“…The significant difference between ATBTA-DNA and BPTA-DNA is that the luminescence is increased even in the low-europium-concentration region for ATBTA-DNA, whereas the intensity did not increase until [TbCl 3 ]/[BPTA-DNA] = 10. This might be due to the Tb 3+ specific property of its coordination to DNA guanine. , 6 Time-resolved fluorometric titration of the free chelates and the oligo DNA (17 bases)-bound chelates with lanthanide ions. Solvent: 1 × SSC, [chelate] = 600 nM.…”
The new europium(III) chelate [2,2',2'',2'''-[[4'-(aminobiphenyl-4-yl)-2,2':6',2''-terpyridine- 6,6''-diyl]bis(methylenenitrilo)]tetrakis(acetato)] europium(III) (ATBTA-Eu3+) and its 4,6-dichloro-1,3,5-triazinyl and succinimidyl derivatives (DTBTA and NHS-ATBTA, respectively) were synthesized and characterized. Both labeling complexes DTBTA-Eu3+ and NHS-ATBTA-Eu3+ are luminescent. Especially DTBTA-Eu3+ is strongly luminescent, with a luminescence quantum yield of 9.1%, molar extinction coefficient of 3.1 x 10(4) cm(-1) M(-1) (335 nm), and luminescence lifetime of 1.02 ms. The excitation and emission maximum wavelengths of DTBTA-Eu3+ are 335 and 616 nm, respectively. The complex is very stable in aqueous buffers, with a conditional formation constant log K(DTBTA-Eu) of 25.0 at pH 8, and can be conjugated to DNA and proteins. The chelates are also highly resistant to thermal decomposition, photodegradation, and ozone oxidation. These properties prove that DTBTA-Eu3+ is suitable as a luminescence label in DNA assays.
“…The significant difference between ATBTA-DNA and BPTA-DNA is that the luminescence is increased even in the low-europium-concentration region for ATBTA-DNA, whereas the intensity did not increase until [TbCl 3 ]/[BPTA-DNA] = 10. This might be due to the Tb 3+ specific property of its coordination to DNA guanine. , 6 Time-resolved fluorometric titration of the free chelates and the oligo DNA (17 bases)-bound chelates with lanthanide ions. Solvent: 1 × SSC, [chelate] = 600 nM.…”
The new europium(III) chelate [2,2',2'',2'''-[[4'-(aminobiphenyl-4-yl)-2,2':6',2''-terpyridine- 6,6''-diyl]bis(methylenenitrilo)]tetrakis(acetato)] europium(III) (ATBTA-Eu3+) and its 4,6-dichloro-1,3,5-triazinyl and succinimidyl derivatives (DTBTA and NHS-ATBTA, respectively) were synthesized and characterized. Both labeling complexes DTBTA-Eu3+ and NHS-ATBTA-Eu3+ are luminescent. Especially DTBTA-Eu3+ is strongly luminescent, with a luminescence quantum yield of 9.1%, molar extinction coefficient of 3.1 x 10(4) cm(-1) M(-1) (335 nm), and luminescence lifetime of 1.02 ms. The excitation and emission maximum wavelengths of DTBTA-Eu3+ are 335 and 616 nm, respectively. The complex is very stable in aqueous buffers, with a conditional formation constant log K(DTBTA-Eu) of 25.0 at pH 8, and can be conjugated to DNA and proteins. The chelates are also highly resistant to thermal decomposition, photodegradation, and ozone oxidation. These properties prove that DTBTA-Eu3+ is suitable as a luminescence label in DNA assays.
“…Lanthanides barely stabilize a DNA duplex but instead destabilize it. By measuring T m using differential scanning calorimetry (DSC), at low Tb 3+ /nucleotide ratios (∼0.35) at pH 6.0, duplex DNA irreversibly dissociates to single strands. − Tb 3+ and Eu 3+ can bind to poly(dG-dC).poly(dG-dC) and poly(dG-m 5 dC).poly(dG-m 5 dC) duplexes and induce a B-Z transition. − Such a transition was attributed to the closer location of the phosphate groups in Z-DNA helices offering multidentate ligand sites for strong Eu 3+ coordination than in the B-DNA. , …”
Metal ions are essential to many chemical, biological, and environmental processes. In the past two decades, many DNA-based metal sensors have emerged. While the main biological role of DNA is to store genetic information, its chemical structure is ideal for metal binding via both the phosphate backbone and nucleobases. DNA is highly stable, cost-effective, easy to modify, and amenable to combinatorial selection. Two main classes of functional DNA were developed for metal sensing: aptamers and DNAzymes. While a few metal binding aptamers are known, it is generally quite difficult to isolate such aptamers. On the other hand, DNAzymes are powerful tools for metal sensing since they are selected based on catalytic activity, thus bypassing the need for metal immobilization. In the last five years, a new surge of development has been made on isolating new metal-sensing DNA sequences. To date, many important metals can be selectively detected by DNA often down to the low parts-per-billion level. Herein, each metal ion and the known DNA sequences for its sensing are reviewed. We focus on the fundamental aspect of metal binding, emphasizing the distinct chemical property of each metal. Instead of reviewing each published sensor, a high-level summary of signaling methods is made as a separate section. In principle, each signaling strategy can be applied to many DNA sequences for designing sensors. Finally, a few specific applications are highlighted, and future research opportunities are discussed.
The Eu3+ ion induces a B to Z transition in poly(dG‐dC) · poly(dG‐dC) and poly(dG‐m5dC) · poly(dG‐m5dC). Other conformations were also elicited by this ion. The conformational changes of these polynucleotides were followed by CD and uv spectroscopy. Eu3+ excitation spectra and Eu3+ excited‐state lifetimes were measured for the Eu3+ ion bound to the duplexes in various conformations. B‐form poly(dG‐dC) and poly(dG‐m5dC) appear to have a single class of the Eu3+ binding site while the Z‐form observed conformation exhibits two. The numbers of H2O molecules coordinated to the Eu3+ ion bound to the various conformations of the duplexes were determined by measuring Eu3+ excited‐state lifetimes in H2O and D2O. The first‐order rate constants for the Eu3− and [Co(NH3)6]3+ induced B to Z transitions were measured. The Eu3+ mediated conversion is much faster than the [Co(NH3)6]3+ induced conversion in both polynucleotides.
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