Automated microfluidic protein immunoblotting

This protocol describes regional photopatterning of polyacrylamide gels in glass microfluidic devices as a platform for seamless integration of multiple assay steps. The technology enables rapid, automated protein immunoblotting, demonstrated in this study for native western blotting. The fabrication procedure is straightforward and requires approximately 3 h from the start of gel photopatterning to completion of native protein western blotting, a substantial time savings over slab-gel immunoblotting. The assay itself requires less than 5 min. Importantly, all assay stages are programmably controlled by a high-voltage power supply and monitored by an epifluorescence microscope equipped with a charge-coupled device camera. Our approach overcomes severe limitations associated with conventional immunoblotting, including multiple steps requiring manual intervention, low throughput and substantial consumption of reagents. We also describe a simple chemical recycling protocol so that glass chips can be reused. The fabrication technique described forms the basis for a diverse suite of bioanalytical tools, including DNA/RNA blotting and multidimensional separations.