Single‐step CE for miniaturized and easy‐to‐use system

Abstract

We developed a novel single-step capillary electrophoresis (SSCE) scheme for miniaturized and easy to use system by using a microchannel chip, which was made from the hydrophilic material polymethyl methacrylate (PMMA), equipped with a capillary stop valve. Taking the surface tension property of liquids into consideration, the capillary effect was used to introduce liquids and control capillary stop valves in a partial barrier structure in the wall of the microchannel. Through the combined action of stop valves and air vents, both sample plug formation for electrophoresis and sample injection into a separation channel were successfully performed in a single step. To optimize SSCE, different stop valve structures were evaluated using actual microchannel chips and the finite element method with the level set method. A partial barrier structure at the bottom of the channel functioned efficiently as a stop valve. The stability of stop valve was confirmed by a shock test, which was performed by dropping the microchannel chip to a floor. Sample plug deformation could be reduced by minimizing the size of the side partial barrier. By dissolving hydroxyl ethyl cellulose and using it as the sample solution, the EOF and adsorption of the sample into the PMMA microchannel were successfully reduced. Using this method, a 100-bp DNA ladder was concentrated; good separation was observed within 1 min. At a separation length of 5 mm, the signal was approximately 20-fold higher than a signal of original sample solution by field-amplified sample stacking effect. All operations, including liquid introduction and sample separation, can be completed within 2 min by using the SSCE scheme.

Recent advances in enhancing the sensitivity of electrophoresis and electrochromatography in capillaries and microchips (2012–2014)

“…Single‐step CE in a PMMA chip employing FASS was presented by Ono et al . The presented system allows introduction of sample and separation solution, FASS of the sample solution, and separation within 2 min, without the use of additional equipment.…”

“…Schematic of the generation of a liquid interface using capillary stop valves and air vents (A) and schematic of the single‐step CE setup (B) for controlled hydrodynamic injection of a sample in a microchip. Reproduced from with permission.…”

Contemporary sample stacking in analytical electrophoresis

“…Ono et al. presented a novel single‐step CE scheme for a miniaturized and easy‐to‐use system by using a microchannel chip made of polymethyl methacrylate. A 100‐bp DNA ladder was concentrated approximately 20‐fold by FASS in 2× TBE buffer containing 2% hydroxyethylcellulose and detected with LIF detection.…”