Spherical lanthanide nanoclusters toward white-light emission and cell membrane imaging

Lanthanide doping is an effective strategy for modulating the emission of emitters. Herein, by changing the cluster composition to control the energy transfer pathway, the application potential of high-nuclearity lanthanide cluster (HLC) as white-light emitter has been confirmed for the first time. Specifically, by precisely controlling the proportion of Gd^III, Tb^III, and Eu^III ions in reactants, we obtained a spherical heterotrimetallic nanocluster Gd₁₀Tb₁₂Eu₁₀, a white-light emitter with quantum yield (QY) of 12.58% and lifetime of 327.14 μs. High-resolution electrospray ionization mass spectrometry (HRESI-MS) demonstrates that homometallic nanoclusters Ln₃₂ (Ln = Gd, Tb, and Eu) are tetracationic clusters and are highly stable in solution. The peripheral dense organic ligands provide a protective layer for the cluster core, which improves the stability of Ln₃₂ in aqueous solution, avoids the contact between metal centers and bioactive molecules, and greatly reduces the biological toxicity. In cell imaging experiments, cationic clusters Ln₃₂ are mainly localized on the cell membrane with negative charge distribution. As far as we know, this is the first time that spherical lanthanide nanoclusters have been used for membrane imaging of living cell, opening the door for the application of HLCs in biological imaging.