3-(10'-Phenothiazinyl)propionic acid is a potent primary enhancer of peroxidase-induced chemiluminescence and its application in sensitive ELISA of methylglyoxal-modified low density lipoprotein.

Using a full factorial design the optimization of experimental conditions of enhanced chemiluminescence reaction (ECR) catalyzed by horseradish peroxidase (HRP) in the presence of 3-(10'-phenothiazinyl)propionic acid (PPA) as a primary enhancer was performed. The effect of concentrations of PPA, hydrogen peroxide, MORPH, luminol, and Tris on a ratio of peroxidase-catalyzed CL to background was studied. The detection limit value of HRP in ECR with PPA was 0.09 pM. Using PPA the ultra-sensitive chemiluminescent ELISA for determination of methylglyoxal-modified low density lipoprotein was developed. The detection limit value for the developed method was 0.5 ng mL(-1). The obtained results open up very promising perspectives for using PPA to improve the sensitivity of enzyme immunoassay kits.

Quantification of 2,4-dichlorophenoxyacetic acid in oranges and mandarins by chemiluminescent ELISA.

Direct competitive enzyme-linked immunosorbent assay (ELISA) for 2,4-dichlorophenoxyacetic acid (2,4-D) was developed. Varying the concentrations of monoclonal anti-2,4-D-antibody and the conjugate of soybean peroxidase and 2,4-D the conditions of ELISA performance were optimised. The chemiluminescent method based on peroxidase-catalysed oxidation of luminol was applied to measure the enzyme activity of the conjugate. A mixture of 3-(10'-phenothiazinyl)propane-1-sulfonate and 4-morpholinopyridine was used as potent enhancer of chemiluminescence signal. It was shown that the values of the lower detection limit, IC50 and the working range were 1.5, 64.0, and 6.5-545ng/mL, respectively. The recovery values of CL-ELISA from 10 spiked samples of oranges (n=5) and mandarins (n=5) cultivated in green house without use of 2,4-D and containing different 2,4-D concentrations (10-300ng/mL) were ranged from 92% to 104% that indicated on the absence of matrix effect for the fruit extracts of interest. Determination of 2,4-D in peel of five oranges and five mandarins purchased from stores in Vietnam showed that 2,4-D content in oranges fruits (79-104µg/kg) was significantly higher than that in mandarins (1.66-2.82µg/kg).