“…It is known that even within the family of cyanine dyes, certain cyanines form fluorescent J-aggregates whereas others do not. 3,10 Therefore, it is not surprising that eosin, the dye used by Ghosh et al, 25 which is chemically different from our cyanines, might exhibit AuNPs size-dependent formation of fluorescent J-aggregates. Ghosh et al 25 also used a single concentration of AuNP and eosin for their determinations, whereas we concluded size preferences based on titrations involving several different concentrations of the cyanine (vide infra) and the AuNPs (Fig.…”