A novel, enzyme-linked immunosorbent assay based on the catalysis of AuNCs@BSA-induced signal amplification for the detection of dibutyl phthalate.

A novel, competitive, enzyme-linked immunosorbent assay (ELISA) was presented in this paper based on the inhibition of catalysis of AuNCs@BSA triggered by dissolved Ag+ for the detection of dibutyl phthalate (DBP). In the immunoassay system, numerous Ag+ was released from AgNPs (labelled on the second antibody, AgNPs@Ab2) in the presence of H2O2 after the competition step, preventing AuNCs@BSA from inducing a color change of 3,3',5,5'-tetramethylbenzidine (TMB) to blue. Due to the signal amplification by the principle, the sensitivity of the modified ELISA was improved with the low limit of detection (LOD) of 4.017μg/L for DBP, which was decreased 16 times relative to that using conventional ELISA with the same antibody. In addition, the established method showed satisfactory accuracy and reliability (recoveries, 85.75-117.73%; CV, 1.33-6.79%) in spike-recovery analysis. To the best of our knowledge, this is the first time that AuNCs@BSA has been used in ELISA as a peroxidase-like catalyst. Our method shows great potential for trace DBP detection from environmental and food samples.