title: One-step sensitive detection of Salmonella typhimurium by coupling magnetic capture and fluorescence identification with functional nanospheres.
abstract: Sensitive, rapid, and reliable detection of bacteria has always been pursued due to the great threat of the bacteria to human health. In this study, a convenient one-step strategy for detecting Salmonella typhimurium was developed. Immunomagnetic nanospheres (IMNS) and immunofluorescent nanospheres (IFNS) were used to specifically capture and recognize S. typhimurium simultaneously. After magnetic separation, the sandwich immune complexes (IMNS-bacteria-IFNS) were detected under a fluorescence microscope with a detection limit as low as ca. 10 CFU/mL. When they were detected by fluorescence spectrometer, a linear range was exhibited at the concentration from 10(5) to 10(7) CFU/mL with R(2) = 0.9994. Compared with the two-step detection strategy, in which the bacteria were first captured with the IMNS and subsequently identified with the IFNS, this one-step strategy simplified the detection process and improved the sensitivity. Escherichia coli and Shigella flexneri both showed negative results with this method, indicating that this method had excellent selectivity and specificity. Moreover, this method had strong anti-interference ability, and it had been successfully used to detect S. typhimurium in synthetic samples (milk, fetal bovine serum, and urine), showing the potential application in practice.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, and Wuhan Institute of Biotechnology, Wuhan University, Wuhan 430072, People's Republic of China.
authors.forename: Cong-Ying
authors.initials: CY
authors.lastname: Wen
authors.forename: Jun
authors.initials: J
authors.lastname: Hu
authors.forename: Zhi-Ling
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Zhi-Quan
authors.initials: ZQ
authors.lastname: Tian
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Ou
authors.forename: Ya-Long
authors.initials: YL
authors.lastname: Liao
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.forename: Min
authors.initials: M
authors.lastname: Xie
authors.forename: Zi-Yong
authors.initials: ZY
authors.lastname: Sun
authors.forename: Dai-Wen
authors.initials: DW
authors.lastname: Pang
mesh_terms: D005453:Fluorescence; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D054118:Nanospheres / Q000737:chemistry*; D010316:Particle Size; D012486:Salmonella typhimurium / Q000276:immunology / Q000302:isolation & purification*; D013050:Spectrometry, Fluorescence; D013499:Surface Properties
chemical_list: D058185:Magnetite Nanoparticles