Biomedical subjects

Qinggang Wang

Publications and source records attributed to Qinggang Wang.

4 recordsLinked to original sources

PubMed2003

Voltage-controlled separation of proteins by electromobility focusing in a dialysis hollow fiber.

Electromobility focusing (EMF) is a relatively new protein separation technique that utilizes an electric field gradient and a hydrodynamic flow. Proteins are focused in order of electrophoretic mobility at points where their electrophoretic migration velocities balance the hydrodynamic flow velocity. Steady state bands are formed along the separation channel when equilibrium is reached. Further separation and detection can be easily achieved by changing the electric field profile. In this paper. we describe an EMF system with on-line UV absorption detection in which the electric field gradient was formed using a dialysis hollow fiber. Protein focusing and preconcentration were performed with this system. Voltage-controlled separation was demonstrated using bovine serum albumin and myoglobin as model proteins. The limitations of the current method are discussed, and possible solutions are proposed.

Dialysis↗

PubMed2002

Equilibrium gradient methods with nonlinear field intensity gradient: a theoretical approach.

Equilibrium gradient methods belong to a family of separation techniques in which analytes are forced to unique equilibrium points by a force gradient and a counter force along the separation pathway. The basic theory for equilibrium gradient methods where the force gradient is induced by a field gradient is developed in this paper. The results indicate that peak capacity can be dynamically improved by using a nonlinear field-intensity gradient in which the first section is steep, and the following section is shallow. Using electromobility focusing (EMF) as an example, a separation model is established. EMF is an equilibrium gradient method that uses an electric field intensity gradient to induce a force gradient on charged analytes, such as proteins, and a constant hydrodynamic flow as an opposing force. Equations relating operating parameters with separation performance are given. Although simulation results show that a peak capacity of over 10,000 is theoretically possible using a single channel in a separation time just under 2 months, if 100 parallel separation units are utilized in an array format under the same operating conditions, the same peak capacity can be obtained in just over 12 h.

Journal Article↗

PubMed2002

Analytical equilibrium gradient methods.

Analytical equilibrium gradient methods are non-linear separation methods in which the separation mechanism involves a force gradient along the separation channel. These methods can be classified into two categories: those in which the gradient is a field gradient applied along the separation channel (i.e., field gradient), and those in which the channel is subjected to a constant field with a gradient formed in some other property (i.e., constant field). Standard deviation of peak width, resolution and peak capacity are important parameters in characterizing equilibrium gradient methods, and general expressions can be obtained from considering both the point of force acting on the analyte and the basic flux equation. Several successful examples, such as density gradient sedimentation, isoelectric focusing and electromobility focusing are discussed. Based on equilibrium gradient methods in the field gradient category, a method to dynamically improve peak capacity is described. An example of such an approach is given using electromobility focusing.

Journal Article↗

PubMed2002

Cycloaliphatic epoxy resin coating for capillary electrophoresis.

Coating the interior surface of a fused-silica capillary with a polymeric material has long been used in capillary electrophoresis (CE) to reduce or eliminate electroosmotic flow and suppress adsorption. A cycloaliphatic epoxide-based resin was bonded to silane treated capillaries and crosslinked with a curing agent. The epoxy resin coating significantly reduced electroosmotic flow over a pH range of 3-10. This coating was sufficiently hydrophilic to suppress protein adsorption. The epoxy resin coated capillary was used to separate several acidic and basic proteins and peptides. Separation efficiencies greater than 400,000 theoretical plates were achieved. The relative standard deviations in migration times for proteins were <0.8%. Speed and simplicity are important advantages of the coating procedure compared to other published coating methods.

Amino Acid Sequence↗