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Jia, M., Dechiruji, H., Wu C., Selberg, J., Pansodtee, P., Teodorescu, M. & Rolandi, M. “Bioelectronic Control of Chloride Ions and Concentration with Ag/AgCl Contacts”. To appear in APL Materials (2020)

PI Colaborators: Marco Rolandi

Abstract— Translation between ionic currents and measurable electronic signals is essential for the integration of natural system and artificial bioelectronic devices. Chloride ions (Cl-) play a pivotal role in bioelectricity, and they are involved in several brain pathologies, including epilepsy and disorders of the autistic spectra. As such, controlling [Cl-] in solution can actively influence biochemical processes and can be used in bioelectronic therapies. Here, we demonstrate a bioelectronic device that uses Ag/AgCl contacts to control [Cl-] in solution by electronic means. We do so by exploiting the potential dependence of the reversible reaction, Ag + Cl- « AgCl + e-, at the contact/solution interface, which is at the basis of the well-known Ag/AgCl reference electrode. In short, a negative potential on the Ag/AgCl contact transfers Cl- from the contact to the solution increasing [Cl-] and vice versa. With this strategy, we demonstrate precise spatiotemporal control of [Cl-] in solution that can be used to affect biochemical reactions dependent on [Cl-].

Wu, C., Selberg, J., Nguyen, B., Pansodtee, P., Jia, M., Dechiraju, H., Teodorescu, M. & Rolandi, M. “A Microfluidic Ion Sensor Array”. Small (2020) p.1906436.

PI Colaborators: Marco Rolandi and Marcella Gomez

Abstract— A balanced concentration of ions is essential for biological processes to occur. For example, [H+] gradients power adenosine triphosphate synthesis, dynamic changes in [K+] and [Na+] create action potentials in neuronal communica- tion, and [Cl−] contributes to maintaining appropriate cell membrane voltage. Sensing ionic concentration is thus important for monitoring and regulating many biological processes. This work demonstrates an ion-selective micro- electrode array that simultaneously and independently senses [K+], [Na+], and [Cl−] in electrolyte solutions. To obtain ion specificity, the required ion-selective membranes are patterned using microfluidics. As a proof of concept, the change in ionic concentration is monitored during cell proliferation in a cell culture medium. This microelectrode array can easily be integrated in lab-on- a-chip approaches to physiology and biological research and applications.

Strakosas, X., Selberg, J., Pansodtee, P., Yonas, N., Manapongpun, P., Teodorescu, M., & Rolandi, M. “A non-enzymatic glucose sensor enabled by bioelectronic pH control”. Scientific reports, 9(1), 10844. (2019)

PI Colaborators: Marco Rolandi and Marcella Gomez

Abstract— Continuous glucose monitoring from sweat and tears can improve the quality of life of diabetic patients and provide data for more accurate diagnosis and treatment. Current continuous glucose sensors use enzymes with a one-to-two week lifespan, which forces periodic replacement. Metal oxide sensors are an alternative to enzymatic sensors with a longer lifetime. However, metal oxide sensors do not operate in sweat and tears because they function at high pH (pH > 10), and sweat and tears are neutral (pH = 7). Here, we introduce a non-enzymatic metal oxide glucose sensor that functions in neutral fluids by electronically inducing a reversible and localized pH change. We demonstrate glucose monitoring at physiologically relevant levels in neutral fluids mimicking sweat, and wireless communication with a personal computer via an integrated circuit board.

Ozel, R. E., Kahnemouyi, S., Fan, H., Mak, W. H., Lohith, A., Seger, A., Teodorescu, M., & Pourmand, N. (2016). “Smartphone Operated Signal Transduction by Ion Nanogating (STING) Amplifier for Nanopore Sensors” Design and Analytical Application” ACS Sensors, 1 (3), 265-271 (2016)

PI Colaborators: Nader Pourmand

Abstract— In this report, we demonstrate a hand-held wireless voltage-clamp amplifier for current measurement of nanopore sensors. This amplifier interfaces a sensing probe and connects wirelessly with a computer or smartphone for the required stimulus input, data processing, and storage. To test the proposed signal transduction by ion nanogating (STING) wireless amplifier, in the current study the system was tested with a nano-pH sensor to measure pH of standard buffer solutions and the performance was compared against the commercial voltage-clamp amplifier. To the best of our knowledge, STING amplifier is the first miniaturized wireless voltage-clamp platform operated with a customized smart- phone application (app).