title: Self-associative behavior and drug-solubilizing ability of poloxamine (tetronic) block copolymers.
abstract: The incidence of the structural features on the self-assembly of different poloxamines (the conventional sequential Tetronic 304, 901, 904, 908, 1107, 1301, and 1307; a reverse-sequential counterpart Tetronic 150R1; and a chemically modified derivative, N-methylated Tetronic 1107) was thoroughly studied in 10 mM HCl by means of pi-A isotherm, surface tension, and pyrene fluorescence measurements. The size and size distribution of the aggregates were investigated by dynamic and static light scattering, and the morphology was probed by transmission electron microscopy. The abilities of the different derivatives to solubilize the drug simvastatin were also evaluated. Poloxamines with both higher PO/EO ratio and molecular weight (T1301 and T150R1) led to micelles with larger and more hydrophobic cores, particularly adequate for hosting hydrophobic molecules and protecting the labile lactone form of simvastatin from hydrolysis. On the other hand, the hydroxy acid form of simvastatin interacted with the central ethylenediamine group under alkaline pH (T304) or when a permanent positive charge due to methylation was present. Micelles of long poloxamine molecules containing large PPO blocks (with 23-29 units, namely, T1301, T1307, and T150R1), particularly the one that also has long PEO blocks, were the most physically stable toward dilution.
authors.affiliation: Departamento de Quimica Fisica, Universidad de Santiago de Compostela, 15782-Santiago de Compostela, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Gonzalez-Lopez
authors.forename: Carmen
authors.initials: C
authors.lastname: Alvarez-Lorenzo
authors.forename: Pablo
authors.initials: P
authors.lastname: Taboada
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sosnik
authors.forename: Isabel
authors.initials: I
authors.lastname: Sandez-Macho
authors.forename: Angel
authors.initials: A
authors.lastname: Concheiro
mesh_terms: D005029:Ethylenediamines / Q000737:chemistry*; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry*; D019821:Simvastatin / Q000737:chemistry*; D012995:Solubility; D013499:Surface Properties; D017186:Titrimetry; D014732:Vibration
chemical_list: D005029:Ethylenediamines; D008823:Micelles; D011108:Polymers; D019821:Simvastatin