The Effect of SBA-15 Surface Modification on the Process of 18β-Glycyrrhetinic Acid Adsorption: Modeling of Experimental Adsorption Isotherm Data

Encapsulation of ZnO and Ho:ZnO Nanoparticles in the Core of Wrinkled Mesoporous Silica

Wrinkled mesoporous silica (WMS) has a flower- or dendritic-like morphology, tunable pore size, and highly ordered and accessible three-dimensional (3D) pore structures. In this research, a method to encapsulate semiconductor nanoparticles in the core of the wrinkled mesoporous silica during synthesis is described. Highly uniform zinc oxide and holmium-doped zinc oxide nanoparticles have been synthesized by a sonochemical method. Zinc oxide and holmium-doped zinc oxide nanoparticles have been encapsulated in wrinkled mesoporous silica during synthesis. The ZnO@WMS and Ho:ZnO@WMS particles have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-vis spectroscopy, fluorescence, dynamic light scattering (DLS), confocal microscopy, and X-ray diffraction (XRD).

Sulfonic Acid Derivative-Modified SBA-15, PHTS and MCM-41 Mesoporous Silicas as Carriers for a New Antiplatelet Drug: Ticagrelor Adsorption and Release Studies

Three mesoporous, siliceous materials, i.e., SBA-15 (Santa Barbara Amorphous), PHTS (Plugged Hexagonal Templated Silica) and MCM-41 (Mobil Composition of Matter), functionalized with a sulfonic acid derivative, were successfully prepared and applied as the carriers for the poorly water-soluble drug, ticagrelor. The siliceous carriers were characterized using nitrogen sorption analysis, X-ray diffraction (XRD), transmission electron microscopy (TEM) and elemental analysis. The adsorption studies were conducted in acetonitrile. At the highest equilibrium concentrations, the amount of ticagrelor Q_e that adsorbed onto the examined silicas was in the range of 83 to 220 mg/g, increasing in the following order: PHTS-(CH₂)₃-SO₃H < SBA-15-(CH₂)₃-SO₃H < MCM-41-(CH₂)₃-SO₃H. The equilibrium adsorption data were analyzed using the Freundlich, Jovanovich, Langmuir, Temkin, Dubinin-Radushkevich, Dubinin-Astakhov and Redlich-Peterson models. In order to find the best-fit isotherm for each model, a nonlinear fitting analysis was carried out. Based on the minimized values of the ARE function, the fit of the isotherms to the experimental points for ticagrelor adsorption onto the modified silicas can be ordered as follows: SBA-15-(CH₂)₃-SO₃H (Redlich-Peterson > Dubinin-Astakhov > Temkin), PHTS-(CH₂)₃-SO₃H (Redlich-Peterson > Temkin > Dubinin-Astakhov), MCM-41-(CH₂)₃-SO₃H (Redlich-Peterson > Dubinin-Astakhov > Langmuir). The values of adsorption energy (above 8 kJ/mol) indicate the chemical nature of ticagrelor adsorption onto propyl-sulfonic acid-modified silicas. The results of release studies indicated that at pH 4.5, modified SBA-15 and MCM-41 carriers accelerate the drug dissolution process, compared to the dissolution rate of free crystalline ticagrelor. Intriguingly, modified PHTS silica provides prolonged drug release kinetics compared to other siliceous adsorbents and to the dissolution rate of crystalline ticagrelor. A Weibull release model was employed to describe the release profiles of ticagrelor from the prepared carriers. The time necessary to dissolve 50% and 90% of ticagrelor from mesoporous adsorbents at pH 4.5 increased in the following order: SBA-15-(CH₂)₃-SO₃H < MCM-41-(CH₂)₃-SO₃H < PHTS-(CH₂)₃-SO₃H.

Entrapping Digestive Enzymes with Engineered Mesoporous Silica Particles Reduces Metabolic Risk Factors in Humans

Engineered mesoporous silica particles (MSP) are thermally and chemically stable porous materials composed of pure silica and have attracted attention for their potential biomedical applications. Oral intake of engineered MSP is shown to reduce body weight and adipose tissue in mice. Here, clinical data from a first-in-humans study in ten healthy individuals with obesity are reported, demonstrating a reduction in glycated hemoglobin (HbA1c) and low-density lipoprotein cholesterol, which are well-established metabolic and cardiovascular risk factors. In vitro investigations demonstrate sequestration of pancreatic  α-amylase and lipase in an MSP pore-size dependent manner. Subsequent ex vivo experiments in conditions mimicking intestinal conditions and in vivo experiments in mice show a decrease in enzyme activity upon exposure to the engineered MSP, presumably by the same mechanism. Therefore, it is suggested that tailored MSP act by lowering the digestive enzyme availability in the small intestine, resulting in decreased digestion of macronutrient and leading to reduced caloric uptake. This novel MSP based mechanism-of-action, combined with its excellent safety in man, makes it a promising future agent for prevention and treatment of metabolic diseases.