Potential Application of A Synthetic Organo-funtionalized High Load Expandable Mica as A Drug Carrier for Controlled Release.

BACKGROUND: In this work the cytotoxicity and gastric and gastrointestinal resistance of a high-load synthetic expandable mica, Na-mica-4, is studied for the first time. The hydrophilic character of this clay mineral can be modified by ion exchange reaction between Na+ inorganic cations housed in the interlayer space, and surfactant molecules, resulting in the formation of an organophilic material. This adsorption capability of organic compounds makes them very useful for a wide range of applications, such as their use as drug carriers. Previous studies have shown the high adsorption capacity of organofunctionalized Na-mica-4 of different types of drugs. Objetive: To carry out initial trials aimed at testing the cytotoxicity of a synthetic organofunctional expandable mica and evaluating its resistance to gastric and gastrointestinal digestion. METHODS: A highly charged sodium mica (Na-mica-4) was synthesized and organofunctional by cationic exchange with an alkylamine, primary amine of 18 carbon atoms (C18-mica-4). Both were characterized by X-ray diffraction, field transmission electron microscopy, surface-specific analysis, differential scanning calorimetry, and thermal gravimetric analysis. In addition, screening cytotoxicity trials were conducted on the human intestinal cell line Caco-2 with C18-mica-4 (0-125 µg/ml). RESULTS: Only one of the endpoints evaluated (the reduction of tetrazolium MTS salt by dehydrogenase enzymes) showed a significant decrease in cellular viability after 48h at the highest concentration tested. C18-mica-4 shows structural resistance to both, gastric and gastrointestinal, digestion. CONCLUSION: A successful development of a functionalized mica has been made with a promising potential application as a carrier to the drug.

Removal of priority and emerging pollutants from aqueous media by adsorption onto synthetic organo-funtionalized high-charge swelling micas.

In this work, the removal of different types of emerging pollutants (four perfluoroalkyl compounds, two preservatives, three surfactants and nine pharmaceutical compounds) from aqueous solution by adsorption onto two novel synthetic clays, a high-charge swelling mica (Na-Mica-4) and an organo-functionalized mica (C18-Mica-4), was evaluated. Na-Mica-4 and C18-Mica- 4 were prepared and characterized by X-Ray diffraction, Zeta potential, specific surface area, thermogravimetric analysis and transmission electron microscopy, before and after adsorption experiments. The influence of the aqueous sample pH, salt addition and extraction time in the removal were evaluated. The results showed the high adsorption affinity of C18-Mica-4 for most of the emerging pollutants analysed after a removal time of 24 h (14 out of 18 pollutants were effectively removed [70-100%]). A high correlation was observed between the log Kow of the selected emerging pollutants and the adsorption onto C18-Mica-4. The results also indicate that adsorption occurs in the interlayer space. While the removal rates with Na-Mica-4 were in the range 8-97% after seven days, some of the compounds, perfluorobutanoic acid and most of pharmaceutically active compounds, were not adsorbed onto the high-charge mica. C18-Mica- 4 was effectively used for the removal of contaminants from four types of water samples.

Novel synthetic clays for the adsorption of surfactants from aqueous media.

The aim of this work was to assess for the first time the use of two high-charge swelling micas (Na-Mica-4 and C18-Mica-4) for the removal of four linear alkylbenzene sulfonates (LAS) from aqueous samples. To this end, Na-Mica-4 was synthesized and organically functionalized with cations of octadecylamine to obtain C18-Mica-4. Na-Mica-4 and C18-Mica-4 were characterized by X-Ray diffraction, Zeta potential, specific surface area and thermogravimetric analysis before and after the adsorption experiments. LAS removal studies were carried out in water samples spiked with a LAS mixture (10 mg L-1). Removal rates with C18-Mica-4 were between 94% and 97% at pH = 2, and between 98% and 99% at pH = 5 after 1 h. For the same amount of Na-Mica-4, removal rates were between 54% and 81% at pH = 2, and between 24% and 66% at pH = 5 after seven days. No significant effects on the removal rates of C18-Mica-4 were observed for pH values between 0.5 and 9. The experimental equilibrium data were fitted to 30 min, with removal rates of up to 98% in all the experiments. C18-Mica-4 characterization tests indicate that LAS adsorption occurs in the interlayer space. Finally, C18-Mica-4 was applied successfully to the removal of the target compounds from influent and effluent wastewater, surface water and tap water samples.