Molecular Dynamics Simulations of Nimodipine Confined in an Ordered Mesoporous Silica Matrix

Pajzderska, A.; Ma, González; Wąsicki, J.

doi:10.1021/acs.jpcc.8b02048

Cited by 3 publications

(3 citation statements)

References 42 publications

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“…If the RanH cation confined in the pores had infinitely many degrees of freedom, it could perform molecular tumbling (e.g., as in plastic crystals) and then its intramolecular part M 2 would average to zero. However, between RanH cations and hydroxyl groups on the surface are formed hydrogen bonds, 64 which limit the possibility of motions. Experimentally observed larger reduction of M 2 washed than M 2 outside is associated with the activation of degrees of freedom in the system and the higher mobility of RanH cations.…”

Section: Methodsmentioning

confidence: 99%

Environmental Effects on the Molecular Mobility of Ranitidine Hydrochloride: Crystalline State versus Drug Loaded into the Silica Matrix

et al. 2019

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The internal molecular mobility of a blockbuster antiulcer drug, ranitidine hydrochloride, was extensively studied by referring to the most-stable crystalline form (polymorph II) and the form loaded in the Santa Barbara amorphous-15 (SBA-15) silica matrix. The drug loading was performed from a solution, resulting in both the deposition at the outer silica surface and in the confinement within the mesopores. Both species were characterized by a number of physicochemical techniques, including calorimetry, powder X-ray diffraction, 13 C solid-state NMR, and attenuated total reflection-IR spectroscopies. The molecular mobility in the samples of interest was thoroughly explored by combining 1 H NMR relaxometry with theoretical modeling in the framework of Monte Carlo and solid-state density functional theory simulations. These allowed for a quantitative description of the 1 H NMR experiments. For the crystal structure, the molecular dynamics in a broad time-scale window of the NMR experiments can be attributed mainly to the reorientation of the methyl groups. The outer-surface deposits were found to be the amorphous form with only a minor contribution of the parent crystalline form. In this case, weakening of the intermolecular forces leads to the reduction of the energy barriers for the reorientation of methyl groups and activates the reorientation of fragments of ranitidine cations. The analysis of the samples confined in silica mesopores revealed that the ranitidine molecules exist in the form of the hydrochloride and cover less than half of the pore surface available in SBA-15, most probably forming the hydrogen bonds with the hydroxyl groups at the surface. Further reduction of the intermolecular interactions accompanying the loss of the crystal packing leads to pronounced conformational changes and results in the activation of the molecular segments and the entire ranitidine cations. In that way, further reduction and unification of the activation energies for the methyl groups is observed in the system. The knowledge of the mechanism of the increasing drug mobility and intermolecular interactions is important for the better understanding of the behavior of the confined molecules and for the future development of drug delivery systems.

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Section: Methodsmentioning

confidence: 99%

Environmental Effects on the Molecular Mobility of Ranitidine Hydrochloride: Crystalline State versus Drug Loaded into the Silica Matrix

et al. 2019

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“…Fluid in nanoconfinement exhibits different properties compared to a bulk fluid, which plays an important role in biological reactions, biomedicine, nanofluidic, geological processes, and hydrocarbon recovery from rocks. Extensive research has been conducted by studying fluid behavior in confinements to investigate reactions on membranes, clay swelling, drug delivery, , fluid transport, , and adsorption. , To elucidate different problems, various confining materials such as carbon compounds, ,− minerals, , and membranes have been employed in experiments and simulations.…”

Section: Introductionmentioning

confidence: 99%

“…Many researchers have utilized molecular dynamics simulations to explore properties of confined fluid. ,− ,− ,− ,,,− Compared to experiments, the geometry and size of nanoconfinement are easier to manipulate through MD simulations. Another advantage of MD simulations is that they can reveal structural and dynamic properties of the fluid and enable the calculation of intra- and inter-relaxation times.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Magnetic Resonance Effects Due to Solid–Fluid Interactions on Confined Water within Quartz-Lined Nanopores via Molecular Dynamics Simulations

2023

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Nuclear magnetic resonance (NMR) relaxation time provides valuable information about properties of fluid and solid surfaces within rocks; however, the complexity of rock samples makes it difficult to quantify the effect of solid–fluid interactions on NMR measurements. Additionally, the ability of 2 MHz NMR equipment to probe nanopores is limited, while detailed analyses of fluid NMR properties in nanopores are possible through molecular dynamics (MD) simulations. We performed atomistic MD simulations to quantify the effect of solid–fluid interactions on confined water within hydroxylated slit and cylindrical quartz-lined rock pores (slit width and cylinder radius from 1 to 9 nm). NMR properties along with density profiles and mean-squared displacements (MSD) were calculated to quantify the effect of solids on relaxation times. MD results indicate that the surface chemistry of slit and cylindrical pores causes differences in density profiles and NMR properties of water confined in silica nanopores. Structural features present in density profiles are important to interpret both MSD and NMR relaxation properties. Intramolecular correlation times are shorter than intermolecular correlation times except when water is confined inside a 1 nm slit pore. These results highlight the importance of pore size on the solid–fluid interactions at the nanoscale. Layer analysis of confined water shows that NMR relaxation times of central layers in small nanopores are not the same as bulk relaxation time. This difference originates an overestimation of pore-size distributions of tight rocks from NMR measurements via Brownstein–Tarr’s equation. Furthermore, relaxation times of water layers indicate that the effect of solid surfaces on NMR relaxation times in a 3 nm slit pore is 15.32% of those in a 9 nm slit pore.

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Molecular dynamics simulations study of the structure and dynamics of nimodipine confined in an ordered mesoporous silica matrix

Pajzderska

Wąsicki

2020

Chemical Physics

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Molecular Dynamics Simulations of Nimodipine Confined in an Ordered Mesoporous Silica Matrix

Cited by 3 publications

References 42 publications

Environmental Effects on the Molecular Mobility of Ranitidine Hydrochloride: Crystalline State versus Drug Loaded into the Silica Matrix

Environmental Effects on the Molecular Mobility of Ranitidine Hydrochloride: Crystalline State versus Drug Loaded into the Silica Matrix

Quantifying Magnetic Resonance Effects Due to Solid–Fluid Interactions on Confined Water within Quartz-Lined Nanopores via Molecular Dynamics Simulations

Molecular dynamics simulations study of the structure and dynamics of nimodipine confined in an ordered mesoporous silica matrix

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