The evaluation of biomolecues interaction kinetics using fluorescently labeled molecules methods versus label free methods via microfluidic device

Biomolecular interaction analysis is at the center of attention in a wide range of disciplines, from biochemistry and biotechnology to medicine. Multiplex assays that are integrated on portable devices are desired to obtain results of high scientific quality within a short time and at low costs. To fulfill this demand, the use of biosensors is uprising. Immunosensors allow high specific and sensitive analyte detection that can be also quantitative. In combination with label-free optical detection technologies, they can form a powerful, low-priced complement to standard analytical methods.

For these reasons, we used a label-free portable biosensor platform named 1-lambda-reflectometry, allowing the detection of multiple analytes of one sample in a short time and cost efficient manner. This direct optical method, is a type of reflectometric interference spectroscopy (RIfS) which is based on the interference of reflected light at thin layers. The change in the reflected light intensity reflects binding or releasing of interactions between molecules. In the present study we applied this technique with a microfluidic device fabricated in our lab. We compared the kinetics of interactions between transcription factors (TF) and their DNA target sequence using fluorescence screening, TIRF measurements and the RIfS technology. Our results showed high correlation between all of these techniques suggesting the potential of applying RIfS for kinetic measurements of macromolecules. Opening a path for high throughput label free measurement systems with significantly reduced costs in compare to todays conventional low throughput fluorescent systems technique.