Simultaneous Determination of Antibiotics, Mycotoxins, and Hormones in Milk by an 8–17 DNAzyme-Based Enzyme-Linked Immunosorbent Assay

The simultaneous detection of three kinds of small-molecule contaminants (antibiotics, mycotoxins, and hormones) in milk was realized by using an 8–17 DNAzyme-based fluorescent enzyme-linked immunosorbent assay (ELISA), in which 8–17 DNAzyme was utilized as the catalytic enzyme for amplifying the signal. Compared with the conventional ELISA in which horseradish peroxidase is used as the catalyzing factor, this 8–17 DNAzyme-based ELISA could achieve multicolor signal output with lower detection limits. The linearities for chloramphenicol, 17β-estradiol, and aflatoxin M 1 were in the range of 0.3 ng/mL–3 μg/mL, 3 ng/mL–3 μg/mL, and 3 pg/mL–3 ng/mL with quantitation limits of 0.3, 3, and 0.003 ng/mL, respectively. This proposed scheme demonstrated that the 8–17 DNAzyme might be an effective substitute for horseradish peroxidase in ELISA for the development of ultrasensitive and multicolor fluorescence immunoassay, which would stimulate the development of ELISA in a new orientation.