Density functional theory and surface enhanced Raman spectroscopy characterization of novel platinum drugs

There is considerable interest in the development of novel platinum-based anticancer drugs that overcome the disadvantages associated with the widely used drug cisplatin, which are its inactivity against some types of tumors and its toxic side effects. In this study we show the suitability of normal Raman spectroscopy (NRS) and surface enhanced Raman spectroscopy (SERS), assisted by density functional theoretical (DFT) calculations, for the characterization of Pt complexes. The Pt complexes studied include the established drugs cisplatin and carboplatin, as well as five novel Pt complexes with anticancer activity. DFT calculations at the B3LYP/LanL2DZ level are a good prediction of the experimental NRS spectra of small and medium sized Pt complexes. The use of SERS allows the investigation of Pt complexes at physiological concentrations, and the binding strengths of the different ligands can be determined. The formation of positively charged hydrolysis products may be necessary for SERS activity. The exiting group in the hydrolysis reaction can be identified.