Electrochemical immunosensor for Enterobacter sakazakii detection based on electrochemically reduced graphene oxide–gold nanoparticle/ionic liquid modified electrode

• An ultrasensitive immunosensor was designed for detection of E. sakazakii.
• ERGO–AuNPs constructed a promising sensing platform with large surface areas and excellent conductivity of electron transportation.
• The employment of the [BMIM]PF6 achieved good biocompatibility of biological activity preservation.
• The HRP effectively improved the electrochemical signal via catalysis.
• The strategy realized high sensitivity good specificity, and good stability.

Enterobacter sakazakii (E. sakazakii) is a gram-negative food-borne pathogen, which can cause serious disease. Rapid screening plays an important role in the prevention and identification of E. sakazakii to cause food poisoning. In this study, a facile and sensitive approach for E. sakazakii detection has been presented. This novel electrochemical immunosensor based on electrochemically reduced graphene oxide–gold nanoparticles (ERGO–AuNP)/1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) was developed for the detection of E. sakazakii. Firstly, a screen-printed carbon electrode (SPCE) was modified by ERGO–AuNP. Then, the mixture of [BMIM]PF6 and HRP-anti-E. sakazakii was assembled onto the modified electrode to improve the sensitivity and selectivity of the immunosensor. The surface morphologies of modified electrodes were characterized by means of AFM and SEM. The electrochemical performance of the immunosensor was evaluated by EIS and CV. The electrochemical immunosensor for E. sakazakii exhibited a linear range from 103 to 109 CFU/mL with a detection limit of 1.19 × 102 CFU/mL (S/N = 3). The good performance of the immunosensor is attributed to the good biocompatibility of ERGO–AuNP films. The proposed immunosensor also exhibits excellent long-term storage stability. In addition, this electrochemical immunosensor based on ERGO–AuNP modified SPCE could also provide many potential applications for the rapid detection of different bacteria.

The conductivity of the electrode was promoted by the electrodeposition of graphene oxide and HAuCl4, and the sensitivity of the immunosensor was enhanced and strengthened. The binding capacity and biocompatibility of ERGO–Au modified electrode were elevated greatly by the IL film. The proposed enzyme immunosensor had high sensitivity, good specificity, acceptable accuracy and reproducibility, and low detection limit characteristics and could be a promising analytical tool in the detection of E. sakazakii in practical samples.Figure optionsDownload as PowerPoint slide