A disposable immunosensor for Shigella flexneri based on multiwalled carbon nanotube/sodium alginate composite electrode

A novel Shigella flexneri immunosensor based on horseradish peroxidase-labeled antibodies to S. flexneri (HRP–anti-S. flexneri) immobilized by physical adsorption on the multiwalled carbon nanotube (MWCNT)/sodium alginate (SA) composite modified screen-printed electrode surface was successfully fabricated. In this strategy, MWCNT/SA biocomposite acted as the matrix to adsorb and immobilize HRP–anti-S. flexneri. The modified electrodes were characterized with an atomic force microscope and cyclic voltammetry (CV). The analytical performance of the proposed immunosensor toward S. flexneri was investigated by CV. Under optimal conditions, the linear range of S. flexneri was from 104 to 1011 cfu/ml with a detection limit of 3.1 × 103 cfu/ml (signal/noise = 3). The specificity, reproducibility, stability, and accuracy of the proposed immunosensor were also evaluated. The proposed immunosensor showed simply fabricative, economical, efficient, and potential application for early assessment of S. flexneri.