Organoplatinum(II) Complexes Self-Assemble and Recognize AT-Rich Duplex DNA Sequences

Area of Science:

• Coordination Chemistry
• Medicinal Inorganic Chemistry
• Biophysical Chemistry

Background:

• AT-rich DNA sequences are implicated in various gene-related diseases.
• Targeting specific DNA sequences offers potential for novel diagnostic and therapeutic strategies.
• Platinum(II) complexes are known for their anticancer properties and DNA-binding capabilities.

Purpose of the Study:

• To synthesize and characterize amphiphilic platinum(II) complexes.
• To investigate the DNA binding preferences and mechanisms of these complexes.
• To evaluate the anticancer activity of the complexes against cancer cell lines and tumor spheroids.

Main Methods:

• Synthesis and structural characterization of platinum(II) complexes [Pt(dmba)(N∧N)]NO3.
• DNA binding studies using viscometry, gel electrophoresis, and fluorescence spectroscopy.
• Cell viability assays (IC50 determination) in 2D cultures and 3D tumor spheroids.

Main Results:

• Complexes selectively recognize AT-rich DNA sequences over DNA, RNA, and proteins.
• Complexes 3 and 4 (monomers) intercalate into DNA, while complex 5 (self-assembled) binds to the minor groove.
• Complex 5 exhibits DNA-dependent excimer emission, indicating aggregation upon DNA binding.
• All complexes show low-micromolar IC50 values against cancer cells and suppress tumor growth in 3D models.

Conclusions:

• Amphiphilic platinum(II) complexes are effective AT-rich DNA binders.
• The distinct binding modes (intercalation vs. minor groove) depend on complex structure and aggregation.
• These complexes demonstrate significant anticancer potential, comparable to cisplatin, warranting further investigation.