title: Microfluidic chip-based online electrochemical detecting system for continuous and simultaneous monitoring of ascorbate and Mg2+ in rat brain.
abstract: This study demonstrates a microfluidic chip-based online electrochemical detecting system for in vivo continuous and simultaneous monitoring of ascorbate and Mg(2+) in rat brain. In this system, a microfluidic chip is used as the detector for both species. To fabricate the detector, a single-channel microfluidic chip is developed into an electrochemical flow cell by incorporating the chip with an indium-tin oxide (ITO) electrode as working electrode, an Ag/AgCl wire as reference electrode, and a stainless steel tube as counter electrode. Selective detection of ascorbate and Mg(2+) is achieved by drop-coating single-walled carbon nanotubes (SWNTs) and polymerizing toluidine blue O (polyTBO) film onto the ITO electrode, respectively. Moreover, the alignment of SWNT-modified and polyTBO-modified electrodes and the solution introduction pattern are carefully designed to avoid any cross talk between two electrodes. With the microfluidic chip-based electrochemical flow cell as the detector, an online electrochemical detecting system is successfully established by directly integrating the microfluidic chip-based electrochemical flow cell with in vivo microdialysis. The microfluidic system exhibits sensing properties with a linear relationship from 5 to 100 μM for ascorbate and from 100 to 2000 μM for Mg(2+). Moreover, this system demonstrates a high selectivity and stability and good reproducibility for simultaneous measurements of ascorbate and Mg(2+) in a continuous-flow system. These excellent properties substantially render this system great potential for continuous and simultaneous online monitoring of ascorbate and Mg(2+) in rat brain.
authors.affiliation: College of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou 510640, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Gao
authors.forename: Ping
authors.initials: P
authors.lastname: Yu
authors.forename: Yuexiang
authors.initials: Y
authors.lastname: Wang
authors.forename: Takeo
authors.initials: T
authors.lastname: Ohsaka
authors.forename: Jianshan
authors.initials: J
authors.lastname: Ye
authors.forename: Lanqun
authors.initials: L
authors.lastname: Mao
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods*; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D009862:Online Systems; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D008274:Magnesium; D001205:Ascorbic Acid