title: A novel biosensor for Escherichia coli O157:H7 based on fluorescein-releasable biolabels.
abstract: New techniques are required for the rapid and sensitive detection of Escherichia coli O157:H7 (E. coli O157:H7), a pathogenic bacterium responsible for serious and sometimes life-threatening diseases in humans. In this study, we developed a highly sensitive and efficient biosensor for the quantitative detection of E. coli O157:H7 by integrating fluorescein-releasable biolabels with a magnetism-separable probe. Hollow silica nanospheres with a diameter of approximately 350 nm were synthesized, enriched with fluorescein, and surface-protected with macromolecule layers of poly (acrylic acid) and poly (dimethyldiallylammonium chloride). These fluorescein-enriched hollow silica nanospheres were characterized using scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. They were further functionalized as immune labels of E. coli O157:H7 for a sandwich-type immune reaction between this bacterium and magnetic nanoparticles (Fe3O4@SiO2). Next, the E. coli O157:H7 cells were captured, magnetically separated, and quantified based on the fluorescence intensity of the fluorescein released from the biolabels of the fluorescein-enriched hollow silica nanospheres. This analytic process can be completed within 75 min, and the biosensor showed a linear relationship ranging from 4 to 4.0 × 10(8)cfu/mL with a detection limit of 3 cfu/mL. These results show that the developed fluorescent sensor has excellent specificity, and good reproducibility and stability. This study used real spiked samples for detection, indicating that this technique has a wide range of potential applications and may be readily adapted for detecting other pathogens.
authors.affiliation: College of Petrochemical Engineering, Changzhou University, Changzhou 213614, PR China; College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang Province, PR China.
authors.forename: Rong-Rong
authors.initials: RR
authors.lastname: Hu
authors.affiliation: College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang Province, PR China. Electronic address: yinzhengzhi@mail.zjxu.edu.cn.
authors.forename: Zheng-Zhi
authors.initials: ZZ
authors.lastname: Yin
authors.affiliation: College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang Province, PR China.
authors.forename: Yan-Bo
authors.initials: YB
authors.lastname: Zeng
authors.affiliation: College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang Province, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
authors.affiliation: College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang Province, PR China.
authors.forename: Hai-Qing
authors.initials: HQ
authors.lastname: Liu
authors.affiliation: College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Shao
authors.affiliation: School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
authors.forename: Shi-Bin
authors.initials: SB
authors.lastname: Ren
authors.affiliation: College of Petrochemical Engineering, Changzhou University, Changzhou 213614, PR China; College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001, Zhejiang Province, PR China. Electronic address: lei.li@mail.zjxu.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Li
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D019453:Escherichia coli O157 / Q000302:isolation & purification* / Q000472:pathogenicity; D019793:Fluorescein / Q000737:chemistry; D005453:Fluorescence; D006801:Humans; D057230:Limit of Detection; D054118:Nanospheres / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D012822:Silicon Dioxide; D019793:Fluorescein
keywords: Biosensor; Escherichia coli O157:H7; Fluorescein-releasable biolabel; Magnetic separation