Enrichment of viable bacteria in a micro-volume by free-flow electrophoresis.
Macro- to micro-volume concentration of viable bacteria is performed in a microfluidic chip. The enrichment principle is based on free flow electrophoresis and is demonstrated for Gram positive bacteria. Bacteria from a suspension flow are trapped on a gel interface that separates the trapping location from integrated actuation electrodes in order to enable non-destructive trapping. The microfluidic chip contains integrated electrolytic gas expulsion structures and phaseguides for gel and liquid handling. Trapping efficiency is systematically optimized to reach 25 times the initial concentration from a theoretical maximum of 30. Finally, enrichment from analytically relevant concentrations down to 3 × 10(2) colony forming units per millilitre is demonstrated with a trapping efficiency of 80% which represents the most important parameter in enrichment.
Laboratory for Sensors, Department for Microsystem Engineering (IMTEK), Albert-Ludwigs-Universität Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany.
Susann
S
Podszun
Paul
P
Vulto
Helene
H
Heinz
Sydney
S
Hakenberg
Carsten
C
Hermann
Thomas
T
Hankemeier
Gerald A
GA
Urban
D015169:Colony Count, Microbial; D004566:Electrodes; D004572:Electrolysis; D046209:Electrophoresis, Microchip / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D006094:Gram-Positive Bacteria / Q000254:growth & development* / Q000302:isolation & purification*