process, when aggregate formation commenced. We did not observe
significant changes in the position of the SPRBmaximum or appearance
of secondary peaks during that time window. The SPRBs depend on
AgNP size, shape, dielectric constant of the medium, and electromagnetic
interactions among adjacent particles. Isolated silver spheres
have only one plasmonic resonance due to their symmetry, but new
resonances can appear when they are organized in small assemblies.
Therefore, multimers have newresonance modeswith a higher absorption
wavelength that the shown by isolated AgNPs (Amendola et al.,
2010). Therefore, we consider that non-aggregated AgNPs are the only
entities contributing to the size of the area under the SPRB. Consequently,
the reduction in the SPRB value, due to the decrease in the number of
surface electrons in the NPs, can be related to the change in Ag nanoparticle
concentration containing an average number of silver atoms, and
can be described by the following reaction law (Espinoza et al., 2012):