27 September 2013 Wide-field interferometric phase microscopy with molecular specificity using plasmonic nanoparticles
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We present a method for adding molecular specificity to wide-field interferometric phase microscopy (IPM) by recording the phase signatures of gold nanoparticles (AuNPs) labeling targets of interest in biological cells. The AuNPs are excited by time-modulated light at a wavelength corresponding to their absorption spectral peak, evoking a photothermal (PT) effect due to their plasmonic resonance. This effect induces a local temperature rise, resulting in local refractive index and phase changes that can be detected optically. Using a wide-field interferometric phase microscope, we acquired an image sequence of the AuNP sample phase profile without requiring lateral scanning, and analyzed the time-dependent profile of the entire field of view using a Fourier analysis, creating a map of the locations of AuNPs in the sample. The system can image a wide-field PT phase signal from a cluster containing down to 16 isolated AuNPs. AuNPs are then conjugated to epidermal growth factor receptor (EGFR) antibodies and inserted to an EGFR-overexpressing cancer cell culture, which is imaged using IPM and verified by confocal microscopy. To the best of our knowledge, this is the first time wide-field interferometric PT imaging is performed at the subcellular level without the need for total internal reflection effects or scanning.
© 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)
Nir A. Turko, Anna Peled, Natan T. Shaked, "Wide-field interferometric phase microscopy with molecular specificity using plasmonic nanoparticles," Journal of Biomedical Optics 18(11), 111414 (27 September 2013). https://doi.org/10.1117/1.JBO.18.11.111414 . Submission:

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