Abstract:Quercetin, as a kind of flavonol compound, has been applied in the fields of food and medicine, because of its attracting physiological functions and pharmacological activities such as anti-oxidation, anti-tumor, lipid-lowering and anti-bacteria. Porous silica is a new type of carrier material and it has many advantages including large specific surface area, good compatibility, ordered and controllable pore channels. More importantly, it is easy to be modified. In this paper, porous silica microspheres were prepared by modified Stöber method, and they were functionalized by introducing amino groups. Based on this, porous silica/quercetin composite materials were synthesized successfully. The prepared porous silica spheres exhibited high specific area (153.63 m2/g) and uniform distribution of pore size (2.40 nm). The control experiments displayed that 0.09 mg quercetin could be loaded per milligram amino-functionalized silica spheres, which was 2.25 times that of the pre-functionalized silica sphere. The possible reason is that amino groups are hydrophilic, so the water dispersion of silica spheres becomes better after introducingamino groups. On the other hand, hydrogen bonds can form easily between amino and hydroxyl groups, so that amino groups functionalized silica spheres can be composite withquercetin easily. The free radical removing activities of the hybrid materials were characterized by DPPH method. The results showed the free radical removing activities of porous silica/quercetin composite materials and pure quercetin were 48.44% and 32.81% under the same condition, respectively. This indicates that the antioxidant activities of composite materials were higher than that of pure quercetin, which may be related to the protective effect of porous silica microspheres on quercetin.
