Selective response of dopamine in the presence of ascorbic acid and uric acid at gold nanoparticles and multi-walled carbon nanotubes grafted with ethylene diamine tetraacetic acid modified electrode

By grafting with ethylene diamine tetraacetic acid (EDTA), novel multi-walled carbon nanotube nano-composites (EDTA-MWCNTs) have been successfully prepared. The integration of gold nanoparticles (AuNPs) and novel functionalized matrix shows very promising applications in the fabrication of biosensors for sensitive detection of dopamine in the presence of ascorbic acid and uric acid with the combination of the charge repelling property of carboxylic anion and the electrocatalytic effect of EDTA. The AuNPs and EDTA-MWCNTs modified film shows excellent sensitivity and selectivity for the dopamine analysis due to the synergic effect of AuNPs and EDTA-MWCNTs. As high as 2000 fold and 150 fold acceptable tolerance of ascorbic acid and uric acid for the determination of trace dopamine is reached, respectively. The linear concentration range for dopamine is from 1.0 × 10-8 to 6.0 × 10-6 mol.L-1, and the detection limit is 3.0 × 10-9 mol.L-1. The response of the sensor is very quick and response time is less than 1 s. The method can be applied to detect the dopamine in human urine samples.