title: Method of determining nanoparticle core weight.
abstract: Polymer-coated metal or metal oxide nanoparticles have a variety of uses in industry, biological research, and medicine. Characterization of nanoparticles often includes determination of the dimensions of the electron-dense core by transmission electron microscopy (TEM), with the weight of the core determined from core volume and core density. However, TEM is labor intensive, has a long turnaround time, and uses equipment that is sometimes not readily available. Here we present an alternative method for determining the weight of nanoparticle cores termed the viscosity/light scattering method, which uses (i) measurements of viscosity over a wide concentration range to obtain the partial specific volume, (ii) measurements of particle diameter by light scattering, to obtain the volume of an individual particle, and (iii) the concentration of nanoparticles (w/v). We have applied this method to determine the weights of nanoparticle cores (iron of amino-CLIO and ferritin), the weights of globular proteins (molecular weight of IgG and albumin), and the weight of polystyrene microspheres. The viscosity/light scattering method is nondestructive of the sample and can be performed with a variety of materials on a routine basis.
authors.affiliation: Center for Molecular Imaging Research, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA.
authors.forename: Fred
authors.initials: F
authors.lastname: Reynolds
authors.forename: Terry
authors.initials: T
authors.lastname: O'loughlin
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Lee
authors.initials: L
authors.lastname: Josephson
mesh_terms: D000418:Albumins / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D005293:Ferritins / Q000737:chemistry; D007074:Immunoglobulin G / Q000737:chemistry; D008670:Metals / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D008863:Microspheres; D008970:Molecular Weight; D049329:Nanostructures; D036103:Nanotechnology / Q000379:methods*; D010087:Oxides / Q000737:chemistry; D010316:Particle Size; D011137:Polystyrenes / Q000737:chemistry; D012542:Scattering, Radiation; D014783:Viscosity; D014894:Weights and Measures
chemical_list: D000418:Albumins; D000588:Amines; D005290:Ferric Compounds; D007074:Immunoglobulin G; D008670:Metals; D010087:Oxides; D011137:Polystyrenes; D005293:Ferritins