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Nm Leads (nm + lead)
Selected AbstractsSeparation of Nile Blue-labelled fatty acids by CE with absorbance detection using a red light-emitting diodeELECTROPHORESIS, Issue 8 2007Michael C. Breadmore Dr. Abstract The separation of fatty acids derivatised with Nile Blue (NB) by CE with detection using a red light-emitting diode (LED) was examined. NB was selected as the derivatisation agent due to its high molar absorption coefficient of 76,000,M,1cm,1 at 633,nm, making it well suited for sensitive absorbance detection using a red 635,nm LED. NB-labelled fatty acids were separated by both MEKC using SDS micelles, i -PrOH and n -BuOH and by NACE in a number of solvents including MeOH, EtOH and ACN. The sensitivity of NACE was superior to MEKC, with detection limits of 5×10,7,7×10,7,M obtained for each acid, approximately 20 times lower than the MEKC method. The NACE detection limits are approximately 100 times lower than previous reports on the separation of fatty acids by CE using indirect absorbance detection, ten times lower than using indirect fluorescence detection and are inferior only to those obtained using precapillary derivatisation and direct fluorescence detection. The efficiency of the NACE method was also superior to MEKC and allowed the separation of unsaturated fatty acids to be examined, although it was not possible to baseline-resolve linoleic (C18:2) and linolenic (C18:3) acids in a reasonable time. The method was used to analyse the fatty acid profile of two edible oils, namely sunflower and sesame oils, after alkali hydrolysis, where it was possible to identify both the saturated and unsaturated fatty acids in each sample. [source] The Impact of Interfacial Mixing on Förster Transfer at Conjugated Polymer HeterojunctionsADVANCED FUNCTIONAL MATERIALS, Issue 1 2009Anthony M. Higgins Abstract Neutron reflectivity and photoluminescence measurements are reported on bilayers of polyfluorene-based conjugated polymers. By using a novel thermal processing procedure it is possible to control the width of the interface between poly(9,9-dioctylfluorene) (F8) and poly(9,9-dioctylfluorene- alt -benzothiadiazole) (F8BT), and measure the impact of interfacial roughness on the resonant energy transfer of excitons at the interface (Förster transfer). It is found that increasing the root mean square (rms) roughness of the F8/F8BT interface over the range of ,1,nm to ,5,nm leads to a greatly enhanced Förster transfer from F8 to F8BT molecules. By comparing photoluminescence measurements with simple calculations it is concluded that the level of enhancement of the F8BT peak at rough interfaces can only be adequately explained if mixing of F8 and F8BT at a molecular level dominates over the interfacial roughness due to thermally excited capillary waves. [source] Controlled application and removal of liposomal therapeutics: Effective elimination of pegylated liposomal doxorubicin by double-filtration plasmapheresis in vitroJOURNAL OF CLINICAL APHERESIS, Issue 2 2010Gerhard Pütz Abstract Introduction: Nanoscale particle-based drug delivery systems like long circulating liposomal doxorubicin show unique pharmacokinetic properties and improved toxicity profiles. Liposomal doxorubicin accumulates in tumor tissue due to the enhanced permeation and retention effect, but only a small fraction of a total dose reaches the tumor site. Accumulation of liposomal doxorubicin is much faster in tumor sites than in certain organs where dose limiting adverse effects occur. Finding a way to detoxify the predominant part of a given dose, circulating in the blood after accumulation is completed, will presumably reduce severe side effects during chemotherapy. Methods: Elimination properties of therapeutic used pegylated liposomal doxorubicin (Doxil®/Caelyx®) and therapeutic used double-filtration plasmapheresis systems were evaluated in vitro and in reconstituted human blood. Results: Liposomes can be filtered by appropriate membranes without leakage of doxorubicin up to a pressure of 1 bar. At higher pressures, liposomes (,85 nm) may squeeze through much smaller pores without significant leakage of doxorubicin, whereas decreasing pore size to ,8 nm leads to increased leakage of doxorubicin. With therapeutic used apheresis systems, liposomal doxorubicin can be efficiently eliminated out of buffer medium and reconstituted human blood. No leakage of doxorubicin was detected, even when liposomes were circulating for 48 h in human plasma before apheresis. Conclusions: Convenient apheresis techniques are capable of a safe and efficient elimination of therapeutic used liposomal doxorubicin in an experimental model system. J. Clin. Apheresis, 2010. © 2010 Wiley-Liss, Inc. [source] Phototoxicity of exogenous protoporphyrin IX and ,-aminolevulinic acid in the photo hen's egg testPHOTODERMATOLOGY, PHOTOIMMUNOLOGY & PHOTOMEDICINE, Issue 5 2004Norbert J. Neumann Background: Oxygen, appropriate light sources, and special photosensitizers are necessary to induce photochemical damage in tumor cells via photodynamic therapy (PDT) ,-aminolevulinic acid (ALA) is increasingly used in PDT, because topical or systemic administration of ALA induces accumulation of endogenous porphyrins preferentially in neoplastic tissues. Subsequent radiation with light of approximately 630 nm leads to selective damage of tumor cells. PDT should optimally leave peritumoral tissues unaffected, but only few data are reported on the effects and the time course of ALA-induced porphyrins in tumor-free tissues. Methods: Therefore, we studied the phototoxic effects of protoporphyrin IX (PP) and ALA-induced porphyrins in a recently established photototoxic model based on tumor-free tissue, the photo hen's egg test (PHET). Results: Employing this test procedure, PP provoked strong phototoxic reactions when irradiated with Ultraviolet A immediately and up to 30 h after substance application. In contrast, ALA induced a significant phototoxic effect only if irradiated 24 h after application. Conclusion: Thus, we observed a delayed phototoxic effect of ALA in tumor-free tissue of the yolk sac (YS) blood vessel system. This delayed phototoxic response 24 h after ALA application is probably caused by endogenously synthesized porphyrins. In contrast, epithelial tumors show a maximum porphyrin accumulation 4,8 h after ALA application whereas in healthy human skin porphyrin synthesis is less intensive but prolonged with maximum levels 24,48 h after ALA application. Thus, ALA induced virtually the same delayed phototoxic effect in the tumor-free YS blood vessel tissue as in healthy human skin. These results show that the PHET is a useful model for the predictive preclinical risk assessment of exogenous or endogenous photosensitizers. [source] Surface enhanced Raman scattering of a lipid Langmuir monolayer at the air,water interfaceBIOPOLYMERS, Issue 1-2 2004C. Mangeney Abstract Surface enhanced Raman spectra were recorded from a phospholipid monolayer directly at the air,water interface. We used an organized monolayer of negatively charged tetramyristoyl cardiolipins as a template for the electrochemical generation of silver deposits. This two-dimensional electrodeposition of silver under potentiostatic control was the substrate for enhancement of Raman spectra. We report the optimized conditions for the Raman enhancement, the microscopic observations of the deposits, and their characterization by atomic force microscopy. Laser excitation at 514.5 nm leads to intense and reproducible surface enhanced Raman scattering spectra recorded in situ from one monolayer of cardiolipin, using 0.5 mol % of 10N nonyl acridine orange or 5 mol % of acridine in the film, and demonstrates the possibility of estimating the pH at the metal/phospholipidic film interface. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004 [source] | ||||||||||