Understanding Biocrystallization in Dinoflagellates: From Biological Pathways to Functionalized Hybrid Materials

• Applicant: Professorin Dr. Anne Jantschke
• Subject Area: Biological and Biomimetic Chemistry ; Analytical Chemistry ; Biomaterials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 438884112

For 500 million years algae have shaped our environment by fixing CO2 through the precipitation of minerals. This biomineralization gives rise to a variety of complex architectures with spectacular morphologies. A paradigm example of regularity in biological systems are the highly ordered, porous shells of unicellular dinoflagellates made of calcium carbonate. Their long-range morphological regularity is beyond the reach of current technology. During the last decades, significant progress has been made in understanding the key biochemical mechanisms responsible for biomineral formation in model organisms like diatoms or coccolithophores. In contrast, the mechanisms that control the intricate mineral construction in dinoflagellates are practically unknown. This is very surprising, because structure formation does not take place in an intracellular, deposition vesicle, but instead in a less controlled, extracellular space, the so-called outer matrix. This makes dinoflagellates a well-suited model system especially in view of biomimetic materials synthesis.During my PostDoc in the group Lia Addadi and Steve Weiner (Weizmann-Institute of Science), we developed a new dinoflagellate biomineralization model. It includes the active uptake of Ca2+, a temporary deposition in MgCaP-precursor bodies, extrusion into the outer matrix and transformation into low Mg-calcite. However, many details of structure morphogenesis are still not understood. Therefore, the project focusses on the following questions:(A) What can we deduce from the biomineral composition about structure morphogenesis?(B) Which organic constituents are forming the outer matrix and how do they influence crystal nucleation and growth?(C) What is the relevance of magnesium and phosphorus for Ca-accumulation, storage and transport? (D) What is the exact chemical composition of the precursor phase – is an amorphous precursor involved?We propose a unique combination of spectroscopic techniques (ICP-OES, vibrational spectroscopy, NMR, mass spectrometry incl. nano-SIMS) with advanced bioimaging (in vivo-fluorescence, cryo electron microscopy, FIB-SEM-EBSD) as a most promising approach. A combined selective isotope-pulse labeling NMR/Raman imaging-approach will allow to observe intracellular changes during calcification in vivo. In addition, we want to explore dinoflagellate-based biomaterials, asking the following questions: (E) Can we preserve the structural integrity of dinoflagellate-derived materials for applications? (F) How can we functionalize or converted the porous structures for different applications? Mesoporous structures are an increasingly important class of materials with high significance in many technological domains. Bio-derived mesoporous systems are even more compelling because of their biocompatibility. For this reason, the project aims to combine the biological fundamentals of structure formation with materials applications.

• DFG Programme: Research Grants