Ratiometric fluorescence monitoring of cerebral Cu²⁺ based on coumarin-labeled DNA coupled with the Cu²⁺-induced oxidation of o-phenylenediamine

Abstract

A novel and facile ratiometric fluorescence method for evaluating Cu has been developed based on coumarin-labeled single-stranded DNA (C-ssDNA) coupled with the Cu-induced oxidation of o-phenylenediamine (OPD). By combining the microdialysis technique, the ratiometric fluorescence method has also been successfully exploited to monitor the cerebral Cu in the rat brain, promising new opportunities for studying the cerebral Cu-associated physiological and pathological events.

Fluorescent and Colorimetric Sensors Based on the Oxidation of o-Phenylenediamine

“…Recently, a Cu 2+ sensor based on C-ssDNA was developed (Scheme 4). 6 Similar to the sensing mechanism of the last example, Cu 2+ -induced oxidation of OPD "turns off" the fluorescence of C-ssDNA due to FRET, which is attributed to the π−π stacking and hydrogen bonding interactions between OPDox and C-ssDNA. The concentrations of Cu 2+ are linearly related with the fluorescence intensity ratios between OPDox and C-ssDNA, with the limit of detection (LOD) as low as 4.32 nM, which is superior to the absorbance assay.…”

Synthesis of two tetra-azolium salts and the recognition performance for guests

“…In the detection of OPD, OPD was captured by 1 through the formation of N-HÁ Á ÁN and C-HÁ Á ÁN hydrogen bonds, and this type of probe has better reversibility compared with the probes in which OPD was oxidized to form new compounds. [17][18][19][20][21] The detection limit of 1 for OPD was 1.25 Â 10 À7 M, and this value was in the medium position compared with the values in the literature. 22,23 F À was held by 2 via the formation of C-HÁ Á ÁF hydrogen bonds, which has good reversibility when compared to the probes in which the Si-O and P-O bonds of the hosts were broken to form new compounds under the induction of F À .…”

“…For example, some researchers used peroxide or metal ions (such as Cu 2+ , Ag + or Au + ) as oxidants to oxidize OPD into colored 2,3-diaminophenazine, which can achieve the detection of OPD through the changes of color and fluorescence. [17][18][19][20][21] Also, OPD can be detected by the reaction of OPD with the host to form a new light-emitting compound. 22 Besides, OPD can be detected by forming hydrogen bonds between OPD and the host to produce changes in color and fluorescence.…”