Immunosensor For Enterobabacter Sakazakii Based On Electrochemically Reduced Graphene Oxide

Enterobacter sakazakii (E. sakazakii) is a food-borne pathogen that has been associated with sporadic cases causing and outbreaks severe meningitis, sepsis, and necrotizing enterocolitis in neonates and infants, the mortality rate is much more than50%.Immunosensor is one of the most popular alternatives for determination, which is based on the specific binding of antibody to its antigen, with an increased sensitivity and selectivity and a reduction in analysis time. In addition, more and more studies have demonstrated that electrochemical sensors can be used to detect pathogens with high sensitivity, fast response, low cost and suitability of constructing portable devices. New materials catch more and more attention to application of biosensors, such as graphene, gold nanoparticles, Ionic Liquid. The comments of this paper were described as follow:1. Preparation and Electrochemical Application of Graphene Sensors based on different graphene modified the screen-printed carbon electrode (SPCE) have developed, and cyclic voltammetry (CV) was carried out to characterize the electrochemical their properties. Moreover, we found that the peak current of ERGO modified SPCE was much higher than that of chemically reduced graphene oxide (CRGO) modified SPCE and bare SPCE.2. Immunosensor for Enterobacter sakazakii Based on Electrochemically Reduced Graphene oxideA novel immunosensor based on electrochemically reduced graphene oxide was developed for detection of bacteria, Enterobacter sakazakii. Firstly, a screen-printed carbon electrode (SPCE) was modified by electrochemical method to deposit the grapheme. The horseradish peroxidase labeled bacteria-specific antibody (HRP-anti-E.sakazakii) was assembled onto the modified electrode to improve the sensitivity of immunosensor. Cyclic voltammetry (CV) was carried out to characterize the electrochemical properties of different electrodes and detect E.sakazakii. Under optimal conditions, the electrochemical immunosensor for E. sakazakii exhibited a linear range of102to109cfu mL-1with a detection limit of9.1×101cfu mL-1(S/N=3). Thus, the novel immunosensor constructed in this study can specifically, sensitively and rapidly detect E. sakazakii, which may contribute to further food-borne pathogen detection.3. Novel imunnosensor for bacterial detection based on electrochemically reduced graphene oxide-Gold nanoparticles/ionic liquid modified electrodeA novel immunosensor based on electrochemically reduced graphene oxide (ERGO)-Gold nanoparticles (AuNPs)/1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) was developed for detection of bacteria, Enterobacter sakazakii. Firstly, a screen-printed carbon electrode (SPCE) was modified by electrochemical method to co-electrodeposit gold nanoparticles decorated graphene (labeled as ERGO-AuNPs). Then, the mixture of [BMIM]PF6and the horseradish peroxidase labeled bacteria-specific antibody (HRP-anti-E. sakazakii) was assembled onto the modified electrode to improve the sensitivity and selectivity of immunosensor. The surface morphologies of modified electrodes were characterized by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM). The electrochemical performance of immunosensor was evaluated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Under optimal conditions, the electrochemical immunosensor for E. sakazakii exhibited a linear range of103to109cfu mL-1with a detection limit of1.19×102cfu mL-1(S/N=3). The good performance of the immunosensor is attributed to the ERGO-AuNPs films’good biocompatibility which allows retaining high enzymatic catalytic activity and its favorable electrical conductivity and electron-transfer ability which promoted electrons transfer among the electrode, the redox center of HRP,[BMIM]PF6, mediator thionine and H2O2. Thus, the proposed immunosensor could sensitively and rapidly detect E. sakazakii and exhibite excellent long-term storage stability. In addition, this ERGO-AuNPs modified SPCE could also provide many potential applications for the rapid detection of different bacteria. 4. Novel imunnosensor for E.sakazakii based on Graphene-Gold nanoparticles/Thionine Modified ElectrodeA novel immunosensor for Enterobacter sakazakii(E. sakazakii) based on electrochemically reduced graphene oxide (ERGO)-Gold nanoparticles(AuNPs)/Thionine/HRP-anti-E. sakazakii was developed. We used the electrochemical approach to the synthesis of high quality Gold nanoparticles decorated graphene nanoparticles (labeled as ERGO-AuNPs) onto screen-printed carbon electrode (SPCE). Then Thionine was chemisorbed by ERGO-AuNPs. Furthermore, horseradish peroxidase labeled antibody to E.sakazakii (HRP-anti-E. sakazakii) was chemisorbed onto Thionine film through the electrostatic force with the amino group of Thionine. The surface morphologies of modified films were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The assemble procedure was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, the electrochemical immunosensor for E. sakazakii exhibited a linear range of103to109cfu mL-1with a detection limit of9.6×101cfu mL-1(S/N=3). The immunosensor displayed high specificity, satisfactory reproducibility, stability and accuracy.