Exploring LCST-\nand UCST-like Behavior of Branched\nMolecules Bearing Repeat Units of Elastin-like Peptides as Side Components

Elastin-like peptides\n(ELPs) exhibit lower critical solution\ntemperature\n(LCST)-type behavior, being soluble at low temperatures and insoluble\nat high temperatures. While the properties of linear, long-chain ELPs\nare well-studied, short-chain ELPs, especially those with branched\narchitectures, have been less explored. Herein, to obtain further\ninsights into multimeric short ELPs, we investigated the temperature-responsive\nproperties of branched molecules composed of a repeating pentapeptide\nunit of short ELPs, Phe-Pro-Gly-Val-Gly, as side components and oligo(Glu)\nas a backbone structure. In turbidimetry experiments, the branched\nELPs showed LCST-like behavior similar to conventional ELPs and upper\ncritical solution temperature (UCST)-like behavior, which are rarely\nobserved in ELPs. In addition, the morphological aspects and mechanisms\nunderlying the temperature-responsiveness were investigated. We observed\nthat spherical aggregates formed, and the branched ELPs underwent\nstructural changes through the self-assembly process. This study demonstrates\nthe unique temperature-responsiveness of branched short ELPs, providing\nnew insights into the future development and use of ELPs with tailored\nproperties.