Self-Assembly of Alkynylplatinum(II) Complexes for Sialic Acid Detection and Differentiation of Cancer Cells from Normal Cells.

A series of platinum(II) complexes incorporating a histidine moiety and/or positively charged group has been designed and synthesized to explore the specific binding between platinum(II) complexes and the analyte and their sensing ability. The specific hydrogen bonding between the histidine moiety and sialic acids, and the electrostatic interaction between the positively charged trimethylammonium group of the platinum(II) complexes and negatively charged carboxylate groups of sialic acids have been found to enhance the binding affinity. The supramolecular assembly of platinum(II) complexes upon binding to sialic acids induces remarkable luminescence changes due to noncovalent Pt(II)Pt(II) and π-π stacking interactions, achieving sensing and visualization of sialic acids. A novel luminescence assay has been developed to differentiate cancer cells from normal cells based on the supramolecular assembly of platinum(II) complexes upon binding to a high level of sialic acids due to its excellent imaging ability toward sialic acids in live cells. The complexes have been adopted to visualize the variation of sialic acids in live cells after treatment with enzymes to remove sialic acids, paving the way for screening of novel anticancer agents. The present sensing strategy for differentiating cancer cells from normal cells facilitates early diagnosis and therapeutic guidance.