Enzyme-linked immunosorbent assay for aflatoxin B1 using a portable pH meter as the readout

Abstract

The pH meter, one of the most common sensors for laboratory measurements, has the advantages of excellent sensitivity, low price, high reliability, and ease of use. In this study, the high sensitivity of the pH meter was coupled with the high selectivity of immunosorbent assay to develop a simple and portable biosensor for aflatoxin B₁ (AFB₁) determination. Urease was first labelled on the AFB₁ antigen, in the presence of AFB₁; the target competed with the urease-labeled AFB₁ antigen to be captured by the antibody. Urease could catalyse the hydrolysis of urea into ammonia and induce the pH increase of the solution; the change could easily be detected using a handheld pH meter or pH-sensitive dye. Under optimized conditions, the pH value enhancement had a linear relationship with the logarithm of the concentration of AFB₁ in the range of 0.62 to 23.42 ng mL⁻¹. The proposed biosensor has been applied to detect AFB₁ in real samples with satisfactory results.