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Droplet-based Testing of Biochemical Reactions in 10,000 Different Conditions

By producing a large number of droplets containing different reagents in slightly different concentrations, it is possible to generate a high resolution map of how a reaction proceeds from different starting conditions. Here, Anthony Genot, a Physicist explains how they interpret the data obtained from the experiment. (Image Credit: Limms Japan) 

In a revolutionary advancement, researchers have developed a droplet-based microfluidic technique for simultaneously testing – different, complex biochemical reactions. The work published in Nature Chemistry, is an international collaboration of Japanese and French scientists of interdisciplinary fields under the LIMMS CNRS/University of Tokyo unit and led by Yannick Rondelez.

Complex biochemical systems need to be studied in different conditions (e.g., different concentration of reagents) not only to understand the biochemical processes but to provide viable diagnostic solutions.

Currently, this kind of study is carried out by computer simulations or laboratory experiments; each with their own set of drawbacks. Simulations, although capable of testing millions of conditions, are based largely on assumptions and might not be able to cover the minute details of real-life biochemical processes. On the other hand, hands-on experiment, even for a simple design is a time-consuming and a labor intensive job.

Keeping these in mind, this novel technology uses microfluidic technology that surmounts the problems of the existing methods by providing information on thousands of reactions, at a lesser amount of volume and reduced sample volume, time and effort.

Microfluidics is the technology of fabricating devices with micro channels for work with fluids of very small volume (microliters to picoliters) being utilized for a wide range of applications such as inkjet printers, biochemical assays, chemical synthesis, drug screening, etc. Compared to traditional technologies, microfluidic technology offers precise control and manipulation of fluids, reduced sample volume and process time.

10,000 windows using a microfluidic platform

Using a micro-fluidic device, the team produced uniform, micron-sized droplets containing random concentration of reagents and obtained around ten thousand data points. The device consisted of inlets for aqueous phase (containing reagents) and oil phase (with surfactant) to make water-in-oil droplets, which is stabilized by the surfactant used with oil.

A single layer of droplets was then immobilized between glass slides and was characterized using fluorescence microscopy, which reads out the fluorescent signal associated with the particular reagent and presents the reactions by a colorful array of dots. This high resolution map so generated, gives the information of the dynamic biochemical reactions and their optimized condition.

Dr Anthony Genot (a CNRS researcher at LIMMS) elucidates, “It was difficult to fine-tune the device at first. We needed to generate thousands of droplets containing reagents within a precise range of concentrations to produce high resolution maps of the reactions we were studying. We expected that this would be challenging. But one unanticipated difficulty was immobilizing the droplets for several days it took for some reactions to unfold. It took a lot of testing to create a glass chamber design that was airtight and firmly held the droplets in place.” It took them almost 2 years to optimize the device and put it to use.

“The map can tell us not only about the best conditions of biochemical reactions, it can also tell us about how the molecules behave in certain conditions. Using this map we’ve already found a molecular behaviour that had been predicted theoretically, but had not been shown experimentally. With our technique, we can explore how molecules talk to each other in test tube conditions. Ultimately, we hope to illuminate the intimate machinery of living molecular systems like ourselves,” said Rondelez.

Bigger picture

One of the biggest potential applications of this exciting innovation that the team anticipates is the development of diagnostics for molecular reactions. Bringing together the French (specialists in molecular engineering) and Japanese scientists (microfluidics expert) on the same platform, the versatile technology with current capacity to simultaneously map 10,000 reactions is overwhelming already. However, the researchers are aiming to increase this window even further by employing a microscope which is quicker than the one used in the current study.

To further cater to your interest, watch the video below of the beautiful process and the effort involved, released by LIMMS.

Source: Biotechin.Asia and Nature Chemistry