In chemiluminescence immunoassay, we need to label the antibody protein with acridine ester before we can detect the tested substance after the immune reaction, so how to label the antibody is very important.
Acridine salts and related compounds have been widely proved to be very useful chemiluminescence markers. Their stability, labeling specificity and detection sensitivity surpass those of radioisotopes. We now compare the six acridine esters of Desheng, so that you can make clear the difference between them, so as to find what you need.
Package picture of Desheng acridine ester
1、 Name and number of acridine ester
Acridine 0: ae-nhs (traditional acridine ester)
Acridine 1: dmae-nhs
Acridine 2: me DMAE NHS
Acridine 3: nsp-dmae-nhs
Acridine 4: nsp-sa-nhs
Acridine 5: nsp-sa
Acridine 6: nsp-sa-adh
2、 Structural differences of acridine esters
There are six kinds of acridine esters, among which No.1-3 are acridine esters; no.4-6 are acridine sulfonamides; No.1-4 are NHS active esters; No.5 is acridine carboxylic acid containing carboxyl group; no.6 is acridine hydrazide containing free amino group.
3、 Hydrolysis resistance and stability
Traditional acridine ester No.0 (ae-nhs) and No.1-3 were modified on their structures to increase the steric hindrance and enhance the hydrolysis resistance. No. 0 is stable only in acidic solution, and it is easy to hydrolyze when pH value is higher than 6.3, but no. 1-3 is not. At room temperature, it is stable in Pb buffer solution with pH 7.0. After 16 days, the luminescent activity only decreases by 3.6%.
The reason is that the bond order of C-N bond is different from that of C-O bond, and the C-N bond is larger than that of C-O bond. Acridine amides (No. 4-6) were more resistant to hydrolysis than acridine esters (No. 0-3). No.4-no.6 was stable in acidic solution (pH < 4.8). The photoquantum yield of protein conjugates did not decrease when they were stored at room temperature for 4 weeks. The lyophilized products could be stored at - 20 ℃ for more than one year
On the basis of No.
5、 Differences in marking methods
Because the essence of antibody is protein, which contains amino group, it can directly react with No.1-4 (NHS active ester) and conduct coupling.
No. 5 is acridine carboxylic acid, which needs to add the condensation agent EDCI to react with amino protein.
No. 6 is acridine hydrazide, containing free amino group. The terminal of acridine hydrazide is suitable for direct coupling of polysaccharide, nucleic acid or protein containing aldehyde group.
6、 Comparison of luminescent properties
Because of no.1-no.6 acridine, their luminescent matrix and mechanism are consistent, and their luminescent properties should have little difference.
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