New triarylamine-based far-red DNA stainers with high two-photon absorption properties

A series of red emitting vinyl-triphenyamines (TP) have been synthesized and evaluated for their two photon absorption (2PA) properties. These compounds are virtually non fluorescent in the free state but exhibit a bright red fluorescence upon binding to double-stranded DNA, both in one- and two-photon absorption. This feature allows one- and two-photon confocal imaging in cells of nuclear DNA with an excellent contrast. Derivatizable analogues for covalent bioconjugation to oligonucleotides are described and variation on the structure is discussed.