Photo‐Responsive Phase‐Separating Fluorescent Molecules for Intracellular Protein Delivery

Abstract

Cellular membranes, including the plasma and endosome membranes, are barriers to outside proteins. Various vehicles have been devised to deliver proteins across the plasma membrane, but in many cases, the payload gets trapped in the endosome. Here we designed a photo‐responsive phase‐separating fluorescent molecule (PPFM) with a molecular weight of 666.8 daltons. The PPFM compound condensates as fluorescent droplets in the aqueous solution by liquid‐liquid phase separation (LLPS), which disintegrate upon photoirradiation with a 405 nm LED lamp within 20 min or a 405 nm laser within 3 min. The PPFM coacervates recruit a wide range of peptides and proteins and deliver them into mammalian cells. Photolysis disperses the payload from condensates into the cytosolic space. Altogether, a type of small molecules that are photo‐responsive and phase separating are discovered; their coacervates can serve as transmembrane vehicles for intracellular delivery of proteins, whereas photo illumination triggers the cytosolic distribution of the payload.

Self-assembly of stabilized droplets from liquid–liquid phase separation for higher-order structures and functions

“…Similarly, biomolecule-based coacervates are relatively safe and easy to manage, allowing them to be manufactured commercially and steadily in the biomedical area. In addition, the responsiveness of the droplets enables targeted release of the drug, thus improving drug utilization 124 , 125 . Yue et al created micrometer-sized peptide coacervates as delivery vesicles that can pass the cell membrane without being endocytosed 126 (Fig.…”

Hydrogen Bonding-Driven Self-Coacervation of Nonionic Homopolymers for Stimuli-Triggered Therapeutic Release

“…26 Recently, coacervate droplets generated from small fluorescent molecules have been used to introduce proteins into mammalian cells upon photoillumination. 27 Thermoresponsive coacervate droplets have also been employed in various biomedical applications, with a well-known example of such a system being an elastinlike polypeptide (ELP), which exhibits lower critical solution temperature (LCST)-type self-coacervation ability. 28 Pathological cells or tissues possess temperatures several degrees higher than the normal body temperature due to an increased metabolic rate.…”

“…Miserez et al constructed histidine-rich squid beak-derived peptide-based coacervate microdroplets that were pH- and redox-responsive and could recruit and release macromolecular therapeutics directly in the cytosol in response to redox triggers . Recently, coacervate droplets generated from small fluorescent molecules have been used to introduce proteins into mammalian cells upon photoillumination . Thermoresponsive coacervate droplets have also been employed in various biomedical applications, with a well-known example of such a system being an elastin-like polypeptide (ELP), which exhibits lower critical solution temperature (LCST)-type self-coacervation ability .…”