Method of labeling antibodies with europium(III)-4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-di-carboxylic acid chelate.

On the basis of Eu(III)-4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-di-carboxylic acid chelate (BCPDA) that was synthesized and characterized for time-resolved fluoroimmunoassay (TRFIA), Donkey anti-hepatitis B surface (anti-HBs) was labeled with BCPDA-Eu3+. Coomassie Brilliant Blue was used to determine the protein concentration and radio immunoassay (RIA) for detecting the biological activity in the labeled protein. Optimal conditions for the protein labeling were obtained by monitoring the reaction. Results suggested that the protein could be labeled with BCPDA under relatively moderate conditions. As a practical application, a protein-BCPDA-Eu3+ chelate was obtained by using BCPDA-protein that reacted with EuCl3 under certain conditions. Some properties of BCPDA and protein-BCPDA-Eu3+, such as absorption spectrum, emission spectrum and fluorescence lifetime, were discussed. The detection limit and the linear working range of the established method were also investigated.