In order to obtain high sensitivity for aflatoxin detection, we
determined optimum synthesis conditions for cysteamine-capped
ZnS QDs. A ZnS colloidal solution is synthesized using a reaction
between Zn2þ and S2 with PVA as a stabilizing agent. We investigated
the effect of reaction temperature variations on the
maximum PL intensity of the finished cysteamine-capped ZnS QDs
and choose the optimum ZnS precipitation temperature to be 25 C.
We also studied the effect of pH and cysteamine/Zn molar ratio and
found the optimum conditions to be pH ¼ 7 and a cysteamine/Zn
molar ratio of 2. The details of these investigations are presented in
Sections 3.2e3.4.