Hydrophobic contribution to amoxicillin release associated with organofunctionalized mesoporous SBA-16 carriers

Mesoporous silica SBA-16, synthesized and organofunctionalized with 3-iodopropyltrimethoxysilane, diethyl iminodiacetate and benzidine through post-synthesis methodology, was applied as a drug delivery system. Amoxicillin was chosen due to its action as a broad-spectrum antibiotic for treatment of a wide range of bacterial infections. The well-characterized SBA-16 silica showed an ordered mesoporous structure, with sorption/desorption data in agreement with type IV isotherms, presenting a H2 hysteresis loop. The surface area values varied from 836 for SBA-16 to 377 m2 g−1 for that containing the largest pendant chain bonded to the inorganic backbone. These available pendant chains permit up to 51 wt.% loadings that are higher than with other similar organofunctionalized silicas. This drug-loaded degree offers better conditions when applied for delivery systems. Thus, drug delivery investigation in simulated intestinal (pH = 7.4) and gastric (pH = 1.2) fluids gave higher values for the first fluid. The efficiency of an amoxicillin-loaded system depended not only on increases of the hydrophobic surface due to the organofunctionalization, but also to hydrogen bond formation between the drug and the available centers attached to the pendant chains.