Controlled method of reducing electrophoretic mobility of macromolecules, particles, or cells

A method of reducing electrophoretic mobility of macromolecules, particles, cells, and other substances is provided which comprises interacting in a conventional electrophoretic separating procedure, the substances with a polymer-linked affinity compound comprised of a hydrophilic neutral polymer such as polyethylene glycol bound to a second component such as a hydrophobic compound, an immunocompound such as an antibody or antibody active fragment, or a ligand such as a hormone, drug, antigen, or a hapten. The reduction of electrophoretic mobility achieved is directly proportional to the concentration of the polymer-linked affinity compound employed, and such reduction can comprise up to 100 percent for particular particles and cells. The present invention is advantageous in that electrophoretic separation can now be achieved for substances whose native surface charge structure had prevented them from being separated by normal electrophoretic means. Depending on the affinity component utilized, separation can be achieved on the basis of the specific/irreversible, specific/reversible, semi-specific/reversible, relatively nonspecific/reversible, or relatively nonspecific/irreversible ligand-substance interactions

Electrophoresis of colloidal dispersions in the low-salt regime

We study the electrophoretic mobility of spherical charged colloids in a low-salt suspension as a function of the colloidal concentration. Using an effective particle charge and a reduced screening parameter, we map the data for systems with different particle charges and sizes, including numerical simulation data with full electrostatics and hydrodynamics and experimental data for latex dispersions, on a single master curve. We observe two different volume fraction-dependent regimes for the electrophoretic mobility that can be explained in terms of the static properties of the ionic double layer.Comment: Substantially revised versio

Electrophoretic separation of large DNAs using steric confinement

We report an alternative method for electrophoretic separation of large DNAs using steric confinement between solid walls, without gel or obstacles. The change of electrophoretic mobility vs confinement thickness is investigated using fluorescence video microscopy. We observe separation at small confinement thicknesses followed by a transition to the bulk behaviour (no separation) at a thickness of about 4 μm (a few radii of gyration for the studied DNA chains). We present tentative explanations of our original observations.Comment: to appear in JCI

Capillary electrophoresis characterisation of a rapid prototyped PMMA chip for particle analysis

Màster en Nanociència i NanotecnologiaA rapid and cheap method has been developed for the fabrication of a capillary electrophoresis chip for the preliminary characterization of particles. The microfluidic chips were fabricated using polymethyl methacrylate (PMMA) with integrated platinum electrodes without the need of using high technology microfabrication techniques. The chips were characterized using electroosmotic flow (EOF) with different channel treatments. The electrodes were characterised with impedance and conductivity measurements using both static and electrophoretic flow, respectively. Nine micron diameter particles were detected and their electrophoretic mobility determined using capillary electrophoresis and conductivity detection

Electrophoretic Analysis of Blood Serum Proteins in Three Species of Water Snakes (Genus Nerodia)

Serum from three species of water snakes (Nerodia rhombifera, N. erythrogaster and N. fasciata) from one geographic region was analyzed electrophoretically on cellulose acetate, and anodic mobility and relative concentration of the fractions were determined by a recording densitometer with an automatic integrator. Classification of fractions was based on mobility (Rf, values), and for identification purposes, bands were labeled in order of decreasing mobility (albumin and alpha₁, alpha₂, alpha₃, beta₁, beta₂, gamma₁, and gamma₂ globulins). Seven fractions were identified in each species with alpha₃ being absent from N. rhombifera and N. erythrogaster, and only one gamma fraction was observed in N. fasciata. In the three species, gamma globulin was the predominant protein (42-46%), and albumin levels were characteristically low ;however, a distinct difference was observed in albumin concentration (N. fasciata, 7%; N. rhombifera and N. erythrogaster, 16-18%). The Rf values and relative concentrations of other globulins showed heterogeneity in the three species, with the protein pattern of N. fasciata being distinct from the other two species

Electrophoretic silica-coating process on a nano-structured copper electrode

A method for silica-coating at the nanoscale by electrophoretic deposition is presented here, using raw or grafted silica dispersions

Electrophoretic mobility of a charged colloidal particle: A computer simulation study

We study the mobility of a charged colloidal particle in a constant homogeneous electric field by means of computer simulations. The simulation method combines a lattice Boltzmann scheme for the fluid with standard Langevin dynamics for the colloidal particle, which is built up from a net of bonded particles forming the surface of the colloid. The coupling between the two subsystems is introduced via friction forces. In addition explicit counterions, also coupled to the fluid, are present. We observe a non-monotonous dependence of the electrophoretic mobility on the bare colloidal charge. At low surface charge density we observe a linear increase of the mobility with bare charge, whereas at higher charges, where more than half of the ions are co-moving with the colloid, the mobility decreases with increasing bare charge.Comment: 15 pages, 8 figure

Silver Staining of Proteins in 2DE Gels

Silver staining detects proteins after electrophoretic separation on polyacrylamide gels. Its main positive features are its excellent sensitivity (in the low nanogram range) and the use of very simple and cheap equipment and chemicals. The sequential phases of silver staining are protein fixation, then sensitization, then silver impregnation, and finally image development. Several variants of silver staining are described here, which can be completed in a time range from 2 h to 1 day after the end of the electrophoretic separation. Once completed, the stain is stable for several weeks

Electrophoretic manipulation of multiple-emulsion droplets

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this report the electrophoretic manipulation of structured oil-water-oil (O/W)/O core-shell droplets is presented. Water shells have been created that allow the electrophoretic manipulation of oil droplets in an oil environment. It was found that the inner droplet regardless of size and composition does not affect the electrophoretic mobility of the outer water shell, neither before nor after contact with a biased electrode. This method can be used for the manipulation of oil droplets in a continuous oil phase or for the transportation of microbial cells that would otherwise be killed at low electric field strengths