Integration of Time-Gated Luminescence and 19F Magnetic Resonance in Lanthanide Complexes-Based Probes for Quantitative Imaging of Mitochondrial Superoxide Anions.

Time-gated luminescence (TGL) bioimaging offers high-sensitivity biosensing with background-free characteristics, yet its limited tissue penetration constrains broad in vivo applications. To address this issue, we developed unique lanthanide complexes to act as modular probes that integrate the high-sensitivity of TGL and deep-tissue imaging capability of 19F magnetic resonance (MR). The probes are constructed from a multifunctional ligand, Mito-BOTTA, comprising a mitochondria-targeting 1-(2-aminoethyl)-4-methylpyridinium group, a superoxide anion (O2 •-)-responsive 3,5-bis(trifluoromethyl)benzenesulfonyl (TFBS) moiety, and a terpyridine polyacid-derived scaffold for coordination to Eu3+, Tb3+, or Gd3+. The coordination with Eu3+/Tb3+-mixture produces a ratiometric TGL probe Mito-BOTTA-Eu3+/Tb3+ that, upon O2 •--triggered cleavage of the TFBS moiety, exhibits a pronounced increase in Tb3+ emission at 538 nm, accompanied by a decrease in Eu3+ emission at 608 nm. This reciprocal spectral response enables precise and autofluorescence-free ratiometric TGL imaging of mitochondrial O2 •- using the I538/I608 ratio as a quantitative readout. In parallel, the complexation with Gd3+ yields Mito-BOTTA-Gd3+, where the paramagnetic Gd3+ ion quenches the 19F MR signal. The cleavage of TFBS in the presence of O2 •- releases the fluorinated TFBS moiety, which restores the 19F MR signal, enabling a complementary "turn-on" MR detection for O2 •-. Both probes demonstrated excellent mitochondrial localization, low cytotoxicity, and robust responsiveness to O2 •- in HepG2 cells as well as in murine models of alcohol- and CCl4-induced acute liver injuries, which suggested the potential of the probes for dual-mode TGL and 19F MR bioimaging of O2 •-, offering a promising approach for the diagnostics of oxidative stress-related diseases.