The role of chain rigidity in lipid self-association: Comparative study of dihexanoyl- and disorbyl-phosphatidylcholines

Elucidating Structural Configuration of Lipid Assemblies for mRNA Delivery Systems

The development of mRNA delivery systems utilizing lipid-based assemblies holds immense potential for precise control of gene expression and targeted therapeutic interventions. Despite advancements in lipid-based gene delivery systems, a critical knowledge gap remains in understanding how the biophysical characteristics of lipid assemblies and mRNA complexes influence these systems. Herein, we investigate the biophysical properties of cationic liposomes and their role in shaping mRNA lipoplexes by comparing various fabrication methods. Notably, an innovative fabrication technique called the liposome under cryo-assembly (LUCA) cycle, involving a precisely controlled freeze-thaw-vortex process, produces distinctive onion-like concentric multilamellar structures in cationic DOTAP/DOPE liposomes, in contrast to a conventional extrusion method that yields unilamellar liposomes. The inclusion of short-chain DHPC lipids further modulates the structure of cationic liposomes, transforming them from multilamellar to unilamellar structures during the LUCA cycle. Furthermore, the biophysical and biological evaluations of mRNA lipoplexes unveil that the optimal N/P charge ratio in the lipoplex can vary depending on the structure of initial cationic liposomes. Cryo-EM structural analysis demonstrates that multilamellar cationic liposomes induce two distinct interlamellar spacings in cationic lipoplexes, emphasizing the significant impact of the liposome structures on the final structure of mRNA lipoplexes. Taken together, our results provide an intriguing insight into the relationship between lipid assembly structures and the biophysical characteristics of the resulting lipoplexes. These relationships may open the door for advancing lipid-based mRNA delivery systems through more streamlined manufacturing processes.

Archaeal cyclopentane fragment in a surfactant's hydrophobic tail decreases the Krafft point

Archaea are prokaryotic microorganisms famous for their ability to adapt to extreme environments, including low and high temperatures. Archaeal lipids often are macrocycles with two polar heads and a hydrophobic core that contains methyl groups and in-line cycles. Here we present the design of novel general-purpose surfactants that have inherited features of archaeal lipids. These are C12 and C14 carboxylic acids containing in-line cyclopentanes. The cyclopentanes disturb the chain packing, which results in remarkable expansion of the operational range of the surfactant into the low-temperature region. We report synthesis and properties of these novel archaea-like surfactants and details of their chain packing derived from thermodynamics model predictions, molecular dynamics simulations, and experimental data on CMC and Krafft points.