Archive for the ‘Hot Articles’ Category

HOT: SERS microfluidic device for fast and reliable bacteria identification

Want your bacteria identified – wait one second!

A team from the Friedrich-Schiller University of Jena have designed a SERS microfluidic system for swiftly analysing large sample sets of bacteria.  Jürgen Popp and co-workers have combined the benefits that a lab-on-a-chip provides – a well defined detection area – with the sensitivities of SERS for fast, reproducible spectra every time.  Their novel sample technique, which involves sonicating the bacteria to break down the cell walls,  avoids previous problems with spectral fluctuations and sample inhomogeneity.

Read how they did it here – the article is free to access until the end of February!

Towards a fast, high specific and reliable discrimination of bacteria on strain level by means of SERS in a microfluidic device
Angela Walter, Anne März, Wilm Schumacher, Petra Rösch and Jürgen Popp
Lab Chip, 2011, Advance Article
DOI: 10.1039/C0LC00536C, Paper

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Microfluidic pinball

A device to deposit polymer layers on oil droplets has been made by researchers from Singapore, who say that their design is faster and

Oil droplets are guided through three liquid streams - two polymers and a washing station - by micropillars arranged in a zigzag fashion

more efficient than conventional deposition techniques and it achieves the highest number of polymer layers reported so far using microfluidics. The device could be used to encapsulate drugs for delivery or be used to create capsules for biosensing.

Dieter Trau from the National University of Singapore and colleagues have used a method that they call ‘microfluidic pinball’ to guide oil droplets through channels created by rows of micropillars, like a pinball machine. The rows are orientated in a zigzag fashion across three liquid streams – two polymers and a washing station. The angles created by the rows, as well as the flow rates in the streams, determine how long droplets stay in each channel.

The droplets are guided along the rows to travel repeatedly through the three streams. The team found that six polyelectrolyte layers could be deposited on a droplet in under three minutes – they were able to see the layers with fluorescence spectroscopy. Atomic force microscopy revealed the thickness of each layer to be approximately 2.8nm.

Read Jennifer Newton’s Chemistry World article online here or go straight to the HOT Lab on a Chip paper:


A microfluidic pinball for on-chip generation of Layer-by-Layer polyelectrolyte microcapsules

Chaitanya Kantak, Sebastian Beyer, Levent Yobas, Tushar Bansal and Dieter Trau,
Lab Chip, 2011
DOI: 10.1039/c0lc00381f

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Playing games with biology

Ingmar Riedel-Kruse and colleagues from Stanford University have developed games which use a
biological system as an essential component in a microfluidic device. These range from a soccer game in which live Paramecium cells are directed to kick a tiny football into a goal, to a new version of the classic pacman in which the player controls live paramecia to collect virtual yeast food while avoiding the virtual zebra fish larvae! There’s also a betting game based on a realtime PCR system.

Live Paramecium cells used in biotic games

Live Paramecium cells used in biotic games

Commenting on the games Steve Quake, also from Stanford, points out that they could prove serious fun with applications in school education as well as in medical applications e.g. serving as early diagnostics for neurodegenerative diseases such as Alzheimers and Parkinsons.

Design, engineering and utility of biotic games
Ingmar H. Riedel-Kruse, Alice M. Chung, Burak Dura, Andrea L. Hamilton and Byung C. Lee

Lab Chip, 2011, Advance Article
DOI: 10.1039/C0LC00399A, Paper

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Point-of-Care Microfluidic Diagnosis in 15 min

Claros Diagnostics has received regulatory approval from the EU  for a new microfluidic point-of-care instrument that measures PSA levels from a finger prick within 15 minutes allowing monitoring of prostrate cancer patients.

The business end of the machine is a $1 credit card sized, injection moulded, microfluidic cartridge that accepts a small drop of blood and is then inserted into a special reader. Captured proteins are tagged with gold nanoparticles and then developed in a silver solution to form silver plated particles which are easily read by a photodetector. PSA levels are then reported within about 15 minutes of  sample input with an accuracy similar to laboratory tests.

Read a related paper on a point-of-care-device for lithium in blood

Microfluidics allows the delivery of rapid results indicate Claros Diagnostics, who aim to make point-of-care PSA monitoring in the doctor’s office a reality. The device recently received EU Regulatory approval and is seeking approval by the U.S. Food and Drug Administration. “Although microfluidics has been a field of scientific endeavour for over 20 years we have not seen full commercialisation of this technology outside the research setting” said Harp Minhas (Editor of the leading journal on micro- and nanofluidics, Lab on a Chip). “However, I have seen evidence that in the next two to three years there are likely to be a flurry of similar point-of-use products that will aim to capture related or overlapping markets.”

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Artery-on-a-chip studies heart disease

Scientists from Canada have developed a microfluidic platform on which fragile blood vessels can be fixed, allowing the factors that promote and sustain cardiovascular diseases to be studied.

Microvascular structure and function are currently studied using either an isometric approach, where small arteries are mounted on two wires, or an isobaric method, where arteries are drained and filled using glass micropipettes. Both of these procedures require manually skilled personnel and are not scalable – key factors which have limited the number of laboratories carrying out essential microvascular research.

Artery on a chip

A full artery is mounted onto the chip for investigation

However, Axel Günther and colleagues at the University of Toronto have overcome several of these limitations by developing a microfluidic platform to mount arteries on, which is scalable, inexpensive and has potential for automation and standardisation. The device could be used to routinely screen drug candidates on viable arteries, potentially speeding up the drug development process and reducing the need for animal experimentation.

The platform involves loading and immobilising small arteries within a microfluidic channel where they can be maintained and analysed under physiological conditions that are very similar to those experienced in vivo. Forces within ranges that blood vessels experience in their natural environment can be explored without the use of mechanical tools. It is the first microfluidic approach to study the whole organ function, says Günther, who believes it is ‘a more elegant and gentle approach’.

Abraham Stroock an expert in coupling deterministic micro and nanoscale structures with physical principles to create interesting phenomena and new technologies from Cornell University in Ithaca, US says, ‘the work represents an important step forward in micromanipulation with ramifications beyond the particular application described. For example, as the basis of a microfluidic assembly line for complex structures from biological or colloidal building blocks.’

‘We are optimistic that a prototype system based on the described technology will be available later this year,’ concludes Günther.

 View the full article here: http://dx.doi.org/10.1039/c004675b

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