In Situ FT-IR Investigation of Etravirine Speciation in Pores of SBA-15 Ordered Mesoporous Silica Material upon Contact with Water

Abstract

Ordered mesoporous silica (OMS) has been recognized as promising adsorbent material for drug molecules with low aqueous solubility. The release of drug molecules from OMS upon contact with aqueous environment enhances their oral bioavailability. The release is governed by a complex interplay of adsorption, diffusion, and intermolecular interaction inside OMS pores. The presence of water hampers in situ FT-IR investigation of the behavior of the drug molecules upon release. The poorly water-soluble etravirine molecule having two nitrile functions was selected for an in situ FT-IR spectroscopic investigation of the release process. The stretching vibration of the nitrile organic function (υ(CN)) is a spectral feature that is accessible to FT-IR even in the presence of water. Etravirine depending on the loading was found to be present in SBA-15 pores as isolated adsorbed molecules, solvated molecules, and aggregates with intermolecular interaction similar to the crystalline state, each with a different spectroscopic fingerprint. Etravirine evacuation from the SBA-15 pores was shown to proceed in the solvated state. Surprisingly, the etravirine clusters inside pores were converted more readily into solvated molecules compared to individually adsorbed molecules.

Hyaluronated mesoporous silica nanoparticles for active targeting: influence of conjugation method and hyaluronic acid molecular weight on the nanovector properties

“…Infrared spectroscopy is a powerful tool to investigate interface interactions in hybrid organicinorganic materials. It can be used to assess the molecular structure of surface grafted functionalizing groups, and the weak interactions taking place between silica surface and adsorbed/encapsulated drug molecules [28,[50][51][52][53][54][55][56][57][58]. The spectra of parent NH2-MSN and HA conjugated samples are reported in Figure 3, in the high and low frequency ranges (top and bottom panel, respectively).…”

Influence of surface functionalization on the hydrophilic character of mesoporous silica nanoparticles

“…[2][3][4][5][6][7][8] The reasons for this success are easily understood on the basis of the wellknown properties of the material, including extremely high specific surface area (around 1000 m 2 g À1 ), ordered porosity with narrow pore size distribution and large pore volume, and the possibility of modulating pore size, thus allowing the accommodation of molecules with different steric hindrance, which are ideal properties for high drug loading and gradual, diffusiondriven release. 2,9,10 Another important aspect explaining the impressive interest in the field of mesoporous silica is related to the possibility of obtaining the materials in the form of nano-and submicrometersized particles, commonly referred to as mesoporous silica nanoparticles (MSNs). 3,[11][12][13] In this form, MSNs can be passively transported in physiological fluids, for instance in the case of extravasation from leaky tumour vessels, making therapeutic delivery into disease cells more efficient while lowering the exposure of healthy tissue to toxic side effects.…”

Morphology Evolution in Hydrothermal Synthesis of Mesoporous Alumina

“…Conventionally, mesoporous alumina can be prepared by template method, including soft template of surfactants [11][12] , amphiphilic polymer [13][14] , and hard template of mesoporous silica [15][16] , carbon [17][18] . Recently, some other methods have been employed to synthesis mesoporous alumina, such as evaporation-induced method [19] , Sol-Gel method [20] and multi-component method [21] .…”