Nature-inspired antioxidants and redox-active organic systems for biomedical research and applications

The imitation of Nature’s chemical principles and logics has emerged as a competitive strategy for the design and implementation of functional molecular systems and biomaterials for innovative technological and biomedical applications. A unique source of inspiration in this context is offered by phenols, polyphenols and especially catechols, in view of their various biological roles. In this frame the present project addressed structure-property-function relationships in synthetic eumelanin and polydopamine by a biomimetic chemistry and modeling approach and in particular: a) the elucidation of the main structural components of polydopamine and their role in wet adhesion and film-forming properties; b) preparation of model eumelanins at high degree of regioregularity and comparative evaluation of their chromophoric and antioxidant properties; c) design and implementation of novel fluorescence turn-on systems for sensing applications or alternative mussel-inspired systems for technological applications; d) preparation and characterization (NMR, mass spectrometry, UV-visible, particle and film morphology, antioxidant properties) of novel adhesive polymers based on control of monomer structure, functional groups and deposition conditions. Main outcomes can be summarized as follows: 1) PDA film deposition: a) requires high dopamine concentrations (>1 mM); b) is not attributable to cyclized 5,6-dihydroxyindole (DHI) intermediates produced by dopamine autoxidation; c) is accelerated by equimolar amounts of periodate causing fast conversion to the o-quinone; d) is enhanced by the addition of hexamethylenediamine (HMDA) and other long chain aliphatic diamines even at low dopamine concentrations (