Micellar Structures of Poly(oxyethylene) - Poly(oxypropylene) Copolymers in Water

I. WOOD; M. PICKHOLZ

San Cristobal

Congreso; Congreso Internacional de Químicos Teóricos de Expresión Latina; 2014

QUITEL

Micellar Structures of Poly(oxyethylene) - Poly(oxypropylene) Copolymers in Water M. Pickholz 1,2, I. Wood1 Email: mpickholz@gmail.com 1 Departamento de Tecnología Farmacéutica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956 Buenos Aires, CP 1113, Argentina 2 Consejo Nacional de Investigaciones Científicas y Técnica (CONICET), Rivadavia 1917 Buenos Aires, CP1033, Argentina Abstract. Block copolymers with amphiphilic character are known to assemble in an aqueous solution into micelles at the nanometer size scale. These micelles have a fairly narrow size distribution and are characterized by their unique core?shell architecture. Pluronic® F127 belongs to the family of triblock copolymers of poly(ethylene oxide)?poly(propylene oxide) (PPO)?poly(ethylene oxide) (PEO), generically called poloxamers. Nowdays, these copolymers attracts considerable attention as a novel method for the delivery of different drugs, since, above the critical micelle concentration, they aggregate forming micellar structures, besides of being biocompatible. The knowledge of the kind of self-assembled structures form by these copolymers could help to decide which kind of drugs are suitable to be carried in these micelles. For instance, we are interested on the encapsulation of sumatriptan ? an antimigraine drug, specially designed as serotonin receptor agonist. In this work, we have used Computer simulations in order to elucidate the behavior of the copolymer F127 in different conditions. We have followed two different strategies in our studied: i) The monomer in different enviromments: water and lipid bilayer; and ii) Several monomers in water phase (over the critical micellar concentration). We carried out Classical Molecular Dynamics (MD) simulations using a Coarse Grain (CG) model within the MARTINI force field that can be used to investigate macromolecular phenomena at the microsecond scale [1]. Main results: We found that F127 adopts a transmembrane conformation, exposing the entire PPO block along the bilayer thickness (since terminals methyl to glycerol groups) and leaving PEO blocks free toward the outside and on both sides of aqueous phase. By the other hand the unimer is found in a coil conformation in water phase. At high concentration, F127 assemble in a micellar structure, having a hydrophobic core and a hydrophilic crown. Keywords. Molecular Dynamics, Coarse Grain, Copolymer, Micelle Acknowledgements. This work has been supported by CONICET, ANPCyT and Universidad de Buenos Aires References. [1] Marrink, S. Risselada, H. Yefimov, S. Tieleman D.P. and de Vries, A. J. Phys. Chem. B, 2007, 111, 7812.