Archive for September, 2015

New method for studying microalgal growth

The device

The study and optimisation of microalgal growth is a hot topic at the moment due to the use of microalgae in many industrial processes, as well as its potential use as biofuel. Previously, I have written about a Lab on a Chip article from the Sinton lab on optimising microalgal growth by varying irradiance conditions.

Now Mingming Wu’s group, from Cornell University, have published an article focused on the effect of nitrogen concentration on cell growth rates. Wu has developed a platform based on agarose gel, as shown in the diagram. The nutrient media can flow through this gel while the cells can’t, maintaining separate microhabitats.

The authors decided to study the effect of nitrogen concentration gradients on the microalgae (C. reinhardtii), using ammonium as the nitrogen source. Nitrogen is essential for microalgae, as it is required for protein and nucleic acid synthesis, and ammonium is the preferred source for this particular strain.

An ammonium gradient was obtained by flowing ammonium-containing media through the source channel, and ammonium-free media through the sink channel (diagram C). As expected, increasing the concentration (within the micromolar range) increased the microalgal growth rates. Fluorescence imaging allowed the authors to quantify the growth kinetics using the Monod equation (similar to the Michaelis-Menten equation for enzyme kinetics). This is the first time this has been achieved for this particular microalgal strain with nitrogen concentration as the variable.

Another interesting find was that when the microalgae were subjected to millimolar ammonium concentrations, growth inhibition was seen. The standard medium for microalgae contains 7.5 mM ammonium, so these results suggest that these concentrations need to be reduced by several orders of magnitude in order to maximise growth rates!

Wu and co-workers have nicely demonstrated the capablilty of their agarose-based platform in quantifying growth kinetics and they highlight that it is 50-fold faster, and more cost effective, than the standard chemostat system. They also observed cell heterogeneity during their experiments and plan to use their system to study this further, along with other aspects of cellular behaviour such as quorum sensing.

To download the full article for free* click the link below:

An array microhabitat system for high throughput studies of microalgal growth under controlled nutrient gradients
Beum Jun Kim, Lubna V. Richter, Nicholas Hatter, Chih-kuan Tung, Beth A. Ahner and Mingming Wu
Lab Chip, 2015,15, 3687-3694
DOI: 10.1039/ C5LC00727E

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About the webwriter

Claire Weston is a PhD student in the Fuchter Group, at Imperial College London. Her work is focused on developing novel photoswitches and photoswitchable inhibitors.

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*Access is free until 19/10/2015 through a registered RSC account – click here to register

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Winner of the Productizing Science© competition 2015

The Productizing Science© Competition provides entrants with the opportunity to take advantage of Dolomite’s experience in developing successful scientific products. Entrants were asked to submit an abstract detailing their innovative scientific concept, and an outline of how the concept could be commercially successful.

Out of all the high quality entries received, Zimmertech excelled with their electrochemical sensor development kit. This innovative concept shows real potential for benefiting the microfluidics market and will aid the development of portable hand-held diagnostic devices for disease detection, allowing laboratory-based assays to be performed in the field.Dolomite

“We are delighted to announce Zimmertech’s Electrochemical sensor development kit as the winner  of the Dolomite and Lab on a Chip‘s Productizing Science® Competition 2015. Zimmertech’s technology will be combined with Dolomite’s outstanding R&D capabilities to develop an easy to use product for rapid investigation of electrochemical sensor concepts and assays.  We look forward to commercialising the product in 2016 and thus truly Productizing Science®.”

Mike Hawes, Chief Commercial Officer, Dolomite Microfluidics

Congratulations to Zimmertech AS and thank you to everyone who took part in the competition!

