Polyphenolic Biomaterials: Functional Materials Inspired by Mussels, Tea, Wine, Coffee and Chocolate
Phillip B Messersmith (Northwestern University)
Polyphenols are found in both plant and animal tissues, where they serve a variety of functions including mechanical adhesion, structural support, pigmentation, radiation protection, and chemical defense. In animals, notable examples of polyphenols are the adhesive proteins secreted by sessile marine organisms for adhering to wet substrates. In mussels, for example, the adhesive proteins are known to contain high levels of 3,4-dihydroxy-L-alanine (DOPA), an amino acid that is believed to be important in adhesion to substrates. In plants, polyphenolic compounds containing benzenediol (catechol) and/or benzenetriol (gallol) functional groups are widely distributed secondary metabolites with a variety of biochemical and physical functions. Plant polyphenols have attracted significant attention for the claimed health benefits associated with consumption of foods and beverages rich in these compounds.
In this talk the biological functions of selected biological polyphenols that are rich in catechol or gallol functional groups will be described. Our research has the overall goal of developing novel materials inspired by biological polyphenols. In the case of mussel-inspired biomaterials, we are interested in understanding the molecular and mechanochemical aspects of mussel adhesion, and in developing biomimetic polymer hydrogels and coatings from synthetic catechol containing polymers. These biologically inspired materials have a variety of functional uses, including tissue repair, drug delivery and antifouling coatings. In the case of plant polyphenols, we recently discovered that polyphenolic compounds extracted from tea leaves, coffee beans, cacao beans and grapes form thin adherent polymerized films on substrates immersed in solutions of the extracts. Deposition is facile on a variety of solid, porous and nanoparticulate substrates composed of metals, ceramics and polymers. In addition to possessing inherent antibacterial and antioxidant properties, the deposited polyphenol films serve as versatile "primers" facilitating secondary modifications of the primer coating such as metallization and covalent grafting of biomolecules and synthetic polymers. These secondary modifications can be exploited for a variety of practical applications, including antibacterial and fouling resistant coatings, electroless metallization of surfaces, plasmonic tuning and surface functionalization of nanoparticles, and antioxidant coatings on medical devices.