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Škvarla J, Škvarla J. An identification of the soft polyelectrolyte gel-like layer on silica colloids using atomic force and electron microscopy. Ultramicroscopy 2017; 181:97-106. [PMID: 28527981 DOI: 10.1016/j.ultramic.2017.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 03/16/2017] [Accepted: 05/09/2017] [Indexed: 11/18/2022]
Abstract
A procedure is introduced for measuring the radius of spherical colloid particles from the curvature of upper parts of their central cross-sectional profiles obtained by atomic force microscopy (AFM). To minimize the possible compression and displacement of the spheres, AFM is operated in a mode rendering a constant ultralow pN force on the tip. The procedure allows us to evaluate the mean radius of nearly monodisperse submicrometer spheres of silica in their natively hydrated state in aqueous electrolyte solutions, irrespective of whether they are coagulated or not. A variation in the volume (swelling degree) of layers delimited by the AFM mean radii of these spheres in KCl solutions and their invariable mean radius in vacuum is obtained that follows a scaling power law derived in polymer physics for swellable polyelectrolyte gels and deduced previously by us from coagulation tests. This supports our former suggestion about the existence of soft polyelectrolyte gel-like layer developed spontaneously around silica surfaces and colloids. We discuss this finding in the context of recent knowledge about the structure of the silica/water interface obtained from direct surface force measurements between macroscopic silica surfaces and from particle size measurements of silica colloids and highlight its importance for colloid chemistry and condensed mattter physics.
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Affiliation(s)
- Jiří Škvarla
- Institute of Earth Resources, Technical University in Košice, Park Komenského 19, Košice 042 00, Slovak Republic.
| | - Juraj Škvarla
- Department of Physical and Macromolecular Chemistry, Charles University in Prague, Hlavova 2030, Prague 2 128 40, Czech Republic.
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Farias MAD, Gonçalves MDC. Synthesis and applications of polystyrene-block-poly(N-vinyl-2-pyrrolidone) copolymers. POLIMEROS 2016. [DOI: 10.1590/0104-1428.2066] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Sodipo BK, Abdul Aziz A. Non-seeded synthesis and characterization of superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles via ultrasound. ULTRASONICS SONOCHEMISTRY 2015; 23:354-359. [PMID: 25315418 DOI: 10.1016/j.ultsonch.2014.09.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 06/04/2023]
Abstract
A non-seeded method of incorporating superparamagnetic iron oxide nanoparticles (SPION) into silica nanoparticles is presented. Mixture of both SPION and silica nanoparticles was ultrasonically irradiated. The collapsed bubbles and shockwave generated from the ultrasonic irradiation produce tremendous force that caused inelastic collision and incorporation of SPION into the silica. Physicochemical analyses using transmission electron microscope (TEM), electronic spectroscopic imaging (ESI), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy demonstrated the formation of SPION/silica composite nanoparticles. The prepared composite nanoparticles exhibited superparamagnetic behaviour and nearly 70% of the initial saturation magnetization (Ms) of the SPION was retained. The presence and reactivity of the silica were demonstrated via assembling decanethiol monolayer on the composite nanoparticles. The silanol group of the silica provided the binding site for the alkyl group in the decanethiol molecules. Therefore, the thiol moiety became the terminal and functional group on the magnetic composite nanoparticles.
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Affiliation(s)
- Bashiru Kayode Sodipo
- Nano-Optoelectronics Research and Technology (NOR) Lab, School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia; Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia.
