Hemin/G-quadruplexes as DNAzymes for the fluorescent detection of DNA, aptamer–thrombin complexes, and probing the activity of glucose oxidase

Abstract

Hemin/G-quadruplex catalyzes the H(2)O(2)-mediated oxidation of Amplex Red to the fluorescent product resorufin. This process is implemented to develop hairpin nucleic acid structures for the detection of DNA, to probe the catalytic activity of glucose oxidase, to use the thrombin-aptamer complex as a catalytic readout structure, and to quantitatively analyze telomere chain composition.

A New Method for the Label-Free Detection of Vascular Endothelial Growth Factor Based on DNAzymes

“…[1][2][3] These structures have been proposed to act as gene promoters for transcription because of their significant biological activity. [4][5][6] Recently, G-quadruplex aptamers have been found to bind hemin to form a type of peroxidase-like enzyme termed as G-quadruplex-based DNAzyme. Such artificial enzymes can effectively catalyze the H 2 O 2 -mediated oxidation of 2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) giving rise to a colour change.…”

Fluorescence reporting of G-quadruplex structures and modulating their DNAzyme activity using polyethylenimine–pyrene conjugate

“…[7][8][9] DNAzymes are known to catalyze the oxidation of many substrates like Amplex Red (AR) to the fluorescent resorufin, and 2,2 0 -azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS 2À ) to the colored radical anion ABTS 1ÀÅ in the presence of H 2 O 2 . 10,11 With this background, it is apparent that accurate and quantitative detection of G-quadruplex structures is of supreme importance. Evidently, the most important and challenging task in the development of G-quadruplex binding ligands as cancer therapeutic agents is the accurate and quantitative detection of G-quadruplex structures in the cellular context.…”

“…Non-fluorescent Amplex red (AR) was used as a DNAzyme reporter, which is known to release red fluorescent resorufin during the reaction. 11 Recently, DNAzyme activity of G-quadruplex/hemin complex in presence of natural polyamine spermine has been studied. 27 In the absence of PEI and PEI-Py, the preformed Te-22-hemin complex showed maximum fluorescence intensity at 587 nm, suggesting the conversion of non-fluorescent Amplex red (AR) to red fluorescent resorufin in the presence of hydrogen peroxide after one minute.…”

A “plasmonic cuvette”: dye chemistry coupled to plasmonic interferometry for glucose sensing

“…Reaction 1 ( Figure 1B) describes the oxidation of β-D-glucose to D-gluconolactone by oxygen catalyzed by GOx to yield H 2 O 2 as a product [30]. The H 2 O 2 generated in Reaction 1 is utilized by horseradish peroxidase (HRP) to oxidize Amplex red (AR), a colorless, non-fluorescent compound, to resorufin, a red, fluorescent compound (Reaction 2, Figure 1C) [31][32][33].…”

“…The H 2 O 2 generated in Reaction 1 is utilized by horseradish peroxidase (HRP) to oxidize Amplex red (AR), a colorless, non-fluorescent compound, to resorufin, a red, fluorescent compound (Reaction 2, Figure 1C) [31][32][33]. Reaction 3 ( Figure 1D) is a much slower, H 2 O 2 -limited side reaction that further oxidizes resorufin into an optically inactive product (OIP), thought to be a complex polymer [30,33,34]. Reactions 1 and 2 are commonly used to detect glucose in a wide variety of applications, such as determining glucose consumption by cancerous cells to better understand tumorigenesis [35], or quantifying starch and glucose concentrations in food [36].…”