2',7'-Dichlorofluorescein is not a probe for the detection of reactive oxygen and nitrogen species

Rapid identification of bacteria by the pattern of redox reactions rate using 2',7'-dichlorodihydrofluorescein diacetate

Bacterial infection is a life-threatening situation, and its rapid diagnosis is essential for treatment. Apart from medical applications, rapid identification of bacteria is vital in the food industry or the public health system. There are various bacterial identification techniques, including molecular-based methods, immunological approaches, and biosensor-based procedures. The most commonly used methods are culture-based methods, which are time-consuming. The objective of this study is to find a fingerprint of bacteria to identify them. Three strains of bacteria were selected, and seven different concentrations of each bacterium were prepared. The bacteria were then treated with two different molar concentrations of the fluorescent fluorophore, dichlorodihydrofluorescein diacetate for 30 minutes. Then, using the fluorescence mode of a multimode reader, the fluorescence emission of each bacterium is scanned twice during 60 minutes. Plotting the difference between two scans versus the bacteria concentration results in a unique fluorescence pattern for each bacterium. Observation of the redox state of bacteria, during 90 minutes, results in a fluorescence pattern that is clearly a fingerprint of different bacteria. This pattern is independent of fluorophore concentration. Mean Squares Errors (MSE) between the fluorescence patterns of similar bacteria is less than that of different bacteria, which shows the method can properly identify the bacteria. In this study, a new label-free method is developed to detect and identify different species of bacteria by measuring the redox activity and using the fluorescence fluorophore, dichlorodihydrofluorescein diacetate. This robust and low-cost method can properly identify the bacteria, uses only one excitation and emission wavelength, and can be simply implemented with current multimode plate readers.

2′,7′-Dichlorofluorescein: Biological, Analytical, and Industrial Progress

Abstrack:

Fluorescein derivatives have attracted a great deal of attention for ubiquitous applications on account of their unique properties. Particularly, the 2′,7′-dichlorofluorescein (DCF) is of paramount importance in biological, analytical, and industrial fields. Mainly, DCF has been employed as a reactant in reactive oxygen species (ROS) formation reactions in biological applications. It has been utilized in oxidative stress and cell spreading measurement. It has been extensively explored to analyze oxidative, respiratory burst, secretory peroxidase, and multidrug resistance-associated proteins (MRPs). It has been widely investigated for detecting/quantification of H2O2, glucose, lipid, cholesterol, other hydroperoxides, and polycationic protamine. Moreover, it has been applied to differentiate dopamine from ascorbic acid. It has also shown immense potential in biolabeling, cancer imaging, and drug delivery. Several studies demonstrated the great promise of DCF as a fluorescent probe for real-time monitoring/quantification of mercury, cadmium, zinc, arsenite, acetate, fluoride, thiocyanate, azide ions, hydrogen peroxide, ammonia, ozone, sulfur dioxide, and drug molecules. Furthermore, the use of DCF to manufacture dyesensitized solar cells and Schottky barrier devices opens up avenues for its industrial applications. Apart from presenting a comprehensive account of the immense potential of DCF in the areas mentioned above, the present review also intends to provide insight into its broader future scope for a myriad of applications to emerge.

Experimental Conditions That Influence the Utility of 2′7′-Dichlorodihydrofluorescein Diacetate (DCFH2-DA) as a Fluorogenic Biosensor for Mitochondrial Redox Status

Oxidative stress has been causally linked to various diseases. Electron transport chain (ETC) inhibitors such as rotenone and antimycin A are frequently used in model systems to study oxidative stress. Oxidative stress that is provoked by ETC inhibitors can be visualized using the fluorogenic probe 2′,7′-dichlorodihydrofluorescein-diacetate (DCFH₂-DA). Non-fluorescent DCFH₂-DA crosses the plasma membrane, is deacetylated to 2′,7′-dichlorodihydrofluorescein (DCFH₂) by esterases, and is oxidized to its fluorescent form 2′,7′-dichlorofluorescein (DCF) by intracellular ROS. DCF fluorescence can, therefore, be used as a semi-quantitative measure of general oxidative stress. However, the use of DCFH₂-DA is complicated by various protocol-related factors that mediate DCFH₂-to-DCF conversion independently of the degree of oxidative stress. This study therefore analyzed the influence of ancillary factors on DCF formation in the context of ETC inhibitors. It was found that ETC inhibitors trigger DCF formation in cell-free experiments when they are co-dissolved with DCFH₂-DA. Moreover, the extent of DCF formation depended on the type of culture medium that was used, the pH of the assay system, the presence of fetal calf serum, and the final DCFH₂-DA solvent concentration. Conclusively, experiments with DCFH₂-DA should not discount the influence of protocol-related factors such as medium and mitochondrial inhibitors (and possibly other compounds) on the DCFH₂-DA-DCF reaction and proper controls should always be built into the assay protocol.