title: Local pH oscillations witness autocatalytic self-organization of biomorphic nanostructures.
abstract: Bottom-up self-assembly of simple molecular compounds is a prime pathway to complex materials with interesting structures and functions. Coupled reaction systems are known to spontaneously produce highly ordered patterns, so far observed in soft matter. Here we show that similar phenomena can occur during silica-carbonate crystallization, the emerging order being preserved. The resulting materials, called silica biomorphs, exhibit non-crystallographic curved morphologies and hierarchical textures, much reminiscent of structural principles found in natural biominerals. We have used a fluorescent chemosensor to probe local conditions during the growth of such self-organized nanostructures. We demonstrate that the pH oscillates in the local microenvironment near the growth front due to chemical coupling, which becomes manifest in the final mineralized architectures as intrinsic banding patterns with the same periodicity. A better understanding of dynamic autocatalytic crystallization processes in such simple model systems is key to the rational development of advanced materials and to unravel the mechanisms of biomineralization.
authors.affiliation: Dipartimento di Chimica 'G. Ciamician', Alma Mater Studiorum, Università di Bologna, I-40126 Bologna, Italy.
authors.forename: M
authors.identifier: 0000-0001-6227-0899
authors.initials: M
authors.lastname: Montalti
authors.affiliation: Laboratorio de Estudios Cristalográficos, Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad de Granada), E-18100 Armilla (Granada), Spain.
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Dipartimento di Chimica 'G. Ciamician', Alma Mater Studiorum, Università di Bologna, I-40126 Bologna, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Genovese
authors.affiliation: Laboratorio de Estudios Cristalográficos, Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad de Granada), E-18100 Armilla (Granada), Spain.
authors.forename: J
authors.initials: J
authors.lastname: Morales
authors.affiliation: Material Physics, BASF SE, RAA/OS-B007, D-67056 Ludwigshafen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kellermeier
authors.affiliation: Laboratorio de Estudios Cristalográficos, Instituto Andaluz de Ciencias de la Tierra (CSIC-Universidad de Granada), E-18100 Armilla (Granada), Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: García-Ruiz
mesh_terms: D040761:Biomimetic Materials / Q000737:chemistry; D002254:Carbonates / Q000737:chemistry*; D011232:Chemical Precipitation; D003460:Crystallization / Q000379:methods*; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D008856:Microscopy, Fluorescence; D008903:Minerals; D015336:Molecular Probe Techniques; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D002254:Carbonates; D005456:Fluorescent Dyes; D008903:Minerals; D012822:Silicon Dioxide