Characterization of biomarkers in breast cancer cells with quantum dots and detection of brain tumor cells using SpectroPen
- Brad Kairdolf, Distinguished Post Doctoral Fellow, Emory University
- Shuming Nie, Distinguished Faculty Chair in Biomedical Engineering & Professor Director for Emory-Georgia Tech Cancer Nanotechnology Center, Emory University
My project employs the principle of fluorescence in using quantum dots to characterize and quantify clinically-relevant, diagnostic biomarkers in different breast cancer cell lines, as well as to detect U87 MG cells (of glioblastoma tumors) using a handheld spectrometer, or SpectroPen.
I hypothesized that multiple antigen biomarkers, stained different colors with bioconjugated quantum dots, in BT-474 and ZR-75-1 breast cancer cells could be visualized simultaneously due to the multiplexing capability of quantum dots, as opposed to more traditional stains. I also hypothesized that the U87 MG tumor cells would emit fluorescence following the cells’ incubation with 5-ALA dye and excitation with violet light, and that there would be a direct relationship between the number of cells emitting fluorescence and the sensitivity of the SpectroPen in detecting the fluorescence.
Immunohistochemistry was utilized to stain the clinically-relevant biomarkers in the breast cancer cells; the quantum dots were bioconjugated to a secondary-antibody, which was “anti” to a primary antibody that was attached to the antigen of interest. DAPI staining was first used to locate the nuclei of the cells.
The U87 MG cells were incubated with 5-ALA that was converted to protoporphyrin-ix, which was “excited” by shining 405 nm LED light on the cells. The cells emitted a red light at 630 nm, which was picked up by the pen and mapped onto a corresponding spectrum to quantify tumor cell “detection.”
In both instances, my hypothesis was correct. The quantum dots provided sensitive staining results and the SpectroPen was able to detect as low as ~1000 U87 cells. Future testing will involve the creation of artificial tissue biomarker controls for patient sample comparison and photodynamic therapy with the SpectroPen.