| Enterobacter sakazakii (E. sakazakii), previously referred to as a 'yellow-pinmented Enterobacter cloacae", was designated as a unique species in1980. E. sakazakii is considered to be an opportunistic pathogen that has been associated with meningitis, necrotizing enterocolitis and bacteraemia in pre-term and immunocompromised full-term infants. The mortality rate is40%-80%.Electrochemical immunosensors based on specific antigen/antibody recognition have been widely used in the fields of clinical diagnosis, environmental analysis, and the food industry because of their high sensitivity, inherent simplicity, miniaturization, low cost, and low power requirements. Emphasis is given to fabricate new biosensors based on new materials, such as multi-wall carbon nanotubes and ionic liquids. The comments of this paper were described as follows:1Preparation of Enterobacter sakazakii antigenIn this experiment, E. sakazakii was successfully prepared, and then inactivated with formaldehyde at a concentration of0.4%(v/v) for12h at room temperature. Experimental results showed that E. sakazakii possessed good bioactivity. Following experiment could be successfully carried on because of the supportment of the above work.2Studies on Immunosensor for E. sakazakii Based on Multi-Wall Carbon Nanotubes and ThionineIn order to establish an accurate electrochemical method for detecting E. sakazakii, a sensitive and stable immunosensor was successfully fabricated. First, multi-wall carbon nanotube/sodium dodecyl-benzene sulfonate homogeneous composite was dropped on the surface of the4-channel screen-printed carbon electrode. Then thionine was chemisorbed by carboxylic MWCNT. Furthermore, horseradish peroxidase labeled antibody to E.sakazakii was chemisorbed onto thionine film through the electrostatic force with the amino group of thionine. The preparation process of modified electrode was characterized with atomic force microscope. Cyclic voltammetry was carried out to characterize the electrochemical properties of different electrodes and detect E. sakazakii. Under optimal conditions, concentration of E. sakazakii from10to108CFU/mL could be detected with a detection limit of5.7X101CFU/mL (S'N=3). The immunosensor exhibited high specificity, satisfactory reproducibility, stability and accuracy. The novel immunosensor had potential application for rapid detection.3A disposable immunosensor for E. sakazakii based on multiwalled carbon nanotube/ionic liquid/thionine modified electrodeA novel immunosensor for E. sakazakii based on screen-printed carbon electrode modified by multiwalled carbon nanotube,1-butyl-3-methylimi-dazolium hexafluorophosphate and thionine was developed for the first time. The surface morphologies of modified electrodes were characterized by means of atomic force microscope. The electrochemical performance of the immunosensor was evaluated by cyclic voltammetry. The background current of the gel of MWCNT-[BMIM]PF6in the construction of sensor was decreased by sodium dodecylbenzene sulfonate. Horseradish peroxidase labeled antibody to E. sakazakii in [BMIM]PF6showed high activity and stability. Under optimal conditions, E. sakazakii could be detected in range of103to109CFU/mL with detection limit of7.7×101CFU/mL in PBS and8.3×102CFU/mL in mimic samples.4Rapid Detection of E. sakazakii with [BMIM]PF6and Multi-wall Carbon Nanotube/Nafion Modified ElectrodeFor the purpose of improving the electrochemical signal and stability of the biosensor based on MWCNT/Nafion composite,[BMIM]PF6/Nafion/horsera-dish peroxidase labeled antibody biocomposite film was dropt onto screen-printed carbon electrode modified by multi-wall carbon nanotubes, a novel immunosensor had been developed for the rapid detection of antigen. The surface morphologies of modified films were characterized by atomic force microscope. The assemble procedure was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry was carried out to quantify the antigen. Using E. sakazakii as a model, under optimal conditions, concentration of E. sakazakii from103to109CFU/mL could be detected with a detection limit of3.4X102CFU/mL (S/N=3).The proposed immunoelectrode presented a satisfactory storage stability (the current response was95.50%of the initial response after being stored at4℃for a month), reproducibility (RSD<6%), selectivity (the current changes of non-target antigen△Ipc<0.3uA), accuracy (100%of the results obtained by the immunosensor were in agreement with those obtained by GB/T4789.40-2010), and high sensitivity. Furthermore, the immunoelectrode was inexpensive, relatively simple to fabricate and had potential application for rapid detection. |
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