title: Molecular Dynamics Simulations of Ibuprofen Release from pH-Gated Silica Nanochannels.
abstract: The iboprufen delivery process from cylindrical silica pores of 3 nm diameter, with polyamine chains anchored at the pore outlets, was investigated by means of massive molecular dynamics simulations. Effects from pH were introduced by considering polyamine chains with different degrees of protonation. High, low, and intermediate pH environments were investigated. The increment of the acidity of the environment leads to a significant decrease of the pore aperture, yielding an effective diameter, for the lowest pH case, that is 3.5 times smaller than the one associated with the highest pH one. Using a biased sampling procedure, Gibbs free energy profiles for the ibuprofen delivery process were obtained. The joint analysis of the corresponding profiles, time evolution of the ibuprofen position within the channel, orientation of the molecule, and instantaneous effective diameter of the gate suggest a three-step mechanism for ibuprofen delivery. A complementary analysis of the translational mobility of ibuprofen along the axial direction of the channel revealed a subdiffusive dynamics in the low and intermediate pH cases. Deviations from Brownian diffusive dynamics are discussed and compared with direct experimental results.
authors.affiliation: †Departamento de Física, Comisión Nacional de Energía Atómica, Avenida Libertador 8250, 1429 Buenos Aires, Argentina.|‡ECyT, UNSAM, Martín de Irigoyen 3100, 1650 San Martín, Provincia de Buenos Aires, Argentina.
authors.forename: Javier
authors.initials: J
authors.lastname: Rodriguez
authors.affiliation: †Departamento de Física, Comisión Nacional de Energía Atómica, Avenida Libertador 8250, 1429 Buenos Aires, Argentina.
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Elola
mesh_terms: D004058:Diffusion; D004337:Drug Carriers / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007052:Ibuprofen / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D049329:Nanostructures / Q000737:chemistry*; D016062:Porosity; D011522:Protons; D012822:Silicon Dioxide / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D004337:Drug Carriers; D011522:Protons; D014867:Water; D012822:Silicon Dioxide; D007052:Ibuprofen