Intracellular Protein-Responsive Supramolecules: Protein Sensing and In-Cell Construction of Inhibitor Assay System

Abstract

Supramolecular nanomaterials responsive to specific intracellular proteins should be greatly promising for protein sensing and imaging, controlled drug release or dynamic regulation of cellular processes. However, valid design strategies to create useful probes are poorly developed, particularly for proteins inside living cells as targets. We recently reported a unique supramolecular strategy for specific protein detection using self-assembling fluorescent probes consisting of a protein ligand and a fluorophore on the live cell surface, as well as in test tube settings. Herein, we discovered that our self-assembled supramolecular probes having a rhodamine derivative (tetramethylrhodamine or rhodamine-green) can incorporate and stay as less-fluorescent aggregates inside the living cells, so as to sense the protein activity in a reversible manner. Using the overexpressed model protein (dihydrofolate reductase), we demonstrated that this turn-on/off mode is controlled by selective ligand-protein recognition inside the live cells. Not only such a model protein, but also endogenous human carbonic anhydrase and heat shock protein 90 were specifically visualized in living mammalian cells, by use of the similar ligand-tethered supramolecular probes. Furthermore, such reversibility allowed us to intracellularly construct a unique system to evaluate the inhibitors affinity toward specific endogenous proteins in live cells, highlighting the potential of dynamic supramolecules as novel intelligent biomaterials.

Supramolecular catalysis and dynamic assemblies for medicine

“…36 As shown in Fig. 9C, probe 19 consists of a ligand (i.e., methotrexate) for targeting dihydrofolate reductase (eDHFR), a fluorophore (i.e., tetramethylrhodamine) for imaging, a hydrophobic module (i.e., phenylalanine) for tuning self-assembling ability, and a linker.…”

Negatively Charged Lipid Membranes Catalyze Supramolecular Hydrogel Formation

“…[1][2][3][4] Furthermore, the groups of Rao, Xu and others have recently shown that enzymatic activation of synthetic self-assembling molecules in a cellular environments find promising applications as imaging and therapeutic agents. [5][6][7][8][9][10][11][12][13] A key challenge in this field is the spatial control over self-assembly. To achieve this, the self-assembling species needs to be formed in the vicinity of the region of interest, after which self-assembly into aggregates effectively immobilizes the formed material.…”

Protein sensing in living cells by molecular rotor-based fluorescence-switchable chemical probes

“…To date, the development of this type of fluorescent probe remains a challenging task and only a limited number of fluorescence-switching strategies have been reported. In most of the designs, fluorescence-switchable probes were constructed by conjugating a protein binding ligand with various fluorescence-switchable fluorophores, such as solvatochromic fluorophores, 10–12 disassembly-induced emission 13–15 and aggregation-induced emission dyes. 16–18 However, due to low to moderate fluorescence enhancement ratios and potential unspecific binding of the fluorescent probes to other intracellular proteins, only a few of them have been demonstrated in sensing intracellular proteins.…”