Surface engineering of algae and synthesis of pyrrolizidines for carbon dioxide capture applications

The three research projects presented in this thesis apply organic synthesis as the main tool to answer interdisciplinary scientific questions. In the first project, organic synthesis is the key to tailor molecules for direct interaction with living organisms. The second project comprises a new method for the preparation of biologically relevant lead structures. The last project examines the synthesis of bifunctional pyrrolizidine diamines and their application in the capture of carbon dioxide.
Chapter 1 starts with a general introduction to the field of chemical surface engineering on living cells. The different functionalization approaches are briefly introduced and selected illus-trative examples are presented.
Chapter 2 describes the surface functionalization of the green alga Chlamydomonas reinhard-tii with the antibiotic vancomycin. We used a peptide-anchor adhering to the surface glycopep-tides of the algae. By synthetic means, we linked this anchor to vancomycin to give a conjugate with good antimicrobial activity. The conjugate adhered to the cell wall of C. reinhardtii, as veri-fied by confocal fluorescent microscopy. Bacterial assays showed that the modified algae inhib-ited the growth of bacteria and led to complete inhibition of bacterial growth, after optimization. Delivery of the vancomycin-conjugate from the surface of the algae to the cell wall of the bacte-ria was mainly driven by diffusion.
In Chapter 3 we report on a method for the preparation of 7a-substituted pyrrolizidine car-boxamides. These compounds can be prepared by reaction of isonitriles with pyrrolines. Using a variety of isonitriles with different electronic and steric properties, we gained access to a diverse range of pyrrolizidine derivatives. An extension of this method by further functionalization of the pyrrolizidines as well as mechanistic studies are presented.
In Chapter 4 our investigations of pyrrolizidines as scavengers for CO2 are described. We quantified the efficiency of CO2 uptake and elucidated the nature of the CO2 adducts as well as the reversibility of the overall process.