Culturing Cells on Druggable Bubbles

When testing the effects of drugs on cells and tissues, laboratory scientists generally use a pretty crude approach. They simply mix the desired concentration of the drug with the culture medium and then add it to separate plastic wells in which cells or tissues have been cultured. Of course, this approach has its limitations: when testing many different concentrations and mixtures of drugs, the amount of wells needed for an experiment grows very quickly to overwhelming numbers. Moreover, all of the drug is generally added at once, not taking into account the gradual pharmacokinetic profiles that you would normally find in the human body.

In a paper in Lab on a Chip, scientists from Corning, Inc. and Massachusetts General Hospital demonstrate a new, microengineered approach for treating cultured cells with drugs. Instead of growing the cells on flat surfaces, cells are grown on micro-modified wells plates that contain regular patterns of tiny holes. The microholes can be filled with dried-up drug and then sealed off with a semi-permeable layer of collagen. When cells are grown on the collagen, culture medium starts seeping into the air-filled microholes. The dried-up drug then dissolves and diffuses through the collagen layer, exposing the microscopic patch of cells around the microhole to the drug (see also the figure below).

A schematic overview of how to will microwells with drug and culture hepatocytes on them

The authors only show the results of a simple proof-of-principle experiment with Nefazodone-filled holes leading to local toxicity for cultured liver cells. The technique looks promising however, and it will be interesting to see further development. How easy will it be to load holes with different concentrations and mixtures of drugs? Can the process of drugs diffusing into the medium be controlled? Can we control time-release profiles by changing the shape of the holes, by changing the surface properties of the holes, or maybe by changing the gas content of the medium?

It will also be interesting to see whether the technique can be combined with high-throughput imaging, like fluorescence microscopy or scanning electrochemical microscopy as was recently shown for cells in microscopic wells by Sridhar, et al.

Make sure to check out the paper by Goral, et al. in which they outline their technique while it is still free* to access.

*Access is free until 9.03.15 through a publishing personal account. It’s quick, easy and free to register!

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

New You Tube Videos

On-Chip Sample Preparation for Complete Blood Count from Raw Blood 


 
  
 
Silicon-nanowire based attachment of silicon chips for mouse embryo labelling 


 
 
  
Infection and immunity on a chip: a compartmentalised microfluidic platform to monitor immune cell behaviour in real time  

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Chip-on-a-cell

Article written by Jennifer Newton

Scientists in Spain have flipped the cell-on-a-chip concept to bring us a chip-on-a-cell

Field emission scanning electron microscopy images of a barcode attached to the zona pellucida of a mouse embryo

Jose Antonio Plaza of the Institute of Microelectronics Barcelona and colleagues affixed polysilicon chips, which act as barcodes, onto the outer surface of the zona pellucida, a membrane that surrounds immature egg cells and embryos. Although silicon nanowires penetrated the membrane to attach the chip, they did not interfere with embryo development in tests on mouse embryos.

To read the full article visit Chemistry World.

Silicon-nanowire based attachment of silicon chips for mouse embryo labelling
S. Durán, S. Novo, M. Duch, R. Gómez-Martínez, M. Fernández-Regúlez, A. San Paulo, C. Nogués, J. Esteve, E. Ibañez and J. A. Plaza  
Lab Chip, 2015, Advance Article
DOI: 10.1039/C4LC01299B, Paper

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

New YouTube Videos

Microfluidic single sperm entrapment and analysis 

 
  
Scaling of Pneumatic Digital Logic Circuits 


 
   
Continuous-Flow Sorting of Stem Cells and Differentiation Products based on Dielectrophoresis 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

New You Tube videos

 
Artificial Blood Vessel Implanted Three-Dimensional Microsystem for Modeling Transvascular Migration of Tumor Cells 

 

 
A novel fluidic control method for nanofluidics by the solvent-solvent interaction in a hybrid chip 

Low-volume multiplexed proteolytic activity assay and inhibitor analysis through a pico-injector array 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

December’s Free HOT Articles

These HOT articles, published in December 2014 were recommended by our referees and are free* to access for 4 weeks

Metal-Amplified Density Assays, (MADAs), including a Density-Linked Immunosorbent Assay (DeLISA)
Anand Bala Subramaniam, Mathieu Gonidec, Nathan D. Shapiro, Kayleigh M. Kresse and George M. Whitesides
Lab Chip, 2015, Advance Article
DOI: 10.1039/C4LC01161A, Paper

Graphical abstract: Metal-Amplified Density Assays, (MADAs), including a Density-Linked Immunosorbent Assay (DeLISA)

High process yield rates of thermoplastic nanofluidic devices using a hybrid thermal assembly technique
Franklin I. Uba, Bo Hu, Kumuditha Weerakoon-Ratnayake, Nyote Oliver-Calixte and Steven A. Soper
Lab Chip, 2015, Advance Article
DOI: 10.1039/C4LC01254B, Paper

Graphical abstract: High process yield rates of thermoplastic nanofluidic devices using a hybrid thermal assembly technique

Real-time tracking, retrieval and gene expression analysis of migrating human T cells
Matthias Mehling, Tino Frank, Cem Albayrak and Savaş Tay
Lab Chip, 2015, Advance Article
DOI: 10.1039/C4LC01038H, Paper

Graphical abstract: Real-time tracking, retrieval and gene expression analysis of migrating human T cells

Take a look at our Lab on a Chip 2014 HOT Articles Collection!

*Access is free until 2.02.15 through a publishing personal account. It’s quick, easy and free to register!

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Saving Stripes: using gratings to prevent destructive air-water interfaces

Researchers at National Taiwan University design grating structures to prevent air-water interfaces from destroying lipid bilayers, enabling robust bioassays of synthetic membranes.

