Layer-by-Layer preparation of microcapsules and nanocapsules of mixed polyphenols with high antioxidant and UV-shielding properties

Microcapsules and nanocapsules based on the contemporary presence of sulfonate lignin and tannic acid have been prepared by the layer-by-layer procedure, using MnCO3 or organosolv lignin as core templates, and polydiallyldimethylammonium chloride or chitosan as positive charged supporting layers. Nanocapsules and microcapsules of mixed polyphenols showed antioxidant activity, UV-shielding properties, and electrochemical responsiveness, higher than that in homopolymer nanocapsule counterparts and of the native polyphenols, suggesting the presence of synergistic effects between the two components. The presence of UV-visible bathochromic shift suggested the formation of J-aggregates characterized by an orientation of the adjacent phenolic rings parallel to the longitudinal direction of the layer, with a head-to-tail like arrangement. Moreover, nanocapsules of mixed polyphenols showed an aggregation state higher than that observed in references, the specific morphology of their surface being dependent on the structural arrangement of the different components.