An enzyme-free immunosorbent assay of staphylococcal enterotoxin B using a three-way DNA junction amplifier with an automatic reset function

Abstract

A highly sensitive immunoadsorption assay without traditional horseradish peroxidase for signal amplification was developed, utilizing a three-way DNA junction amplifier instead. The formation of a three-way DNA junction and release of trigger DNA with recycling was accomplished by toehold-mediated strand displacement. The fluorescent dye N-methyl mesoporphyrin IX, with highly structure-specific binding affinity towards G-quadruplexes, was employed for label-free and simple signal output. High sensitivity was achieved for concentrations as low as 7.21 pg mL⁻¹ by targeting Staphylococcal enterotoxin B for detection, and its applicability was confirmed by a recovery study of precooked dishes.