| 1. |
- Seitanidou, Maria S, 1985-, et al.
(author)
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Graphene-Enabled Electrophoretic Ion Pump Delivery Devices
- 2022
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In: Advanced Materials Interfaces. - : Wiley. - 2196-7350. ; 9:12
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Journal article (peer-reviewed)abstract
- Organic electronic ion pumps (OEIPs) have been investigated as a promising solution for precise local delivery of biological signaling compounds. OEIP miniaturization provides several advantages, ranging from better spatiotemporal control of delivery to reduced invasiveness for implanted devices. One miniaturization route is to develop OEIPs based on polyelectrolyte-filled capillary fibers. These devices can be easily brought into proximity of targeted cells and tissues and could be considered as a starting point for other "iontronic" implants. To date, OEIPs and other such iontronics exhibit a limited electrode capacity as they generally rely on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) electrodes. While this material is well studied and viable in mixed ion-electron systems, its bulk capacitance is limited by eventual redox reactions. Graphene is an excellent alternative for high-performance electrodes and low-cost solution-processed graphene derivatives are particularly promising, exhibiting high charge mobility and ideal structural properties (lightness, flexibility). Here, the application of solution-processed reduced graphene oxide (RGO) as high-performance driving electrodes for OEIPS is presented. RGO electrodes are characterized and compared with standard PEDOT:PSS (and Ag/AgCl) electrodes. The RGO exhibits greater charge storage capacity and thus increased operational lifetime. The graphene-enabled OEIPs exhibit improved neurotransmitter transport, without imposing limitations to the applied current level.
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| 2. |
- Strakosas, Xenofon, 1985-, et al.
(author)
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An electronic proton-trapping ion pump for selective drug delivery
- 2021
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In: Science Advances. - : American Association for the Advancement of Science. - 2375-2548. ; 7:5
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Journal article (peer-reviewed)abstract
- The organic electronic ion pump (OEIP) delivers ions and charged drugs from a source electrolyte, through a charge-selective membrane, to a target electrolyte upon an electric bias. OEIPs have successfully delivered γ-aminobutyric acid (GABA), a neurotransmitter that reduces neuronal excitations, in vitro, and in brain tissue to terminate induced epileptic seizures. However, during pumping, protons (H+), which exhibit higher ionic mobility than GABA, are also delivered and may potentially cause side effects due to large local changes in pH. To reduce the proton transfer, we introduced proton traps along the selective channel membrane. The traps are based on palladium (Pd) electrodes, which selectively absorb protons into their structure. The proton-trapping Pd-OEIP improves the overall performance of the current state-of-the-art OEIP, namely, its temporal resolution, efficiency, selectivity, and dosage precision.
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