Sandwich ELISA and immunochromatographic strip of Kunitz trypsin inhibitor using sensitive monoclonal antibodies

Kunitz trypsin inhibitor (KTI) is a predominant anti-nutritional factor in soybean. The objective of this study was to develop a sandwich enzyme-linked immunosorbent assay and immunochromato graphic strip (ICS) method for the semi-quantification of KTI in soybean. The limit of detection was 0.1481 ng/ml, and the linear dynamic range was 0.2–20 ng/ml. KTI recovery was 98.40–110.66% from KTI-spiked milk samples, with coefficients of variation of 4.41–10.62%. Based on ICS results, KTI had cutoff values of 5 ng/ml and 2.5 ng/ml in 0.05% Tween-added phosphate-buffered saline and milk, respectively. ICS has potential applications for the fast detection of KTI.