A Photometric Procedure for Weight Determination of Submicroscopic Particles Quantitative Electron Microscopy

Zeitler, E.; Bahr, G. F.

doi:10.1063/1.1777179

Cited by 127 publications

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“…12,13 Consequently, it can be shown that the effective ͑average͒ optical potential of an optical lattice, i , for the voxel around the point ͑x , y͒ is…”

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confidence: 99%

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

Pradhan

Damania

Joshi

et al. 2010

Applied Physics Letters

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We report a study of the nanoscale mass-density fluctuations of heterogeneous optical dielectric media, including nanomaterials and biological cells, by quantifying their nanoscale light-localization properties. Transmission electron microscope images of the media are used to construct corresponding effective disordered optical lattices. Light-localization properties are studied by the statistical analysis of the inverse participation ratio ͑IPR͒ of the localized eigenfunctions of these optical lattices at the nanoscale. We validated IPR analysis using nanomaterials as models of disordered systems fabricated from dielectric nanoparticles. As an example, we then applied such analysis to distinguish between cells with different degrees of aggressive malignancy. © 2010 American Institute of Physics. ͓doi:10.1063/1.3524523͔Quantifying the degree of nanoscale disorder is a major research interest in characterizing the optical ͑electronic͒ properties of disordered condensed-matter systems. 1 Statistical properties, such as the mean and standard deviation ͑std͒, of the inverse participation ratio ͑IPR͒ of the spatially localized optical eigenfunctions of these optical systems are important quantitative measures of the degree of disorder of these lattices, where IPR of an eigenfunction E is defined as IPR= ͉͐E͑r͉͒ 4 dr ជ ͓in units of inverse area in two dimension ͑2D͔͒. 2,3 The average value of the IPR of a uniform lattice is a fixed universal number ͑ϳ2.5 in 2D͒, but the value increases with an increasing degree of disorder ͑or degree of localization͒. IPR has been well-studied in condensed-matter physics for characterizing the degree of disorder of homogeneous and heterogeneous media in a single parameter. [4][5][6] In this paper, we report the study of light-localization properties of biological cells by first constructing optical lattices of these cells via transmission electron microscopy ͑TEM͒ imaging 7 and then studying the statistical properties of IPR of the eigenfunctions of these lattices. In our most recent optical experiments, we show that the degree of nanoscale disorder increases with the degree of carcinogenesis for both control and precancerous cells ͑in cell lines, mouse model, and different organs in human studies, such as pancreas, colon, and lung͒. [8][9][10] These nanoscale changes may result from the rearrangements of DNA, RNA, lipids, or proteins. We want to verify and quantify these nanoscale changes as observed in optical studies by TEM.It has been shown that the optical refractive index ͑n͒ is linearly proportional to the local density ͑ ͒ of intracellular macromolecules for a majority of the scattering substances found in living cells, such as proteins, lipids, DNA, or RNA, i.e., n = n 0 + ⌬n = n 0 + ␣ , where n 0 is the refractive index of the medium, is the local concentration of solids, with ␣ ϳ 0.18. 11 Furthermore, we consider that the absorption of the contrast agent by the cell is linearly proportional to the total mass present in the thin cell voxel. Therefore, if TEM imaging is perfo...

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“…12,13 Consequently, it can be shown that the effective ͑average͒ optical potential of an optical lattice, i , for the voxel around the point ͑x , y͒ is…”

mentioning

confidence: 99%

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

Pradhan

Damania

Joshi

et al. 2010

Applied Physics Letters

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“…Cantilever-based techniques have recently been demonstrated for mass detection at the zeptogram level (10 À21 g) [8,9]. Electronmicroscopy-based techniques have a long history [6,7,[10][11][12][13][14][15][16][17][18]. In Zeitler and Bahr's early work of 1962, the mass of nanoparticles has been determined down to 10 À18 g using STEM with an accuracy of 10% [17].…”

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confidence: 99%

Weighing Supported Nanoparticles: Size-Selected Clusters as Mass Standards in Nanometrology

Young

Chen

et al. 2008

Phys. Rev. Lett.

