Time-resolved probes based on guanine/thymine-rich DNA-sensitized luminescence of terbium(III)

Min Zhang, Huynh Nhu Le, Xiao Qin Jiang, Bin Cheng Yin, Bang Ce Ye

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Abstract

In this study, we have developed a novel strategy to highly sensitize the luminescence of terbium(III) (Tb3+) using a designed guanine/thymine-rich DNA (5′-[G3T]5-3′) as an antenna ligand, in which [G3T]5 improved the luminescence of Tb3+ by 3 orders of magnitude due to energy transfer from nucleic acids to Tb3+ (i.e., antenna effect). Furthermore, label-free probes for the luminescent detection of biothiols, Ag+, and sequence-specific DNA in an inexpensive, simple, and mix-and-read format are presented based on the [G3T]5-sensitized luminescence of Tb3+ (GTSLT). The long luminescence lifetime of the probes readily enables time-resolved luminescence (TRL) experiments. Hg2+ can efficiently quench the luminescence of Tb3+ sensitized by [G 3T]5 (Tb3+/[G3T]5); however, biothiols are readily applicable to selectively grab Hg2+ for restoration of the luminescence of Tb3+/[G3T] 5 initially quenched by Hg2+, which can be used for turn on detection of biothiols. With the use of cytosine (C)-rich oligonucleotide c[G3T]5 complementary to [G3T]5, the formed [G3T]5/c[G3T]5 duplex cannot sensitize the luminescence of Tb3+. However, in the presence of Ag+, Ag+ can combine the C base of c[G3T] 5 to form C-Ag+-C complexes, leading to the split of the [G3T]5/c[G3T]5 duplex and then release of [G3T]5. The released [G3T] 5 acts as an antenna ligand for sensitizing the luminescence of Tb3+. Therefore, the Tb3+/[G3T] 5/c[G3T]5 probe can be applied to detect Ag+ in a turn on format. Moreover, recognition of target DNA via hybridization to a molecular beacon (MB)-like probe (MB-[G3T] 5) can unfold the MB-[G3T]5 to release the [G3T]5 for sensitizing the luminescence of Tb 3+, producing a detectable signal directly proportional to the amount of target DNA of interest. This allows the development of a fascinating label-free MB probe for DNA sensing based on the luminescence of Tb 3+. Results and methods reported here suggest that a guanine/thymine-rich DNA-sensitized luminescence probe of Tb3+ represents a new opportunity for versatile background-free biosensing applications.

Original languageEnglish
Pages (from-to)11665-11674
Number of pages10
JournalAnalytical Chemistry
Volume85
Issue number23
DOIs
StatePublished - 3 Dec 2013
Externally publishedYes

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