Spatiotemporally Controllable Peptide-Based Nanoassembly in Single Living Cells for a Biological Self-Portrait

Simultaneous precise localization and activity evaluation of a biomolecule in a single living cell is through an enzyme-specific signal-amplification process, which involves the localized, site-specific self-assembly, and activation of a presignaling molecule. The inactive presignaling tetraphenylethylene (TPE)-peptide derivative, TPE-YpYY, is nondetectable and highly biocompatible and these small molecules rapidly diffuse into living cells. Upon safely arriving at an active site, and accessing the catalytic pocket of an enzyme, TPE-YpYY immediately and quantitatively accumulates in situ in response to enzymatic activity, forms an enzyme anchor TPE-YYY nanoassembly, displays aggregation-induced emission behavior, and finally lights up the active enzyme, indicating its activity, and allowing its status in living cells to be tracked. This simple and direct self-portrait method can be used to monitor dynamic self-assembly processes in individual living cells and may provide new insights that reveal undiscovered biological processes and that aid in developing biomedical hybrid devices. In the future, this strategy of molecular design can be further expanded to the noninvasive investigation of other bioactive molecules, thus facilitating quantitative imaging.

When activated by an enzyme, a synthesized cell-permeable probe forms biomolecule-anchored complexes and thus simultaneously evaluates the real-time location and bioactivity of the enzyme in single live cells. This simple and direct method can be used to monitor single-cell dynamic self-assembly processes in vitro and in vivo, which may provide new insights into previously undiscovered biological processes.

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