Biomimetic-compartmented nanoprobe for in-situ imaging of iron storage and release from ferritin in cells.

Ferritin plays an important role in regulating the homeostasis of iron in cells by storing/releasing iron. Current methods usually explored the determination of iron content, but in-situ imaging of the iron storage/release from ferritin in cells cannot be achieved. Hence, an engineered self-assembled biomimetic-compartmented nanoprobe (APO@CDs) has been constructed. The protein shell of APO (apoferritin) acted as ion channel module to control iron ions entering/exiting ferritin cavity; the inner core of CDs (carbon dots) acted as signal module for iron ions response. Compared with CDs, the response sensitivity and specificity to iron ions (Fe3+) have been improved by using APO@CDs, and the cytotoxicity was significantly reduced. Additionally, compared with cells containing APO@CDs alone, the normalized fluorescence gray value of Fe3+-treated cells was significantly decreased (0.275), indicating that Fe3+ has effectively entered the ferritin. Furtherly, that of Fe3+-treated cells incubated with deferoxamine (DFO) was significantly enhanced (0.712), showing that Fe3+ was released from ferritin under the mediation of DFO. The results demonstrate that APO@CDs can be successfully applied to in-situ imaging of iron storage/release from ferritin in cells, providing a potential platform for the in-situ dynamic study of the iron storage/release in biomedical field.