Tumor cell uptake and selectivity of gadolinium(III)-phosphonium complexes: The role of delocalisation at the phosphonium centre.

The synthesis of a series of bifunctional Gd(III) complexes 1-3 covalently bound to arylphosphonium cations possessing a varying degree of delocalisation at the phosphonium centre is presented. The influence of the degree of delocalisation was investigated with regards to in vitro cytotoxicity, cellular uptake of Gd, tumor-cell selectivity and intracellular localisation of Gd within human glioblastoma (T98G) and human glial (SVG p12) cells. Cellular uptake and selectivity studies for the Gd(III) complexes indicate that a reduced delocalisation at the phosphonium centre can lead to an enhanced Gd uptake into SVG p12 cells which results in a decrease in the overall tumor cell selectivity.