Controlled Precipitation of Biominerals using Catanionic Surfactant Self-Assembly Structures

• Applicant: Professor Dr. Helmut Cölfen (†)
• Subject Area: Biological and Biomimetic Chemistry
• Term: from 2004 to 2009
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5415807

Lyotropic phases could be used with great success as template for the synthesis of mesoporous ceramics via a sol-gel process. However, ion crystals could so far not be templated by such approach - likely as a result of the fluidity of the lyotropic phases. Salt-free catanionic surfactant systems offer a potential solution to this problem as their frozen bilayer structure displays great rigidity over large length scales. Furthermore, they show quite unique self-assembly structures. These phases shall be used as a template for the crystallization of CaCO3 within the water regime in the catanionic phase. For this, various crystallization techniques shall be employed which work at low ionic strength in order to reproduce the catanionic phase on the nm scale. The catanionic phases of particular interest are the lamella phases as well as the nanodisks and icosahedra. If CaCO3 could be mineralized within the lamellar phase, a layered organic-inorganic hybrid material similar to nacre with its superior mechanical properties would result. To achieve this, the catanionic aggregation has to be investigated in presence of the Ca2+ counterions and if necessary, the phase diagrams have to be determined. Also, it shall be explored, if very small pre-formed CaCO3 nanoparticles can be incorporated into the catanionic phases as material reservoir for later nanoparticle fusion via pH cycles. If it is possible to reproduce the organic template, other phase structures shall be employed in order to synthesize mesoscopically structured CaCO3 with various morphologies which will form a basis for the production of mesoscopically structured ionic crystals via the reproduction of soft superstructures in complex fluids. Such materials could find numerous potential uses for example as high strength materials, mesoporous storage or delivery systems, new optical or magnetic devices and so forth.

• DFG Programme: Research Grants
• International Connection: France
• Participating Persons: Dr. Monique Dubois; Professor Dr. Thomas Zemb