If they must be used in the hydrophilic phase, the QDs should be processed by surface modification, which is a prerequisite for applications in biology and biomedicine. However, this phase transfer usually results in a significant decrease in the emission quantum yield (QY). Another disadvantage is that the thick surface coating layer can dramatically increase the size of the QD composites, which can prevent their use in some applications.

CdTe QDs can be obtained in water, but their emission efficiency is susceptible to the environment, not like that of core-shell QDs. So from the CdTe QDs synthesized in water, we developed a method to grow CdSe shells on CdTe QDs in water. The resulting CdTe/CdSe core/shell quantum dots can be treated easily with bioconjugates with only a minor size expansion and tests show that folate-conjugated CdTe/CdSe QDs could enter tumor cells efficiently.

The researchers presented their work in Nanotechnology.