Figure 2.

(A) SERS spectra of the AuNPs/OPD, AuNPs and OPD solutions; (B) Raman response of the AuNPs/OPD solution under incubation at 37 °C for (a) 0 h, (b) 1 h, (c) 2 h, (d) 3 h, (e) 6 h, (f) 12 h, (g) 24 h; (C) SERS intensities at the bands of 1500 cm⁻¹ and 1262 cm⁻¹ plotted with different incubation times. Error bars were based on three independent measurements.