Plant-Inspired Pyrogallol-Containing Functional Materials

Pyrogallol-containing molecules are ubiquitous in the plant kingdom. The chemical synthesis of these molecules remains challenging. Thus, they are obtained via purification from heterogeneous mixtures of plant extracts. Previous studies have focused on their biological roles, such as antioxidants. Additionally, the molecules are used as ink colorants and in tanning processes for leather. Recently, many disciplines have paid attention to adhesiveness of pyrogallol-containing molecules, including the control of interface properties in energy storage/generation and medical devices, as well as the changes in wettability related to membrane technologies. In particular, pyrogallol-containing molecules act as "molecular glues," binding to virtually all biomacromolecules, for example, DNA/RNA, soluble proteins, insoluble extracellular matrices, and peptides. Furthermore, the cohesion of pyrogallol by forming pyrogallol-to-pyrogallol covalent bonds is useful for the preparation of bulk hydrogels and thin films. The content of this review focuses on interactions with biomacromolecules used as molecular glues, used as modifiers in material-independent surface chemistry, and applied as chemical moieties to form covalent linkages to fabricate hydrogels and related biomaterials. Future perspectives include the development of new pyrogallol-containing materials, the understanding of chirality in adhesion, and the improvement of the mechanical stability for applications in various biomedical, energy, and industrial devices.