Gold nanoparticle-based lateral flow strips for rapid and sensitive detection of Virginiamycin M1

Analysis of virginiamycin M1 in swine feed, muscle and liver samples by quantum dots-based fluorescent immunochromatographic assay

Based on a highly sensitive and specific monoclonal antibody (mAb) against virginiamycin M1 (VIR M1), a quantum dots-based fluorescent immunochromatographic assay (QDs-ICA) for quick and sensitive analysis of VIR M1 was established for the first time. The mAb showed a half-maximal inhibitory concentration (IC₅₀) of 0.5 ng/mL and cross-reactivity (CR) values below 0.1% for other three analogues when used in enzyme-linked immunosorbent assay (ELISA). The mAb was conjugated to ZnCdSe/ZnS (core/shell) QDs with maximum emission wavelength of 610 nm (orange-red) which was selected as fluorescent probe to increase QDs-ICA sensitivity. The cut-off value of QDs-ICA was 12.5 ng/mL. QDs-ICA showed a linear range from 0.7 to 14.5 ng/mL with a limit of quantification of 0.7 ng/mL. Compared with existing methods for the analysis of VIR M1, the QDs-ICA exhibited higher sensitivity. For analysis of VIR M1 concentrations spiked into swine feed, muscle and liver samples, recovery rates ranged from 94.0% to 111.6% with the highest coefficient of variation (CV) of 6.7% for intra-assay, and for inter-assay ranged from 94.7% to 107.6% with the highest CV of 9.4%. In conclusion, the QDs-ICA could be a potential method for analyzing VIR M1 in animal feed and animal-derived food.

Development of a lateral-flow ICA strip for the detection of colchicine

Colchicine (COL), which is extracted from colchicine and papaya, is widely used in medicine. However, COL poisoning causes serious adverse complications including death. Therefore, there is a need to develop a sensitive COL detection method. In this study, we developed a highly sensitive monoclonal antibody 1E4 with a half-maximal inhibitory concentration and linear range of 0.43 ng mL^-1 and 0.09-2.16 ng mL^-1, respectively. Using 1E4, we developed a lateral-flow immunochromatographic assay (ICA) strip for COL detection. Based on the results, the detection interval was 1-25 ng mL^-1 in milk, 2.5-50 ng mL^-1 in beef, 1-25 ng mL^-1 in edible lily and 2.5-25 ng mL^-1 in daylily. The lateral-flow ICA strip can be used as an effective tool for COL detection in food samples on site.