Polymer wall coatings for capillary electrophoresis

Horváth, Judit; Dolnı́k, Vladislav

doi:10.1002/1522-2683(200102)22:4<644::aid-elps644>3.0.co;2-3

Cited by 456 publications

(94 citation statements)

References 114 publications

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“…In spite of the large amount of experimental work [13][14][15][16] on the mechanisms controlling the EOF in polymer coated capillaries, a complete understanding of the problem is still missing [17]. The scaling theory of Harden et al [18] focused on the interplay between the deformation of the adsorbed polyelectrolytes and the fluid motion.…”

Section: Introductionmentioning

confidence: 99%

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Marconi

Monteferrante

Melchionna

2014

Phys. Chem. Chem. Phys.

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Motivated by recent experiments, we present a theoretical investigation of how the electro-osmotic flow occurring in a capillary is modified when its charged surfaces are coated by charged polymers. The theoretical treatment is based on a three dimensional model consisting of a ternary fluid-mixture, representing the solvent and two species for the ions, confined between two parallel charged plates decorated by a fixed array of scatterers representing the polymer coating. The electro-osmotic flow, generated by a constant electric field applied in a direction parallel to the plates, is studied numerically by means of Lattice Boltzmann simulations. In order to gain further understanding we performed a simple theoretical analysis by extending the Stokes-Smoluchowski equation to take into account the porosity induced by the polymers in the region adjacent the walls. We discuss the nature of the velocity profiles by focusing on the competing effects of the polymer charges and the frictional forces they exert. We show evidence of the flow reduction and of the flow inversion phenomenon when the polymer charge is opposite to the surface charge. By using the density of polymers and the surface charge as control variables, we propose a phase diagram that discriminates the direct and the reversed flow regimes and determine its dependence on the ionic concentration.

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Section: Introductionmentioning

confidence: 99%

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Marconi

Monteferrante

Melchionna

2014

Phys. Chem. Chem. Phys.

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“…Different strategies, using either covalently bonded polymers (see e.g. [7]) or reversibly adsorbed polymers (so called "dynamic coating", see e.g. [8,9]), have been developed.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Comb Polymers Adsorption on Solid Surfaces

et al. 2005

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We propose a theoretical investigation of the physical adsorption of neutral combpolymers with an adsorbing skeleton and non-adsorbing side-chains on a flat surface.Such polymers are particularly interesting as "dynamic coating" matrices for bioseparations, especially for DNA sequencing, capillary electrophoresis and lab-on-chips. Separation performances are increased by coating the inner surface of the capillaries with neutral polymers. This method allows to screen the surface charges, thus to prevent electro-osmosis flow and adhesion of charged macromolecules (e.g. proteins)on the capillary walls. We identify three adsorption regimes: a "mushroom" regime, in which the coating is formed by strongly adsorbed skeleton loops and the side-chains anchored on the skeleton are in a swollen state, a "brush" regime, characterized by a uniform multi-chains coating with an extended layer of non-adsorbing side-chains and a non-adsorbed regime. By using a combination of mean field and scaling approaches, we explicitly derive asymptotic forms for the monomer concentration profiles, for the adsorption free energy and for the thickness of the adsorbed layer as a function of the skeleton and side-chains sizes and of the adsorption parameters. Moreover, we obtain the scaling laws for the transitions between the different regimes. These predictions can be checked by performing experiments aimed at investigating polymer adsorption, such as Neutron or X-ray Reflectometry, Ellipsometry, Quartz Microbalance, or Surface Force Apparatus.

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“…The substantial electroosmotic flow (EOF) as well as potential interactions between the polypeptides and the channel walls can induce band spreading over the distance of the microchannel. The effect of solute-wall interactions and a biopolymer's electoosmotic flow has been reported for DNA separations in polymer microchips [33][34][35][36]. Dispersion of the analytes over a large distance in the microchannel translates into less material under the laser at any given position, which adversely affects the achievable detection limit.…”

Section: Resultsmentioning

confidence: 99%

Interfacing capillary gel microfluidic chips with infrared laser desorption mass spectrometry

Little

Murray

2006

J. Am. Soc. Mass Spectrom.

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We report on the fabrication and performance of a gel microfluidic chip interfaced to laser desorption/ionization (LDI) mass spectrometry with a time-of-flight mass analyzer. The chip was fabricated from poly(methylmethacrylate) with a poly(dimethyl siloxane) cover. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis was performed in the channel of the microfluidic chip. After electrophoresis, the cover was removed and either the PDMS chip or the PMMA cover was mounted in a modified MALDI ion source for analysis. Ions were formed by irradiating the channel with 2.95 m radiation from a pulsed optical parametric oscillator (OPO), which is coincident with IR absorption by N-H and O-H stretch of the gel components. No matrix was added. The microfluidic chip design allowed a decrease in the volume of material required for analysis over conventional gel slabs, thus enabling improvement in the detection limit to a pmol level, a three orders of magnitude improvement over previous studies in which desorption was achieved from an excised section of a conventional gel. ( T he rapid expansion of the field of proteomics has created an increased demand for selective, sensitive, and high-throughput methods of analysis. Soft ionization methods, such as matrix-assisted desorption/ionization (MALDI) [1,2] and electrospray (ESI) [3,4] are suitable for achieving the goal of identification and structural determination of proteins. Mass spectrometry (MS) has become the primary analysis method in this area because of its high throughput, sensitivity, and high mass accuracy. However, the large number and broad concentration range of the proteins present in the expressed proteome of a typical organism requires that one or more fractionation or separation steps be performed on the sample before mass spectrometry analysis.One of the most commonly utilized techniques for protein separation is sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) [5][6][7][8][9]. The molecular weight of a protein is determined by the migration distance after electrophoretic separation together with several marker proteins of known molecular weights that bracket the protein of interest. Currently, most proteome analyses are based on the separation of complex protein mixtures by 1D or 2D gel electrophoresis, followed by mass spectrometric analysis of proteolytic digests of gel spots to identify individual proteins [10 -13]. However, this protocol requires intermediate sample processing steps such as extraction of the protein from the gel [13], blotting the protein onto a membrane [14], or electroelution [15], which introduces a number of laborious and time-consuming manual steps that are difficult to automate.Various efforts have been directed toward direct analysis of gel and planar chromatography separations by laser desorption ionization (LDI) mass spectrometry. The mass spectrometric analysis of peptides and proteins by UV-MALDI directly from polyacrylamide gels has been reported previously [16]. Here, ultrathin gels (less than 10 m) ...

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Polymer wall coatings for capillary electrophoresis

Cited by 456 publications

References 114 publications

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Electro-osmotic flow in coated nanocapillaries: a theoretical investigation

Theoretical Study of Comb Polymers Adsorption on Solid Surfaces

Interfacing capillary gel microfluidic chips with infrared laser desorption mass spectrometry

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