Study of Interaction between Metallothionein and CdTe Quantum Dots

Quantum dots (QDs) belong to a new class of fluorescent agent for biochemical, medicinal or other purposes. However, QDs based on cadmium or other metals can be risky for an organism. As one of the mechanism how to detoxify cadmium-based QDs expression of metallothioneins (MT) can be considered. Due to high affinity of metallothionein to cadmium(II) ions, we attempted to develop an approach for studying of possible interaction with QDs. We prepared QDs with CdTe core and studied the interaction with MT, which we isolated from livers of Cd-administered rabbits. To study the interaction, we used the mixture of both components MT (3.6 μM): CdTe QDs (0, 0.34, 0.68, 1.02, 1.36, 1.7, 2.04 and 2.47 μM). The mixtures were studied by spectrophotometry within the range from 200 to 750 nm with detected maxima at 260 and 505 nm. Same mixtures were also analysed by differential pulse voltammetry Brdicka reaction, which supported data from spectrophotometry. Subsequently, we used fast protein liquid chromatography for purification of protein–quantum dot conjugates. We obtained the different chromatograms for (1) Apo MT, (2) CdTe QDs and (3) MT–QD complex. We also collected the fractions and subsequently analysed them on the content of Cd and MT, which confirmed the formation of CdTe QDs–MT complex.