Mesoporous silica as topical nanocarriers for quercetin: Characterization and in vitro studies

The flavonoid quercetin is extensively studied for its antioxidant and chemopreventive properties. However the poor water-solubility, low stability and short half-life could restrict its use in skin care products and therapy. The present study was aimed to evaluate the potential of aminopropyl functionalized mesoporous silica nanoparticles (NH₂-MSN) as topical carrier system for quercetin delivery. Thermo gravimetric analysis, X-ray diffraction, high resolution transmission electron microscopy, nitrogen adsorption isotherms, FT-IR spectroscopy, zeta potential measurements and differential scanning calorimetry allowed analyzing with great detail the organic-inorganic molecular interaction. The protective effect of this vehicle on UV-induced degradation of the flavonoid was investigated revealing a certain positive influence of the inclusion on the photostability over time. Epidermal accumulation and transdermal permeation of this molecule were ex vivo evaluated using porcine skin mounted on Franz diffusion cells. The inclusion complexation with the inorganic nanoparticles increased the penetration of quercetin into the skin after 24 h post-application without transdermal delivery. The effect of quercetin alone or given as complex with NH₂-MSN on proliferation of JR8 human melanoma cells was evaluated by sulforhodamine B colorimetric proliferation assay. At a concentration 60 μM the complex with NH₂-MSN was more effective than quercetin alone, causing about 50% inhibition of cell proliferation.