Monoclonal antibody-based homogeneous immunoassay for three banned agonists and molecular modeling insight

ABSTRACTA homogeneous fluorescence polarization immunoassay (FPIA) was developed for the detection of an agonist salbutamol (SAL). Based on salbutamol-succinate-fluoresceinthiocarbamyl hexylenediamine (SAL-SUC-HDF), a fluorescein tracer with 6-carbon bridge was found to be more sensitive, the optimal FPIA showed the working range from 31.7 to 264.1 ng/mL with an IC50 value of 91.4 ng/mL and a limit of detection 16.9 ng/mL. The cross-reactivity to brombuterol and clenbuterol was unexpectedly found to reach 447.3% and 255.8%, respectively. Computer-assisted molecular modeling revealed that the steric structure and electron density surfaces’ effect appeared to be s two important factors to the broad-specific recognition to other agonists.