Living organisms are able to control the formation of inorganic compoundslike calcium phosphate, calcium oxalate, iron oxide, or iron sulfide.Furthermore, they are able to generate highly structured, hierarchicallyordered composites with attractive properties like high mechanicalstrength or impact toughness. This ability to control the formation of agiven inorganic, e.g. to stabilize a given crystal phase, size, and shapeis a fascinating and highly complex scientific problem that we are onlybeginning to understand. While we know now that proteins and sugars areresponsible for the observed highly ordered organic-inorganic hybridstructures, little is known as to how these organic matrix moleculescontrol nucleation and crystal growth of individual mineral particles– let alone the complex organization of matter on larger lengthscales – on a molecular level. Even less is known about specificinteractions of peptide fragments with the metal ions and the growingcrystal and how they influence crystal nucleation and growth.
The goal of the proposed research is to deepen our understanding ofbiomineralization and in particular to improve our understanding ofnucleation, crystal growth, and crystal-peptide interactions. We will usea synthetically simple system to investigate those processes: (1) we willsynthesize “solid” lipid/peptide amphiphile (PA) hybridtemplates via the Langmuir-Blodgett or Langmuir-Schäfer technique andinvestigate their structure in situ in dependence of the ions present. Wewill also investigate the structure of the peptide amphiphiles and thelipid/PA hybrids in solution both with and without metal cations present.(2) We will investigate the precipitation of calcium phosphates andoxalates and iron oxides and sulfides on these templates and in solutionwith the PAs and the lipid/PA hybrid templates present. Experimentally, wewill use light scattering for solution studies, in situ Raman microscopyfor high time resolution chemical information, in situ and ex situ AFM forcrystal size, shape, and number density determination, and variouselectron microscopic techniques for chemical and structuralinvestigations.
On a scientific level, this study will provide insight in twobiomineralization key questions: (1) we will measure how the structure ofshort peptide with 3 to about 20 amino acids and their supramolecularassemblies change in the presence of a ions and (2) we will quantify howdifferent peptide segments affect crystal nucleation, growth, growthkinetics, morphogenesis, crystal phase formation, and – ultimately– the formation of a higher order structure. In short, ourexperiments will provide the highest chemical and temporal resolutionrealized in biomineralization studies so far. The system is syntheticallyversatile so that it will be possible to develop a combinatorial-likeapproach to biomineralization.