title: Plasmon resonance and the imaging of metal-impregnated neurons with the laser scanning confocal microscope.
abstract: The staining of neurons with silver began in the 1800s, but until now the great resolving power of the laser scanning confocal microscope has not been utilized to capture the in-focus and three-dimensional cytoarchitecture of metal-impregnated cells. Here, we demonstrate how spectral confocal microscopy, typically reserved for fluorescent imaging, can be used to visualize metal-labeled tissues. This imaging does not involve the reflectance of metal particles, but rather the excitation of silver (or gold) nanoparticles and their putative surface plasmon resonance. To induce such resonance, silver or gold particles were excited with visible-wavelength laser lines (561 or 640 nm), and the maximal emission signal was collected at a shorter wavelength (i.e., higher energy state). Because the surface plasmon resonances of noble metal nanoparticles offer a superior optical signal and do not photobleach, our novel protocol holds enormous promise of a rebirth and further development of silver- and gold-based cell labeling protocols.
authors.affiliation: Department of Biology, Neuroscience Program, Agnes Scott College, Decatur, United States.
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Thompson
authors.affiliation: Department of Entomology, Graduate Program in Neuroscience, University of Minnesota, Saint Paul, United States.
authors.forename: Cynthia M
authors.initials: CM
authors.lastname: Harley
authors.affiliation: University Imaging Centers Core Facility, University of Minnesota, Saint Paul, United States.
authors.forename: Grant M
authors.initials: GM
authors.lastname: Barthel
authors.affiliation: University Imaging Centers Core Facility, University of Minnesota, Saint Paul, United States.
authors.forename: Mark A
authors.initials: MA
authors.lastname: Sanders
authors.affiliation: Department of Entomology, Graduate Program in Neuroscience, University of Minnesota, Saint Paul, United States.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Mesce
mesh_terms: D000818:Animals; D006110:Grasshoppers; D021621:Imaging, Three-Dimensional / Q000379:methods*; D018402:Manduca; D008670:Metals / Q000378:metabolism*; D018613:Microscopy, Confocal / Q000379:methods*; D009474:Neurons / Q000737:chemistry* / Q000166:cytology*; D013194:Staining and Labeling / Q000379:methods*; D020349:Surface Plasmon Resonance
chemical_list: D008670:Metals
keywords: Golgi stain; insect; motoneurons; mouse; nanoparticles; neuroscience; noble metals; primate; super resolution microscopy; surface plasmon resonance