed for the assay of anti‐HIV drug 2′,3′‐dideoxyinosine (didanosine, DDI). Both modified electrodes showed electrocatalytic activity towards the oxidation of dideoxyinosine in phosphate buffer pH 7.4 with a working concentration range of 10?6–10?4 mol/L and a detection limit of 10?7 mol/L magnitude order. The sensor proved to be highly reliable for the assay of the purity of DDI ‐ raw material as well as for the uniformity content test of Videx tablets. 相似文献
54.
Anca Petran Teodora Radu Alexandrina Nan Diana Olteanu Adriana Filip Simona Clichici Ioana Baldea Maria Suciu Rodica Turcu 《Journal of nanoparticle research》2017,19(1):10
The paper presents the synthesis, characterization, and in vitro cytotoxicity tests of Fe3O4 magnetic nanoclusters coated with ethylenediaminetetraacetic acid disodium salt (EDTA). Electron microscopy analysis (SEM) evidences that magnetite nanoparticles are closely packed into the clusters stabilized with EDTA with well-defined near spherical shapes and sizes in the range 100–200 nm. From XRD measurements, we determined the mean size of the crystallites inside the magnetic cluster about 36 nm. The saturation magnetization determined for the magnetic clusters stabilized with EDTA has high value, about 81.7 emu/g at 300 K. X-ray photoelectron spectroscopy has been used to determine both the elemental and chemical structure of the magnetic cluster surface. In vitro studies have shown that the magnetic clusters at low doses did not induce toxicity on human umbilical vein endothelial cells or lesions of the cell membrane. In contrast, at high doses, the magnetic clusters increased the lipid peroxidation and reduced the leakage of a cytoplasmic enzyme, lactate dehydrogenase (LDH), in parallel with increasing the antioxidant defense. 相似文献
55.
Magdalena Lungu Ştefania Gavriliu Elena Enescu Ioana Ion Alexandra Brătulescu Grigore Mihăescu Luminiţa Măruţescu Mariana Carmen Chifiriuc 《Journal of nanoparticle research》2014,16(1):1-15
Recent studies have revealed the existence of liver cancer stem cells (CSCs). Therefore, there is an urgent need for new and effective treatment strategies specific to liver CSCs. In this work, the poly(d,l-lactide-coglycolide) nanoparticles containing paclitaxel were prepared by emulsification-solvent evaporation method. The nanoparticles decorated with anti-CD133 antibody, termed targeted nanoparticles, were prepared by carbodiimide chemistry for liver CSCs. The physicochemical characteristics of the nanoparticles (i.e., encapsulation efficiency, particle size distribution, morphology, and in vitro release) were investigated. Cellular uptake and accumulation in tumor tissue of nanoparticles were observed. To assess anti-tumor activity of nanoparticles in vitro and in vivo, cell survival assay and tumor regression study were carried out using liver cancer cell lines (Huh7 and HepG2) and their xenografts. Particle size of targeted nanoparticles was 429.26 ± 41.53 nm with zeta potential of ?11.2 mV. Targeted nanoparticles possessed spherical morphology and high encapsulation efficiency (87.53 ± 5.9 %). The accumulation of targeted nanoparticles depends on dual effects of passive and active targeting. Drug-loaded nanoparticles showed cytotoxicity on the tumor cells in vitro and in vivo. Targeted nanoparticles resulted in significant improvement in therapeutic response through selectively eliminating CD133 positive subpopulation. These results suggested that the novel nanoparticles could be a promising candidate with excellent therapeutic efficacy for targeting liver CSCs. 相似文献
56.
57.
Ioana ?uvaina 《Annals of Global Analysis and Geometry》2012,41(1):109-123
Let
N0=\mathbb C2/H{N_0={\mathbb C}^2/H} be an isolated quotient singularity with H ì U(2){H\subset U(2)} a finite subgroup. We show that for any
\mathbb Q{\mathbb Q} -Gorenstein smoothings of N
0 a nearby fiber admits ALE Ricci-flat K?hler metrics in any K?hler class. Moreover, we generalize Kronheimer’s results on
hyperk?hler 4-manifolds (J Differ Geom 29(3):685–697, 1989), by giving an explicit classification of the ALE Ricci-flat K?hler surfaces. We construct ALF Ricci-flat K?hler metrics
on the above non-simply connected manifolds. These provide new examples of ALF Ricci-flat K?hler 4-manifolds, with cubic volume
growth and cyclic fundamental group at infinity. 相似文献
58.
Frégeau MO Jacquet D Morjean M Bonnet E Chbihi A Frankland JD Rivet MF Tassan-Got L Dechery F Drouart A Nalpas L Ledoux X Parlog M Ciortea C Dumitriu D Fluerasu D Gugiu M Gramegna F Kravchuk VL Marchi T Fabris D Corsi A Barlini S 《Physical review letters》2012,108(12):122701
An atomic clock based on x-ray fluorescence yields has been used to estimate the mean characteristic time for fusion followed by fission in reactions 238U + 64Ni at 6.6 MeV/A. Inner shell vacancies are created during the collisions in the electronic structure of the possibly formed Z=120 compound nuclei. The filling of these vacancies accompanied by a x-ray emission with energies characteristic of Z=120 can take place only if the atomic transitions occur before nuclear fission. Therefore, the x-ray yield characteristic of the united atom with 120 protons is strongly related to the fission time and to the vacancy lifetimes. K x rays from the element with Z=120 have been unambiguously identified from a coupled analysis of the involved nuclear reaction mechanisms and of the measured photon spectra. A minimum mean fission time τ(f)=2.5×10(-18) s has been deduced for Z=120 from the measured x-ray multiplicity. 相似文献
59.
The coupling of chloramphenicol on Biozan R (Hercules) by activation with dicyclohexylcarbodiimide was studied. The esterification is influenced by the chloramphenicol/dicyclohexylcarbodiimide ratio, concentration of the reactants and reaction time.The microbial tests performed with products of different chloramphenicol contents attest their antimicrobial activity and their possible use, especially in ophtalmology. 相似文献
60.
Mihaela Deaconu Ioana Nicu Robert Tincu Ana-Maria Brezoiu Raul-Augustin Mitran Eugeniu Vasile Cristian Matei Daniela Berger 《Chemical Papers》2018,72(8):1869-1880
Doxycycline, an antibiotic from the tetracycline class with a broad spectrum of activity, was used to prepare drug delivery systems based on pristine and functionalized mesostructured silica supports. MCM-41-type materials with different textural, structural, and surface properties were used to assess their influence on the drug release kinetics. Small- and wide-angle XRD, FTIR spectroscopy and N2 adsorption/desorption isotherms were used to characterize the carriers before and after doxycycline loading. The drug release experiments were performed in vitro in 0.2 M phosphate buffer solution at 37 °C, and the slowest drug release kinetics was obtained for magnesium-modified MCM-41 carrier. All drug-loaded materials exhibited good antibacterial activity against Klebsiella pneumoniae ATCC 10031 strain, similar to the drug alone. 相似文献