Specific Cell Surface Protein Imaging by Extended Self-Assembling Fluorescent Turn-on Nanoprobes

Abstract

Visualization of tumor-specific protein biomarkers on cell membranes has the potential to contribute greatly to basic biological research and therapeutic applications. We recently reported a unique supramolecular strategy for specific protein detection using self-assembling fluorescent nanoprobes consisting of a hydrophilic protein ligand and a hydrophobic BODIPY fluorophore in test tube settings. This method is based on recognition-driven disassembly of the nanoprobes, which induces a clear turn-on fluorescent signal. In the present study, we have successfully extended the range of applicable fluorophores to the more hydrophilic ones such as fluorescein or rhodamine by introducing a hydrophobic module near the fluorophore. Increasing the range of available fluorophores allowed selective imaging of membrane-bound proteins under live cell conditions. That is, overexpressed folate receptor (FR) or hypoxia-inducible membrane-bound carbonic anhydrases (CA) on live cell surfaces as cancer-specific biomarkers were fluorescently visualized using the designed supramolecular nanoprobes in the turn-on manner. Moreover, a cell-based inhibitor-assay platform for CA on a live cell surface was constructed, highlighting the potential applicability of the self-assembling turn-on probes.

Make Caffeine Visible: a Fluorescent Caffeine “Traffic Light” Detector

“…BODIPY dyes are known to self-assemble and self-quench in aqueous solutions3637. To understand how CO fluoresces upon addition of caffeine, we first conducted dynamic light scattering (DLS) analysis.…”

Self-Assembly of Bodipy-Derived Extended π-Systems

“…86 A Bodipy probe with a folate receptor 39 (Figure 16b) exhibited extremely weak emission in aqueous solution due to aggregation induced quenching. 87 The emission was found to increase gradually upon addition of dihydrofolate reductase indicating the disassembly of nanoparticles (Figure 16c). Thus, the self-assembled nanoparticles of 39 were used as a turn on probe for live cell imaging of cancer cells, which over express foliate receptor.…”

Protein recognition using synthetic small-molecular binders toward optical protein sensing in vitro and in live cells

“…Very recently, it has been demonstrated that such a supramolecular protein imaging method can be applied to intracellular proteins, as well as cell-surface proteins under live cell conditions. 187,188 Fig. 12 Two key strategies to sense proteins of interest using protein-ligand interaction (a) with a ligand tethering an environmental-sensitive probe and (c) with an amphiphilic ligand derivative tethering a hydrophobic probe.…”