title: A one-step homogeneous sandwich immunosensor for Salmonella detection based on magnetic nanoparticles (MNPs) and quantum Dots (QDs).
abstract: Simple immuno-magnetic separation tandem fluorescent probes based on quantum dots-antibody (QDs-Ab) were developed to detect Salmonella with sensitivity of 500 cfu mL-1. With two monoclonal antibodies, which recognize different antigenic determinant on the surface of Salmonella, we prepared antibody-coated magnetic nanoparticles (MNPs) and conjugates of QDs-Ab. The immune-magnetic beads were verified with high enrichment efficiency for Salmonella (90%). A sandwich structure formed if the Salmonella solution was mixed together with immune-beads and QDs-Ab, and the fluorescent single from QDs was related to the amount of Salmonella. A linear response between fluorescence intensity and various concentrations of Salmonella (2.5 × 103 to 1.95 × 108 cfu mL-1) were observed with this proposed method. The total assay time for Salmonella was 30 min, and no cross-reaction to other microbial strains, such as Staphylococcus aureus, Escherichia coli (E. coli) and Escherichia coli O157:H7 (E. coli O157:H7), were found using this detection system. All our results showed that the simple homogeneous immunoassay could be applied in Salmonella screening without time-consuming extra-enrichment of bacteria.
authors.affiliation: School of Food Science and Technology, State Key Lab of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu, China. kuangh@jiangnan.edu.cn.
authors.forename: Hua
authors.initials: H
authors.lastname: Kuang
authors.forename: Gang
authors.initials: G
authors.lastname: Cui
authors.forename: Xiujin
authors.initials: X
authors.lastname: Chen
authors.forename: Honghong
authors.initials: H
authors.lastname: Yin
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Yong
authors.forename: Liguang
authors.initials: L
authors.lastname: Xu
authors.forename: Chifang
authors.initials: C
authors.lastname: Peng
authors.forename: Libing
authors.initials: L
authors.lastname: Wang
authors.forename: Chuanlai
authors.initials: C
authors.lastname: Xu
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial; D001431:Bacteriological Techniques / Q000379:methods; D003429:Cross Reactions; D004926:Escherichia coli / Q000276:immunology; D019453:Escherichia coli O157 / Q000276:immunology; D005456:Fluorescent Dyes; D005516:Food Microbiology; D064088:Hazard Analysis and Critical Control Points; D006801:Humans; D007118:Immunoassay / Q000379:methods; D018189:Immunomagnetic Separation / Q000379:methods*; D058185:Magnetite Nanoparticles; D045663:Quantum Dots; D012475:Salmonella / Q000276:immunology* / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D005456:Fluorescent Dyes; D058185:Magnetite Nanoparticles