Integrated capillary electrophoresis on flexible silicone microdevices: Analysis of DNA restriction fragments and detection of single DNA molecules on microchips

Microchips for integrated capillary electrophoresis systems were produced by molding a poly(dimethylsiloxane) (PDMS) silicone elastomer against a microfabricated master. The good adhesion of the PDMS devices on clean planar surfaces allows for a simple and inexpensive generation of networks of sealed microchannels, thus removing the constraints of elaborate bonding procedures, The performance of the devices is demonstrated with both fast separations of phi X-174/HaeIII DNA restriction fragments labelled with the intercalating dye YOYO-1 and fluorescently labelled peptides, Detection limits in the order of a few zeptomoles (10(-21) mel) have been achieved for each injected DNA fragment, corresponding to a mass detection limit of similar to 2 fg for the 603 base pair fragment. Single lambda-DNA molecules intercalated with YOYO-1 at a base pair-to-dye ratio of 10:1 could be detected with an uncomplicated laser-induced fluorescence detection setup, High single-molecule detection efficiency (>50%) was achieved under electrophoretically controlled mass transport conditions in PDMS microchannels.