This doctoral thesis is an effort to understand how lipid phase-separation induced by diacylglycerol analogues in lipid-based nanoparticles affects their in vivo behavior, leading to specific... Show moreThis doctoral thesis is an effort to understand how lipid phase-separation induced by diacylglycerol analogues in lipid-based nanoparticles affects their in vivo behavior, leading to specific nanoparticle-protein communications and selective cell targeting. By studying how lipid composition affects morphology and this in turn affects the nano-bio interface, a comprehensive picture and prediction of nanoparticle behavior and cell selectivity is provided. More specifically, liposomes containing diacylglycerol analogues are found to phase separate and to be able to specifically target subsets of endothelial cells in zebrafish embryos. The mechanism behind this selective targeting is the result of a triglyceride lipase mediated mechanism due to phase separation and lipid composition, and is conserved in higher organisms (mice). Moreover, mRNA-based lipid nanoparticles that contain diacylglycerol analogues exhibit the same selectivity which leads to cell-specific mRNA delivery and transfection. Show less
The work described in this dissertation contributes to a better mechanistic understanding of nanoparticles in vivo. To achieve that goal, we used the zebrafish as a highly predictive pre-screening... Show moreThe work described in this dissertation contributes to a better mechanistic understanding of nanoparticles in vivo. To achieve that goal, we used the zebrafish as a highly predictive pre-screening model of nanoparticles. This approach enables the investigation of the fundamental behavior of nanoparticles, correlation of the physicochemical properties of the formulated nanoparticles with their biodistribution and identification of important nano-bio interactions. Zebrafish established transgenic lines were used to study specific interactions. In addition, genetically modified zebrafish applying CRISPR/Cas9 were generated. These strategies not only show key mechanistic features of nanoparticles in circulation, but also promote the rational design of more efficient nanoparticles systems.After understanding the fundamental behavior of nanoparticles, this thesis describes the identification of a key interaction between stabilins receptors (expressed in liver sinusoidal endothelial cells) and nanoparticles. Next, the scope is changed to design nano-systems that target specific cell types showing liposomes capable of switching the surface charge in situ and in vivo using light as an external trigger and a rationally designed lipid nanoparticle formulation containing mRNA able to preferentially target the hepatic reticuloendothelial system. In addition, a phase-separated liposomes hijacking a lipase mediated transport to selectively target endothelial lipase in vivo was studied. Show less
Nature__s own building block, peptide/protein derived materials have been of great interest for supramolecular chemists. The amino acids in peptides/proteins are linked via amide bonds, which makes... Show moreNature__s own building block, peptide/protein derived materials have been of great interest for supramolecular chemists. The amino acids in peptides/proteins are linked via amide bonds, which makes them more stable against degradation as compared to other natural materials such as oligonucleotides. Peptides adopt a secondary structure which is determined by their amino acid sequence resulting in a structure with a specific fold like a beta sheet, a helix or a random coil conformation.These secondary structures can govern the supra-molecular structure of the macromolecule to achieve specific function. Peptides can be short, such as dipeptides or as long as a small protein, which are able to selfassemble into a designed nanostructure and thus providing a wide choice of biomaterials for a chemical biologist. In last decade, peptides have been shown to have great versatility and inherent high affinity for their target to carry out various functions which is the scope of this thesis presented here. Show less
