Novel techniques for drug loading quantification in mesoporous SBA-15 using chemometric-assisted UV and FT-IR data.

Albendazole is a crystalline drug that is poorly soluble in water, thus the dissolution rate in gastrointestinal fluids is limited. Mesoporous materials loaded with poorly water-soluble drugs become an interesting strategy to increase their solubility/dissolution rate as the drug state changes from crystalline to amorphous. In order to determine the drug loading content into mesoporous materials analytical methods such as elemental analysis, UV and HPLC are commonly used. However, elemental analysis and HPLC are destructive and relatively expensive. In addition, UV is time consuming. Moreover, UV and HPLC require the drug release from the mesoporous material before the quantification step. Therefore, the aim of this work was to develop quantifications techniques based on chemometric models combined with UV and FT-IR spectra without needing the drug release from the mesoporous material. Partial least squares regression (PLSR) was used as chemometric regression method. Albendazole content in the SBA-15 powders was first quantified by elemental analysis as reference measurement for multivariate calibration. The excellent drug loading predictions prove that robust calibration models can be obtained from both techniques (i.e., 0.999 and 0.998 adjusted correlation coefficient for UV and FT-IR, respectively). Additionally, the adjusted correlation coefficients determined from the validation models for UV and FT-IR are 0.963 and 0.930, respectively. It is important to highlight that the prediction adjustment of the FT-IR model (root-mean-square error of prediction=2.196%) presented lower error than the UV model (root-mean-square error of prediction=3.553%). Therefore, this development contributes to improve the overall time and cost of drug loading determination into mesoporous materials.

Synthesis and characterization of mesoporous SBA-15 and SBA-16 as carriers to improve albendazole dissolution rate.

Albendazole (ABZ, anti-parasitic active pharmaceutical ingredient) is a crystalline low water-soluble drug, thus the dissolution rate in gastrointestinal fluids is limited. Consequently, the improvement of the water solubility and dissolution rate of ABZ implies a great challenge for a more efficient treatment of hydatidosis. In this context, SBA-15 and SBA-16 ordered mesoporous silica materials were synthetized and loaded with ABZ. X-ray diffraction, FT-IR spectroscopy, nitrogen physisorption manometry, particle size distribution and scanning electronic microscopy were used to characterize unloaded and loaded materials (ABZ/SBA-15 and ABZ/SBA-16). The loaded ABZ amount in the carriers was estimated by elemental analysis. For the loaded materials, the drug solubility and release profile were evaluated. In addition, mathematical models were compared to explain the dissolution kinetics of ABZ from mesoporous solids. ABZ was successfully loaded into the mesopores. The amorphous state of the adsorbed ABZ was confirmed by differential scanning calorimetry that resulted in a notable increment in the dissolution rate compared to crystalline ABZ. Drug release behaviors were well simulated by the Weibull model for ABZ/SBA-15 and by the Gompertz function for pure ABZ and ABZ/SBA-16. The SBA-15 carrier exhibited the highest drug loading and dissolution rate becoming a promising material to improve ABZ bioavailability.

Green synthesis of nanocrystalline faujasite zeolite.

In this work, the synthesis of 28 and 38 nm Na-Y zeolite nanocrystals is reported. The process was performed via green synthesis without any organic structure directing agents (SDAs), at low temperature and applying ultrasound-assisted aging. The zeolite nanoparticles obtained were characterized by X ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption - desorption isotherm at 77 K. A simple, fast, efficient and environmentally friendly procedure to synthetize nanocrystalline FAU zeolite is described in the present study. The sonochemical pretreatment was found to directly affect the Na-Y zeolite properties. The final product obtained via ultrasound pretreatment shows high phase purity and crystallinity degree with crystal size smaller than 38 nm and elevated surface area (SBET ∼ 950 m2 g-1). The hierarchical micro- and mesoporous FAU zeolites exhibit a pore volume of ∼0.4 cm3 g-1.