Microchip capillary electrophoresis with a cellulose-DNA-modified screen-printed electrode for the analysis of neurotransmitters

Abstract

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.

Recent advances in amino acid analysis by CE

“…A microfluidic chip, based on CE coupled with a cellulose-ssDNA modified electrode, has been used by Johirul et al [40] for the simultaneous analysis of dopamine, norepinephrine, 3,4-dihydroxy-L-phenylalanine (L-DOPA), 3,4-dihydroxyphenylacetic acid (DOPAC), and ascorbic acid (AsA). The sensitivity of the modified electrode was about 12 times higher than that of a bare electrode as the S/N was enhanced.…”

Assay of Levodopa in Brain by CE

“…The rabbits of test group were administrated with 1 g L-DP gel (about 20 mg L-DP) through nasal cavity by syringe matching hose; the rabbits (fasted for 12 hours before administration) of control group were administrated with L-DP tablets through gavage. The rabbits were killed by decapitation at the time of 1 hour after administration, and the rabbit heads put into liquid nitrogen immediately [4].…”

Microssistemas de análises químicas: introdução, tecnologias de fabricação, instrumentação e aplicações

“…Trabalhos que têm como objetivo apresentar novas técnicas de microfabricação ou sistemas de detecção geralmente apresentam separações de catecolaminas como compostos modelos [131][132][133] . A determinação simultânea de dopamina, norepinefrina, L-DOPA, DOPAC e ácido ascórbico em amostras de plasma, foi realizada por Johirul e colaboradores 134 usando eletroforese de zona em microdispositivos construídos em vidro. Com detecção amperométrica utilizando eletrodos de carbono modificados com celulose-DNA, limites de detecção em torno de 1 μmol L -1 foram obtidos nesse trabalho.…”