(168g) Adsorption, Stabilization and Recovery of Polyphenolic Flavonoids By TiO2 Functionalized Mesoporous Silica Nanoparticles
Here, the adsorption of quercetin and rutin (0.05-10 mg/ml in ethanol) is investigated on MSNPs (165 nm diameter) that are functionalized with submonolayer coverage (7-85%) of TiO2. The amount of flavonoid adsorbed onto the particles was found to be a strong function of titania grafting density on the silica surface. As a function of quercetin concentration, strong binding occurs at low solution concentration followed by a gradual approach to saturation at higher concentration. Nanoparticles with approximately 60% of monolayer coverage of titania adsorb 230 mg quercetin/gram silica, which is more than 100 times the capacity of nonporous particles with similar titania coverage. The flavonoid recovery from nanoparticles was also investigated using biocompatible ethanolic citric acid solution (20% w/v) and a five step multistage desorption process were able to recover more than 90% of the bound flavonoids cumulatively. The radical scavenging activity (RSA) of recovered and particle bound quercetin were measured and most of the RSA was retained after binding quercetin, and after recovery of bound quercetin into solution. The materials developed here have the potential to be used to strongly and directly bind flavonoids and related secondary metabolites from plant cells, and will serve as a synthetic platform to isolate, recover, and potentially deliver these compounds in biological systems.