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Micellar Core (micellar + core)
Selected AbstractsPronounced Catalytic Effect of a Micellar Solution of Sodium Dodecyl Sulfate (SDS) on the Efficient C-S Bond Formation via an Odorless Thia-Michael Addition Reaction through the in situ Generation of S -Alkylisothiouronium SaltsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 5 2009Habib Firouzabadi Abstract A pronounced catalytic effect of sodium dodecyl sulfate (SDS) was observed on the in situ production of S -alkylisothiouronium salts via the reaction of primary, allyl and benzyl halides with thiourea in SDS droplets .Hydrolysis of the generated S -alkylisothiouronium salts in the palisade layer of the droplets produces the corresponding thiol moieties which are immediately added to the electron-deficient olefins that are present in the micellar core to produce the thia-Michael adducts. The entire route is an almost odorless process. The yields of the products are good to excellent and the method is applicable to large-scale operation without any problem. [source] In vitro degradability and stability of hydrophobically modified pH-sensitive micelles using MPEG-grafted poly(,-amino ester) for efficient encapsulation of paclitaxelJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Min Sang Kim Abstract Methoxypoly(ethylene glycol)-grafted poly(,-amino ester) was synthesized for the fabrication of pH-sensitive micelles, and these micelles were modified with deoxycholic acid to facilitate the hydrophobic interaction between the micellar core and paclitaxel. The micelle properties were studied by dynamic light scattering and fluorescence spectrometry. An in vitro degradation study showed that the synthesized polymers degraded hydrolytically within 24 h under physiological conditions. The stability of paclitaxel-loaded pH-sensitive micelles was evaluated in vitro. The introduced deoxycholic acid more stabilized the micelles at pH 7.4 compared to the micelles without modification. But the pH-sensitive region of the micelles was lowered from pH 6.8 to pH 5.8. These results indicate that pH-sensitive micelles with improved stability have great potential as hydrophobic drug carriers for tumor targeting. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Thermodynamic micellization model for asphaltene precipitation inhibitionAICHE JOURNAL, Issue 2 2000Huanquan Pan Aromatic solvents and oil-soluble amphiphiles are recognized as asphaltene precipitation inhibitors in oil production and transportation. In the absence of the model describing the effect of these inhibitors on asphaltene precipitation from crudes, proposed is a thermodynamic micellization model explaining the inhibition mechanism for both aromatic solvents and oil-soluble amphiphiles. The model shows that aromatic solvents are concentrated in the micellar shell, and the interfacial tension between the asphaltene micellar core and shell is reduced as the micelles becomes stabler. A crude, mixed with a small amount of an oil-soluble amphiphile, achieves a high micellar stability. The amphiphiles behave like resin species of the crude and coadsorb onto the micellar core with resins. The adsorption enthalpy of an amphiphile onto the micellar core is much higher than that of the resin and, therefore, amphiphiles can be very effective inhibitors. The results suggest that the adsorption enthalpy data can be used to screen the amphiphiles for asphaltene precipitation inhibition. For a given oil-soluble amphiphile, this model can predict the amount of the amphiphile required to inhibit the precipitation. [source] Temperature Effect on the Fluroescence Anisotropy Decay Dynamics of Coumarin-153 Dye in Triton-X-100 and Brij-35 Miscellar Solutions,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2005Manoj Kumbhakar ABSTRACT The fluorescence anisotropy decay dynamics of the fluorescent probe Coumarin-153 (C153) have been investigated in two neutral micelles, Triton-X-100 (TX-100) and Brij-35 (BJ-39, at different temperatures and analyzed on the basis of the wellknown two-step model. Because steady-state fluorescence spectra of the above probe do not show any noticeable changes with respect to temperature, for either of the studied micelles, suggests a similar polarity in the microenvironment around the probe at all the temperatures studied. The anisotropy results indicated that, for both the micelles, the fluidity inside the Palisade layer increases with temperature. However, the temperature effect on the anisotropy decay is relatively more pronounced in TX-100 than in BJ-35. It is inferred that the temperature effect on the anisotropy decay in the BJ-35 micelle is mainly due to the thermal effect on the microviscosity in the micellar phase. In the case of TX-100, the results indicate that, along with the above thermal effect, an additional effect is observed due to the increased size and hydration of the micelle with temperature, with the result being that the fluorescence anisotropy decay in TX-100 is more sensitive to temperature than in BJ-35. In the TX-100 micelle, our studies show that with an increase in temperature, even though the micellar size increases substantially, the distance of the probe from the micellar core does not increase that significantly. Thus, with increasing temperature, the probe undergoes a relative migration toward the micellar core to avoid the increased hydration in the micellar Palisade layer. [source] Cancer-associated pH-responsive tetracopolymeric micelles composed of poly(ethylene glycol)- b -poly(L -histidine)- b -poly(L -lactic acid)- b -poly(ethylene glycol)POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 12 2008Kyung Taek Oh Abstract To create a novel vector for specifically delivering anticancer therapy to solid tumors, we used diafiltration to synthesize pH-sensitive polymeric micelles. The micelles, formed from a tetrablock copolymer [poly(ethylene glycol) -b -poly(L -histidine)- b -poly(L -lactic acid)- b -poly(ethylene glycol)] consisted of a hydrophobic poly(L -histidine) (polyHis) and poly(L -lactic acid) (PLA) core and a hydrophilic poly(ethylene glycol) (PEG) shell, in which we encapsulated the model anticancer drug doxorubicin (DOX). The robust micelles exhibited a critical micellar concentration (CMC) of 2.1,3.5,µg/ml and an average size of 65,80,nm pH 7.4. Importantly, they showed a pH-dependent micellar destabilization, due to the concurrent ionization of the polyHis and the rigidity of the PLA in the micellar core. In particular, the molecular weight of PLA block affected the ionization of the micellar core. Depending on the molecular weight of the PLA block, the micelles triggering released DOX at pH 6.8 (i.e. cancer acidic pH) or pH 6.4 (i.e. endosomal pH), making this system a useful tool for specifically treating solid cancers or delivering cytoplasmic cargo in vivo. Copyright © 2008 John Wiley & Sons, Ltd. [source] Functional Polymeric Micelles Formed from a Novel Cationic Star Block CopolymerCHEMPHYSCHEM, Issue 10 2003Ren-Hua Jin Dr. Flowers made from stars: A star polymer, which consists of a porphyrin center to which four arms with cationic poly(ethyleneimine) (PEI) and hydrophobic poly(phenyloxazoline) (PPOZ) segments were attached, was synthesized and shown to form micelles in both aqueous and organic media (see picture). In aqueous media, the star formed a micelle in which a hydrophobic PPOZ core was surrounded by cationic corona PEI. The porphyrin moieties enclosed in the micellar core can effectively communicate with an ionic substrate enriched in the cationic corona. In organic media, the star gave a flowerlike micelle in which the ionomer segment PEI assembled to form a core and the nonionic PPOZ segments formed a looplike corona coating the core. [source] | |||||||||||||