Scientists from Cytoptics Corporation have successfully developed a chloride ion QD-based nanosensor for cell-based applications. The Cl-QD nanosensor was synthesized by conjugating an anion receptor to the QD. Upon binding of the chloride ion to the receptor, the light intensity of the QD quenched according to the chloride ion concentration bound to the anion receptor.

Intracellular probe

Because QD-based nanosensors are practically impermeable to cells, the researchers further developed a cationic liposome loading technique to enable cell penetration. Cl-QDs that entered the cells were trapped in the cytosols and responded in a similar manner as if they were in solution. Using this loading technique, the researchers were able to transfer the Cl-QD nanosensors into the cells without compromising the integrity of the cells.

Pictures taken five days after loading the cells with Cl-QDs (see image) showed robust cell viability and indicate that measurements of [Cl]i can now be performed over an extended time duration. The team further showed that when different types of chloride channels in cells were manipulated pharmacologically, the dynamic responses of [Cl]i measured by the Cl-QDs were physiologically and toxicologically consistent with the characteristics of these channels.

These data indicate that this new intracellular chloride nanosensor could have broad applications in drug discovery.

More details can be found in the journal Nanotechnology.