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

, Alexander N. Walczak

, Debleena Sengupta

, Victor Tieu

, Caroline M. Ajo-

Franklin

, Michel M. Maharbiz

University of California, Berkeley, Berkeley, CA, USA,

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.