A bimodal time-gated luminescence-magnetic resonance imaging nanoprobe based on a europium(III) complex anchored on BSA-coated MnO 2 nanosheets for highly selective detection of H 2 O 2 .

A novel nanocomposite, [Eu(BTD) 3 (DPBT)]-BSA@MnO 2 , is reported to serve as an effective nanoprobe for bimodal time-gated luminescence (TGL) and magnetic resonance (MR) imaging of H 2 O 2 in vitro and in vivo . The nanoprobe was fabricated by immobilizing visible-light-excitable Eu 3+ complexes in bovine serum albumin (BSA)-coated lamellar MnO 2 nanosheets. The TGL of the Eu 3+ complex was effectively quenched by the MnO 2 nanosheets. Upon exposure to H 2 O 2 , the MnO 2 nanosheets underwent reduction to Mn 2+ , which simultaneously triggered rapid, selective and sensitive "turn-on" responses toward H 2 O 2 in both TGL and MR detection modes. The presence of a protective "corona" formed by BSA enables the nanoprobe to withstand high concentrations of glutathione (GSH), a strong reducing agent of MnO 2 nanosheets. This capability allows the nanoprobe to be utilized for detecting H 2 O 2 in living biosamples. The combined utilization of TGL and MR detection modes enables the nanoprobe to image H 2 O 2 across a wide range of resolutions, from the subcellular level to the whole body, without any depth limitations. The results obtained from these modes can be cross-validated, enhancing the accuracy of the detection. The capability of the nanoprobe was validated by TGL imaging of endogenous and exogenous H 2 O 2 in live HeLa cells, as well as bimodal TGL-MR imaging of H 2 O 2 in tumor-bearing mice. The research achievements suggest that the integration of luminescent lanthanide complexes with protein-coated MnO 2 nanosheets offers a promising bimodal TGL-MR sensing platform for H 2 O 2 in vitro and in vivo .