Similarities and Differences between Chemiluminescence Reagent Acridinium Ester and APS-5

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There are many types of chemiluminescent reagents, among which the luminescent reagents containing acridine structure have stable structure, high luminous efficiency and better performance. Both the luminescent reagent acridinium ester and APS-5 contain acridine structure. Here we compare the similarities and differences between the two.

Structural characteristics of acridine esters

Acridine esters include two types of acridine esters and acridine sulfonamides. On the 9th carbon of the acridine parent, the former is connected to a formate, and the latter is connected to a carbonyl group and a sulfonamide connected to it. Acridine on the 10th position of the nitrogen atom is all connected to the methyl group, and then through the sulfuric acid ester, sulfonic acid and nitrogen to form a salt or internal salt, this structure can increase the hydrophilicity of acridine ester. Both the formate or carbonyl sulfonamide on carbon 9 can continue to be connected to the group used for labeling. For example, NHS ester can directly label the primary amino group of the protein.

Structure comparison of acridine ester, acridine sulfonamide and APS-5

Structural characteristics of APS-5

Its full name is (4-chlorophenylmercapto)(10-methyl-9,10-dihydroacridine methylene) disodium phosphate, and its parent is the methylene group connected to the double bond on the 9th carbon of acridine dihydrogen, The methylene group is then connected to the phosphoric acid group and the chlorobenzene sulfhydryl group.

Similarities and Differences of Chemiluminescence Reaction between Acridine Ester and APS

Acridine esters (including acridine sulfonamide) can be directly oxidized by hydrogen peroxide under alkaline conditions to form an intermediate with a carbonyl group on the 9th carbon of acridine and containing a peroxycycloethane structure. This intermediate Unstable, it will quickly remove the carbonyl group in the form of CO2 and convert to 9-acridone in an excited state, and then return to the ground state and produce chemiluminescence.

The luminescence mechanism of APS-5 is similar to that of acridinium esters. It is first converted into acridinone containing peroxycycloethane structure, and then removed CO2 to become 9-acridone in the excited state, and then return to the ground state to emit photons. However, unlike acridine esters, the luminescence reaction needs to be catalyzed by alkaline phosphatase to remove the phosphate group and sulfhydryl group to produce a chemiluminescent structure.

In addition, lucigenin is bis(N-methylacridine) nitrate. The two acridines in the structure are directly connected by carbon atom number 9. Similar to acridine esters, chemiluminescence is produced by the oxidation of hydrogen peroxide. Desheng is a manufacturer of chemiluminescence reagents and has rich experience in acridinium ester, luminol, AMPPD and other luminescence reagents.