Properties of cremophor EL micelles probed by fluorescence.
Using 1-anilino,8-naphthalenesulfonic acid (ANS) as a probe, we examined properties of micelles of Cremophor EL, an amphipathic agent which can solubilize hydrophobic photosensitizing agents and promote their distribution to plasma lipoprotein. In aqueous solution, Cremophor micelles persisted for several hours after dilution below the critical micellar concentration (CMC). After equilibrium was reached, we found a CMC of 0.009% (wt/vol). Fluorescence data suggest that the micellar environment of ANS binding has a dielectric constant of approximately 27. Cremophor also reverses examples of multi-drug resistance associated with impaired accumulation of anti-tumor agents, e.g. daunorubicin. Although the latter drug is relatively hydrophilic, fluorescence spectroscopy and anisotropy studies indicate an association with Cremophor. Moreover, resistance reversal occurred only at Cremophor concentrations above the CMC.
Kessel
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Department of Pharmacology, Wayne State University School of Medicine, Detroit 48201.
D000817:Anilino Naphthalenesulfonates; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D003630:Daunorubicin / Q000737:chemistry / Q000378:metabolism*; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D005990:Glycerol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D007941:Leukemia P388; D051379:Mice; D008823:Micelles; D013050:Spectrometry, Fluorescence / Q000379:methods; D013501:Surface-Active Agents / Q000737:chemistry* / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; D008823:Micelles; D013501:Surface-Active Agents; C027132:1-anilino-8-naphthalenesulfonate; C000515:cremophor EL; D005990:Glycerol; D003630:Daunorubicin