Nanoparticles as a novel stationary phase for µEC in plastic microchip: from open-channel to fully-filled channel – NanoChrom

Over the past decade, the field of “Lab-on-a-Chip” has gained in maturity. This term applies to miniaturised devices which integrate the full sequence of analyses, from the raw sample to the result reading. Lab-on-a-Chip design touches on an incredibly diverse number of analytical chemistry applications and equally receives great input from a spectrum of scientific and engineering disciplines. In this sense, « Lab-on-a-Chip » is truly interdisciplinary in nature and has served as a focal point to bring together the different actors of miniaturization. The core of most “Lab-on-a-Chip” is the separation unit which is an indispensable tool for analytical chemists. Various electrokinetic separation techniques have been implemented in Lab-on-a-Chip. To realize efficient separation of a wide range of solutes (charged and neutral), selectivity can be improved by implementing interaction with a stationary phase. The miniaturization of conventional liquid chromatography technique requires the implementation of extremely sophisticated pumping systems able to deliver relatively low flow rates, as well as small volume injection loops limiting external effects. Instead of surrounding a miniaturised separation system with cumbersome chromatographic environment (pumps, loop), it can be wiser to combine electric field with stationary phase to miniaturize conventional analyzers. The so-called electrochromatography-on-chip (µEC) represents the most appropriate separation technique in “Lab-on-Chip”. The stationary phases that are nowadays employed for the implementation of electrochromatography in microsystems present many limitations in terms of realization, sample capacity or solute dispersion. The project that we propose here tends to answer these issues by implementing a completely novel concept in microsystems: in-situ synthesis of multilayered nanoparticles for EC purposes. These functionalized nanoparticles will be directly synthesized in-situ, rooted from the surface of the microsystem. This will avoid tedious packing or multiple surface functionalization. By controlling the thickness of the multilayered nanoparticles, a high surface-to-volume ratio will be implemented, leading to a dramatic increase in sample capacity in open channel EC. The realization of a packed bed generated in-situ will circumvent tedious packing procedure, while the sub 1 µm particle size will lead to tremendous separation efficiency in EC, the band broadening being only due to molecular diffusion.
The use of nanoparticles in chromatography represents a major breakthrough in separation science. Indeed, the actual liquid chromatography tends to decrease particle diameters, which immediately results in inoperable pressure. The implementation of nanoparticles in electrochromatography technique can be seen as the future of liquid chromatography, aiming at faster analysis time, better separation efficiencies and smaller columns. This challenge has to be overstepped and this is the purpose of this proposal.