Supported lipid bilayers (SLBs) are useful as platforms to simulate cell membranes for evaluating transport of toxins and viral particles1 and screening new pharmaceutical reagents. Yet a significant challenge is maintaining the integrity of SLBs throughout an experiment. Air-water interfaces, commonly formed during reagent changes and rinses, peel apart SLBs and delaminate them from the substrate. Strategies to preserve SLB integrity involve coating SLBs with polymers to increase their rigidity or adding proteins and sugars to form protective layers with a high bending modulus above the membrane. These methods modify the chemical structure and environment of SLBs, preventing analysis of membrane properties and specific assays of membrane-tethered species. Thus, Chung-Ta Han and Ling Chao developed a substrate with patterned gratings to prevent air-water interfaces from directly contacting SLBs when an air bubble is introduced into a microchannel with SLBs.Han2015_Figure2

The grating structures, fabricated by standard photolithography, are perpendicular to fluid flow in the microchannel and act as obstacles to air-water interfaces contacting SLBs directly by a ‘tenting’ mechanism (see figure at right). Holding the obstacle height constant at 2 μm, Han and Chao evaluated obstacle spacing at different flow rates influenced SLB stability after treatment with an air bubble. 40 μm spacing was found to efficiently preserve SLBs from air-water interfaces at a practical range of flow rates: 60 – 6000 mm/min. The authors also confirmed the integrity of the membranes by comparable diffusivity measurements within the SLBs before and after air-bubble treatment. Finally, the authors demonstrated that air bubbles did not affect receptor-ligand interactions between species embedded in the SLBs and surrounding buffer when SLBs were protected using the microfabricated obstacles.

This platform uses integrated barriers to protect SLBs from air-water interfaces, creating SLBs with native properties to study biomolecule behavior within membranes and perform high throughput analytical assays utilizing synthetic membranes.

Download the full article now – free* access for a limited time only!

Using a patterned grating structure to create lipid bilayer platforms insensitive to air bubbles
Chung-Ta Han and Ling Chao. Lab Chip, 2015, 15, 86 – 93.
DOI: 10.1039/c4lc00928b
[1] I. Kusters, A. M. Van Oijen and A. J. Driessen, ACS Nano, 2014, 8, 3380-3392.

*Access is free until 06.02.15 through a registered RSC Publishing account.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

New YouTube Videos

A high-power ultrasonic microreactor and its application in gas-liquid mass transfer intensification 
 
  
 
Chemically induced coalescence in droplet-based microfluidics
 
   
An Optopneumatic Piston for Microfluidics 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

Cytometry Unplugged: acoustophoretic focusing enables impedance-based particle sizing and counting

Groups collaborating across Sweden, Denmark, and Korea develop a chip-integrated acoustic focusing technique to precisely arrange particles for fast sizing and counting using impedance analysis.

The size and number of particles in a mixture can be quickly determined using a Coulter counter. Changes in resistance across a Coulter counter orifice through which particles pass correspond to the volume particles occupy as they displace the ionic carrier fluid (impedance spectroscopy). As fabrication methods transition to planar electrode formats to facilitate device development, the precise position of particles in the orifice becomes crucial to obtaining accurate results. Using planar electrodes on the channel bottom, the electric field across the orifice varies and thus sizing information from amplitude changes in impedance depend on consistent particle positioning. Previous methods using fluid flow focusing require complex fabrication steps and suffer from ion diffusion between virtual channel boundaries (fluid-fluid interfaces). Thus, Carl Grenvall in the Biomedical Engineering department in Lund University and his colleagues developed an acoustic actuation method to focus particles into the middle of the channel before they pass into the sensing aperture containing planar electrodes.

The team used two different frequencies to form standing waves in horizontal and vertical directions of the ‘prefocusing channel’ to guide particles to the center of the aperture where impedance was analyzed. Concentration studies helped determine the optimal density of particles to enable rapid sample analysis yet prevent formation of doublets. Confocal imaging confirmed simulation results to show distribution of focused particles and narrow confinement – 2.04% coefficient of variation after removing doublets, which is on par with other experimental and commercial cytometry platforms. The group was able to discriminate particle sizes from 3, 5, and 7 μm as well as separate 7 μm beads in a diluted blood sample. This demonstration of efficient particle focusing in two dimensions is an exciting development to create integrated simple-to-manufacture microchip impedance microscopy platforms. Standing wave acoustophoresis is gentle on cells as several studies even reporting in-field cell culturing1, thus suggesting further opportunities for integration of microscale cytometers into microscale experimental platforms.

Download the full paper for free* for a limited time only!

Two-dimensional acoustic particle focusing enables sheathless chip Coulter counter with planar electrode configuration
Carl Grenvall, Christian Antfolk, Christer Zoffmann Bisgaard, and Thomas Laurell. Lab Chip, 2014, 14, 4629 – 4637.
DOI: 10.1039/c4lc00982g

*Access is free through a registered publishing personal account until 03/02/2015.

[1] M. A. Burguillos, C. Magnusson, M. Nordin, A. Lenshof, P. Augustsson, M. J. Hansson, E. Elmer, H. Lilja, P. Brundin and T. Laurell, PloS one, 2013, 8, e64233.

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)

New YouTube videos

Malaria detection using inertial microfluidics 

Three-dimensional Cell Manipulation and Patterning using Dielectrophoresis via a Multi-layer Scaffold Structure 

High-throughput, deterministic single cell trapping and long-term clonal cell culture in microfluidic devices 

Digg This
Reddit This
Stumble Now!
Share on Facebook
Bookmark this on Delicious
Share on LinkedIn
Bookmark this on Technorati
Post on Twitter
Google Buzz (aka. Google Reader)