Supporting Information

The detailed indirect competition ELISA for BPA detection as follows:

1. Coating each well of 96-well plate with 100 µL of BPA antigen dilution (diluted by the coating

solution).

2. Incubate the 96-well plate for 2h at room temperature.

3. Remove the coating solution and wash three times with 200 µL of PBS-Tween 20 and pat dry of the

plate on a paper towel.

4. Blocking the remaining protein-binding sites in each well with 100 µL of blocking solution(0.5%

ovalbumin in PBS) and incubate the plate at 37 ℃ for 2 h.

5. Remove the blocking solution and wash three times with 200 µL of PBS-Tween 20 solution.

6. Add 100 µL of BPA at various concentration or samples with 100 µL anti-BPA monoclonal

antibody, and then incubate the plate at 37 ℃ for 0.5 h.

7. Remove the excess antibody and BPA in each well and wash three times with PBS-Tween 20 and

pat dry of the plate on a paper towel.

8. Add 100 µL of diluted secondary antibody (horseradish peroxidase-conjugated goat anti-rabbit

antibody, 1: 3000 with PBS-Tween 20) and incubate the plate at 37 ℃ for 0.5 h.

9. Remove the excess secondary antibody of each well and wash three times with PBS-Tween 20 and

pat dry of the plate on a paper towel.

10. Add 100 µL of the substrate solution per well (3,3',5,5'-Tetramethylbenzidine (TMB) and

hydrogen peroxide) and incubate the plate at room temperature for 15 min in dark.

11. Add 100 µL of the stop solution per well (H2SO4, 2 mol/L) and record the absorption of each well

with a plate reader at 450 nm.

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Fig. S1. Representative TEM images of (A) Au nanoroads and (B) Au nanoparticles.

Fig. S2. The corresponding UV-vis of Au NRs, Au NPs, and the assemblies.

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Fig. S3. Representative TEM images of assemblies for different hybridization times, (A) 0 and (B) 30 min and (C) 2 (D) 4, (E) 8 and (F) 12h.

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Fig. S4. Representative SERS spectra of different targets. The concentration of different targets: BPA (0.5 ng/mL), BPC (50 ng/mL), DPA (50 ng/mL), DES (50 ng/mL). Control was without any targets spiked in.

Fig. S5. UV-Vis spectra for BPA detection with various concentrations.

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