Fig. 3.

The comparison of membrane types for Salmonella test strips. a M240, b M180, c M120, d M075. Strips a3, b2, b4, b6, b9, b10, b13, c5, d5 were prepared with naked 1 GNPs. 5 × 10⁶, 3 × 10⁶ and 3 × 10⁶ positive control cells were loaded in 100 μL PBS for Salmonella, E. coli and V. cholerae, respectively for single and mixture format (a). Mixtures were prepared by adding of 33 and 25 µL of each live bacteria into 100 µL PBS for three and four types of bacteria, separately for dipstick assay (b). 100 µL of live bacteria was added into 100 µL PBS for single bacteria dipstick assay (b–d). Salm: Salmonella positive control cells. D.soil: Dry soil bacteria sample