Detection of Silver and TiO2 Nanoparticles in Cells by Flow Cytometry
Evaluation of the potential hazard of man-made nanomaterials has been hampered by a limited ability to observe and measure nanoparticles in cells. A FACSCalibur™ flow cytometer and a Stratedigm S-1000 flow cytometer were used to measure changes in light scatter from cells after incubation with either silver nanoparticles (AgNP) or TiO2 nanoparticles. Within the range of between 0.1 µg/mL and 30 µg/mL the nanoparticles caused a proportional increase of the side scatter and decrease of the forward scatter intensity signals. At the lowest concentrations of TiO2 (ranging between 0.1 µg/mL and 0.3 µg/mL), the flow cytometer can detect as few as 5-10 nanoparticles per cell. The influence of nanoparticles on the cell cycle was detected by non-ionic detergent lysis of nanoparticle incubated cells that were stained with DAPI or propidium iodide (PI). Viability of nanoparticle treated cells was determined by PI exclusion. Surface plasmonic resonance (SPR) was detected primarily in the far-red fluorescence detection channels after excitation with the 488 nm laser.