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Published February 23, 2012 | Published
Book Section - Chapter Open

Label-free photoacoustic microscopy of cytochrome c in cells


Cytochrome c is a heme protein normally bound to mitochondria and is important for mitochondrial electron transport and apoptosis initiation. Since cytochrome c is nonfluorescent, it is always labeled with fluorescent molecules for imaging, which, however, may affect normal cellular functions. Here, label-free photoacoustic microscopy (PAM) of mitochondrial cytochrome c was realized for the first time by utilizing the optical absorption around the Soret peak. PAM was demonstrated to be sensitive enough to image mitochondrial cytochrome c at 422 nm wavelength. Mitochondrial cytochrome c in the cytoplasm of fixed fibroblasts was clearly imaged by PAM as confirmed by fluorescent labeling. By showing mitochondrial cytochrome c in various cells, we demonstrated the feasibility of PAM for label-free histology of mouse ear sections. Therefore, PAM can sensitively image cytochrome c in unstained cells at 422 nm wavelength and has great potential for functional imaging of cytochrome c in live cells or in vivo.

Additional Information

© 2012 Society of Photo-Optical Instrumentation Engineers (SPIE). This work was sponsored in part by National Institutes of Health grants R01 EB000712, R01 EB008085, R01 CA134539, U54 CA136398, R01 CA157277, and 5P60 DK02057933. L.W. has a financial interest in Microphotoacoustics, Inc. and Endra, Inc., which, however, did not support this work.

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