Microchip capillary electrophoresis with a cellulose-DNA-modified screen-printed electrode for the analysis of neurotransmitters.
A microfluidic chip based on capillary electrophoresis coupled with a cellulose-single-stranded DNA (cellulose-ssDNA) modified electrode was used for the simultaneous analysis of dopamine (DA), norepinephrine (NE), 3,4-dihydroxy-L-phenylalanine (L-DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), and ascorbic acid (AA). The modification of the electrode improved the electrophoretic analysis performance by lowering the detection potential and enhancing the signal-to-noise characteristic without surface poisoning of the electrode. The sensitivity of the modified electrode was about 12 times higher than those of the bare ones. The test compounds were separated using a 62 mm long separation channel at the separation field strength of +200 V/cm within 220 s in a 10 mM phosphate buffer (pH 7.4). The most favorable potential for the amperometric detection was 0.7 V (vs. Ag/AgCl). A reproducible response (relative standard deviation of 1.3, 1.3, 2.1, 3.1, 3.4% for DA, NE, L-DOPA, DOPAC, and AA, respectively, for n = 9) for repetitive sample injections reflected the negligible electrode fouling at the cellulose-ssDNA modified electrode. Square-wave voltammetric analyses reflected the sensitivities of the modified electrode for DA, NE, L-DOPA, DOPAC, and AA which were 1.78, 0.82, 0.69, 2.45, and 1.23 nC/microM with detection limits of 0.032, 0.93, 1.13, 0.31, and 0.62 microM, respectively. The applicability of this microsystem to real sample analysis was demonstrated.
Department of Chemistry and Center for Innovative BioPhysio Sensor Technology, Pusan National University, Keumjeong-ku, Busan, South Korea.
Muhammad
M
Johirul
Alam
A
Shiddiky
Rog-Eun
RE
Kim
Yoon-Bo
YB
Shim
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis; D000818:Animals; D001205:Ascorbic Acid / Q000032:analysis; D002021:Buffers; D002417:Cattle; D002482:Cellulose / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D004298:Dopamine / Q000032:analysis; D046209:Electrophoresis, Microchip / Q000295:instrumentation; D007980:Levodopa / Q000032:analysis; D008839:Microelectrodes; D018377:Neurotransmitter Agents / Q000032:analysis*; D009638:Norepinephrine / Q000032:analysis
D002021:Buffers; D004277:DNA, Single-Stranded; D018377:Neurotransmitter Agents; D015102:3,4-Dihydroxyphenylacetic Acid; D007980:Levodopa; D002482:Cellulose; D001205:Ascorbic Acid; D004298:Dopamine; D009638:Norepinephrine