Gold nanoparticles (NPs) have tremendous potential in biomedicine. They can be used as absorbing labels inside living cells for the purpose of biomedical imaging, biosensing as well as for photothermal therapy. We demonstrate photothermal imaging of highly-absorbing particles using a pump-probe setup. The photothermal signal is recovered by heterodyne detection, where the excitation pump laser is at 532 nm and the probe laser is at 638 nm. The sample is moved by a scanning stage. Proof of concept images of red polystyrene microspheres and gold nanoparticles are obtained with this home-built multimodal microscope. The increase in temperature at the surface of the gold NPs, due to the pump laser beam, can be directly measured by means of this photothermal microscope and then compared with the results from theoretical predictions. This technique will be useful for characterization of nanoparticles of different shapes, sizes and materials that are used in cancer diagnosis and therapy.

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Keywords biomedical imaging, cancer diagnosis and therapy, characterization of nanoparticles, gold nanoparticles, heterodyne detection, multimodal microscope, Photothermal microscopy, pump-probe setup
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Conference Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XII
Lussier, S.-A. (Simon-Alexandre), Moradi, H. (Hamid), Price, A. (Alain), & Murugkar, S. (2015). Imaging highly-absorbing nanoparticles using photothermal microscopy. Presented at the Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications XII. doi:10.1117/12.2080278