G Quadruplex‐Based FRET Probes with the Thrombin‐Binding Aptamer (TBA) Sequence Designed for the Efficient Fluorometric Detection of the Potassium Ion

Abstract

The dual-labeled oligonucleotide derivative, FAT-0, carrying 6- carboxyfluorescein (FAM) and 6-carboxytetramethylrhodamine (TAMRA) labels at the 5' and 3' termini of the thrombin-binding aptamer (TBA) sequence 5'-GGT TGG TGT GGT TGG-3', and its derivatives, FAT-n (n=3, 5, and 7) with a spacer at the 5'-end of a TBA sequence of T(m)A (m=2, 4, and 6) have been designed and synthesized. These fluorescent probes were developed for monitoring K(+) concentrations in living organisms. Circular dichroism, UV-visible absorption, and fluorescence studies revealed that all FAT-n probes could form intramolecular tetraplex structures after binding K(+). Fluorescence resonance energy transfer and quenching results are discussed taking into account dye-dye contact interactions. The relationship between the fluorescence behavior of the probes and the spacer length in FAT-n was studied in detail and is discussed.

Fluorescence Detection of Potassium Ion Using the G-Quadruplex Structure

“…22 Thus, we synthesized a FAT-0 probe, which possessed a TBA sequence carrying FAM and TAMRA groups at the 5′-and 3′-termini, respectively (Table 1). 23,24 As shown in Fig. 6, the FAT-0 probe formed a chair-type structure upon the addition of K + with two dyes located in a close proximity.…”

“…Fortunately, no fluorescence changes were observed upon the addition of Na + excess, and the FAT-5 probe exhibited quite good binding selectivity for K + over the Na + ion. 23,24 …”

Metal‐Induced Specific and Nonspecific Oligonucleotide Folding Studied by FRET and Related Biophysical and Bioanalytical Implications

“…[5] The adaptive binding property has been used to design fluorescence resonance energy transfer (FRET)-based sensors with end-labeled fluorophores since FRET is known to be sensitive to such distance changes. Many molecules include adenosine/ATP, [6] cocaine, [7] arginiamide, [8] K I , [9][10][11][12] Mg II /Ca II , [13] Ag I , [14] Hg II , [15,16] thrombin, [17] and (platelet-derived growth factor) PDGF [18,19] have been detected using this method. One particularly interesting example is the Hg II binding DNA shown in Figure 1A.…”

Nukleinsäure‐basierte molekulare Werkzeuge

“…B. die Grundlage für eine Reagens-lose elektrochemische Detektionsplattform für K + -Ionen. [138] In anderen Studien wurde FRET -entweder zwischen zwei Farbstoffen [139] oder zwischen einer Oberfläche, die mit einem kationisch geladenen Polymer funktionalisiert ist, und einem fluoreszenzmarkierten GFO -zum Nachweis von K + genutzt. [140] Auch viele Aptamere enthalten G-Quadruplexe; eines der bekanntesten Beispiele ist das Thrombin-bindende Aptamer (TBA).…”