The most widely used 12 trap is 9, 10- diphenylanthracene (DPA), which reacts quickly and
In particular, it reacts with 1O2 to form a thermally stable internal peroxide at the rate of k =1.3106m1s1.
The decrease in absorbance at 355 nm was used as a measure of internal peroxide formation.
However, DPA derivatives are not very sensitive probes because the detection is based on.
Measurement of absorbance [79].
Umezaka et al [79] fused DPA with fluorophore (fluorescein) in order to bind the first fluorophore.
Reaction characteristics and fluorescence characteristics of the second one. Fluorescein was selected as
Fluorophore because it has high fluorescence quantum yield in aqueous solution.
Excited at long wavelengths. From this fusion, 9-[2-(3- carboxyl -9, 10- diphenyl) anthracyl ]-6-
Hydroxy -3H- xanthone -3- one (DPAXs) (figure 1 1) [79]. Therefore, DPAXs is the first chemical trap.
For 1O2 which allows fluorescence detection. They react with 1O2 to produce DPAX.
Internal peroxide (DPAX-EPs) (figure 1 1). DPAXs itself hardly fluoresces, while DPAXEPs.
There is strong fluorescence. Mechanism of fluorescence attenuation
DPAX and its enhancement in DPAX-EPs are still unclear [79].
It is known that the fluorescence intensity of fluorescein derivatives will decrease under acidic conditions.
The result of protonation of phenolic oxygen atoms. for
The fluorescence intensity is stabilized at physiological pH, and the electron-withdrawing group is bound to the 2- and 7- positions of the xanthene chromophore, resulting in Cl (DPAX-2) and.
F (DPAX-3) (figure 1 1). This modification reduces the pKa value of phenolic oxygen atoms.
[79].
DPAX-2 is used to detect the generation of 65438+O2 from two different power generation systems: namely
MoO4
2/H2O2 system and 3-(4- methyl-1- naphthyl) propionic acid internal peroxide (EP- 1)
The system works at different pH values (10.5 and 7.4 respectively). In both cases, it has increased.
When in contact with the generating system, the fluorescence of the probe is verified. these
The results confirmed the advantages of DPAXs in detecting 1O2 in neutral or alkaline aqueous solution.
[79]. The probe's behavior on H2O2, NO and O2! Research has also been carried out, but there is no change.
Observe the fluorescence intensity of any of these active substances. These facts
The specificity of the probe for 1O2 was confirmed [79].
The detection of 65438+O2 in biological samples was also studied. To this end, DPAX-2
Diacetate (DPAX-2-DA) was prepared because it was considered to be more permeable to cells.
DPAX-2-DA was hydrolyzed by lactonase to produce DPAX-2. DPAX-2 and
DPAX-2DA is tested and compared in the same analysis system. However, cells are stained.
Both cases are similar. This observation may mean that DPAX-2 itself is also membrane permeable.