基于纳米抗体的胶体金免疫层析法快速检测蔬菜中腐霉利

为探索纳米抗体在小分子有害物胶体金免疫层析方法（colloidal gold immuno-chromatography assay,GICA）应用的可行性，以农药腐霉利为模型，系统研究胶体金标记参数、胶体金工作缓冲液以及样品前处理方法等对GICA的影响。结果表明：胶体金颗粒大小、标记pH值及抗体用量是保证纳米抗体-金标探针稳定性的关键因素。在最佳工作条件下，纳米抗体GICA检测腐霉利的检出限、半抑制浓度和可视检出限分别为0.44、6.29μg/L和200μg/L，其灵敏度比基于传统单克隆抗体的GICA提高了4.1倍。采用QuEChERS对韭菜、黄瓜、番茄等样品进行前处理，利用纳米抗体优良的有机溶剂耐受性，省去了有机溶剂吹干程序，加标样品平均回收率介于80.1%～109.6%之间，且对实际样品的检测与标准气相色谱-质谱法结果一致。本研究表明纳米抗体作为一种新型原料可替代传统抗体用于小分子有害物的快速检测，所建立的腐霉利GICA方法具有灵敏、准确、快速和简便等优势，可用于蔬菜腐霉利残留的快速筛查。

Rapid Detection of Procymidone in Vegetables by Nanobody-Based Colloidal Gold Immunochromatography Assay

To explore the feasibility of applying nanobodies in colloidal gold immunochromatography assay (GICA) for small-molecule harmful substances, this study systematically investigated the effects of colloidal gold labeling parameters, colloidal gold working buffer and sample pretreatment methods on GICA using the pesticide procymidone as a model. The results showed that the size of colloidal gold particles, labeling pH and the amount of antibody used were the key factors to ensure the stability of the nanobody-gold-labeled probes. Under the optimal conditions, the limit of detection, half-maximal inhibitory concentration (IC50) and visual detection limit of GICA for procymidone were 0.44, 6.29 and 200 μg/L, respectively. The sensitivity was 5.1-fold higher than that of conventional monoclonal antibody-based GICA. The quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure was used for the pretreatment of Chinese leek, cucumber and tomato samples. Based on the excellent organic solvent tolerance of nanobodies, the organic solvent blow-drying procedure was omitted. The average recoveries of the spiked samples ranged from 80.1% to 109.6%, and the results for the actual samples were consistent with those of gas chromatography-mass spectrometry (GC-MS). This study showed that nanobodies are a potential alternative to conventional antibodies for immunoassays for the rapid detection of small molecules. The proposed nanobody-based GICA can be used for the rapid screening of procymidone in vegetables with the advantages of high sensitivity, high accuracy, rapidity and simplicity.