Click-ready iridium(iii) complexes as versatile bioimaging probes for bioorthogonal metabolic labeling

Area of Science:

• Inorganic Chemistry
• Bioanalytical Chemistry
• Chemical Biology

Background:

• Iridium(iii)-polypyridine complexes offer unique photophysical properties for bioimaging.
• Click chemistry and bioorthogonal reactions are powerful tools for selective biomolecule labeling.
• Monitoring intracellular glycoconjugates is crucial for understanding cellular functions.

Purpose of the Study:

• To synthesize and characterize novel iridium(iii)-polypyridine complexes functionalized for click chemistry.
• To validate their utility as probes for bioorthogonal chemistry and intracellular metabolic labeling.
• To explore their application in advanced bioimaging techniques.

Main Methods:

• Synthesis and photophysical characterization of iridium(iii)-polypyridine complexes.
• Copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) ligation for cellular conjugation.
• Bioorthogonal metabolic engineering (MOE) studies using monosaccharide reporters.
• Multi-modal bioimaging including confocal microscopy, time-resolved luminescence imaging, X-ray fluorescence nanoimaging, and ICP-MS.

Main Results:

• The synthesized iridium(iii) complexes exhibit high photostability and emit in the far-red to near-IR region with long lifetimes and large Stokes shifts.
• Efficient conjugation to chemical reporters within cells via CuAAC ligation was achieved.
• Successful monitoring of nascent intracellular sialylated glycoconjugates using various imaging techniques was demonstrated.
• The complexes were effective in both single and dual click-labeling experiments.

Conclusions:

• Novel iridium(iii)-polypyridine complexes are versatile tools for bioorthogonal chemistry and bioimaging.
• These probes enable specific and sensitive detection of intracellular glycoconjugates through metabolic labeling.
• The developed platform facilitates advanced cellular analysis with multi-modal imaging techniques.