Azide vs Alkyne Functionalization in Pt(II) Complexes for Post-treatment Click Modification: Solid-State Structure,...

Area of Science:

• Coordination Chemistry
• Bioinorganic Chemistry
• Chemical Biology

Background:

• Tracking platinum(II) complexes is vital for understanding their interactions with cellular biomolecules.
• Post-treatment fluorescent labeling using bioorthogonal reactions like copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is a promising strategy.

Purpose of the Study:

• To synthesize and characterize an azide-functionalized platinum(II) complex, cis-[Pt(2-azidobutyl)amido-1,3-propanediamine)Cl2] (1).
• To compare its properties with a previously reported alkyne-functionalized congener.
• To evaluate its potential for cellular imaging and tracking.

Main Methods:

• Synthesis and characterization of the azide-functionalized Pt(II) complex.
• Single-crystal X-ray diffraction to determine solid-state structure.
• In vitro DNA binding studies and click reactivity assays using fluorescent labeling.
• In cellulo studies using HeLa cells and confocal fluorescence microscopy.

Main Results:

• Complex 1 exhibits a distinct pseudo-chain Pt-Pt dimer arrangement in the solid state compared to its alkyne congener.
• Both complexes show similar DNA binding and click reactivity in vitro.
• Complex 1 demonstrates enhanced in vitro click reactivity compared to other azide-appended Pt(II) complexes.
• In cellulo studies reveal superior imaging potential for complex 1, with clear nuclear and nucleolar localization.

Conclusions:

• The azide-functionalized Pt(II) complex (1) is a viable tool for post-treatment fluorescent labeling and tracking of platinum agents.
• Complex 1 exhibits promising cellular imaging capabilities, highlighting its potential for localization studies in various cell lines.
• This work paves the way for future isolation and purification of platinum-bound cellular targets.