1: J Control Release. 2007 Feb 12;117(2):196-203. Epub 2006 Nov 7. Characterization of self-assembling copolymers in aqueous solutions using Electron Paramagnetic Resonance and Fluorescence spectroscopy. Beghein N, Rouxhet L, Dinguizli M, Brewster ME, Arien A, Preat V, Habib JL, Gallez B. Universite Catholique de Louvain, Unite de Chimie Pharmaceutique et Radiopharmacie and Unite de Resonance Magnetique Biomedicale, Avenue Mounier 73.40, 1200 Brussels, Belgium. Electron Paramagnetic Resonance and fluorescence spectroscopy have been used to determine the micropolarity and microviscosity of self-assembling systems based on mmePEG-p(CL-co-TMC) having different PEG chain lengths and different CL/TMC ratios and PEG/MOG/SA (45/5/50) polymers with different PEG chain lengths. Four reporter probes have been used: two spin probes, 16-doxyl stearic acid and 5-doxylstearic acid, and two fluorescent probes, pyrene and 1,3-bis(1-pyrenyl) propane (P3P). We found that the micelles based on mmePEG-p(CL-co-TMC) polymers are of a biphasic nature. The micelles are made of a hydrophilic corona with low viscosity while the core of the micelle is more hydrophobic and more viscous. The outer shell is made up of PEG chains, the hydrophobic part of the chains making the core. The partial hydration of the shell seems to lead to a looser chain network than that associated with deeper domains in the micelles. By contrast, in micelles composed of PEG/MOG/SA, there is no clear domain separation. This is consistent with a spatial configuration of random polymeric chains forming a loose network. In these micelles, the microviscosity is low and the hydrophobicity is high. PMID: 17196699 [PubMed - in process] Related Links Inner core segment design for drug delivery control of thermo-responsive polymeric micelles. [J Control Release. 2000] PMID:10699274 Self-assembling PEG-p(CL-co-TMC) copolymers for oral delivery of poorly water-soluble drugs: a case study with risperidone. [J Control Release. 2005] PMID:15681087 Micellar nanocarriers: pharmaceutical perspectives. [Pharm Res. 2007] PMID:17109211 Self-association and micelle formation of biodegradable poly(ethylene glycol)-poly(L-lactic acid) amphiphilic di-block co-polymers. [J Biomater Sci Polym Ed. 2006] PMID:16909943 Physicochemical characterization of degradable thermosensitive polymeric micelles. [Langmuir. 2004] PMID:15461534