Thermosensitive Hybrid Elastin-like Polypeptide-Based ABC Triblock Hydrogel

We report the synthesis of a well-defined hybrid ABC triblock terpolymer containing a synthetic poly(trimethylene carbonate) (PTMC) block A and a thermosensitive BC diblock of recombinant elastin-like polypeptides (ELPs). The triblock in diluted solution (0.1–0.3% w/v), at low temperatures in ultrapure water, forms micellar structures of 10–60 nm sizes in diameter as characterized by dynamic light scattering (DLS) and liquid atomic force microscopy (AFM). While heated above its transition temperature (Tt), larger particles of 200–300 nm sizes are obtained, consistent with the formation of coacervates. When concentrated, the viscosity of the triblock copolymer solution progressively increases, giving a free-standing gel at 4% w/v formed by a network of micron-sized particles. The formed hydrogels are thermally reversible, and their sol–gel transitions are fast and sharp. The gel formation mechanism appears to interestingly biomimic tropoelastin, the native monomeric form of natural elastin, as demonstrated by optical and cryogenic-scanning electron microscopy (cryo-SEM) imaging.