title: Bubble-free electrode actuation for micro-preparative scale electrophoresis of RNA.
abstract: A microfluidic chip is presented for lysis and one-step RNA purification from bacteria. Bacteria are lysed by joule-heating followed by a gel electrophoresis step for clean-up and subsequent elution of small RNA. Bubble formation during electrophoresis at constant current is suppressed through the use of a silver chloride cathode and a silver anode. To prevent silver chloride sediment in the bulk solution, the anode was immersed in a saturated chloride solution. Salt bridges in the form of polyacrylamide gels are used that could be precisely patterned with the help of phaseguides. Bubble-free actuation could be performed for more than 20 min under a constant current. For longer actuation times, cathodic silver-chloride became depleted and a silver-chloride sediment formed in the anodic microchamber at increasing distance from the anode with time. The chip functioning was verified by extraction of transfer-messenger RNA from Escherichia coli and subsequent amplification using reverse transcription real-time PCR. Incorporation of salt bridges enables effective bubble free actuation of Ag/AgCl electrodes in a microfluidic chip. This opens up new possibilities in a surge towards fully integrated diagnostic cartridges that are miniaturized and disposable.
authors.affiliation: Leiden Academic Centre for Drug Research (LACDR), Division of Analytical Biosciences, Leiden University, Einsteinweg 55, 2333CC, Leiden, The Netherlands. p.vulto@lacdr.leidenuniv.nl
authors.forename: Paul
authors.initials: P
authors.lastname: Vulto
authors.forename: Phillip
authors.initials: P
authors.lastname: Kuhn
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Urban
mesh_terms: D004566:Electrodes; D046209:Electrophoresis, Microchip / Q000295:instrumentation*; D004867:Equipment Design; D004926:Escherichia coli / Q000235:genetics*; D012329:RNA, Bacterial / Q000302:isolation & purification*; D018030:Silver Compounds / Q000737:chemistry
chemical_list: D012329:RNA, Bacterial; D018030:Silver Compounds; C096222:tmRNA; C037548:silver chloride