Figure 2.

Selective bioconjugation reaction scheme of amino QDs (QD-amine) to free sulhydryl-containing IgG antibodies. The reaction involves a) the mild reduction of IgG with cysteamine to yield partially reduced IgG antibody fragments (rIgG); b) the activation of QD-NH₂ by nucleophilic reaction with NHS-moiety of sulfo-SMCC, resulting in maleimide-functionalized quantum dot (QD-maleimide); and c) the rIgG and QD-maleimide conjugation (QD-rIgG) via the formation of a thioether bond.