title: Advantages of fluorescent microspheres compared with colloidal gold as a label in immunochromatographic lateral flow assays.
abstract: Label selection is of vital importance for immunochromatographic assays. In this study, the fluorescent microsphere test strip and colloidal gold immunochromatographic test strip (FM-ICTS and CG-ICTS) were developed for the detection of Escherichia coli O157:H7 on the basis of the sandwich format. Two types of labels, namely, colloidal gold particles (CG) and carboxyl-modified fluorescent microspheres (FMs), were compared while coupling with anti-E. coli O157:H7 monoclonal antibody (mAb). The FM-ICTS and CG-ICTS were also compared. Results show that the coupling rate between FMs and mAb was higher than that between CG and mAb. Under optimum conditions, the sensitivity of FM-ICTS was eight times higher than that of CG-ICTS. Approximately 0.1 μg of mAb was used in every FM-ICTS, whereas 0.4 μg of mAb was used in every CG-ICTS. The coefficient of variation of FM-ICTS and CG-ICTS was 4.8% and 16.7%, respectively. The FM-ICTS and CG-ICTS can be stored at room temperature for 12 months and specific to five E. coli O157:H7 strains. Milk sample inoculated with E. coli O157:H7 were tested by the FM-ICTS and CG-ICTS. The FM-ICTS sensitivity was 10(4) CFU/ml while the CG-ICTS sensitivity was 10(5) CFU/ml. The sensitivity, consumption of antibodies, and coefficient of variation of FM-ICTS were better than those of CG-ICTS for the detection of E. coli O157:H7.
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors.forename: Quan-Yuan
authors.initials: QY
authors.lastname: Xie
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Jiangxi Zodolabs Bioengineering Co, Ltd., Nanchang 330047, China.
authors.forename: Yan-Hua
authors.initials: YH
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China; Institute of Food Safety, Chinese Academy of Inspection and Quarantine, Beijing 100123, China.
authors.forename: Qi-Rong
authors.initials: QR
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors.forename: Heng-Yi
authors.initials: HY
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors.forename: Yong-Hua
authors.initials: YH
authors.lastname: Xiong
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Liu
authors.affiliation: Institute of Food Safety, Chinese Academy of Inspection and Quarantine, Beijing 100123, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Jin
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China. Electronic address: talktolaiwh@163.com.
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Lai
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis* / Q000276:immunology; D002846:Chromatography, Affinity / Q000379:methods*; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000382:microbiology; D019453:Escherichia coli O157 / Q000276:immunology* / Q000302:isolation & purification; D005456:Fluorescent Dyes / Q000737:chemistry*; D017979:Gold Colloid / Q000737:chemistry*; D008863:Microspheres; D011934:Reagent Strips / Q000737:chemistry*; D012680:Sensitivity and Specificity
chemical_list: D000907:Antibodies, Bacterial; D005456:Fluorescent Dyes; D017979:Gold Colloid; D011934:Reagent Strips
keywords: Colloidal gold; Escherichia coli O157:H7; Fluorescent microsphere; Immunochromatographic assay