Project Summary As ion channels react to external influences such as transmembrane voltage, chemicals or mechanical stress, they act as gatekeepers of natural cells. With the ability to genetically modify their structure, a wide field of chemosensing and biosensing applications is now emerging. However, the long-term stability of these channels in lipid membranes is questionable and genetic modification is a complex process. These problems could be alleviated if natural ion channels are replaced by solid-state nanopores; the current state-of-the art in nanopores, however, are merely non-selective open channels. Although modifying the ionic current using a nanopore with an electric field perpendicular to the direction of ion transport has been previously investigated, it was only recently that semiconductor nanofabrication technology has become mature enough to be employed for nanopore fabrication with embedded electrostatic electrodes. The proposed research effort will transformatively recreate the functionality of a natural ion channel. By making the channel reconfigurable via electric fields generated through an arrangement of embedded electrodes at the nanoscale level, the proposed platform will be universal and not limited to one particular application. Fundamental studies on the translocation of macromolecules, such as Bovine Serum Albumin will be possible. Electrostatically controllable nanopores can be used as a tunable filter and localized drug release platform. The nanopores can also trap molecular adapter proteins for highly specific biosensors. The proposal also aims to combine electroactive polymers and electrostatically controlled nanopores. This is a revolutionary idea that will enable the amplification of the nanopore on/off ratio by using the conformational change of the polymer, induced solely via electric fields inside the pore, not relying on changes in solution properties like pH. Specific goals of this proposal include the following: Fabrication of a solid state device structure using lithographically patterned electrostatic gates at different positions along the nanopore. Development of a control circuit to establish a particular electric field distribution inside the nanopore. Study of molecule and nanoparticle transport through a nanopore with embedded electrodes under different substrate bias conditions, evaluating the parameters at which molecules and particles can be trapped and released. Lining of nanopores with electroactive polymers and study of the influence of a substrate bias on the polymer chain conformation on the transport properties through the nanopore. Intellectual merit: The nanopore platform will enable a paradigm shift to fundamental studies of ionic, molecular and nanoparticle translocation through nanopore structures, which can be reconfigured through electrostatic fields within the nanopore. This can be used to modify the translocation rate through the nanopore and even to unclog the pore, which has thus far hindered the widespread success of nanopore membranes. Transformative research will result by combining electroactive polymers with electrostatic substrate biasing, enabling the induction of more substantial changes in nanopore properties, such as constriction diameter and surface energy. This can be accomplished without changing critical parameters such as solution pH or transmembrane bias, thus allowing for an unprecedented level of control over translocation properties. Broader Impacts: The reconfigurable nanopore platform will have a major impact on molecular filtration, biosensing, and localized drug release and thus potentially improve society at large. The investigator aims to integrate the proposed transdisciplinary research as an emerging technology for his education objectives. Graduate and undergraduate students will be inspired to pursue a career in the field of science and engineering, entering the workforce with essential skills for a promising successful future. The proposed middle and high school outreach program modules will expose students to critical physical concepts underlying the proposed research, including electric fields, surface tension and low noise electronics. By developing these activities as modules, they can be made available to more students than those impacted directly by the investigator. This is particularly important for reaching students in underrepresented minority groups.
|Effective start/end date||3/1/12 → 8/31/18|
- National Science Foundation (NSF): $408,000.00
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