Functional hyaluronic acid conjugates based on natural polyphenols exhibit antioxidant, adhesive, gelation, and self-healing properties

Abstract

Polyphenols are naturally occurring compounds found in fruits and vegetables. They are bulky molecules comprising of hydroxyl groups in the forms of catechol and other phenolic groups. The catechol functionality is believed to be responsible for the adhesive and cross-linking characteristics. Natural polyphenols were grafted onto hyaluronic acid (HA) using epichlorohydrin chemistry, and the successful preparation of novel HA conjugates were confirmed. The reduction potential of polyphenols was inversely related to the DPPH radical scavenging activity of the conjugates, which in turn was linearly related to the adhesion strength of the conjugates. Although polypropylene had no site for hydrogen bonding, the adhesion strength of the conjugates onto polypropylene reflected the numbers of hydroxyl and catechol groups in general. The adhesive strength of the conjugates increased by 20-fold compared to that of the native HA. Although, hesperidin has no catechol groups, it still improved the adhesion strength. Reversible coordination with metal ions facilitated ionic gelation and self-healing properties. Adhesive, antioxidant, gelation, and self-healing properties were successfully achieved simultaneously. These functional properties could make the natural conjugates promising candidates for biomedical applications and environmentally safe materials. (C) 2017 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.