An activatable nanoprobe based on nanocomposites of visible-light-excitable europium(III) complex-anchored MnO 2 nanosheets for bimodal time-gated luminescence and magnetic resonance imaging of tumor cells.

Bimodal imaging probes that combine magnetic resonance imaging (MRI) and photoluminescence imaging are quite appealing since they can supply both anatomical and molecular information to effectively ameliorate the accuracy of detection. In this study, an activatable nanoprobe, [Eu(BTD) ₃ (DPBT)]@MnO ₂ , for bimodal time-gated luminescence imaging (TGLI) and MRI has been constructed by anchoring visible-light-excitable Eu ³⁺ complexes on lamellar MnO ₂ nanosheets. Due to the luminescence quenching effect and non-magnetic resonance (MR) activity of MnO ₂ nanosheets, the developed nanoprobe presents quite weak TGL and MR signals. After exposure to H ₂ O ₂ or GSH, accompanied by the transformation from MnO ₂ to Mn ²⁺ , the nanoprobe exhibits rapid, sensitive, and selective "turn-on" responses towards GSH and H ₂ O ₂ in TGL and MR detection modes. Furthermore, the nanoprobe displays high stability, low cytotoxicity, good biocompatibility and water dispersion. Given the high contents of GSH and H ₂ O ₂ in cancer cells, the nanoprobe was used for the identification of cancer cells by TGLI of intracellular GSH and H ₂ O ₂ , as well as for the tracing of tumor cells in tumor-bearing mice by tumor-targeting in vivo MRI and TGLI of tumor tissues. The research outcomes proved the potential of [Eu(BTD) ₃ (DPBT)]@MnO ₂ as a useful nanoprobe for the tracing and accurate detection of cancer cells in vitro and in vivo via bimodal TGLI and MRI.