Prediction of Specific Biomolecule Adsorption on Silica Surfaces as a Function of pH and Particle Size

Fateme S. Emami; Valeria Puddu; Rajiv J. Berry; Vikas Varshney; Siddharth V. Patwardhan; Carole C. Perry; Hendrik Heinz

doi:10.1021/cm5026987

Nanoparticle core properties affect attachment of macromolecule-coated nanoparticles to silica surfaces

Environmental Chemistry ◽

10.1071/en13191 ◽

2014 ◽

Vol 11 (3) ◽

pp. 257 ◽

Cited By ~ 10

Author(s):

Ernest M. Hotze ◽

Stacey M. Louie ◽

Shihong Lin ◽

Mark R. Wiesner ◽

Gregory V. Lowry

Keyword(s):

Particle Size ◽

Layer Thickness ◽

Adsorbed Layer ◽

Engineered Nanoparticles ◽

Soft Particle ◽

Nanoparticle Transport ◽

Silica Surfaces ◽

Coated Particle ◽

Coated Nanoparticles ◽

Coating Type

Environmental context The increasing use of engineered nanoparticles has led to concerns over potential exposure to these novel materials. Predictions of nanoparticle transport in the environment and exposure risks could be simplified if all nanoparticles showed similar deposition behaviour when coated with macromolecules used in production or encountered in the environment. We show, however, that each nanoparticle in this study exhibited distinct deposition behaviour even when coated, and hence risk assessments may need to be specifically tailored to each type of nanoparticle. Abstract Transport, toxicity, and therefore risks of engineered nanoparticles (ENPs) are unquestionably tied to interactions between those particles and surfaces. In this study, we proposed the simple and untested hypothesis that coating type can be the predominant factor affecting attachment of ENPs to silica surfaces across a range of ENP and coating types, effectively masking the contribution of the particle core to deposition behaviour. To test this hypothesis, TiO2, Ag0 and C60 nanoparticles with either no coating or one of three types of adsorbed macromolecules (poly(acrylic acid), humic acid and bovine serum albumin) were prepared. The particle size and adsorbed layer thicknesses were characterised using dynamic light scattering and soft particle electrokinetic modelling. The attachment efficiencies of the nanoparticles to silica surfaces (glass beads) were measured in column experiments and compared with predictions from a semi-empirical correlation between attachment efficiency and coated particle properties that included particle size and layer thickness. For the nanoparticles and adsorbed macromolecules in this study, the attachment efficiencies could not be explained solely by the coating type. Therefore, the hypothesis that adsorbed macromolecules will mask the particle core and control attachment was disproved, and information on the properties of both the nanoparticle surface (e.g. charge and hydrophobicity) and adsorbed macromolecule (e.g. molecular weight, charge density extended layer thickness) will be required to explain or predict interactions of coated nanoparticles with surfaces in the environment.

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Microstructural characterization of laser-melted/roller-quenched dicalcium silicate

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100104972 ◽

1988 ◽

Vol 46 ◽

pp. 582-583

Author(s):

C. J. Chan ◽

K. R. Venkatachari ◽

W. M. Kriven ◽

J. F. Young

Keyword(s):

Particle Size ◽

Raw Materials ◽

Shape Change ◽

Microstructural Characterization ◽

Particle Size Effect ◽

Dicalcium Silicate ◽

Laser Melting ◽

Uniform Size ◽

Cell Shape Change ◽

Wide Range

Dicalcium silicate (Ca2SiO4) is a major component of Portland cement. It has also been investigated as a potential transformation toughener alternative to zirconia. It has five polymorphs: α, α'H, α'L, β and γ. Of interest is the β-to-γ transformation on cooling at about 490°C. This transformation, accompanied by a 12% volume increase and a 4.6° unit cell shape change, is analogous to the tetragonal-to-monoclinic transformation in zirconia. Due to the processing methods used, previous studies into the particle size effect were limited by a wide range of particle size distribution. In an attempt to obtain a more uniform size, a fast quench rate involving a laser-melting/roller-quenching technique was investigated.The laser-melting/roller-quenching experiment used precompacted bars of stoichiometric γ-Ca2SiO4 powder, which were synthesized from AR grade CaCO3 and SiO2xH2O. The raw materials were mixed by conventional ceramic processing techniques, and sintered at 1450°C. The dusted γ-Ca2SiO4 powder was uniaxially pressed into 0.4 cm x 0.4 cm x 4 cm bars under 34 MPa and cold isostatically pressed under 172 MPa. The γ-Ca2SiO4 bars were melted by a 10 KW-CO2 laser.

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Analytical Electron Microscopy study of two vehicle-aged automotive exhaust catalysts having dissimilar activities

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153336 ◽

1989 ◽

Vol 47 ◽

pp. 272-273

Author(s):

Sooho Kim ◽

M. J. D’Aniello

Keyword(s):

Electron Microscopy ◽

Particle Size ◽

Noble Metal ◽

Catalyst Deactivation ◽

Analytical Electron Microscopy ◽

Microscopy Study ◽

Metal Particles ◽

Automotive Exhaust ◽

Exhaust Catalysts ◽

Analytical Electron

Automotive catalysts generally lose-agtivity during vehicle operation due to several well-known deactivation mechanisms. To gain a more fundamental understanding of catalyst deactivation, the microscopic details of fresh and vehicle-aged commercial pelleted automotive exhaust catalysts containing Pt, Pd and Rh were studied by employing Analytical Electron Microscopy (AEM). Two different vehicle-aged samples containing similar poison levels but having different catalytic activities (denoted better and poorer) were selected for this study.The general microstructure of the supports and the noble metal particles of the two catalysts looks similar; the noble metal particles were generally found to be spherical and often faceted. However, the average noble metal particle size on the poorer catalyst (21 nm) was larger than that on the better catalyst (16 nm). These sizes represent a significant increase over that found on the fresh catalyst (8 nm). The activity of these catalysts decreases as the observed particle size increases.

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