Disposable Immunosensor for Escherichia Coli O157:H7 Based on a Multi-Walled Carbon Nanotube-Sodium Alginate Nanocomposite Film Modified Screen-Printed Carbon Electrode

Abstract

A disposable immunosensor for the detection of Escherichia coli O157:H7 based on a multiwalled carbon nanotube–sodium alginate nanocomposite film was constructed. The nanocomposite was placed on a screen-printed carbon electrode, and horseradish peroxidase-labeled antibodies were immobilized to E. coli O157:H7 on the modified electrode to construct the immunosensor. The modification procedure was characterized by atomic force microscopy and cyclic voltammetry. Under optimal conditions, the proposed immunosensor exhibited good electrochemical sensitivity to E. coli O157:H7 in a concentration range of 10³–10¹⁰ cfu/mL, with a relatively low detection limit of 2.94 × 10² cfu/mL (S/N = 3). This immunosensor exhibited satisfactory specificity, reproducibility, stability, and accuracy, making it a potential alternative tool for early assessment of E. coli O157:H7.

Keywords:

• Detect
• Escherichia coli O157:H7
• Immunosensor
• Multiwalled carbon nanotubes
• Sodium alginate

Acknowledgments

This work was supported by the National High Technology Research and Development Program (“863” Program) of China (No. 2007AA091806), the National Natural Science Foundation of China (No. 30571623), and the Morningstar Fund of Shanghai Jiaotong University (No. 13X100010018).

Notes

^a Identical samples were analyzed by the proposed immunoelectrode and compared the ΔI_p with a reference value (0.800 µA) to judge the quality of samples (i.e., ΔI_p ≥ 0.800 µA means positive).

^b The ΔI_p of one negative sample (by ELISA) was detected to >0.800 µA.