Microfluidic Western Blot and LC/MS for Analysis of Islets of Langerhans

Microfluidics enables miniaturization of analytical tools and facile coupling to small samples. A ubiquitous tool for bioanalysis is the western blot. We have developed a western blot based on capillary and microchip electrophoresis. In this system, protein-SDS complexes are separated by electrophoretically driven sieving through a gel. The outlet of the capillary is interfaced to a inkjet style droplet generator which dispenses separated proteins onto a membrane that is moved as the separation progresses. The resulting captures proteins are analyzed by immunoassay. The system reduces analysis time, reagent consumption, and time required for western blot. We demonstrate its suitability for several biological samples including islets of Langerhans. For small molecule analysis, we describe a fraction collector chip that allows collection of samples from perfused biological samples, in this case islets. The resulting fractions are analyzed by LC-MS. This method allows multiple signaling and metabolic processes to be monitored from just a few islets at a time. Combined these tools represent continued growth of microfluidic tools for bioanalysis and provide insight into islet function.