In this work we report the advantages of using glassy carbon electrodes (GCE) modified with multi-walled carbon nanotubes (MWCNT) dispersed in different polyelectrolytes for the detection of uric acid and dopamine.
Highly selective and sensitive voltammetric uric acid (UA) quantification in the presence of ascorbic acid (AA) was obtained using GCE modified with a dispersion of MWCNT in polylysine (Plys) (GCE/MWCNT-Plys). The electrocatalytic activity of MWCNT deposited on the glassy carbon surface allowed an important decrease in the overvoltage for the oxidation of AA, making possible a clear definition of the oxidation processes of both bioanalytes. An important enhancement in the sensitivity for UA quantification was obtained by Differential Pulse Voltammetry (DPV) after 1-min preconcentration at -0.25 V and medium exchange, allowing the detection of 2.2 x 10-6 M UA in the presence of 1.0 x 10-3 M AA. The proposed sensor was successfully used for the detection of UA in serum samples.
The use of GCE modified with MWCNT dispersed in Nafion (GCE/MWCNT-Naf) in connection with a preconcentration step and DPV-stripping after medium exchange, allowed the sensitive and selective quantification of dopamine even in the presence of 1.0 x 10-3 M AA.
In summary, the modification of GCE with MWCNT dispersed in polyelectrolytes represents an interesting and promising alternative for the development of different electrochemical sensors.
