chemistry

At Sakurai Laboratory, we design nanomedicines by organic synthesis and polymer synthesis. Specifically, we are designing molecules of micelles that self-assemble in water or organic solvents, designing next-generation nanoparticles using controlled polymerization methods, and designing complexes using nucleic acids and polysaccharides.

Platonic micelle

Our research group found that calixalene-based amphipathic compounds form spherical micelles in water, and as a result of structural precision analysis, the number of micelle associations was 6, and other associations. We found that numbers do not exist (monodispersity). Such micelles with no distribution in the number of meetings cannot be explained by the conventional concept of micelles. Similar monodispersity was also confirmed for other similar compounds and natural lipids, and if the number of associations is 30 or less, the number of associations is selected from 2, 4, 6, 8, 12, and 20. I found it to be one of the numbers. Most of the meetings found by this research group match the number of faces of Platonic's regular polyhedrons (tetrahedrons, hexahedrons, octahedrons, dodecahedrons, icosahedrons). For this reason, we named this mysterious micelle "Platonic micelle".

From the above, when amphipathic compounds such as soap molecules and lipids form spherical micelles in water and the number of associations is 30 or less, all the compounds have not been noticed by the researchers so far. I came to think that I am taking the number of meetings selected from any of the numbers selected from 2, 4, 6, 8, 12, and 20. That is, Platonicity: "discontinuous number of associations" & "matching the number of faces of Platonic's regular polyhedron" is a general rule applicable to micelles in general, and the fact that no one noticed it for 104 years after the discovery of spherical micelles. Is.

Reference: Discovered discontinuity in the number of micelle meetings – may the description in high school chemistry textbooks change? (Link)

SPG / nucleic acid complex

Β-1,3 glucan (SPG), which is a polysaccharide in which glucose is linked by β-1,3 type bonds, forms a triple helix structure in water, but under polar organic solvents such as DMSO and alkaline conditions. The spiral is unwound to form a single chain with a random coil shape. When returned to water from this state, the triple helix reshapes through hydrophobic interactions and hydrogen bonds. Sakurai discovered that when nucleic acid is mixed in this process, one nucleic acid and two SPGs form a triple helix structure. This SPG / nucleic acid complex enables selective drug delivery by recognition of glucan dectin-1. Utilizing this, we are conducting research on drug delivery targeting antigen-presenting cells and the like.