Catechol‐Based Biomimetic Functional Materials

Abstract

Abstract.Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o -dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex oxidation mechanisms; its excellent chelating properties, greatly exemplifi ed by, but by no means exclusive, to the binding of Fe 3 + ; and the diverse modes of interaction of the vicinal hydroxyl groups with all kinds of surfaces of remarkably different chemical and physical nature. Thanks to this diversity, catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds. Such versatility has allowed catechols to participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of some transition metal ions. As a result of such an astonishing range of functionalities, catechol-based systems have in recent years been subject to intense research, aimed at mimicking these natural systems in order to develop new functional materials and coatings. A comprehensive review of these studies is discussed in this paper.

Resolving Non‐Specific and Specific Adhesive Interactions of Catechols at Solid/Liquid Interfaces at the Molecular Scale

“…The strongest binding energy of 29  k B T is measured for the interaction between Dopa and a titania‐coated tip. This is not unexpected since it has been pointed out previously that bidentate H‐bonding and metal coordination leads to strong adhesion between catechols and metal‐oxide surfaces 3a, 5. While our approach only provides equilibrated interaction free energies, insight into the exact binding mechanism is not possible.…”

“…Both surface forces apparatus (SFA)2b, 3 and single‐molecule force spectroscopy (SM‐AFM)4 experiments indicated that Dopa adheres well to metal‐oxide surfaces by bidentate H‐bonding and metal coordination 3a, 5. In particular, Lee et al 4a.…”

Switchable Materials Containing Polyzwitterion Moieties

“…Application of this switch is shown in Figure 1. Poly (7) in the polycationic state destroyed almost 99.9% of E. coli and dead bacteria remained on the surface (Figure 1a), and, after hydrolysis to poly (8) (Figure 1b), almost 98% of the dead bacteria were released (Figure 1c). Additionally, poly (8) showed non fouling properties for proteins and Poly (9) [49] Poly(8) pH 13, 1 h (copolymer with poly(EGMA)…”

“…Polymers 2015, 7, Reversible switch allowing switch between polycationic coating with antibacterial character and subsequently after switch release of dead bacteria and forming nonfouling surface have particular interest in coating for surgical or medical tools and application.…”

“…As an example, the surface properties and characteristics of polypeptides may vary markedly due to changes in the secondary/tertiary structures as a response to an external trigger [6] or an adhesion-repellent switch in a muscle is triggered by changes in pH or by the presence of cooperative ions [7].…”