Natural polyphenols in drug delivery systems: Current status and future challenges

Natural polyphenols have attracted great interests in medicine, food and cosmetics due to their versatile functions such as antioxidant, anticancer and antibacterial. The polyphenolic structures (i.e. catechol, and pyrogallol) in natural polyphenols are responsible for strong noncovalent interactions via multiple hydrogen bonding and hydrophobic interactions, and dynamic covalent complexation with boronate groups and multiple metal ions. In this review, we focused on the preparation and applications of natural polyphenol-based coating films, nanoparticles, nanocapsules, and hydrogels emerged from their chemical and functional signatures. The beneficial role and mechanism of natural polyphenols in facilitating the delivery of proteins, nucleic acids and conventional drug molecules were reviewed. Finally, the challenges of natural polyphenol-based delivery systems and perspectives in rational design of next generation natural polyphenol biomaterials will be discussed.