A Flow Injection Chemiluminescent Immunosensor for Ultrasensitive Detection of Brombuterol Based on Resin Beads and Enzymatic Amplification

This study described the use of a rapid and sensitive flow injection chemiluminescence immunoassay based on the specific binding of antigens and antibodies for the detection of brombuterol residues in the swine meat and feed samples. Carboxylic resin beads were used as a solid-phase carrier for supporting more coating antigens through acylamide bonds. Under the mechanism of competitive immunity, the brombuterol in solution competed with the coating antigen immobilized on the resin beads for the limited binding sites of antibody. Then, horseradish peroxidase-labeled secondary antibodies were introduced into the immunosensor to combine with polyclonal antibodies. The chemiluminescence intensity of the luminol-p-iodophenol-H2O2 system was catalyzed by horseradish peroxidase, and thus, signal amplification was achieved. Under the optimal conditions of the concentration of coating antigen, antibody and enzymatic secondary antibody, brombuterol could be detected quantitatively. The chemiluminescence intensity decreased linearly with the logarithm of the brombuterol concentration in the range of 0.001 to 300 ng mL−1. The limit of detection (3σ) and the limit of quantitation were 0.33 pg mL−1 and 1.1 pg mL−1, respectively. This method had undergone a series of test conditions and exhibited good specificity, stability, and reproducibility. The immunosensor can also detect real samples and provide prospects for the detection of other small molecule compounds, such as isoproterenol, enrofloxacin, and ofloxacin.