Fig. 2

a UV–Vis-NIR spectra and b zeta potential of Au NRs, CTAB-coated Au@Pt NRs, PSS-modified Au@Pt NRs and Au@Pt NR-antigen conjugates. The numbers 1, 2, 3, 4 and 5 in b represent the amount of conjugating antigen. (1) 0.001 mg/mL, (2) 0.01 mg/mL, (3) 0.1 mg/mL, (4) 1 mg/mL and (5) 10 mg/mL. All error bars were calculated based on the standard deviation of three measurements