New Mesoporous Silica Materials Loaded with Polyphenols: Caffeic Acid, Ferulic Acid and p-Coumaric Acid as Dietary Supplements for Oral Administration

Abstract

In this study, two types of mesoporous silica with different pore structures and volumes were synthesized by the soft-templating method. The two types of mesoporous silica, type MCM-41 and MCM-48, were loaded with three polyphenols—caffeic acid, p-coumaric acid and trans-ferulic acid—in the same ratio of mesoporous silica:polyphenol (1:0.4 w/w). The materials obtained were characterized from a morphological and structural point of view through different analysis techniques. Through X-ray diffraction (XRD), the crystallization plane and the ordered structure of the mesoporous silica were observed. The difference between the two types of materials containing MCM-41 and MCM-48 was observed through the different morphologies of the silica particles through scanning electron microscopy (SEM) and also through the Brunauer–Emmet–Teller (BET) analysis, that the surface areas and volumes of pores was different between the two types of mesoporous silica, and, after loading with polyphenols, the values were reduced. The characteristic bands of silica and of polyphenols were easily observed by Fourier-transform infrared spectroscopy (FTIR), and, through thermogravimetric analysis (TGA), the residual mass was determined and the estimated amount of polyphenol in the materials and the efficient loading of mesoporous silica with polyphenols could be determined. The in vitro study was performed in two types of simulated biological fluids with different pH—simulated gastric fluid (SGF) and simulated intestinal fluid (SIF). The obtained materials could be used in various biomedical applications as systems with controlled release of natural polyphenols and the most suitable application could be as food supplements especially when a mixture of such materials is used or when the polyphenols are co-loaded within the mesoporous silica.