Monodisperse Micelles with Aggregation Numbers Related to Platonic Solids

Photodynamic therapy using self-assembled nanogels comprising chlorin e6-bearing pullulan

With minimal invasiveness and spatiotemporal therapeutic effects, photodynamic therapy is one of the most promising candidates for cancer treatment. Here, we developed a facile self-assembled nanogel using photosensitizer-grafted polysaccharides called chlorin e6-bearing pullulan. Chlorin e6 is used as a photosensitizer in cancer therapy. The anti-cancer effect of photodynamic therapy with our nanogel system was 780 times higher than that of the commercially available photosensitizer Photofrin. Finally, we demonstrated that actively growing cancer cell spheroids can be completely suppressed after treatment. Our system could efficiently induce tumor regression in tumor xenograft mice.

Polymer Micelles Composed of Molecular-Bottlebrush-Based Surfactants: Precisely Controlling Aggregation Number Corresponding to Polyhedral Structures

Over the past few decades, there has been remarkable progress in the construction of self-assemblies in the field of supramolecular chemistry, such as micelles with precisely controlled and refined structures. One promising approach represents the previously proposed concept of Platonic micelles, in which the aggregation number (N_agg ) is discretized in accordance with vertexes of regular polyhedra (i.e., Platonic solids), i.e., 4, 6, 8, 12, and 20 units. Herein, attempt is made to construct Platonic polymer micelles using rigid and persistent architecture of molecular-bottlebrush-based surfactant (MBS). The structure of MBS micelles is carefully elucidated using small-angle X-ray and light scattering and analytical centrifugation measurements. This study shows that the N_agg of MBS micelles is consistent with one of the Platonic numbers when N_agg is intentionally set in the range of 4-20. In addition, some of the MBS micelles demonstrate a discontinuous change in N_agg , when the salt concentration is changed, which is an important factor in controlling micellar N_agg . This is one of the characteristic aggregation behaviors of Platonic micelles in surfactant systems, which strongly indicates the formation of Platonic micelles from macromolecular surfactants.

Characterizing block-copolymer micelles used in nanomedicines via solution static scattering techniques

Block copolymers are well recognized as excellent nanotools for delivering hydrophobic drugs. The formulation of such delivery nanoparticles requires robust characterization and clarification of the critical quality attributes correlating with the safety and efficacy of the drug before applying to regulatory authorities for approval. Static solution scattering from block copolymers is one such technique. This paper first outlines the theoretical background and current models for analyzing this scattering and then presents an overview of our recent studies on block copolymers.