Biomimetic fabrication of information-rich phenolic-chitosan films

Phenolics appear to be everywhere: they dominate the organic content of our landscape (humics and lignins); they impart color to plants and animals (flavonoids and melanins); they enable biology to harvest energy (quinone redox couples in respiration and photosynthesis); and they may enhance our health (dietary antioxidants). Biology enlists the diverse physicochemical properties of phenolics to perform a variety of functions that are not yet fully understood or appreciated. In this review, the synthesis, structures and functions of biological phenols is briefly sketched while an array of examples is provided to illustrate their diverse functions. The focus of this review however is recent studies which show that the biomimetic incorporation of phenolics into thin chitosan films can controllably impart mechanical, optical and redox properties. These studies demonstrate the potential for accessing nature's rich diversity of phenolics to impart functionality to soft matter.