Since one of the major challenges in the fabrication of SERS probes is to maintain batch-to-batch reproducibility, with SERS enhancement varying across different samples, depending on their preparation protocol, we evaluated reproducibility, in terms of Raman SERS signals, for six different batches. Figure reports the Raman spectra, while the intensity of the Raman peaks at 1069 and 1577 cm -1 is displayed in Figure . A striking similarity was observed with calculated RSD of the two intensities 3.9 % and 2.6 %, respectively, thereby demonstrating excellent reproducibility.