The region of the marker bands of the SERS spectra acquired for the samples prepared at various molar ratios of Cys-cabn and Cys-CABN are presented in Fig. , while the entire examined spectral region is presented in Fig. . There is a clear evolution of the relative intensities of marker bands in Fig. , following changes in the composition of the cysteine solution added to AgNPs. This evolution was quantified in two ways. Firstly, the relative Notably, a similar but much less pronounced evolution of signal shape can be observed for other SERS bands, as shown in Fig. , proving that although the isotopic shift is widespread among the spectral features, only the selected marker bands were separated so distinctively.