Experimental and theoretical study of quercetin complexes formed on pure silica and Zn-modified mesoporous MCM-41 and SBA-16 materials

Abstract SBA-16 and MCM-41 silica materials were synthesized and modified by post-synthesis method with different amounts of Zn (2 and 4~wt.%). Quercetin, a flavonol compound, was loaded by incipient wetness impregnation method on the pure silica and Zn-modified mesoporous MCM-41 and SBA-16 supports. The parent and drug loaded formulations were characterized by powder XRD, N2 physisorption, thermal analysis, TEM, UV Vis and FT-IR spectroscopies. The formation of Zn:quercetin complex was studied by FT-IR spectroscopy and quantum-chemical calculations. Loading of quercetin on mesoporous carriers made the sustained delivery of the bioactive compound possible in a buffer with pH~=~5.5, typical of dermal formulations. The results from the release experiments are in good accordance with the interaction energy between the bioactive molecule and non-modified and Zn-modified mesoporous materials, predicted by the quantum-chemical calculations. For the first time the formation of the most stable Zn quercetin complexes loaded on the mesoporous silica materials were determined. The obtained mesoporous delivery systems with Zn-quercetin complex are promising as dermal formulations.