A review of chemical gradient systems for cell analysis

Somaweera, Himali; Ibraguimov, Akif; Pappas, Dimitri

doi:10.1016/j.aca.2015.12.008

Cited by 94 publications

(64 citation statements)

References 85 publications

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“…Chemical gradients are also used extensively in toxicity screening, where the influence of different drug concentrations on cell function is analyzed to derive dose–response curves (Prill et al, 2016). Hence, there is a great interest in platforms that can maintain variable, stable tempospatial gradients (Kim et al, 2010; Somaweera et al, 2016). …”

Section: Introductionmentioning

confidence: 99%

“…Flow-based devices use laminar flow and diffusive mixing to create a chemical gradient. Some platforms are based on sequentially mixing and splitting a solution in a microchannel, resulting in a stable concentration gradient in a single compartment (Somaweera et al, 2016). Other designs are using microfluidic “jets,” injection of minute amounts (pLs) of fluid into an open pool to generate gradients on open surfaces (Keenan et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microfluidic Concentric Gradient Generator Design for High-Throughput Cell-Based Studies

Tsur

Zimerman

Maor

et al. 2017

Front. Bioeng. Biotechnol.

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Gradients of diffusible signaling molecules play important role in various processes, ranging from cell differentiation to toxicological evaluation. Microfluidic technology provides an accurate control of tempospatial conditions. However, current microfluidic platforms are not designed to handle multiple gradients and cell populations simultaneously. Here, we demonstrate a rapidly adaptable microfluidic design able to expose multiple cell populations to an array of chemical gradients. Our design is based on pressure-equilibrated concentric channels and a pressure-dissipating control layer, facilitating the seeding of multiple cell populations in a single device. The design was numerically evaluated and experimentally validated. The device consists of 8 radiating stimuli channels and 12 circular cell culture channels, creating an array of 96 different continuous gradients that can be simultaneously monitored over time.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Microfluidic Concentric Gradient Generator Design for High-Throughput Cell-Based Studies

Tsur

Zimerman

Maor

et al. 2017

Front. Bioeng. Biotechnol.

View full text Add to dashboard Cite

show abstract

“…In recent years, microfluidics has found numerous applications in the biomedical and environmental monitoring fields, for instance, in ecotoxicology [1,2], cell analysis [3,4,5,6], fertilization in vitro (IVF), cell culture [7,8], food detection [9] and soil analysis [10,11]. Due to its low-cost, versatility, and high integration [12,13], electrowetting-on-dielectric (EWOD) is at the forefront of digital microfluidics.…”

Section: Introductionmentioning

confidence: 99%

Biocompatible/Biodegradable Electrowetting on Dielectric Microfluidic Chips with Fluorinated CTA/PLGA

2018

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One of the major hurdles in the development of biocompatible/biodegradable EWOD (Electrowetting-on-dielectric) devices is the biocompatibility of the dielectric and hydrophobic layers. In this study, we address this problem by using reactive ion etching (RIE) to prepare a super-hydrophobic film combining fluorinated cellulose triacetate (CTA) and poly (lactic-co-glycolic acid) (PLGA). The contact angle (CA) of water droplets on the proposed material is about 160°. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) characterizations indicate that a slight increase in the surface roughness and the formation of CFx (C-F or CF2) bonds are responsible for the super-hydrophobic nature of the film. Alternating Current (AC) static electrowetting and droplet transportation experiments evidence that contact angle hysteresis and contact line pinning are greatly reduced by impregnating the CTA/PLGA film with silicon oil. Therefore, this improved film could provide a biocompatible alternative to the typical Teflon® or Cytop® films as a dielectric and hydrophobic layer.

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“…There are comprehensive review papers in literature that have outlined the development and the variety of flow-based microfluidic devices for bacterial chemotaxis [17][18][19] as well as for general biomedical research. [20][21][22] Here, we summarize a few flow-based microfluidic designs that many of these devices share in common. The simplest design of a microfluidic gradient generator is shown in Figure 1(a), where two streams of fluid, one containing a chemoeffector, join together at a junction.…”

Section: Flow-based Microfluidics Gradient Generators For Bacterimentioning

confidence: 99%

Perspectives in flow-based microfluidic gradient generators for characterizing bacterial chemotaxis

2016

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Chemotaxis is a phenomenon which enables cells to sense concentrations of certain chemical species in their microenvironment and move towards chemically favorable regions. Recent advances in microbiology have engineered the chemotactic properties of bacteria to perform novel functions, but traditional methods of characterizing chemotaxis do not fully capture the associated cell motion, making it difficult to infer mechanisms that link the motion to the microbiology which induces it. Microfluidics offers a potential solution in the form of gradient generators. Many of the gradient generators studied to date for this application are flow-based, where a chemical species diffuses across the laminar flow interface between two solutions moving through a microchannel. Despite significant research efforts, flow-based gradient generators have achieved mixed success at accurately capturing the highly subtle chemotactic responses exhibited by bacteria. Here we present an analysis encompassing previously published versions of flow-based gradient generators, the theories that govern their gradient-generating properties, and new, more practical considerations that result from experimental factors. We conclude that flow-based gradient generators present a challenge inherent to their design in that the residence time and gradient decay must be finely balanced, and that this significantly narrows the window for reliable observation and quantification of chemotactic motion. This challenge is compounded by the effects of shear on an ellipsoidal bacterium that causes it to preferentially align with the direction of flow and subsequently suppresses the cross-flow chemotactic response. These problems suggest that a static, non-flowing gradient generator may be a more suitable platform for chemotaxis studies in the long run, despite posing greater difficulties in design and fabrication.

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A review of chemical gradient systems for cell analysis

Cited by 94 publications

References 85 publications

Microfluidic Concentric Gradient Generator Design for High-Throughput Cell-Based Studies

Microfluidic Concentric Gradient Generator Design for High-Throughput Cell-Based Studies

Biocompatible/Biodegradable Electrowetting on Dielectric Microfluidic Chips with Fluorinated CTA/PLGA

Perspectives in flow-based microfluidic gradient generators for characterizing bacterial chemotaxis

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