Halochromic modulation of amorphous calcium carbonate crystallization driven by pH-responsive bioinspired organic pigments

Le résumé fourni par la source

Colors in biominerals often arise from the occlusion of low-molecular-weight organic pigments within calcium carbonate (CaCO3) mineral phases during biomineralization processes; however, the physicochemical origin of these colors has been overlooked. Here, inspired by the growth of colored sea urchin spines that occurs through amorphous CaCO3 (ACC) precursors, we show an in-vitro halochromic modulation of ACC crystallization. In this mechanism, the deprotonation of a natural red pigment naphthazarin (NZ) is driven by pH variations during mineral formation and subsequently stabilized within CaCO3- hybrid pigments. The latter show lavender-blue to violet-blue hues upon crystallization. NZ has a minimal impact on ACC formation and crystallization occurring through local dissolution and reprecipitation mechanisms; however, it limits the formation of vaterite and calcite distorted nanodomains and leads to the emergence of deprotonated NZ nano-occlusions whose interaction with calcite is likely mediated by water. Overall, this study brings insights into the processes behind the coloration of biomineralized organisms.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.