Engineering Approaches to Biomolecular Motors

Engineering Approaches to Biomolecular Motors: From in vitro to in vivo Poster Abstracts

33-POS Board 33 Impedance-based Electrochemical Readout of Bacterial Flagellar Rotation Tom J. Zajdel 1 , Alexander N. Walczak 1 , Debleena Sengupta 1 , Victor Tieu 1 , Caroline M. Ajo- Franklin 2 , Michel M. Maharbiz 1 . 1 University of California, Berkeley, Berkeley, CA, USA, 2 Lawrence Berkeley National Laboratory, Berkeley, CA, USA. The objective of this work is to construct a low-power biosensor suitable for use in microrobotics applications. The target detection limit is 1 nM and the target response time is on the order of 30 seconds or less. When detecting bioanalytes, speed, sensitivity, and sensor size are subject to fundamental physical constraints set by diffusion noise (Berg & Purcell 1977). The chemical sensors and signaling pathways used by Escherichia coli during chemotaxis - the organism's motility control in response to its surroundings - are known to approach the fundamental limits on response time and sensitivity for its volume (approximately 1 fL) (Bialek & Setayeshgar 2005, Kaizu et al. 2014). Despite this capability, no modern engineered biosensing system approaches these limits within a volume approaching that of the bacterium (Su et al. 2011, Arlett et al. 2011). We demonstrate a biosensor that can monitor chemotactic motor switching in a single Escherichia coli cell tethered by a single flagellum. A nanoelectrode array detects the electrical impedance perturbation of an E. coli cell as it passes between electrode pairs. With this array, we are able to obtain an electronic report of the cell’s motor bias in response to the presence of chemoeffectors within 30 seconds. Our results suggest that this platform enables biosensing that approaches the performance of a chemotactic bacterium while minimizing power consumption and instrumentation overhead.

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