Preparation of an ionic bipolar diode and transistor (BJT)

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Ionic Transport Through Nanopores: From Living Cells to Ionic Diodes and Transistors Zuzanna S. Siwy Department of Physics and Astronomy University of California, Irvine

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Our main object of studies is a single nanopore in a polymer filmWe study ionic transport through single conical nanopores+-Main Object of Our StudiesSeveral nanometers, typically 2-6 nm~ 1 mm12 mm

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OutlineMotivation for studies of single nanopores Fabrication of single nanopores by the track-etching technique. Motivation for studying conically shaped nanopores. Preparation of ionic devices controlling transport of ions in water solutions: Preparation of ionic unipolar rectifiers. Preparation of an ionic bipolar diode and transistor (BJT); similarities and differences to semiconductor devices. On the way to make a field effect transistor for ions. Ionic diodes as biosensors. 5. Nanoprecipitation in nanopores and electrochemical oscillations. 6. Conclusions.

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Impermeable lipid bilayer membraneMembrane-Bound Transport Proteins Allow for highly selective transport of ions, sugars, amino acids, etc. across the lipid bilayer membraneLessons from Nature Transport Proteins are Nature’s Nanotubes

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Biological Pores are Smart “Holes” – Very Selective Transport of Millions of Ions per 1 sPotassium selective channel with four K+ in the selectivity filter (right panel). R. MacKinnon, P. Agre 2003< 1 nmE. Gouaux, R. MacKinnon, Science 310, 1461 (2005). S. Berneche, B.Roux, Nature 414, 73 (2001).A potassium selective channel is a very important player in the nerve signaling.

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W. Nonner, D. Gillespie, D. Henderson, B. Eisenberg, J. Phys. Chem. 105, 6427 (2001); E.W. McCleskey, J. Gen. Physiol. 113, 765 (1999)[Ca2+] << [Na+]Ca2+ and Na+ have basically the same diameter.Selectivity of L-Type Calcium Channels (Heart Muscle Regulation)Negative groups COO-

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Preparation of the Simplest Calcium Channel/PorePHYSICS approachGillespie, D., Boda, D., He Y. Apel, P., Siwy, Z.S. (2008) Synthetic Nanopores as a Test Case for Ion Channel Theories: The Anomalous Mole Fraction Effect. Biophysical Journal 95, 609-619. Our synthetic analogue (a synthetic hole) is indeed Ca2+ selective!Theoretical predictions: highly charged lining of the pore and small pore volume lead to Ca2+ selectivity.

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Diode - Like Characteristics of Biological ChannelsI [pA]V [mV]T. Baukrowitz et al. EMBO 18, 847 (1999)Y. Jiang et al. Nature 417, 515 (2002)Many biological channels are switches for ionsA diode perfectly rectifies currents so that it flows in one directionrectifierdiode

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Nanopores – Studying Interactions at the NanoscaleNanopores give a unique possibility to control transport of ions and charged molecules in water-based solutions.Nanopores have very large surface!

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Nanopores as Basis for BiosensorsSub-femtoliter volume! Very few molecules actually fit there! Basis for single molecule detection!

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Preparation of various components of IONIC CIRCUITS for ions and molecules in a water solution: urgent need for systems that operate in water. For that we need: TEMPLATE - robust single nanopores with tunable geometry and surface chemistry i.e. tunable electrochemical potential. I Will Talk About..

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OutlineMotivation for studies of single nanopores. Fabrication of single nanopores by the track-etching technique. Motivation for studying conically shaped nanopores. Preparation of ionic devices controlling transport of ions in water solutions: Preparation of ionic unipolar rectifiers. Preparation of an ionic bipolar diode and transistor (BJT); similarities and differences to semiconductor devices. On the way to make a field effect transistor for ions. Ionic diodes as biosensors. 5. Nanoprecipitation in nanopores and electrochemical oscillations. 6. Conclusions.