| | - Azlan Abdul Aziz
- Nano-Optoelectronics Research and Technology (NOR) Lab, School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia; Nano-Biotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia
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4
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Mirenda M, Levi V, Bossi ML, Bruno L, Bordoni AV, Regazzoni AE, Wolosiuk A. Temperature response of luminescent tris(bipyridine)ruthenium(II)-doped silica nanoparticles. J Colloid Interface Sci 2013; 392:96-101. [DOI: 10.1016/j.jcis.2012.09.059] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Revised: 09/08/2012] [Accepted: 09/26/2012] [Indexed: 10/27/2022]
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Bell NC, Minelli C, Tompkins J, Stevens MM, Shard AG. Emerging techniques for submicrometer particle sizing applied to Stöber silica. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10860-10872. [PMID: 22724385 DOI: 10.1021/la301351k] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The accurate characterization of submicrometer and nanometer sized particles presents a major challenge in the diverse applications envisaged for them including cosmetics, biosensors, renewable energy, and electronics. Size is one of the principal parameters for classifying particles and understanding their behavior, with other particle characteristics usually only quantifiable when size is accounted for. We present a comparative study of emerging and established techniques to size submicrometer particles, evaluating their sizing precision and relative resolution, and demonstrating the variety of physical principles upon which they are based, with the aim of developing a framework in which they can be compared. We used in-house synthesized Stöber silica particles between 100 and 400 nm in diameter as reference materials for this study. The emerging techniques of scanning ion occlusion sensing (SIOS), differential centrifugal sedimentation (DCS), and nanoparticle tracking analysis (NTA) were compared to the established techniques of transmission electron microscopy (TEM), scanning mobility particle sizing (SMPS), and dynamic light scattering (DLS). The size distributions were described using the mode, arithmetic mean, and standard deviation. Uncertainties associated with the six techniques were evaluated, including the statistical uncertainties in the mean sizes measured by the single-particle counting techniques. Q-Q plots were used to analyze the shapes of the size distributions. Through the use of complementary techniques for particle sizing, a more complete characterization of the particles was achieved, with additional information on their density and porosity attained.
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Affiliation(s)
- Nia C Bell
- Department of Materials, Imperial College London, London, SW7 2AZ, UK
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Yu Q, Wang P, Hu S, Hui J, Zhuang J, Wang X. Hydrothermal synthesis of hollow silica spheres under acidic conditions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7185-7191. [PMID: 21553827 DOI: 10.1021/la200719g] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
It is well-known that silica can be etched in alkaline media or in a unique hydrofluoric acid (HF) solution, which is widely used to prepare various kinds of hollow nanostructures (including silica hollow structures) via silica-templating methods. In our experiments, we found that stöber silica spheres could be etched in generic acidic media in a well-controlled way under hydrothermal conditions, forming well-defined hollow/rattle-type silica spheres. Furthermore, some salts such as NaCl and Na(2)SO(4) were found to be favorable for the formation of hollow/rattle-type silica spheres.
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Affiliation(s)
- Qiyu Yu
- Department of Chemistry, Tsinghua University, Beijing 100084, PR China
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Bacri L, Oukhaled AG, Schiedt B, Patriarche G, Bourhis E, Gierak J, Pelta J, Auvray L. Dynamics of Colloids in Single Solid-State Nanopores. J Phys Chem B 2011; 115:2890-8. [DOI: 10.1021/jp200326w] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- L. Bacri
- LAMBE UMR CNRS 8587, Evry and Cergy-Pontoise University, France
| | - A. G. Oukhaled
- LAMBE UMR CNRS 8587, Evry and Cergy-Pontoise University, France
- LPN/CNRS, UPR 20, Marcoussis, France
| | - B. Schiedt
- LAMBE UMR CNRS 8587, Evry and Cergy-Pontoise University, France
- LPN/CNRS, UPR 20, Marcoussis, France
| | | | | | - J. Gierak
- LPN/CNRS, UPR 20, Marcoussis, France
| | - J. Pelta
- LAMBE UMR CNRS 8587, Evry and Cergy-Pontoise University, France
| | - L. Auvray
- Matière et Systèmes Complexes, UMR 7057, Paris Diderot University, France
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Linares EM, Rippel MM, Galembeck F. Clay platelet partition within polymer blend nanocomposite films by EFTEM. ACS APPLIED MATERIALS & INTERFACES 2010; 2:3648-3653. [PMID: 21117636 DOI: 10.1021/am100812m] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Transmission electron microscopy (TEM) is the main technique used to investigate the spatial distribution of clay platelets in polymer nanocomposites, but it has not often been successfully used in polymer blend nanocomposites because the high contrast between polymer phases impairs the observation of clay platelets. This work shows that electron spectral imaging in energy-filtered TEM (EFTEM) in the low-energy-loss spectral crossover region allows the observation of platelets on a clear background. Separate polymer domains are discerned by imaging at different energy losses, above and below the crossover energy, revealing the material morphology. Three blends (natural rubber [NR]/poly(styrene-butyl acrylate) [P(S-BA)], P(S-BA)/poly(vinyl chloride) [PVC], and NR/starch) were studied in this work, showing low contrast between the polymer phases in the 40-60 eV range. In the NR/P(S-BA) and P(S-BA)/PVC blend nanocomposites, the clay platelets accumulate in the P(S-BA) phase, while in the P(S-BA)/PVC nanocomposites, clay is also found at the interfaces. In the NR/starch blend, clay concentrates at the interface, but it also penetrates the two polymer phases. These observations reveal that nanostructured soft materials can display complex morphochemical patterns that are discerned thanks to the ability of EFTEM to produce many contrast patterns for the same sample.
