Designed formulation based on α-tocopherol anchored on chitosan microspheres for pH-controlled gastrointestinal controlled release.

Chitosan microspheres were prepared and vitamin E (α-tocopherol) was anchored onto the polymer. The amount of α-tocopherol entrapped onto a gram of the microspheres based system was 13.4±0.

Nanosized silica modified with carboxylic acid as support for controlled release of herbicides.

Hexagonal mesoporous silica modified with carboxylic acid (SiAc) has been obtained by reaction between chloroacetic acid and 3-aminopropyltrimethoxysilane, which was immobilized on porous material by a sol-gel process in the presence of an n-dodecylamine template. SiAc was characterized by TG, FT-IR, (29)Si NMR, (13)C NMR, SEM, surface charge density, surface area and porous diameter, which proved that the carboxylic group was chemically bonded to an inorganic structure, and the material presented a nanometric structure with spheres <50 nm and porous diameter of 10 nm. Herbicides 2,4-D and picloram were anchored on SiAc porous gel to produce the materials named SiD and SiPi, respectively.