Fine-tuning the release of molecular guests from mesoporous silicas by controlling the orientation and mobility of surface phenyl substituents

Date
2018-05-15
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Manzano, J. Sebastián
Singappuli-Arachchige, Dilini
Parikh, Bosky L.
Slowing, Igor
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Elsevier
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Chemistry
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Ames Laboratory
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ChemistryAmes Laboratory
Abstract
Phenyl-functionalized mesoporous silica materials were used to explore the effect of non-covalent interactions on the release of Ibuprofen into simulated body fluid. Variations in orientation and conformational mobility of the surface phenyl groups were introduced by selecting different structural precursors: 1) a rigid upright orientation was obtained using phenyl groups directly bound to surface Si atoms (Ph-MSN), 2) mobile groups were produced by using ethylene linkers to connect phenyl groups to the surface (PhEt-MSN), and 3) groups co-planar to the surface were obtained by synthesizing a phenylene-bridged periodic mesoporous organosilica (Ph-PMO). The Ibuprofen release profiles from these materials and non-functionalized mesoporous silica nanoparticles (MSN) were analyzed using an adsorption-diffusion model. The model provided kinetic and thermodynamic parameters that evidenced fundamental differences in drug-surface interactions between the materials. All phenyl-bearing materials show lower Ibuprofen initial release rates than bare MSN. The conformationally locked Ph-MSN and Ph-PMO have stronger interactions with the drug (negative ΔG of adsorption) than the flexible PhEt-MSN and bare MSN (positive ΔG of adsorption). These differences in strength of adsorption are consistent with differences between interaction geometries obtained from DFT calculations. B3LYP-D3-optimized models show that π-π interactions contribute more to drug adsorption than H-bonding with silanol groups. The results suggest that the type and geometry of interactions control the kinetics and extent of drug release, and should therefore serve as a guide to design new drug delivery systems with precise release behaviors customized to any desired target.
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This is a manuscript of an article published as Manzano, J. Sebastián, Dilini Singappuli-Arachchige, Bosky L. Parikh, and Igor I. Slowing. "Fine-tuning the release of molecular guests from mesoporous silicas by controlling the orientation and mobility of surface phenyl substituents." Chemical Engineering Journal 340 (2018): 73-80. DOI: 10.1016/j.cej.2017.12.015. Copyright 2017 Elsevier B.V. Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). Posted with permission.
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