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Affiliation(s)
- Elisângela M Linares
- Institute of Chemistry, University of Campinas, Caixa Postal 6154, 13083-970 Campinas, São Paulo, Brazil
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Thierry B, Zimmer L, McNiven S, Finnie K, Barbé C, Griesser HJ. Electrostatic self-assembly of PEG copolymers onto porous silica nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:8143-8150. [PMID: 18590299 DOI: 10.1021/la8007206] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
A critical requirement toward the clinical use of nanocarriers in drug delivery applications is the development of optimal biointerfacial engineering procedures designed to resist biologically nonspecific adsorption events. Minimization of opsonization increases blood residence time and improves the ability to target solid tumors. We report the electrostatic self-assembly of polyethyleneimine-polyethylene glycol (PEI-PEG) copolymers onto porous silica nanoparticles. PEI-PEG copolymers were synthesized and their adsorption by self-assembly onto silica surfaces were investigated to achieve a better understanding of structure-activity relationships. Quartz-crystal microbalance (QCM) study confirmed the rapid and stable adsorption of the copolymers onto silica-coated QCM sensors driven by strong electrostatic interactions. XPS and FT-IR spectroscopy were used to analyze the coated surfaces, which indicated the presence of dense PEG layers on the silica nanoparticles. Dynamic light scattering was used to optimize the coating procedure. Monodisperse dispersions of the PEGylated nanoparticles were obtained in high yields and the thin PEG layers provided excellent colloidal stability. In vitro protein adsorption tests using 5% serum demonstrated the ability of the self-assembled copolymer layers to resist biologically nonspecific fouling and to prevent aggregation of the nanoparticles in physiological environments. These results demonstrate that the electrostatic self-assembly of PEG copolymers onto silica nanoparticles used as drug nanocarriers is a robust and efficient procedure, providing excellent control of their biointerfacial properties.
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Affiliation(s)
- Benjamin Thierry
- Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus, Mawson Lakes, Adelaide, South Australia 5095, Australia.
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Valadares LF, do Carmo Bragança F, da Silva CA, Leite CAP, Galembeck F. Low-energy-loss EFTEM imaging of thick particles and aggregates. J Colloid Interface Sci 2007; 309:140-8. [PMID: 17286981 DOI: 10.1016/j.jcis.2006.12.059] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 12/18/2006] [Accepted: 12/20/2006] [Indexed: 11/18/2022]
Abstract
Electron spectroscopy imaging is a powerful tool for the elucidation of colloidal particle morphology and microchemistry, but it normally requires the use of very thin samples, typically less than 50 nm, to avoid the effects of multiple scattering. This work shows that many aspects of the internal morphology of thick particles and aggregates and the chemical component distribution are revealed using low-energy-loss electron imaging in the transmission electron microscope, benefiting from multiple scattering as well as small but significant differences in the low-energy-loss spectra of aggregate constituents. Low-loss images reveal morphological details of thick aggregates made out of colloidal polymers (natural rubber and styrene-acrylic latex) and inorganic particles (silica, montmorillonite, and aluminum phosphate) at a spatial resolution close to that achieved in the bright-field images and much better than in the elemental maps, showing the advantages of the simultaneous use of low-loss images and standard thin-cut elemental maps.
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Affiliation(s)
- Leonardo Fonseca Valadares
- Institute of Chemistry, Universidade Estadual de Campinas, Caixa Postal 6154, 13084-971 Campinas, SP, Brazil
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