Template-directed formation of luminescent lanthanide complexes: Versatile tools for colorimetric identification of single nucleotide polymorphism

We present the facile technique of colorimetric SNP (single nucleotide polymorphism) analysis through DNA-templated cooperative complexation between a luminescent lanthanide ion (Ln(III): Tb(III) or Eu(III)) and two ODN (oligodeoxyribonucleotide) conjugates carrying a metal chelator. Families of complexane-type chelators and heterocyclic aromatic ligands were covalently attached to ODNs to form conjugates for application as capture and sensitizer probes. The sequences of the conjugates were designed so as to form a ternary tandem duplex with the target, where their auxiliary units face each other, providing a microenvironment to accommodate Ln(III). Only the combination of EDTA (ethylenediaminetetraacetic acid) conjugates and phen (1,10-phenanthroline) conjugates provided significant emissions with quantum yields of 3.3% and 1.5% for Tb(III) and Eu(III), respectively, in the presence of the target. Biallelic polymorphism in the TPMT (thiopurine S-methyltransferase) gene, wt/wt (G/G), mut/mut (C/C), and wt/mut (G/C), were distinguished as emissions in green, red, and yellow, respectively; the colors were identified even by the naked eye.