Fluorescent azobenzene-confined coiled-coil mesofibers

• Published in: Soft matter 2023-01, Vol.19 (3), p.497-51
• Main Authors: Punia, Kamia, Britton, Dustin, Hüll, Katharina, Yin, Liming, Wang, Yifei, Renfrew, P. Douglas, Gilchrist, M. Lane, Bonneau, Richard, Trauner, Dirk, Montclare, Jin K
• Format: Article
• Language: English
• Subjects: Azo compounds; Azo Compounds - chemistry; Biomaterials; Biomedical materials; Encapsulation; Fibrils; Fluorescence; Hybrid systems; Hydrophobicity; Medical imaging; Nanofibers; Protein Conformation; Protein structure; Proteins; Self-assembly; Thickening
• ISSN: 1744-683X; 1744-6848
• DOI: 10.1039/d2sm01578a

Fluorescent protein biomaterials have important applications such as bioimaging in pharmacological studies. Self-assembly of proteins, especially into fibrils, is known to produce fluorescence in the blue band. Capable of self-assembly into nanofibers, we have shown we can modulate its aggregation into mesofibers by encapsulation of a small hydrophobic molecule. Conversely, azobenzenes are hydrophobic small molecules that are virtually non-fluorescent in solution due to their highly efficient photoisomerization. However, they demonstrate fluorogenic properties upon confinement in nanoscale assemblies by reducing the non-radiative photoisomerization. Here, we report the fluorescence of a hybrid protein-small molecule system in which azobenzene is confined in our protein assembly leading to fiber thickening and increased fluorescence. We show our engineered protein Q encapsulates AzoCholine, bearing a photoswitchable azobenzene moiety, in the hydrophobic pore to produce fluorescent mesofibers. This study further investigates the photocontrol of protein conformation as well as fluorescence of an azobenze-containing biomaterial. Upon addition of the hydrophobic small molecule, Azocholine, Q is capable of transforming into a fluorescent mesofiber due to fluorogenic encapsulation and fiber thickening.