Abstract
In this work, a novel, simple, and time-saving fluorescence approach for the detection of biothiols (glutathione and cysteine) was developed by employing a DNA probe labeled with 2-aminopurine. As an adenine analogue, 2-aminopurine exhibits high fluorescence intensity that can be rapidly quenched in the presence of DNA. In the presence of Ag+, the fluorescence increased significantly, which was a result of the formation of cytosine–Ag+–cytosine base pairs and the release of 2-aminopurine. Upon addition of either glutathione or cysteine, the structure of cytosine–Ag+–cytosine was disrupted, a product of the stronger affinity between biothiols and Ag+. As a result, the 2-aminopurine-labeled DNA probe returned to its former structure, and the fluorescence signal was quenched accordingly. The detection limit for glutathione and cysteine was 3 nM and 5 nM, respectively. Furthermore, the determination of biothiols in human blood serum provided a potential application for the probe as a diagnostic tool in clinical practice.
Highlights
In recent years, the detection of biothiols, i.e., thiol-containing amino acids and peptides, as well as glutathione (GSH) and cysteine (Cys) has attracted significant attention due to the important effects these compounds exhibit in physiological systems [1,2]
After incubation with Ag, a recovery of the fluorescence signal was observed, which was attributed to the formation of a C–Ag++–C structure that led to the release of, which was attributed to the formation of a C–Ag –C structure that led to the release of 22-aminopurine
The sensing system featured a linear interval within a concentration range of 3 to 1000 nM for GSH and 5 to 1000 nM for Cys, respectively
Summary
The detection of biothiols, i.e., thiol-containing amino acids and peptides, as well as glutathione (GSH) and cysteine (Cys) has attracted significant attention due to the important effects these compounds exhibit in physiological systems [1,2]. Despite promising results displayed by these methods, deficiencies remain, including the need for sophisticated sample preprocessing procedures, expensive equipment, professional instrument operation, long reaction times, as well as tedious sample modifications. Such requirements tremendously limit the overall range of applications using conventional techniques. Sensors 2019, 19, 934 fluorescence-based approaches in an effort to develop a time-saving process that features high sensitivity [19,20,21,22], ease of operation, and lower detection limits. The method we present was successfully applied to the detection of biothiols in human serum samples, providing a promising application for clinical diagnosis
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