Figure 2.

pH-activatable multimodal imaging by nanomaterial degradation. a) Calcium carbonate (CaCO₃) NPs were synthesized with a polydopamine coating that degraded under slightly acidic conditions (upper). TEM images confirmed this under different pH conditions (lower). b) CaCO₃ NPs absorbed NIR light for PA imaging (upper) and chelated metal ions for MR imaging (lower). c) Degradation of the CaCO₃ backbone reduced polydopamine FL quenching of Ce6 for activated FL imaging. Reproduced with permission.^[25] Copyright 2018, American Chemical Society.