Synthesis of ternary CuInS₂/ZnS quantum dot bioconjugates and their applications for targeted cancer bioimaging

This contribution introduces the use of cadmium-free CuInS₂ quantum dots (QDs) for targeted and multiplexed optical imaging of tumors in mice. CuInS₂/ZnS QDs were synthesized in a non-aqueous phase using the hot colloidal synthesis method. Previous challenges involving stable aqueous dispersion of highly luminescent CuInS₂/ZnS QDs have been overcome by encapsulating them within functionalized phospholipid micelles, which also facilitated their conjugation with folic acid for targeted delivery. Luminescence signals of QDs of multiple colors were readily differentiated from background autofluorescence in whole animal optical imaging. In addition, two-photon excitation studies revealed that the prepared water-dispersible QDs are suitable for two-photon in vitro and in vivo imaging. This study demonstrates the important key steps in realizing of the potential of CuInS ₂ QDs as low-toxicity, photostable, cadmium-free and highly luminescent probes for cancer detection and sensing.