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TU Dresden » Faculty of Mechanical Science and Engineering » Institute for Materials Science » Chair of Materials Science and Nanotechnology



Thursday, 10 December 2009
(at 13:00 in room 115, Hallwachsstr. 3)
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Richard-Willstaetter-Vorlesung 2009: Molecular interfaces in neuroelectronic hybrids

Shlomo Yitzchaik

Institute of Chemistry and the Krueger Family Center for Nanoscience and Nanotechnology
The Hebrew University of Jerusalem
  Israel  






In this contribution, we report on fundamental studies that explore the route for molecular tuning of silicon's electrical properties. The developed molecular electronics tools enabled the transduction of molecular-recognition events into measurable potentiometric signal. It is shown for the first time that bio-recognition of acetylcholine (ACh) can be translated to conformational changes in the enzyme, acetylcholine-esterase (AChE), which in turn induces a measurable change in surface potential. Our results show that a highly sensitive detector for ACh can be obtained by the dilute assembly of AChE on a depletion type floating gate derived field effect transistor (FG-FET). A wide concentration range response is observed for the neurotransmitter ACh (10-2-10-9M) and for AChE inhibitor, carbamylcholine - CCh, (10-6-10-11M). These enhanced sensitivities are modeled theoretically and explained by the combined response of the device to local pH changes and molecular dipoles variations due to enzyme-substrate recognition event. Integration of neurons with microelectronic devices has been a subject of intense studies over the last decade. One of the major problems in assembling efficient neuro-electronic hybrid systems is the weak electrical coupling between the components. This is mainly attributed to the fundamental property of living cells to form and maintain an extracellular cleft between the plasma membrane and any substrate to which they adhere. This cleft shunts the current generated by propagating action potentials and thus reduces the signal-to-noise ratio. Reducing the cleft thickness and thereby increasing the seal resistance formed between the neurons and the sensing surface is thus a challenge and could improve the electrical coupling coefficient. Using electron microscopic analysis, and field potential recordings, we examined here the use of gold micro-structures which mimic dendritic spines in their shape and dimensions to improve the adhesion and electrical coupling between neurons and microelectronic devices. We found that neurons cultured on gold spines matrix, functionalized by a cysteine terminated peptide with a number of RGD repeats, readily engulf the spines, forming tight membrane-spine apposition. The field potentials generated by action potentials of cultured Aplysia neurons are significantly larger in neurons cultured on gold spine electrodes in comparison with the field potentials recorded by flat electrodes.

Brief Bio:

Coming from macromolecular and surface chemistry background, Shlomo Yitzchaik developed novel routes to assemble molecules on surfaces including the topotactic self-assembly (TSA) and the molecular layer epitaxy (MLE) methodologies that are applicable to solid-state 2D-surfaces. He pioneered the studies for molecular tuning of the electronic properties of silicon. In addition, he has developed a modular method to link molecular transducers to various sensor-devices surfaces that interfaces living cells with electronic devices. Prof. Yitzchaik also explored new photoactive conducting nanowires and gels. From 1995-present he has an academic appointment in the Institute of Chemistry, at the Hebrew University of Jerusalem. He received his PhD on "Photochromic Mesophases" in 1992 from the Weitzman Institute of Science in Israel under the supervision of Prof. Valeri Krongauz and spends 3 years as a post doctoral fellow at Northwestern University (USA) working with Prof. Tobin J. Marks on "Chromophoric Superlattices". He has authored over 100 papers and holds 20 patents in the fields of material science, solid-state organic chemistry and thin-film technologies. Some of the awards he has received include the Israeli Chemical Society, the prestigious Kaye Award from the Hebrew University as well as the Israel Vacuum Society's award for his development and contribution in the field of molecular layers.



related paper (pdf)

Invited by Gesellschaft Deutscher Chemiker

Within the Richard-Willstaetter-Vorlesung 2009

last modified: 2018.10.24 Mi
author: webadmin