To estimate the SERS EF, we employed the SM-SERS EF 42 method, using the formula EF = (ISERS/NSERS)/(Ibulk/Nbulk), where I and N represent the SERS signal intensity and the number of molecules, respectively. To avoid overestimating the EF values, Ibulk and Nbulk were carefully determined. Due to the fluorescence resonance of the Cy5 dye with the 633 nm laser, resulting in signal saturation that complicated Raman signal acquisition, we selected a 473 nm laser (2.4 μW) for bulk Raman measurements to avoid this issue.