Controlling the contents of microdroplets by exploiting the permeability of PDMS

Shim, Jung-uk; Patil, Santoshkumar N.; Hodgkinson, James T.; Bowden, Steven D.; Spring, David R.; Welch, Martin; Huck, Wilhelm T. S.; Hollfelder, Florian; Abell, Chris

doi:10.1039/c0lc00615g

Cited by 35 publications

(30 citation statements)

References 67 publications

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“…The thousand fold difference between the thresholds observed in homogenous solution and using the separated droplets presumably reflects hindered diffusion of OdDHL by the heterogeneous phases and the layers of surfactants. The threshold found in this paper (1 μM) was lower than reported previously (10 μM) [20] using a system where autoinducer was delivered through a PDMS membrane.…”

Section: Resultscontrasting

confidence: 73%

Intra-Species Bacterial Quorum Sensing Studied at Single Cell Level in a Double Droplet Trapping System

Bai

Patil

Bowden

et al. 2013

IJMS

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In this paper, we investigated the intra-species bacterial quorum sensing at the single cell level using a double droplet trapping system. Escherichia coli transformed to express the quorum sensing receptor protein, LasR, were encapsulated in microdroplets that were positioned adjacent to microdroplets containing the autoinducer, N-(3-oxododecanoyl)- l-homoserine lactone (OdDHL). Functional activation of the LasR protein by diffusion of the OdDHL across the droplet interface was measured by monitoring the expression of green fluorescent protein (GFP) from a LasR-dependent promoter. A threshold concentration of OdDHL was found to induce production of quorum-sensing associated GFP by E. coli. Additionally, we demonstrated that LasR-dependent activation of GFP expression was also initiated when the adjacent droplets contained single E. coli transformed with the OdDHL synthase gene, LasI, representing a simple quorum sensing circuit between two droplets.

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Section: Resultscontrasting

confidence: 73%

Intra-Species Bacterial Quorum Sensing Studied at Single Cell Level in a Double Droplet Trapping System

Bai

Patil

Bowden

et al. 2013

IJMS

Self Cite

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“…The porous structure of the PDMS microfluidic chip allowed for diffusion of the QS trigger molecule into droplets from a nearby reservoir. 145 Bai et al trapped two droplets containing different bacterial strains and proved that the diffusion of a QS inducer from one droplet to another can initiate QS in a neighbouring droplet with other complementary bacterial strains. 146 In a similar work, Weitz et al used droplets with different bacterial strains and inducer molecules to show various chemical communication patterns between droplets (Fig.…”

Section: Microbial Physiology and Interactions Between Bacteriamentioning

confidence: 99%

“…Still, fluorescent labelling has drawbacks. It is comfortable and popular to use fluorescent protein expressing bacteria, 96,[145][146][147] yet this approach is limited to the specifically engineered strains and cannot be easily translated to other microorganisms.…”

Section: Detection and Analysis Of Microbes In Dropletsmentioning

confidence: 99%

Droplet microfluidics for microbiology: techniques, applications and challenges

2016

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Droplet microfluidics has rapidly emerged as one of the key technologies opening up new experimental possibilities in microbiology. The ability to generate, manipulate and monitor droplets carrying single cells or small populations of bacteria in a highly parallel and high throughput manner creates new approaches for solving problems in diagnostics and for research on bacterial evolution. This review presents applications of droplet microfluidics in various fields of microbiology: i) detection and identification of pathogens, ii) antibiotic susceptibility testing, iii) studies of microbial physiology and iv) biotechnological selection and improvement of strains. We also list the challenges in the dynamically developing field and new potential uses of droplets in microbiology.

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“…These include modular systems that allow many tubes/channels and T-junctions to be joined together easily, 16,17 and a robot-driven capillary that first "prints" arrays of drops on a hydrophilicpatterned surface and then adds additional drops to specified locations (applied to single-cell RT-PCR). 18 Whilst these methods alter drop contents in a "digital" way (i.e., by adding discrete volumes), there remains no "analogue" variant that allows continuous changes in drop content (i.e., by gradual advection into, or out of, pre-formed drops) -aside from molecular diffusion through walls/fluids 19,20 (where control is limited by the porosity of the wall to molecules of interest). The use of multiple emulsions has a long history in microfluidics.…”

Section: Introductionmentioning

confidence: 99%

Merging drops in a Teflon tube, and transferring fluid between them, illustrated by protein crystallization and drug screening

et al. 2015

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The ability to manipulate drops with small volumes has many practical applications. Current microfluidic devices generally exploit channel geometry and/or active external equipment to control drops. Here we use a Teflon tube attached to a syringe pump and exploit the properties of interfaces between three immiscible liquids to create particular fluidic architectures. We then go on to merge any number of drops (with volumes of micro- to nano-liters) at predefined points in time and space in the tube; for example, 51 drops were merged in a defined order to yield one large drop. Using a different architecture, specified amounts of fluid were transferred between 2 nl drops at specified rates; for example, 2.5 pl aliquots were transferred (at rates of ~500 fl s(-1)) between two drops through inter-connecting nano-channels (width ~40 nm). One proof-of-principle experiment involved screening conditions required to crystallize a protein (using a concentration gradient created using such nano-channels). Another demonstrated biocompatibility; drugs were mixed with human cells grown in suspension or on surfaces, and the treated cells responded like those grown conventionally. Although most experiments were performed manually, moderate high-throughput potential was demonstrated by mixing ~1000 different pairs of 50 nl drops in ~15 min using a robot. We suggest this reusable, low-cost, and versatile methodology could facilitate the introduction of microfluidics into workflows of many experimental laboratories.

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Controlling the contents of microdroplets by exploiting the permeability of PDMS

Cited by 35 publications

References 67 publications

Intra-Species Bacterial Quorum Sensing Studied at Single Cell Level in a Double Droplet Trapping System

Intra-Species Bacterial Quorum Sensing Studied at Single Cell Level in a Double Droplet Trapping System

Droplet microfluidics for microbiology: techniques, applications and challenges

Merging drops in a Teflon tube, and transferring fluid between them, illustrated by protein crystallization and drug screening

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