title: Characterization and application of quantum dot nanocrystal-monoclonal antibody conjugates for the determination of sulfamethazine in milk by fluoroimmunoassay.
abstract: 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%.
authors: 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.
authors: Jianzhong
authors: J
authors: Shen
authors: Fei
authors: F
authors: Xu
authors: Haiyang
authors: H
authors: Jiang
authors: Zhanhui
authors: Z
authors: Wang
authors: Jing
authors: J
authors: Tong
authors: Pengju
authors: P
authors: Guo
authors: Shuangyang
authors: S
authors: Ding
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015200:Fluoroimmunoassay / Q000295:instrumentation / Q000379:methods*; D008892:Milk / Q000737:chemistry*; D053758:Nanoparticles; D045663:Quantum Dots; D013418:Sulfamethazine / Q000032:analysis* / Q000737:chemistry / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D013418:Sulfamethazine