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.

本研究针对维吉尼亚霉素M1（VIR M1）制备了高灵敏度与高特异性的单克隆抗体（mAb），并首次建立了基于量子点的荧光免疫层析检测法（QDs-ICA），用于VIR M1的快速灵敏分析。该单克隆抗体在酶联免疫吸附试验（ELISA）中显示出0.5 ng/mL的半数抑制浓度（IC₅₀），且对其余三种结构类似物的交叉反应性（CR）均低于0.1%。将该单克隆抗体与最大发射波长为610 nm（橙红色）的ZnCdSe/ZnS（核/壳型）量子点偶联，作为荧光探针以提升QDs-ICA的检测灵敏度。本QDs-ICA的临界值为12.5 ng/mL，线性范围为0.7~14.5 ng/mL，定量限为0.7 ng/mL。相较于现有VIR M1分析方法，该QDs-ICA具备更高的检测灵敏度。针对加标于猪饲料、肌肉及肝脏样品中的VIR M1进行检测时，批内回收率介于94.0%~111.6%，最高变异系数（CV）为6.7%；批间回收率介于94.7%~107.6%，最高CV为9.4%。综上，该QDs-ICA可作为分析动物饲料及动物源食品中VIR M1的潜在检测方法。