Endogenous H 2 S-activated Ag nanoparticles embedded in programmed DNA-cubes for specific visualization of colorectal cancer cells.

To avoid the unexpected aggregation and reduce the cytotoxicity of nanomaterials as optical probes in cell imaging applications, we propose a programmed DNA-cube as a carrier for silver nanoparticles (Ag NPs) to construct a specific hydrogen sulfide (H 2 S) responsive platform (Ag NP@DNA-cube) for diagnosing colorectal cancer (CRC) in this study. The DNA-cube maintains good dispersion of Ag NPs while providing excellent biocompatibility. Based on the characteristic overexpression of endogenous H 2 S in CRC cells, the Ag NPs are etched by H 2 S within target cells into silver sulfide quantum dots, thereby selectively illuminating the target cells. The Ag NP@DNA-cube exhibits a specific fluorescence response to CRC cells and achieves satisfactory imaging.