Visualizing Senescent-Normal Cell Boundaries Through Environment-Dependent Bidirectional Luminescent Contrast

Unlike tumors, senescent tissues lack well-defined boundaries at the cellular level because senescence develops gradually, leading to spatial intermixing of the senescent and normal cells. This ambiguity poses a major conceptual challenge for surgical decision-making, where insufficient resection risks recurrence while excessive removal compromises tissue integrity. Existing probes fail to resolve this ambiguity because signal-silent regions may represent either normal cells or unlabeled senescent populations. Therefore, designing new signal logic for luminescent probes (e.g., environment-dependent bidirectional signal modulation, depending on the cellular environment of the normal and senescent cells, respectively), is crucial for precise delineation of senescent-normal cell boundaries. In this work, luminescent probes enabling bidirectional photomodulation were constructed by modifying hydrophilic β-galactose groups onto hydrophobic hydroxyl-hexathiobenzene, which can exhibit the following performance: (1) Direction 1: In normal cells, the probes remain non-emissive, but become emissive upon photoexcitation-induced aggregation (signal up-regulated); (2) Direction 2: In senescent cells, β-galactosidase (β-Gal)-triggered deglycosylation immediately generates hydrophobic products with an aggregation-induced emission characteristic, whose strong emission can be down-regulated upon a following photoexcitation-induced molecular reorganization. This environment-dependent bidirectional photomodulation using the same probe enables dynamic contrast between senescent and normal cells, thereby providing a new paradigm of resolving biological ambiguity at the cellular scale.