See Overview 2008

Dawid Zalewski (promotion date: 24 October 2008)

Electrokinetic methods for preparative electrophoresis on a chip

Promotion date: 24 October 2008

Thesis advisor: Prof. dr.. Han Gardeniers

Assistant thesis advisor: Dr. ir. Richard Schasfoort

Capillary electrophoresis (CE) on a chip has one important drawback: the amount of an analyte obtained from a single run is very limited. Consequently, post-separation processing of the separated sample is challenging. To increase the amount of material available for a follow-up analysis, one can either pool fractions separated in subsequent runs or employ a method for continuous sample separation.

In this project, the aim was the development of microfluidic electrokinetic-only strategies for microchip preparative CE. Particularly, the techniques for single fraction manipulation in complex channel networks were researched, and methods that allow for fully automated control of such procedures were proposed. These techniques were later applied to develop a micropreparative CE device, that was able to separate complex samples and pool identical fractions with no user interaction required.

Furthermore, an approach for continuously-operating zone electrophoresis was introduced and investigated. This new method, called continuous-flow zone electrophoresis (CFZE) separates analytes solely by electrophoresis and electro-osmosis. Unlike free-flow electrophoresis devices, no mechanical pumping is required. A preparative mode of CFZE, named synchronized, continuous-flow zone electrophoresis (SCFZE) was also investigated. This method allows for rapid and highly selective sample fractionation.

What did you like most in your thesis-project?

In the third year of my PhD studies the initial ideas started to work out and I could finally show some working examples of preparative CE systems on a chip. This was really a breakthrough, and quite quickly I could make further steps in improving the methods I was developing. I also received a lot of support within MESA+ at this time – this really helped boosting the research.

Are the concepts of electrophoresis-on-a-chip, like the ones you investigated, a feasible technology for future applications?

I really believe so. Electrophoresis and related techniques are used in many laboratories around the world. For example DNA analysis and the Human Genome Project wouldn’t have been possible without electrophoresis. And there are many more applications like proteomics, food quality assessment etc. Certainly, the solutions I developed during my studies can help improving some critical aspects; preparative electrophoresis is meant for providing sufficient amounts of separated material to perform effective post-processing. Since traditional chip-scale separations can only provide picoliters of a sample per run, the methods proposed in my thesis may enable new applications.

What are the pros and cons of doing research?

After spending four years on my PhD, I must admit that research is still very appealing to me. It is an extraordinary kind of freedom you are given, which allows you to push your own ideas. That makes it so special.

And there are always people around who are willing to help you and contribute to your work, however small the experiment you would like to perform. I experienced this atmosphere at MESA+ during the project, time and time again. There is also freedom in visiting any lab you want, usually the only thing you have to do is to ask somebody.

On the other hand, in academic research, it always takes a very long time before some results appear. To stay focused on a long-term goal is not always easy.

What are your future plans?

I’m starting a post-doc project here. I will work in the Cooling and Instrumentation group of the Low Temperature Division on a micro-cooling project. It concerns localised, cryogenic cooling of low temperature electronic devices.

What is, in your view, important for MESA+ to face the future with confidence?

MESA+ has surely an excellent position in nanotechnology and the future of the institute looks promising. I think being more active in attracting researchers from around the world could secure this status or perhaps even push it higher. Attracting big names is one way, because with their vision, they can construct new research lines. But also advertising MESA+ at the top universities in other countries could help bringing a stream of talented PhD students and post-docs who would materialize these new ideas.