Novel Platinum(II) Tetrazine Complex Capable of Live-Cell IEDDA Reaction

Area of Science:

• Inorganic Chemistry
• Bioorthogonal Chemistry
• Chemical Biology

Background:

• Platinum(II) complexes are investigated for anticancer properties and bioorthogonal applications.
• Tetrazine ligation chemistry, specifically inverse electron demand Diels-Alder (IEDDA) reactions, offers high efficiency and selectivity.
• Developing robust probes for live-cell imaging with minimal background is crucial for understanding biological processes.

Purpose of the Study:

• To synthesize and characterize the first platinum(II) tetrazine complex.
• To evaluate its in vitro cytotoxicity and bioorthogonal reactivity.
• To establish a live-cell imaging strategy using fluorescence lifetime changes.

Main Methods:

• Synthesis of trans-[Pt(II)Cl2(dmso)(CH3-Tz-Bz-NH2)] (1).
• In vitro cytotoxicity assays against MDA-MB-231 cells.
• Inverse electron demand Diels-Alder (IEDDA) reactions with trans-cyclooctene (TCO) and bicyclononyne (BCN) derivatives.
• Live-cell imaging using fluorescence lifetime imaging microscopy (FLIM).

Main Results:

• The novel platinum(II) tetrazine complex (1) was successfully synthesized.
• Complex 1 demonstrated significant in vitro cytotoxicity against MDA-MB-231 cancer cells.
• A live-cell bioorthogonal reaction was achieved using complex 1 and a BCN-functionalized BF2-azadipyrromethene fluorophore.
• A distinct change in fluorescence lifetime (0.3 ns) was observed, enabling imaging without fluorogenic probes or washing steps.

Conclusions:

• The developed platinum(II) tetrazine complex is a promising tool for bioorthogonal chemistry and live-cell imaging.
• The observed fluorescence lifetime shift provides a robust method for tracking platinum complex reactions in live cells.
• This approach simplifies bioorthogonal cell imaging strategies for platinum complexes, avoiding complex probe design and purification steps.