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

Area of Science:

• Cell Biology
• Biochemistry
• Materials Science

Background:

• Lysosomes are vital cellular organelles involved in degradation and various cellular processes.
• Long-term tracking of lysosomes is crucial for understanding their functions and evaluating drug delivery systems.
• Existing methods for lysosome tracking have limitations in duration and imaging capabilities.

Purpose of the Study:

• To design and synthesize a novel water-soluble iridium(III) complex for long-term lysosome imaging.
• To investigate the photophysical properties and pH responsiveness of the synthesized complex.
• To evaluate the complex as a two-photon phosphorescent probe for tracking lysosomes in living cells and 3D tumor spheroids.

Main Methods:

• Synthesis of a water-soluble triscyclometalated iridium(III) complex (Ir-lyso) with morpholine moieties.
• Characterization of the complex's photophysical properties, including pH responsiveness and two-photon absorption.
• Live-cell imaging experiments using the Ir-lyso complex to track lysosomes in cells and 3D tumor spheroids over extended periods.

Main Results:

• The synthesized Ir-lyso complex exhibits pH-responsive phosphorescence, decreasing with increasing pH without quenching.
• Ir-lyso demonstrates excellent two-photon properties, enabling effective lysosome visualization in living cells and 3D tumor spheroids.
• The complex successfully labeled lysosomes for over 4 days, facilitating long-term tracking during cell migration and apoptosis.

Conclusions:

• The developed iridium(III) complex serves as a novel and effective two-photon phosphorescent probe for long-term lysosome tracking.
• This represents the first use of metal complexes as two-photon probes for extended lysosome visualization.
• The probe facilitates detailed studies of lysosome dynamics in cellular processes like migration and apoptosis.