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1. Irradiation with e.g. Xe, Au, U (~2.2 GeV i.e. ~ 15% c)2. Chemical etchingLinear accelerator UNILAC, GSI Darmstadt, Germany E. Loriot1 ion  1 latent track  1 pore !Heavy Ions as a Working ToolLatent tracksR.L. Fleischer, P.B. Price, R.M. Walker (1975)

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1. Irradiation with e.g. Xe, Au, U (~2.2 GeV i.e. ~ 15% c)2. Chemical etchingLinear accelerator UNILAC, GSI Darmstadt, Germany E. Loriot1 ion  1 latent track  1 pore !Heavy Ions as a Working ToolR.L. Fleischer, P.B. Price, R.M. Walker (1975)

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Tuning the Pore Shape during EtchingVbVtVb – Rate of non-specific etching the so-called bulk etchingVt - Rate of etching along the latent trackRecipes for cylindrical and conical nanopores: Cylindrical pores: high Vt and low Vb; for PET 0.5 M NaOH in 70 ºC Conical pores: low Vt and high Vb; for PET 9 M NaOH, RT

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Why Do We Want to Work with Asymmetric Pores?Cylindrical poreTapered coneddDL>>

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UNaOHacidic solutionCurrent (pA)time (min)Conical Pores are Obtained by Putting Etch Solution on One Side of Membrane and Stop Solution of the OtherZ. Siwy et al. Nucl. Instr. Meth. B 208, 143-148 (2003); Applied Physics A 76, 781-785; Surface Science 532-535, 1061-1066 (2003). Single ion irradiation

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Gold Replica of a Single Conical PoreP. Scopece et al. Nanotechnology 17, 3951 (2006)

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Etch solution 9 M NaOHFor polyethylene terephthalateElectro-Stopping Technique to Prepare Double-Conical PoresEtch solution 9 M NaOH

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P. Apel, DubnaCross – Section of Membranes with Double-Conical Nanopores

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Hydrolysis of Ester Bonds with NaOH in PET Causes Formation of COOH GroupsOH-The surface density of COOH groups was estimated to be ~ 1.0 per nm2____________________

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OutlineMotivation for studies of single nanopores Fabrication of single nanopores by the track-etching technique. Motivation for studying conically shaped nanopores. Preparation of ionic devices controlling transport of ions in water solutions: Preparation of ionic unipolar rectifiers. Preparation of an ionic bipolar diode and transistor (BJT); similarities and differences to semiconductor devices. On the way to make a field effect transistor for ions. Ionic diodes as biosensors. 5. Nanoprecipitation in nanopores and electrochemical oscillations. 6. Conclusions.

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Transport Properties of Conical Nanopores

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Z. Siwy et al. Europhys. Lett. 60, 349 (2002); Z. Siwy et al. Surface Science 532-535, 1061 (2003)Single Conical Nanopores Rectify Ion CurrentCurrent (nA)Voltage (mV)VtVbVb - Vt~ 3 nm~ 600 nm0.1 M KCl, pH 80.1 M KCl, pH 3

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t+ ~ 0.80PET and Kapton pores are selective for positive ions (cations) Which Ions Are Transported?Z. Siwy, A Fulinski, Phys. Rev. Lett. 89, 198103 (2002); Am. J. Phys. 72, 567 (2004). Siwy Z., Adv. Funct. Mat.16, 735 (2006).UNIPOLAR DEVICE – mainly pass through _________________

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Why do Asymmetric and Charged Pores Rectify Siwy Z., Fulinski A. Phys. Rev. Lett. 89, 198103 (2002); Siwy Z., Fulinski A. The American Journal of Physics 74 (2004) 567; Siwy Z., Adv. Funct. Mat.16, 735 (2006).The profile of electric potential V(z) of a cation in an asymmetric nanoporezCervera, J., Schiedt, B., Ramirez, P. Europhys. Lett. 71, 35-41 (2005).

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Last Updated: 8th March 2018

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