Long-Term Lysosomes Tracking with a Water-Soluble Two-Photon Phosphorescent Iridium(III) Complex

Lysosomes
are the stomachs of the cells that degrade endocytosis and intracellular
biomacromolecules and participate in various other cellular processes,
such as apoptosis and cell migration. The ability of long-term tracking
of lysosomes is very important to understand the details of lysosomal
functions and to evaluate drug and gene delivery systems. For studying
lysosomes, we designed and synthesized a water-soluble triscyclometalated
iridium­(III) complex (Ir-lyso) attaching morpholine moieties.
The phosphorescent intensity of Ir-lyso is responsive
to pH and decreases with an increase in the pH but not quenching in
high pH. With excellent two-photon properties, Ir-lyso was used to light up the lysosomes in living cells and 3D tumor
spheroids. Moreover, Ir-lyso could label lysosomes more
than 4 days, so we developed this complex to act as a long-term probe
for tracking lysosomes during cell migration and apoptosis. To the
best of our knowledge, this is the first paradigm of metal complexes
as the two-photon phosphorescent probe for long-term lysosomes tracking.