A new instrument for the measurement of very small electrophoretic mobilities using phase analysis light scattering (PALS)

McNeil-Watson, Fraser K.; Tscharnuter, W.; Miller, John F.

doi:10.1016/s0927-7757(97)00267-7

Cited by 90 publications

(64 citation statements)

References 3 publications

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“…However, phase analysis takes place over many cycles of the respective waveforms, whereas spectral analysis is sensitive to the period of one cycle. For that reason, when a small mobility is present, only phase shifts can be detected accurately [38].…”

Section: Methodsmentioning

confidence: 99%

Electrophoretic mobility of model colloids and overcharging: theory and experiment

et al. 2002

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Several theories claim that ion±ion correlations play an important role in the electric double layer of colloids. One of the most outstanding predictions is overcharging, which would take place at high electrolyte concentrations and surface charge densities. The counterion concentration next to the surface can become so large that the particle charge is overcompensated and the overcharging occurs. Sometimes this would also involve a reversal of the ± potential, but this phenomenon has been observed rarely through mobility measurements. This study explores the matter further. The electrophoretic mobility is measured for latex particles with moderate and extremely large surface charge densities at high ionic strengths (up to 2 M) in solutions of symmetric electrolytes. The results are analysed within the so-called hypernetted chain/mean-spherical approximation (HNC/MSA) and a Poisson±Boltzmann approach. In this way, the relevance of ion±ion correlations in practice and the occurrence of overcharging are probed experimentally.

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Section: Methodsmentioning

confidence: 99%

Electrophoretic mobility of model colloids and overcharging: theory and experiment

et al. 2002

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“…The most frequently used method, known as laser Doppler velocimetry, is based on the analysis of the intensity autocorrelation function of the scattered light. The method of phase analysis light scattering (PALS) [36][37][38] has the adavantage of being suited for particles moving very slowly, for instance, close to their isoelectric point. The method is capable of detecting electrophoretic mobilities as low as 10 -12 m 2 V -1 s -1 , that is, 10 -4 µm s -1 /V cm -1 in practical mobility units (note that mobilities typically measurable with standard techniques must be above ∼10 -9 m 2 V -1 s -1 ).…”

Section: Electrophoretic Light Scattering (Els)mentioning

confidence: 99%

Measurement and Interpretation of Electrokinetic Phenomena (IUPAC Technical Report)

Delgado

González‐Caballero

Hunter

et al. 2005

Pure and Applied Chemistry

528

398

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Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the Measurement and interpretation of electrokinetic phenomena (IUPAC Technical Report)Abstract: In this report, the status quo and recent progress in electrokinetics are reviewed. Practical rules are recommended for performing electrokinetic measurements and interpreting their results in terms of well-defined quantities, the most familiar being the ζ-potential or electrokinetic potential. This potential is a property of charged interfaces, and it should be independent of the technique used for its determination. However, often the ζ-potential is not the only property electrokinetically characterizing the electrical state of the interfacial region; the excess conductivity of the stagnant layer is an additional parameter. The requirement to obtain the ζ-potential is that electrokinetic theories be correctly used and applied within their range of validity. Basic theories and their application ranges are discussed. A thorough description of the main electrokinetic methods is given; special attention is paid to their ranges of applicability as well as to the validity of the underlying theoretical models. Electrokinetic consistency tests are proposed in order to assess the validity of the ζ-potentials obtained. The recommendations given in the report apply mainly to smooth and homogeneous solid particles and plugs in aqueous systems; some attention is paid to nonaqueous media and less ideal surfaces.

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“…The mobility was then converted to the ζ potential by application of the Smoluchowski theories. 26 The hydrodynamic diameter of the various MNPs suspensions prepared previously was monitored by using dynamic light scattering (DLS, Brookhaven BI-90 PALS) over a period of 16 h. The samples were sonicated with an ultrasonic probe for 30 s prior to the first measurement and left undisturbed for subsequent measurements. Concurrent with the size analysis, a drop of the MNPs suspended in the various media was also deposited onto a carbon-coated copper grid and dried at room temperature for visualization under a Transmission Electron Microscope (TEM, JEOL JEM 1400) operating with an accelerating voltage of 100 kV and beam current of 55 μA.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Insight into Serum Protein Interactions with Functionalized Magnetic Nanoparticles in Biological Media

Wiogo¹,

Lim

Bulmuş³

et al. 2012

Langmuir

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Surface modification with linear polymethacrylic acid (20 kDa), linear and branched polyethylenimine (25 kDa), and branched oligoethylenimine (800 Da) is commonly used to improve the function of magnetite nanoparticles (MNPs) in many biomedical applications. These polymers were shown herein to have different adsorption capacity and anticipated conformations on the surface of MNPs due to differences in their functional groups, architectures, and molecular weight. This in turn affects the interaction of MNPs surfaces with biological serum proteins (fetal bovine serum). MNPs coated with 25 kDa branched polyethylenimine were found to attract the highest amount of serum protein while MNPs coated with 20 kDa linear polymethacrylic acid adsorbed the least. The type and amount of protein adsorbed, and the surface conformation of the polymer was shown to affect the size stability of the MNPs in a model biological media (RPMI-1640). A moderate reduction in r 2 relaxivity was also observed for MNPs suspended in RPMI-1640 containing serum protein compared to the same particles suspended in water. However, the relaxivities following protein adsorption are still relatively high making the use of these polymer-coated MNPs as Magnetic Resonance Imaging (MRI) contrast agents feasible. This work shows that through judicious selection of functionalization polymers and elucidation of the factors governing the stabilization mechanism, the design of nanoparticles for applications in biologically relevant conditions can be improved.

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A new instrument for the measurement of very small electrophoretic mobilities using phase analysis light scattering (PALS)

Cited by 90 publications

References 3 publications

Electrophoretic mobility of model colloids and overcharging: theory and experiment

Electrophoretic mobility of model colloids and overcharging: theory and experiment

Measurement and Interpretation of Electrokinetic Phenomena (IUPAC Technical Report)

Insight into Serum Protein Interactions with Functionalized Magnetic Nanoparticles in Biological Media

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