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Abstract Much effort in the field of nanopore research has been directed toward reproducing the efficient transport phenomena of biological ion channels. For synthetic nanopores to replicate channel function on the scale of a cellular membrane, it is necessary to consider the modes of crosstalk between channels as well as to develop approaches to prepare nanopore arrays consisting of pores with different transport properties, akin to a membrane in an axon. In this manuscript, first ion concentration polarization (ICP) is identified as the primary means of the crosstalk, and subsequently, the extent and degree of ICP is tuned via targeted chemical modification of the pore walls’ functional groups. Next, two fabrication methods of a model two‐nanopore array are presented in a silicon nitride membrane in which one nanopore contains a bipolar ionic junction and functions as an ionic diode, while the other one is a homogeneously charged ionic resistor. The targeted chemical modification of a thin gold layer at the opening of one pore in an array that leaves the other pore located a few tens of nm away, unmodified, is utilized. These results provide an important framework for designing abiotic ionic circuits that can mimic physiological multichannel ion transport and communication.
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Fluidic bacterial diodes rectify magnetotactic cell motility in porous environments
Abstract Directed motility enables swimming microbes to navigate their environment for resources via chemo-, photo-, and magneto-taxis. However, directed motility competes with fluid flow in porous microbial habitats, affecting biofilm formation and disease transmission. Despite this broad importance, a microscopic understanding of how directed motility impacts the transport of microswimmers in flows through constricted pores remains unknown. Through microfluidic experiments, we show that individual magnetotactic bacteria directed upstream through pores display three distinct regimes, whereby cells swim upstream, become trapped within a pore, or are advected downstream. These transport regimes are reminiscent of the electrical conductivity of a diode and are accurately predicted by a comprehensive Langevin model. The diode-like behavior persists at the pore scale in geometries of higher dimension, where disorder impacts conductivity at the sample scale by extending the trapping regime over a broader range of flow speeds. This work has implications for our understanding of the survival strategies of magnetotactic bacteria in sediments and for developing their use in drug delivery applications in vascular networks.
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- PAR ID:
- 10308048
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 12
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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