Effects of surface acidity and pore size of mesoporous alumina on degree of loading and controlled release of ibuprofen

We report here the simultaneous influence of surface functionality and pore size of mesoporous alumina (Al2O3) host on ibuprofen (IBU) loading and release. Variation in surface acidity is due to the changes in surface density of OH group. Most importantly density variation of OH did not affect the morphological parameters such as surface area, pore size and distribution. Through a novel synthesis method, high degree of IBU loading was possible into Al2O3(X) (X: acidic (A), basic (B), neutral (N)). IBU content as high as 26% (w/w Al2O3(A)–IBU) could be impregnated into Al2O3(A) while Al2O3(B) had the lowest IBU content of 22% (w/w Al2O3(A)–IBU). The in vitro IBU release kinetics are heavily influenced by the varying Al2O3 surface acidity. Systematic observation showed release of IBU from Al2O3(B) taking place at a significantly faster rate compared to Al2O3(A). The release kinetics was also observed to be dependent on concentration ratio of Al2O3 to IBU and pH of the release medium. We envisage that the present study will be beneficial for design of better mesoporous materials for controlled drug delivery systems.