Issue 9, 2006

A capillary–PDMS hybrid chip for separations-based sensing of neurotransmittersin vivo

Abstract

A chip fabricated by multilayer soft lithography of poly(dimethylsiloxane) was created for separations-based sensing of neurotransmitters in vivo. The chip incorporated a pneumatically actuated peristaltic pump and valving system to combine low-flow push–pull perfusion sampling, on-line derivatization, and flow-gated injection onto an embedded fused-silica capillary for high speed separation of amine neurotransmitters from the brain of living animals. Six 160 µm wide by 10 µm high control channels, actuated with an overlapping 60° pulse sequence, simultaneously drove sample and buffers through fluidic channels of the same dimensions. Tunable sampling flow rates of 40 to 130 nL min−1 and separation buffer flow rates of 380 to 850 nL min−1 were achieved with actuation frequencies between 3 and 10 Hz. On-line sampling of amine neurotransmitters with separation efficiencies in excess of 250 000 plates, detection limits of ∼40 nM, and relative standard deviations of 4% for glutamate and aspartate were achieved in vitro. Electropherograms with resolution of γ-aminobutyric acid, glutamine, taurine, serine, glycine, o-phosphorylethanolamine, glutamate, and aspartate could be collected every 30 s for over 4 h in vivo. It was also shown that pharmacological agents could be delivered and subsequent changes in neurotransmitter profile could be measured when delivering either 70 mM K+ artificial cerebrospinal fluid or 200 µM L-trans-pyrrolidine-2,4-dicarboxilic acid with the chip. These results demonstrate the ability of this chip to sample and monitor chemicals in the complex environment of the central nervous system with high selectivity and sensitivity over extended periods.

Graphical abstract: A capillary–PDMS hybrid chip for separations-based sensing of neurotransmitters in vivo

Article information

Article type
Paper
Submitted
09 Mar 2006
Accepted
22 Jun 2006
First published
20 Jul 2006

Lab Chip, 2006,6, 1205-1212

A capillary–PDMS hybrid chip for separations-based sensing of neurotransmitters in vivo

N. A. Cellar and R. T. Kennedy, Lab Chip, 2006, 6, 1205 DOI: 10.1039/B603561B

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