title: Rapid and ultrasensitive Salmonella Typhimurium quantification using positive dielectrophoresis driven on-line enrichment and fluorescent nanoparticleslabel.
abstract: This paper describes a convenient and sensitive methodology for Salmonella Typhimurium (S. Typhimurium) detection in microfluidic channels using positive dielectrophoresis (pDEP) driven on-line enrichment and fluorescent nanoparticles label. In the protocol, S. Typhimurium was first incubated with the anti-S. Typhimurium antibody conjugated RuBpy-doped fluorescent nanoparticles (Ab(S. Typhimurium)-FNPs). After incubation, the reacted mixture of S. Typhimurium and Ab(S. Typhimurium)-FNPs bioconjugates was directly introduced into the pDEP-based microfluidic system. On applying an AC voltage to the electrodes in a pDEP frequency region, the FNPs labeled S. Typhimurium cells moved to the electrodes and accumulated in the electrode gap, while the free Ab(S. Typhimurium)-FNPs were flowed away. The enriched FNPs labeled S. Typhimurium were detected by fluorescence microscopy at the focused detection areas. This new method constructed a simultaneous on-line enrichment and detection platform, eliminated the separation and washing-out steps usually required for FNPs label involved bioassay. Utilizing signal amplification effects produced by pDEP on-line enrichment and FNPs label, the detection limit for S. Typhimurium in deionized water is 56 colony forming units per milliliter (cfu/mL). We applied the established approach to detecting artificially contaminated bottled mineral water samples; S. Typhimurium of 110 cfu/mL was accurately detected. It is believed that the proposed method will find wide applications in biomedicine fields demanding higher sensitive bacterial identification.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Biology, College of Chemistry and Chemical Engineering, Hunan University, Key Laboratory for Bio-Nanotechnology and Molecule Engineering of Hunan Province, Changsha 410082, PR China.
authors.forename: Xiaoxiao
authors.initials: X
authors.lastname: He
authors.forename: Chong
authors.initials: C
authors.lastname: Hu
authors.forename: Qian
authors.initials: Q
authors.lastname: Guo
authors.forename: Kemin
authors.initials: K
authors.lastname: Wang
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Li
authors.forename: Jingfang
authors.initials: J
authors.lastname: Shangguan
mesh_terms: D000906:Antibodies / Q000276:immunology; D004586:Electrophoresis; D005456:Fluorescent Dyes; D005516:Food Microbiology; D006801:Humans; D057230:Limit of Detection; D008460:Meat / Q000382:microbiology; D044085:Microfluidics / Q000379:methods; D053758:Nanoparticles / Q000737:chemistry*; D012486:Salmonella typhimurium / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D000906:Antibodies; D005456:Fluorescent Dyes