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New YouTube Videos

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Top 10 most accessed Lab on a Chip articles in June 2015

In June 2015, our most downloaded Lab on a Chip articles were:

Shia-Yen Teh, Robert Lin, Lung-Hsin Hung and Abraham P. Lee
DOI: 10.1039/B715524G

Ali Kemal Yetisen, Muhammad Safwan Akram and Christopher R. Lowe
DOI: 10.1039/C3LC50169H

Russell H. Cole, Niek de Lange, Zev J. Gartner and Adam R. Abate
DOI: 10.1039/C5LC00333D

Ching-Hui Lin, Yi-Hsing Hsiao, Hao-Chen Chang, Chuan-Feng Yeh, Cheng-Kun He, Eric M. Salm, Chihchen Chen, Ing-Ming Chiu and Chia-Hsien Hsu
DOI: 10.1039/C5LC00541H

Friedrich Schuler, Frank Schwemmer, Martin Trotter, Simon Wadle, Roland Zengerle, Felix von Stetten and Nils Paust
DOI: 10.1039/C5LC00291E

Mei He, Jennifer Crow, Marc Roth, Yong Zeng and Andrew K. Godwin
DOI: 10.1039/C4LC00662C

Joost F. Swennenhuis, Arjan G. J. Tibbe, Michiel Stevens, Madhumohan R. Katika, Joost van Dalum, Hien Duy Tong, Cees J. M. van Rijn and Leon W. M. M. Terstappen
DOI: 10.1039/C5LC00304K

A. Liga, A. D. B. Vliegenthart, W. Oosthuyzen, J. W. Dear and M. Kersaudy-Kerhoas
DOI: 10.1039/C5LC00240K

A. Wasay and D. Sameoto
DOI: 10.1039/C5LC00342C

Ivo Leibacher, Peter Reichert and Jürg Dual
DOI: 10.1039/C5LC00083A

Interesting read? Let us know your thoughts below.

And remember, you can submit directly to Lab on a Chip!

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New YouTube Videos

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New YouTube Videos

Viscosity measurement based on the tapping-induced free vibration of sessile droplets using MEMS-based piezoresistive cantilevers 


 
 
  
An array microhabitat system for high throughput studies of microalgal growth under controlled nutrient gradients 


 
 
  
A Cost-Effective Fluorescence Mini-Microscope with Adjustable Magnifications for Biomedical Applications 

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A wireless chemical sensor for long-term monitoring

For effective treatment of many illnesses, in particular cancer, long-term monitoring of certain biomarkers is required. A needle probe with a chemically sensitive tip can be used, however this is invasive as it has to be inserted every time a new measurement is taken. There are also issues with tissue heterogenicity, as it is possible that changes in the measurements are solely due to a different local environment within the tissue.

Size of sensor

Previously the Cima lab at MIT reported an improved alternative for long-term in vivo monitoring. A capsule containing an NMR contrast agent was inserted in vivo and measurements were recorded using an MRI scanner. They have now done one better and eliminated the need of very costly MRI equipment by developing a small NMR sensor that simply requires a small external reader coil.

Both the sensor and reader contain a circuit with a coil and when both are in range magnetic inductance occurs, causing field amplification inside the chamber of the sensor.  This effectively means that a reading is taken only from tissue within the sensor, rather than surrounding tissue, and this is responsible for the high selectivity seen.

Different components of the system

In order to test their wireless sensor, Cima and coworkers separately measured pH and oxygen tension, both in vivo and in vitro. For the pH experiments, a polymer gel was used as the NMR contrast agent that had an exchangeable H atom with an appropriate pKa value. Using a tumor mouse model, pH readings were found to be lower when the sensor was nearer the tumor, as expected from the acidic nature of tumors. For the oxygen experiments, silicone was used as the contrast agent. The paramagnetic nature of molecular oxygen alters the relaxation time and this can therefore be used to determine the concentration of oxygen in the sensor.

From the success of their experiments, the authors conclude that they have demonstrated the flexibility of the sensor with these two measurements, and indeed there is huge potential for this NMR probe to greatly simplify in vivo monitoring.


To download the full article for free* click the link below:

Miniaturized, biopsy-implantable chemical sensor with wireless, magnetic resonance readout
C. C. Vassiliou, V. H. Liu and M. J. Cima
Lab Chip, 2015, 15, 3465-3472
DOI: 10.1039/C5LC00546A

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About the webwriter

Claire Weston is a PhD student in the Fuchter Group, at Imperial College London. Her work is focused on developing novel photoswitches and photoswitchable inhibitors.

—————-

*Access is free until 01/10/2015  through a registered RSC account.

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