Design of gel-to-sol UCST transition peptides by controlling polypeptide β-sheet nanostructures

Creating stimulus-responsive materials solely by controlling polypeptide secondary nanostructures is challenging. We synthesized a methyl poly(ethylene glycol)- b -poly(O-benzyl-L-threonine) (mPEG-PBnLT) diblock copolymer that exhibited gel-to-sol UCST (Upper Critical Solution Temperature) transition behavior in an aqueous solution. The transition temperature window was easily adjusted by changing the copolymer concentration or length of the PBnLT block. Disassembly of the initial β-sheet nanoassemblies caused nanofibril transformation to spherical aggregates with increasing temperature, resulting in a gel-to-sol UCST transition. This result inspires a brand-new strategy for the structural design and functional control of materials.