Quantum Dots for Imaging Cancer Cells

Quantum dots (QDs) for cancer imaging are colloidal semiconductor nanocrystals that have their energy band gaps corresponding to emit visible and/or NIR lights under ultraviolet excitation. One of the goals of this research  was to apply these properties to enhance the imaging of lung cancer cells. To ensure more good than harm is done with the use of QDs for imaging cells, we determined the cytotoxicity and IC50 factor of the QDs. Additionally, we were interested in visualizing and quantifying the emission data from the QDs as well as the uptake and distribution of the QD in A549 cell line (human lung cancer cells). To determine the cytotoxicity, different concentrations of our QDs ranging from 0 μg/mL control concentration to 100 μg/mL were injected into the A549 cell line. Viability data on cell samples impregnated by QDs was found by inserting the microplate assay into the plate reader. The IC50, half maximal inhibitory concentration, is considered to be the optimal safe concentration of the QDs to use. IC50 was found to be 71.2 μg/mL. We also studied dimethyl sulfoxide (DMSO) as a material to coordinate with the QDs. The idea is that DMSO should ease the passage of the QDs into the cells due to its effects on cell function through expression. The optimum DMSO concentration and incubation time is still under investigation.

The most recent part of the study was focused on the visualizing and quantification of the QDs with the use of both the spectrometer and the fluorescence microscope. Under the fluorescence microscope, clear images of the distribution of QD’s uptake were taken. With the use of the spectrometer, we collected the emission data from the pure Quantum dots with the same density used to impregnate the cells. This data provides information about the wavelength being emitted and its intensity. In the next step, measurements were taken in the same way to acquire the emission data from the cell impregnated by QDs and fixed on microscope slides. Comparing the emissions from the cell slides to the pure quantum dots showed a significant reduction in emission intensity.