Thermoresponsive Microparticle Gels for Electrophoresis: PNIPAm Templated Page

Jeffery W. Thompson, Holly A Stretz, and Pedro E. Arce. Chemical Engineering, Tennessee Technological University, Tennessee Technological University Department of Chemical Engineering, PO Box 5013, Cookeville, TN 37083

Gel electrophoresis is a widely used technique for the separation of biomacromolecules, including DNA, proteins, antibiotics and others. Clinical studies, diagnostics, and lab production are some excellent examples where electrophoresis seems to work well for a large family of these molecules. However, for cases where the physical or transport properties, i.e. electrophoretic mobility and/or diffusivity are similar, as well as biomolevualr sizes are of the same order, the separation becomes very challenging. The fibrous gel morphology exposes the biomacromolecules to a “differentiating” material allowing the physical properties mentioned above to yield a motion that is different for biomacromolecules with different transport properties.

Therefore, controlling the nature and sizes of this architecture or morphology may have a beneficial impact on the separation efficiency. Rill et. al. (1995) proposed a modified architecture by templating gels with DNA (or surfactant) templates that were removed from the gels once the polymerization took place, by electrophoresis action. The resulting material, hypothesized as a “dual” porous structure, displaying both small (of the order of the inter-fiber voids) and larger (of the order of the templating agent) pores or voids, led to an improved separation efficiency.

Templating agents in gels, as mentioned above, are not the only approach to modifying gel morphology Embedded nanoparticles of varying properties are another option because of the multitude of potential alternatives that they offer regarding the physical properties of the gel. For example, the presence of nanoparticles within the gel has the potential to modify the electrokinetic properties of the gel; therefore, these nanoparticles may influence electro-osmotic flows, as it has been shown in preliminary studies for sensor applications (Matos et. al., 2006). Sedrick et. al. (AIChE/ACS, 2008) have synthesized these types of gels by using laponite nanoparticles of a given size and properties. TEM images show an interesting and excellent potential structure that may lead to an improved separation efficiency based on the modified architecture of the nano-composite gels.

Nanocomposite gels whose morphology is sensitive to temperature for drug delivery and bioseparations of proteins or DNA holds great potential. These materials feature, for example, nano or microparticles embedded in the gel structure that creates a thermo-sensitive and composite polymer with different and unique transport properties. The synthesis and characterization of thermally responsive particles as well as including them in gel matrices are described. The particles are synthesized with a precipitation polymerization crosslinking reaction and inserted into gels. In addition, electrophoresis runs are used to test the new gels in proteins motion. Both UV and visual characterization are used to determine and compare the transport (i.e. mobility and dispersion) characteristics of the new gels with standard gels in the electrophoresis runs. The new nanocomposite gels offer excellent potential to improve separation. Details for the current and future work will be offered.