Polyphenol Nanoparticles from Commonly Consumed Tea for Scavenging Free Radicals, Stabilizing Pickering Emulsions, and Inhibiting Cancer Cells

Utilization of natural renewable resources for developing functional nanomaterials has attracted much attention because of the economic and environmental benefits. Tea polyphenol-derived functional nanomaterials with potent antioxidant capacity and beneficial effects are of great interest in food industry, cosmetics, and biomedical purposes. The traditional way of utilizing natural tea polyphenol resources involves the multistep extraction, tedious encapsulation in nanocarriers, and/or modification to improve its stability and bioactivities. Here, we introduce a one-pot simple method to efficiently prepare functional nanoparticles via polyphenolic condensation reaction from tea infusion. Electron microscopy images confirm the tunable size and structure (porous or core-shell) of the prepared particles. These particles are potent in scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, and active oxygen/nitrogen species in stimulated cells, are capable of forming stable Pickering emulsions, and also act as active agents for inhibiting cancer cells. High-performance liquid chromatography analysis and total phenol measurement reveal good selectivity and high efficiency of the present strategy in capturing active components (catechins) from tea by the formation of nanoparticles. In a word, the simple, efficient, and innovative method for preparing multifunctional catechin nanoparticles from tea infusion lays a solid foundation for large-scale application of natural polyphenol materials in a much more economical way.