Nanolab in a Cell: Crystallization-Induced <i>In Situ</i> Self-Assembly for Cancer Theranostic Amplification

Conducting crystallization-assisted self-assembly in living biosystems to obtain large-size nanoparticles and achieve a specific physiological purpose remains an appealing yet significantly challenging task. In this study, we designed Au(I)-disulfide nanosheets containing an aggregation-induced emission photosensitizer, namely, NSs@TTVP, which exhibited pH-responsive crystallization-driven self-assembly capability in lysosomes of cancer cells and tumor tissues of mice. The crystallization process endowed NSs@TTVP with a microscale morphology, stronger fluorescence output, and highly enhanced reactive oxygen species production efficiency. The <i>in vivo</i> results demonstrated that NSs@TTVP shows both long-term retention in tumors and extensive destruction to cancer cells, making it supremely powerful for fluorescence imaging-guided tumor tracking and inhibition.