title: Gold Nanoparticle Quantitation by Whole Cell Tomography.
abstract: Many proposed biomedical applications for engineered gold nanoparticles require their incorporation by mammalian cells in specific numbers and locations. Here, the number of gold nanoparticles inside of individual mammalian stem cells was characterized using fast focused ion beam-scanning electron microscopy based tomography. Enhanced optical microscopy was used to provide a multiscale map of the in vitro sample, which allows cells of interest to be identified within their local environment. Cells were then serially sectioned using a gallium ion beam and imaged using a scanning electron beam. To confirm the accuracy of single cross sections, nanoparticles in similar cross sections were imaged using transmission electron microscopy and scanning helium ion microscopy. Complete tomographic series were then used to count the nanoparticles inside of each cell and measure their spatial distribution. We investigated the influence of slice thickness on counting single particles and clusters as well as nanoparticle packing within clusters. For 60 nm citrate stabilized particles, the nanoparticle cluster packing volume is 2.15 ± 0.20 times the volume of the bare gold nanoparticles.
authors.affiliation: Quantum Electronics and Photonics Division, National Institute of Standards and Technology (NIST) , Boulder, Colorado 59840, United States.
authors.forename: Aric W
authors.initials: AW
authors.lastname: Sanders
authors.affiliation: Applied Chemicals and Materials Division, National Institute of Standards and Technology (NIST) , Boulder, Colorado 59840, United States.
authors.forename: Kavita M
authors.initials: KM
authors.lastname: Jeerage
authors.affiliation: Department of Molecular, Cell, and Developmental Biology, University of Colorado , Boulder, Colorado 59840, United States.
authors.forename: Cindi L
authors.initials: CL
authors.lastname: Schwartz
authors.affiliation: Quantum Electronics and Photonics Division, National Institute of Standards and Technology (NIST) , Boulder, Colorado 59840, United States.|Applied Chemicals and Materials Division, National Institute of Standards and Technology (NIST) , Boulder, Colorado 59840, United States.
authors.forename: Alexandra E
authors.initials: AE
authors.lastname: Curtin
authors.affiliation: Applied Chemicals and Materials Division, National Institute of Standards and Technology (NIST) , Boulder, Colorado 59840, United States.
authors.forename: Ann N
authors.initials: AN
authors.lastname: Chiaramonti
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D006046:Gold / Q000032:analysis* / Q000737:chemistry; D053768:Metal Nanoparticles / Q000032:analysis* / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D058953:Neural Stem Cells; D051381:Rats; D014054:Tomography / Q000379:methods*
chemical_list: D006046:Gold
keywords: focused ion beam tomography; gold nanoparticles; helium ion microscopy; multiscale correlative microscopy; nanoparticle internalization; scanning electron microscopy