title: Spatial modulation spectroscopy for imaging and quantitative analysis of single dye-doped organic nanoparticles inside cells.
abstract: Imaging of non-fluorescent nanoparticles in complex biological environments, such as the cell cytosol, is a challenging problem. For metal nanoparticles, Rayleigh scattering methods can be used, but for organic nanoparticles, such as dye-doped polymer beads or lipid nanoparticles, light scattering does not provide good contrast. In this paper, spatial modulation spectroscopy (SMS) is used to image single organic nanoparticles doped with non-fluorescent, near-IR croconaine dye. SMS is a quantitative imaging technique that yields the absolute extinction cross-section of the nanoparticles, which can be used to determine the number of dye molecules per particle. SMS images were recorded for particles within EMT-6 breast cancer cells. The measurements allowed mapping of the nanoparticle location and the amount of dye in a single cell. The results demonstrate how SMS can facilitate efforts to optimize dye-doped nanoparticles for effective photothermal therapy of cancer.
authors.affiliation: Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556-5670, USA. ghartlan@nd.edu.
authors.forename: Mary Sajini
authors.initials: MS
authors.lastname: Devadas
authors.forename: Tuphan
authors.initials: T
authors.lastname: Devkota
authors.forename: Samit
authors.initials: S
authors.lastname: Guha
authors.forename: Scott K
authors.initials: SK
authors.lastname: Shaw
authors.forename: Bradley D
authors.initials: BD
authors.lastname: Smith
authors.forename: Gregory V
authors.initials: GV
authors.lastname: Hartland
mesh_terms: D045744:Cell Line, Tumor; D005456:Fluorescent Dyes / Q000737:chemistry*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles / Q000737:chemistry / Q000378:metabolism*; D019265:Spectroscopy, Near-Infrared
chemical_list: D005456:Fluorescent Dyes