Fe3O4@CuS-based immunochromatographic test strips and their application to label-free and dual-readout detection of Escherichia coli O157:H7 in food
2020
Zhang, Meng | Bu, Tong | Tian, Yongming | Sun, Xinyu | Wang, Qinzhi | Liu, Yingnan | Bai, Feier | Zhao, Shuang | Wang, Li
Herein, a label-free and dual-readout immunochromatographic test strip (ITS) for the sensitive detection of Escherichia coli (E. coli) O157:H7 by taking advantages of the strong capture ability of Fe₃O₄@CuS nanostructures (NSs) towards bacteria and their ultrahigh photothermal effects (PTEs) was reported. Especially, without the customarily antibody (Ab)-labeled probe, Fe₃O₄@CuS NSs could be adsorbed onto the surfaces of bacteria to form Fe₃O₄@CuS-bacteria conjugates and then trapped by immobilized Abs on the test line (T-line), forming a characteristic yellow band. After direct immunoreactions, the PTEs of Fe₃O₄@CuS NSs endowed T-line to be irradiated by an 808 nm infrared light, obtaining satisfactory sensitivity and accuracy. Under optimal conditions, E. coli O157:H7, as low as 10³ and 10² CFU/mL, could be monitored in colorimetric and photothermal modes. Additionally, E. coli O157:H7 was successfully detected in beef, chicken, milk and honey samples by this proposed platform with a recovery of 80–120%.
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