Optoelectronic Tuning of Quantum Dots by Biological Cells

Quantum dots (QDs) have applications and promising myriad applications in photovoltaic cells, biomedical imaging, targeted drug delivery, and quantum information processing. These have led to much research on their interactions with other systems. For biological systems, research has focused on the biocompatibility and cytotoxicity of QDs in the context of imaging/therapy. However, there is a paucity of work on how biological systems might be used to alter the optoelectronic properties of QDs. Here, we show that these properties can be altered by biological macromolecules following controlled changes in cellular activities. Using CdSe/ZnS core-shell QDs, spectroscopic analysis of optically excited colloidal QDs with HL60, K562, and HCN2 cell lines are performed. Our results show statistically significant (p < 0.0001) quenching of the emission spectra of the colloidal dispersions due to the reactive oxygen species (ROS) produced by these cells following chemotherapy and radiotherapy. This optical modulation constitutes what we describe as cyto-molecular tuning. This type of tuning will possibly enhance applications of QDs in green energy and biomedical imaging.