Activatable phototheranostics is highly appealing to meet the demand of
precision medicine. However, although it displays efficacy in the construction of activatable
photosensitizers (PSs), direct covalent decoration still shows some inevitable issues, such as complex molecular design, tedious synthesis, possible photoactivity changes, and potential toxicity. Herein, we propose a novel concept of
biomarker displacement activation (BDA) using host-guest strategy. To exemplify BDA, we engineered a PS-loaded nanocarrier by utilizing a macrocyclic amphiphile, where the fluorescence and photoactivity of PS were completely annihilated by the complexation of macrocyclic receptor (OFF state). When nanocarriers were accumulated into
tumor tissues via the enhanced permeability and retention effect, the overexpressed
biomarker adenosine triphosphates displaced PSs, accompanied by their fluorescence and photoactivity recovered (ON state). These reinstallations are unattainable in normal tissues, allowing us to concurrently achieve selective
tumor imaging and targeted
therapy in vivo. Compared with widely used covalent approach, the present BDA strategy provides the following advantages: (1) employment of approved PSs without custom covalent decoration; (2) traceless release of PSs with high fidelity by
biomarker displacement; (3) adaptability to different PSs for establishing a universal platform and promised facile combination of diverse PSs to enhance photon utility in light window. Such a host-guest BDA strategy is easily amenable to other ensembles and targets, so that versatile biomedical applications can be envisaged.