Integrated optical sensors for microfluidic free-flow electrophoresis

• Applicant: Professor Dr. Stefan Nagl
• Subject Area: Analytical Chemistry
• Term: from 2011 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 192305443

Miniaturization of analytical techniques on microchips aims for faster chemical analysis on smaller scales; in order to conserve resources, enable the investigation of biological and medical samples that are available only in very small amounts and perform analysis where it is needed. Electrophoretic separation procedures on microchips are capable of sample analysis with high resolution and sensitivity but are complex to develop and read out because many relevant parameters can only be observed indirectly. Integration of optical sensors in microfluidic separation procedures aims to overcome these constraints.In the previous project period the integration of planar optical chemical sensors and sensor arrays in microfluidic free flow electrophoresis (micro-FFE) platforms was demonstrated for the first time. Environmental parameters such as pH can now be analyzed spatially resolved and in real time in micro-FFE.In this project, two important parameters in FFE, the pH gradient in isoelectric focusing (IEF) and temperature differences produced by Joule heating in FFE (IEF) are investigated by chip-integrated optical sensors and the results are used for improvement and optimization of microanalytical separation procedures. Initially this will be performed on selected protein mixtures and the results are later adapted for analysis of real world samples. This will be exemplarily demonstrated on proteins and organelles from cell culture lysates. To this end, detection methods will be developed for FFE in order to provide for simultaneous recording of both labeled analytes and sensor layer without interferences. These are based on ratiometric multispectral data acquisition combined with fluorescence lifetime measurements.In further project sections these analytical procedures are then extended. In order to gain more information from chip-integrated sensor layers, simultaneous spatially resolved dual sensing of pH and temperature in micro electrophoresis will be investigated. The analysis of native, unlabeled proteins in micro-FFE with integrated sensor layers will be developed. In the final part micro-FFE chips with integrated chemical sensors will be coupled to a microfluidic reactor in order to enable both chemical synthesis and subsequent electrophoretic analysis on a microchip using integrated optical chemical sensor layers.

• DFG Programme: Research Grants