title: Magnetic-nanobead-based competitive enzyme-linked aptamer assay for the analysis of oxytetracycline in food.
abstract: This study presents a novel analytical method for the detection of oxytetracycline (OTC) in complex food matrices based on a direct competitive enzyme-linked aptamer assay and magnetic separation technology. In this protocol, free OTC competed with horseradish peroxidase labeled OTC (OTC-HRP) for binding to the OTC aptamer immobilized on magnetic beads. The parameters that can affect the response, such as avidin concentration, aptamer concentration, OTC-HRP concentration, incubation temperature, incubation time, blocking agent, and binding buffer, were optimized. Under the optimal conditions, the linear range for the OTC concentration detection is 0.5-100 ng mL(-1), with a concentration of OTC needed to obtain 50 % of the maximum signal of 14.47 ng mL(-1). The limit of detection and the limit of quantitation were 0.88 and 3.40 ng mL(-1), respectively. There was no obvious cross-reactivity with most of the tetracycline pesticides. The recovery rates ranged from 71.0 to 91.2 % for the food samples, including chicken, milk, and honey, and the relative standard deviation was less than 15.0 %. The proposed method was applied to measure OTC in real samples, and was validated using high-performance liquid chromatography. This method has the advantages of magnetic separation and the concentration effect of magnetic nanoparticles, the specificity of the aptamer, and the high-throughput of microtiter plates; it offers a promising approach for the screening of OTC because it is simple, rapid, highly sensitive, and has low cost.
authors: Analysis and Testing Center, Xinjiang Academy of Agriculture and Reclamation Science, Wuyi Road No. 221, Shihezi, 832000, China, shzlcx2002@163.com.
authors: Chunxia
authors: C
authors: Lu
authors: Zonggui
authors: Z
authors: Tang
authors: Changbin
authors: C
authors: Liu
authors: Lichao
authors: L
authors: Kang
authors: Fengxia
authors: F
authors: Sun
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D001360:Avidin / Q000737:chemistry; D019921:Biotinylation; D004350:Drug Residues / Q000737:chemistry*; D005504:Food Analysis / Q000379:methods*; D005506:Food Contamination; D059346:Magnets; D049329:Nanostructures; D010118:Oxytetracycline / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D000900:Anti-Bacterial Agents; D052157:Aptamers, Nucleotide; D001360:Avidin; D010118:Oxytetracycline