(424b) Insulator-Based Dielectrophoresis Applied to Immunoglobuline G and Bovine Serum Albumin Concentration

Dielectrophoresis (DEP) is a well established technique to manipulate particles and biological objects such as bacteria and mammalian cells. Its capability of sorting, fractionation and separation make it also very attractive as a new method for biomolecule separation without gel- matrices or chromatographic phases. Here, we exploit dielectrophoresis of the proteins immunoglobulin G (IgG) and bovine serum albumin (BSA) in a tailored microfluidic device and demonstrate concentration of proteins due to DEP streaming behavior.

An insulator-based microfluidic device serves as the basis of our DEP studies. Insulating posts fabricated with standard photolithographic and softlithographic methods create electric field gradients upon application of external fields. Those electric field gradients are used to manipulate proteins by DEP. First, we investigated the electric field distribution in the obtained microstructures. From those, the migration behavior of proteins was simulated with a numerical model that combined DEP forces with electrokinetic and diffusional transport mechanisms. We could demonstrate, that proteins exhibiting positive DEP behavior are concentrated in streamlines. In contrary to this, proteins with negative DEP show concentration depletion in the same streaming regions.

Next, we found experimentally that both proteins – IgG and BSA – showed DEP streaming behavior. This experimentally observed streaming behavior was in excellent qualitative agreement with numerical simulations in the case of positive DEP. A concentration factor of up to 24% was obtained for IgG, indicating the potential of protein concentration via DEP in microfluidic devices. Furthermore, our experiments demonstrate that protein aggregation in iDEP can be effectively reduced by the addition of zwitterionic detergents.

In the future, we will extend protein iDEP manipulation to combined micro- and nanostructured devices, in which we expect increased concentration behavior due to increased electric field gradients. Our goal is further to exploit protein DEP and the underlying polarization behavior quantitatively to apply DEP of proteins for separation and fractionation.

Dielectrophoresis (DEP) is a well established technique to manipulate particles and biological objects such as bacteria and mammalian cells. Its capability of sorting, fractionation and separation make it also very attractive as a new method for biomolecule separation without gel- matrices or chromatographic phases. Here, we exploit dielectrophoresis of the proteins immunoglobulin G (IgG) and bovine serum albumin (BSA) in a tailored microfluidic device and demonstrate concentration of proteins due to DEP streaming behavior.

An insulator-based microfluidic device serves as the basis of our DEP studies. Insulating posts fabricated with standard photolithographic and softlithographic methods create electric field gradients upon application of external fields. Those electric field gradients are used to manipulate proteins by DEP. First, we investigated the electric field distribution in the obtained microstructures. From those, the migration behavior of proteins was simulated with a numerical model that combined DEP forces with electrokinetic and diffusional transport mechanisms. We could demonstrate, that proteins exhibiting positive DEP behavior are concentrated in streamlines. In contrary to this, proteins with negative DEP show concentration depletion in the same streaming regions.

Next, we found experimentally that both proteins – IgG and BSA – showed DEP streaming behavior. This experimentally observed streaming behavior was in excellent qualitative agreement with numerical simulations in the case of positive DEP. A concentration factor of up to 24% was obtained for IgG, indicating the potential of protein concentration via DEP in microfluidic devices. Furthermore, our experiments demonstrate that protein aggregation in iDEP can be effectively reduced by the addition of zwitterionic detergents.

In the future, we will extend protein iDEP manipulation to combined micro- and nanostructured devices, in which we expect increased concentration behavior due to increased electric field gradients. Our goal is further to exploit protein DEP and the underlying polarization behavior quantitatively to apply DEP of proteins for separation and fractionation.