Imaging of Cancer Cells using Gold Nanoparticels and Fluorescent Dyes by Multiphoton Microscopy

Due to the special optical properties, optical probes including metal nanoparticles (NPs), quantum dots, and fluorescent dyes, are increasingly used as labeling tools in biological imaging. Using multiphoton microscopy and fluorescence lifetime imaging (FLIM) system, we recorded the images from gold NPs conjugated to monoclonal ACT1 antibody, fluorescence dye Alexa 488 (A488) conjugated to ACT1, and dye Hoechst 33258 (H258) after incubation in cell culture with lymphoma cell lines (Karpas 299). From these images, we can easily discriminate the imaging difference due to the different emission intensity, distinct fluorescence lifetime between cells and the three optical probes. Our results present that Au-ACT1 conjugates and A488-ACT1 conjugates bind homogeneously and specifically to the surface of cells, and H258 is stained on cell nuclear. Compared with Karpas 299 cells, stronger emission intensity of gold NPs is observed at the same excitation power; and it can be comparable to, even more than that of fluorescent dyes in the same laser excitation. Gold NPs has more photostable than the other fluorescent probes. These results suggest gold NPs are useful for the study of cellular imaging and cancer diagnosis as molecular labeling tools.