Cephalexin loading and controlled release studies on mesoporous silica functionalized with amino groups

KIT-6 mesoporous silica has been synthesized using the sol-gel method and functionalized with 3-aminopropyl triethoxysilane by grafting route to obtain KIT-6/NH2. These samples were used as carriers in the loading and controlled release of cephalexin (CFX). The effect of temperature and gastric and intestinal pH on the stability of pure CFX and loaded in KIT-6 and KIT-6/NH2 were investigated. The properties of the synthesized materials and their CFX loading capacity were studied through FTIR, ads-des N2 at 77 K, TEM, SEM, XPS, and TGA. The controlled release tests were carried out in a simulated physiological medium at gastric (1.2) and intestinal pH (6.8). Furthermore, the biocompatibility of both materials was studied through cell viability tests in Caco-2 intestinal cells. The results revealed that KIT-6 and KIT-6/NH2 had similar CFX loading capacities. It was found that CFX degrades at pH 6.8, however, KIT-6 and KIT-6/NH2 were able to protect it from the aforementioned degradation. Moreover, KIT-6 materials presented a good performance as CFX carriers since both materials provided diffusion-controlled release profiles during 24 h, satisfying the Korsmeyer-Peppas kinetic model. Mesoporous silicas presented in this work are promising candidates to be used in CFX controlled release systems due to their chemical interactions, textural properties, and high cell viability.