Shen Jianzhong, Xu Fei, Jiang Haiyang, Wang Zhanhui, Tong Jing, Guo Pengju, Ding Shuangyang
National Reference Laboratories for Veterinary Drug Residue, Department of Veterinary Pharmacology and Toxicology, College of Veterinary Medicine, China Agricultural University, Beijing, 100094, People's Republic of China.
Anal Bioanal Chem. 2007 Dec;389(7-8):2243-50. doi: 10.1007/s00216-007-1609-0. Epub 2007 Sep 26.
Quantum dot (Qdot) nanocrystals have been increasingly used as fluorescence labels in fluoroimmunoassays recently because of their excellent optical characteristics. In this paper, a new monoclonal antibody (MAb) against sulfamethazine (SMZ) was successfully produced and linked to Qdot nanocrystals by covalent coupling. The Qdot-MAb conjugates were characterized by SDS-PAGE and high-performance capillary electrophoresis (HPCE). An enzyme-linked immunosorbent assay (ELISA) method was utilized to evaluate the antigen-antibody binding affinity and then a novel direct competitive fluorescence-linked immunosorbent assay (cFLISA) for the detection of SMZ in milk by using Qdots as fluorescent labels was evaluated. The results showed that the 50% inhibition values (IC50) of the cFLISA were 4.3 ng/mL in milk and 5.2 ng/mL in PBS, and the limits of detection (LODs) were 0.6 ng/mL in milk and 0.4 ng/mL in PBS, respectively. The recoveries of SMZ from spiked milk samples at levels of 10-100 ng/mL ranged from 94 to 106%, with coefficients of variation (CVs) of 2.1-9.2%.
量子点（Qdot）纳米晶体因其优异的光学特性，近年来在荧光免疫分析中越来越多地用作荧光标记物。本文成功制备了一种针对磺胺二甲嘧啶（SMZ）的新型单克隆抗体（MAb），并通过共价偶联将其与量子点纳米晶体相连。采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和高效毛细管电泳（HPCE）对量子点-单克隆抗体偶联物进行了表征。利用酶联免疫吸附测定（ELISA）方法评估抗原-抗体结合亲和力，然后评估了一种以量子点作为荧光标记物检测牛奶中SMZ的新型直接竞争荧光免疫吸附测定（cFLISA）。结果表明，cFLISA在牛奶中的50%抑制值（IC50）为4.3 ng/mL，在磷酸盐缓冲液（PBS）中为5.2 ng/mL，牛奶中的检测限（LOD）为0.6 ng/mL，PBS中的检测限为0.4 ng/mL。添加水平为10 - 100 ng/mL的加标牛奶样品中SMZ的回收率为94%至106%，变异系数（CV）为2.1%至9.2%。
