Here,on the basis of mimotope of small analytes,we demonstrated a new approach for development of sensitive and environmentally friendly immunoassay for toxic small analytes based on the peptide-MBP fusion protein.In this work,using mycotoxin fumonisin B 1(FB 1)as a model hapten,phage displayed peptide(mimotope)that binds to the anti-FB 1 antibody were selected by biopanning from a 12-mer peptide library.The DNA coding for the sequence of peptide was cloned into Escherichia coli ER2738 as a fusion protein with a maltose binding protein(MBP).The prepared peptide-MBP fusion protein are "clonable"homogeneous and FB 1-free products and can be used as a coating antigen in the immunoassay.The half inhibition concentration of the quantitative immunoassay setup with fusion protein(F1-MBP and F15-MBP)was 2.15 ± 0.13 ng/mL and 1.26 ± 0.08 ng/mL,respectively.The fusion protein(F1-MBP)was also used to develop a qualitative Elispot assay with a cutoff level of 2.5 ng/mL,which was 10-fold more sensitive than that measured for chemically synthesized FB 1 - BSA conjugates based Elispot immunoassay.The peptide-MBP fusion protein not only can be prepared reproducibly as homogeneous and FB 1-free products in a large-scale but also can contribute to the development of a highly sensitive immunoassay for analyzing FB 1.Furthermore,the novel concept might provide potential applications to a general method for the immunoassay of various toxic small molecules.