Conductive polymers for biological applications

Although the speed, accuracy, and precision of biomedical diagnostics has significantly improved over the past few decades, the ability to perform real-time, dynamic, and high throughput assays on a versatile technological platform remains challenging. Current diagnostic technologies typically require between 15 minutes to a few hours to assess biomolecule concentrations of interest, and necessitate the use of one chip or sensing cartridge per measurement. Consequently, existing bioanalytical technologies cannot be used for real-time, active analyses of biomolecule concentrations via re-useable sensing platforms. Yet, the ability to dynamically monitor and control biomolecular interactions would be tremendously powerful in point-of-care diagnostic sensors for acute diagnosis of cardiovascular events or metabolic diseases, implantable devices, and surgical instruments.;Towards this end, we have developed conductive polymer biosensors which can be utilized to selectively and reversibly toggle biomolecular interactions. Impedance measurements indicated that this polymer system can be used for rapid detection and monitoring of protein concentrations between 300 nM - 500 muM. Moreover, this technology can be used to bind and release protein-coated beads of interest by changing the voltage applied to the polymer. Here I present the conditions in which the unique capability to toggle protein-protein interactions occurs, both when proteins are in solution and bound to the surface of microspheres. This technology can be utilized in conjunction with sensitive adhesion-based separation assays in order to recover cell or particle populations of interest. Overall, antibody-doped PPy represents an electrically controllable, re-useable sensing platform which can be exploited to collect rapid and repeated measurements of protein concentrations with molecular specificity.;In addition to biosensors, conductive polymers and hydrogels can be used for artificial muscle applications. In order to improve actuation of hydrogels, we engineered porous structures into polyelectrolyte hydrogels. These porous hydrogels generated large deformation as a result of enhanced deswelling mechanisms. Measurements of the mechanical properties and hydrogel water uptake revealed that porous hydrogels bend to a larger extent due to their increased flexibility and decreased volume density. We suggest that the fast and large actuation of polyelectrolyte hydrogels can be accomplished by increasing the hydrogel porosity.