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We present a new approach to quantify the mass and 3D shape of nanoparticles on supports, using sizeselected nanoclusters as mass standards in scanning transmission electron microscope. Through quantitative image intensity analysis, we show that the integrated high angle annular dark field intensities of size-selected gold clusters soft-landed on graphite display a monotonic dependence on the cluster size as far as $6500 atoms. We applied this mass standard to study gold nanoparticles prepared by thermal vapor deposition and by colloidal wet chemistry, and from which we deduced the shapes of these two types of nanoparticles as expected. DOI: 10.1103/PhysRevLett.101.246103 PACS numbers: 81.07.Àb, 61.46.Bc, 61.46.Df, 68.37.Ma Since the properties of nanoclusters and nanoparticles depend critically on their size [1,2], the measurement of their mass is crucial. For example, knowledge of the mass, i.e., the number of atoms in the clusters, when coupled with the measured projected area of the nanoparticles, would enable us to deduce the 3D shape of the nanoparticles. This is of particular importance in areas such as environmental health [3] and catalysis [4,5], because it regulates the effective surface area of the (typically supported) particles. However, atom counting is a challenging task for nanoparticles on surfaces, in terms of accuracy, efficiency, and mass range. Here we show that soft-landed size-selected atomic clusters can be used as mass standards which enable surface mass spectrometry by scanning transmission electron microscopy (STEM). For Au clusters on carbon surfaces, we find that the measured relationship between mass and the high angle annular dark field (HAADF) intensity in STEM displays a monotonic dependence on cluster size as far as $6; 500 atoms. This extends the applicable mass range for STEM-based mass spectrometry by about 3 orders of magnitude [6,7]. The method is demonstrated by the 3D shape determination of colloidal, evaporated and size-selected Au nanoparticles.There are a number of ways that the masses of nanoparticles on surfaces can be measured. Cantilever-based techniques have recently been demonstrated for mass detection at the zeptogram level (10 À21 g) [8,9]. Electronmicroscopy-based techniques have a long history [6,7,[10][11][12][13][14][15][16][17][18]. In Zeitler and Bahr's early work of 1962, the mass of nanoparticles has been determined down to 10 À18 g using STEM with an accuracy of 10% [17]. The advantage of this approach is that the mass information obtained can be directly correlated to the structure and properties of the particle studied. The concept of atomic-level mass determination by STEM, as developed by Howie, is a quantitative application of the HAADF-STEM imaging method [18,19]. This requires an accurate knowledge of the electron scattering cross section ( ) as a function of the number of atoms (N) and the number of electrons in the focused electron beam. Ab initio calculation of high angle electron scattering cross section of nanoparticles is a challenging...

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“…There was no measurable contamination of specimens exposed to normal beam currents for up to 30 min. Electrography was at carefully controlled magnifications and controlled background exposure (14,15). Plates were processed according to a standard technique.…”

Section: Methodsmentioning

confidence: 99%

“…More importantly, the chromosomes appear in natural contrast since no special fixatives or heavy-metal stains are required for their visualization. By means of certain operating conditions of the electron microscope, controlled exposure, and controlled photographic processing, a close proportionality of the dry mass of the object to photometric transmission in the electrographic negative can be achieved (14,15). Since the relationship of mass and contrast (difference of transmission T -Tot) is independent of the object's shape and its chemical composition, the electron microscope constitutes a sensitive balance.…”

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confidence: 99%

Karyotyping of Single Human Chromosomes from Dry Mass Determined by Electron Microscopy

Bahr

Golomb

1971

Proc. Natl. Acad. Sci. U.S.A.

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Human chromosomes from cultures of peripheral lymphocytes were prepared for electron microscopy by surface spreading and critical-point drying.Total and partial determinations of chromosomal dry mass were made from contrast in electron microscopic negatives. The distribution of dry weights was analyzed with respect to the Denver-Chicago classifications. There is considerable variability of mass within each group, but no statistically significant differences between four donors. A single chromosome can be correctly classified from its total mass and the ratio of long-to short-arm mass.The identification and taxonomy of human chromosomes, i.e., karyotyping, has been the subject of a number of publications and scientific meetings (2-6). Widely accepted standards of nomenclature and measurement appear to have reached a final state with the proceedings of the Chicago Conference (4). Its chromosome classifications are intended for light microscopic images of stained metaphases.Several sophisticated, computer-assisted, light-microscopic systems for automation of karyotyping have been described in which the metaphase plate is either scanned directly or in a photograph of it (7-12). Relative total length and arm ratio are the main features by which the eye and the computer classify a chromosome. Only in the system of Mendelsohn and collaborators is use also made of the stain content of individual chromosomes.Electron microscopic studies of thin-sectioned human chromosomes have been singularly unsuccessful because of lack of specific contrast; however, surface spreading and (in particular) critical-point drying (13) renders chromosomes in what appears to be their natural configuration. More importantly, the chromosomes appear in natural contrast since no special fixatives or heavy-metal stains are required for their visualization. By means of certain operating conditions of the electron microscope, controlled exposure, and controlled photographic processing, a close proportionality of the dry mass of the object to photometric transmission in the electrographic negative can be achieved (14,15). Since the relationship of mass and contrast (difference of transmission T -Tot) is independent of the object's shape and its chemical composition, the electron microscope constitutes a sensitive balance. Masses from 10-10 to 10-18 g may be determined. This technique of dry-mass determination is most suitable for quantitative studies of individual chromosomes. It has previously been used in a rather detailed study of human chromosomal fibers, especially the relation of fiber mass to DNA content (16), and further in an analysis of chromosomes from Burkitt's lymphoma (17).In the present study, the dry mass and related features of a large number of human chromosomes were determined in order to see whether such parameters would lead to distinct two-or three-space clusters analogous to Groups A through G of the Chicago classification. Unfortunately, the most productive technique of preparation is that of chance selection of groups...

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A Photometric Procedure for Weight Determination of Submicroscopic Particles Quantitative Electron Microscopy

Cited by 127 publications

References 5 publications

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

Quantification of nanoscale density fluctuations using electron microscopy: Light-localization properties of biological cells

Weighing Supported Nanoparticles: Size-Selected Clusters as Mass Standards in Nanometrology

Karyotyping of Single Human Chromosomes from Dry Mass Determined by Electron Microscopy

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