An activatable nanoprobe based on nanocomposites of visible-light-excitable europium(III) complex-anchored MnO 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)(DPBT)]@MnO, for bimodal time-gated luminescence imaging (TGLI) and MRI has been constructed by anchoring visible-light-excitable Eu complexes on lamellar MnO nanosheets. Due to the luminescence quenching effect and non-magnetic resonance (MR) activity of MnO nanosheets, the developed nanoprobe presents quite weak TGL and MR signals. After exposure to HO or GSH, accompanied by the transformation from MnO to Mn, the nanoprobe exhibits rapid, sensitive, and selective "turn-on" responses towards GSH and HO 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 HO in cancer cells, the nanoprobe was used for the identification of cancer cells by TGLI of intracellular GSH and HO, as well as for the tracing of tumor cells in tumor-bearing mice by tumor-targeting MRI and TGLI of tumor tissues. The research outcomes proved the potential of [Eu(BTD)(DPBT)]@MnO as a useful nanoprobe for the tracing and accurate detection of cancer cells and bimodal TGLI and MRI.