Tetraphenylethene-based Zn complexes for the highly sensitive detection of single-stranded DNA

Abstract

Metal–ligand coordination interactions were utilized to develop tetraphenylethene-based DNA probes. Z- and E-TPE derivatives based on Zn²⁺-DPA (dipicolylamine) units, namely Z-TPE2Zn and E-TPE2Zn, were tested, respectively, to oligonucleotides with different lengths and different sequences. TPE2Zn exhibited a high fluorescence enhancement when detecting ssDNA as short as 5 nt. The fluorescence intensity of Z-TPE2Zn could increase to more than 100-fold of its initial value when enough DNA was added. This fluorescent on/off ratio was much higher than that of the classical DNA probe of ethidium bromide (EB). Absorption titration experiments indicated that thymine and guanine could coordinate with the Zn²⁺-DPA unit more effectively than adenine and cytosine. These experiments might aid the design of metal complex-based DNA probes with high sensitivity and selectivity.