Interaction of Newly Platinum(II) with Tris(2-carboxyethyl)phosphine Complex with DNA and Model Lipid Membrane

Structural properties of plasmid DNA and model lipid membrane treated with newly synthesized platinum(II) complex cis-[PtCl₂{P(CH₂CH₂COOH)₃}₂] (cis-DTCEP for short) were studied and compared with effects of anticancer drug cisplatin, cis-[Pt(NH₃)₂Cl₂] (cis-DDP for short). Time Correlated Single Photon Counting Fluorescence Correlation Spectroscopy (TCSPC-FCS) was employed to study interactions between those platinum complexes and DNA. The TCSPC-FCS results suggest that bonding of cis-DTCEP derivative to DNA leads to plasmid strain realignment towards much more compact structure than in the case of cis-DDP. Application of both differential scanning calorimetry and infrared spectroscopy to platinum complexes/DPPC showed that cis-DTCEP slightly increases the phospholipid's main phase transition temperature resulting in decreased fluidity of the model membrane. The newly investigated compound-similarly to cis-DDP-interacts mainly with the DPPC head group however not only by the means of electrostatic forces: this compound probably enters into hydrophilic region of the lipid bilayer and forms hydrogen bonds with COO groups of glycerol and PO₂^- group of DPPC.