Polyphenols as Morphogenetic Agents for the Controlled Synthesis of Mesoporous Silica Nanoparticles

Abstract

Non-surfactant-induced synthesis of mesopo-rous silica nanoparticles (MSNPs) is gaining increasinginterest because of their low toxicity and simple purificationcompared to conventional surfactant-based methods. Tannicacid (TA), considered as a glucose-derived polyphenol, wasfirst employed a few years ago and has attracted great researchinterest. Despite recent progress, the mechanisms resulting inthe porous structure remain to be elucidated. In this work, wehave employed TA and four structurally related polyphenols(gallic acid, ethyl gallate, eudesmic acid, and quercetin) toelucidate the effect of the chemical structure and properties ofpolyphenols on their templating ability. Our results unravelthe mechanism of MSNP formation templated by TA, whichform a supramolecular framework as the skeleton for the silicaspecies to attach. The structure of the supramolecular network results in irregular pores. Additionally, the pKavalue of thetemplates may be accounted for the particle size. Small-angle X-ray scattering was used to provide precise information on themorphology, especially the porosity of the resulting MSNPs in addition to electron microscopy, dynamic light scattering,nitrogen adsorption and desorption Brunauer−Emmett−Teller method, and thermogravimetric analysis.