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B. Lendl:
"Mid-IR imaging of chemical reactions in a microchip reactor";
Hauptvortrag: Federation of the Analytical Chemistry and Spectroscopies Societies (FACSS), Reno, Nevada, USA (eingeladen); 02.10.2011 - 07.10.2011.

Microfluidic devices are advantageous for the study chemical reactions due to their low sample consumption, fast mixing times and, in many cases, short path lengths making them ideal for infrared spectroscopy. The microfluidic devices used in this work are made from silicon, calcium fluoride and silicone, have a path length of 8 μm, allowing infrared measurements of aqueous solutions, and are 200 μm wide by 1 cm long. Two liquids flow continuously into the mixer, forming alternately stacked layers, 2 μm high, at the entrance to the measurement channel. These layers mix, via diffusion, resulting in mixing times of approximately 1 ms as predicted from computational fluid dynamics (CFD) calculations. Infrared measurements at particular points along the channel correspond to specific reaction times, with measurement spots close to the channel entrance giving rise to shorter reaction times and those closer to the end of the channel yielding longer reaction times.

Two different geometries of inlet channels were devised, one wedge-shaped (with the dimensions of the wedge tapering from 10 - 22 μm) and one straight edged, and the performance of each type was assessed following the formation of HDO from H2O and D2O. For this, focal plane array infrared imaging was used to take a 64x64 pixel image covering an area of 170 x 170 μm at the entrance to the channel. The wedge-shaped channels gave rise to a more uniform distribution of the analytes across the width of the channel, as well as faster mixing times compared to the straight-edged channels.

With the performance of the different mixer designs characterised, we used the wedge-shaped mixers, in conjunction with single point infrared analysis probing a 100 x 100 μm spot, to investigate the timescales involved in the base pairing and duplex formation between single stranded polycytidylic and polyinosinic acid. Through the application of 2D Correlation Analysis (2D CoS) we were able to identify changes in both RNA backbone orientation and base-stacking interactions upon the formation of the double stranded RNA analogue polyinosinic:polycytidylic acid.

Microfluidic devices are advantageous for the study chemical reactions due to their low sample consumption, fast mixing times and, in many cases, short path lengths making them ideal for infrared spectroscopy. The microfluidic devices used in this work are made from silicon, calcium fluoride and silicone, have a path length of 8 μm, allowing infrared measurements of aqueous solutions, and are 200 μm wide by 1 cm long. Two liquids flow continuously into the mixer, forming alternately stacked layers, 2 μm high, at the entrance to the measurement channel. These layers mix, via diffusion, resulting in mixing times of approximately 1 ms as predicted from computational fluid dynamics (CFD) calculations. Infrared measurements at particular points along the channel correspond to specific reaction times, with measurement spots close to the channel entrance giving rise to shorter reaction times and those closer to the end of the channel yielding longer reaction times.

Two different geometries of inlet channels were devised, one wedge-shaped (with the dimensions of the wedge tapering from 10 - 22 μm) and one straight edged, and the performance of each type was assessed following the formation of HDO from H2O and D2O. For this, focal plane array infrared imaging was used to take a 64x64 pixel image covering an area of 170 x 170 μm at the entrance to the channel. The wedge-shaped channels gave rise to a more uniform distribution of the analytes across the width of the channel, as well as faster mixing times compared to the straight-edged channels.

With the performance of the different mixer designs characterised, we used the wedge-shaped mixers, in conjunction with single point infrared analysis probing a 100 x 100 μm spot, to investigate the timescales involved in the base pairing and duplex formation between single stranded polycytidylic and polyinosinic acid. Through the application of 2D Correlation Analysis (2D CoS) we were able to identify changes in both RNA backbone orientation and base-stacking interactions upon the formation of the double stranded RNA analogue polyinosinic:polycytidylic acid.