A sensitive, colorimetric immunosensor based on Cu-MOFs and HRP for detection of dibutyl phthalate in environmental and food samples

Abstract A sensitive and artful colorimetric immunosensor based on horseradish peroxidase (HRP) was designed by labelling metal–organic frameworks (Cu-MOFs) on the second antibody (Cu-MOFs@Ab 2 ) as signal amplification for the detection of trace dibutyl phthalate (DBP). In this system, when Cu-MOFs@Ab 2 was captured by antigen- primary antibody (Ab 1 ) complex, tremendous Cu(II) will be released from Cu-MOFs in the presence of nitric acid (HNO 3 ), and Cu(II) will be further reduced to Cu(I) after the addition of sodium ascorbate (SA), consequently, inhibiting the HRP to catalyse the colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into blue oxidized TMB (ox TMB). Under the optimized conditions, the limit of detection (LOD) was 1 μg L −1 , which was almost 60 times lower than that using a conventional ELISA with the same antibody. In addition, our method showed good accuracy and reproducibility (recoveries of 87.73–103.4%; CV values of 1.46–5.95%) through a spike-recovery analysis. The proposed immunosensor indicated great potential for trace DBP determination from environmental and food samples.