Azobenzene-Modified Temperature-Responsive Short Elastin-like Peptides for Photo-Controlled Phase Transition

Elastin-like peptides (ELPs) have attracted attention as temperature-responsive biomaterials that can be used as drug carriers. In this study, temperature- and photoresponsive self-assembling peptide analogues were developed by conjugating short ELPs (total 20 amino acid residues) and azobenzene derivatives. The synthesized ELP-azobenzene conjugates exhibited reversible spectral changes upon UV or visible-light irradiation and temperature-responsive phase separation in aqueous solutions. The aggregation ability of the <i>trans</i>-isomers of the ELP-azobenzene conjugates was stronger than that of the <i>cis</i>-isomers. This phenomenon was attributed to the change in the hydrophilicity of the azobenzene moiety associated with photoisomerization from the <i>trans</i>- to the <i>cis</i>-isomer. In addition, aggregates of the ELP-azobenzene conjugate could be controlled by light irradiation. Therefore, this study provides a methodology for photo- and temperature-responsive ELP analogues with low molecular weights that can be easily synthesized by simple chemical reactions and are potential candidates for drug carriers that enable precise control of drug release.