Screen-Printed Electrodes Modified with Multi-Walled Carbon Nanotubes for Cisplatin Detection

A screen-printed electrode modified with multi-walled carbon nanotubes functionalized with carboxyl groups (MWCNT-COOH/SPE) in a 0.1 mol L^-1 NaCl solution (pH 7) containing 800 μmol L^-1 of sodium dodecyl sulfate (SDS) was used in the selective quantification of the widely used antitumor drug, cisplatin (Fig. 1). The MWCNT-COOH/SDS/SPCE sensor was characterized by cyclic voltammetry, and the differential pulse voltammetry was used for the detection and quantification of analyte, or evaluated in presence of other antitumor drugs, like carboplatin, oxaliplatin, doxorubicin and gemcitabine. For solutions of cisplatin, the electrochemical analysis showed a linear correlation coefficient of 0.9974 to cisplatin at concentrations between 1.45 × 10^-5 and 1.0 × 10^-4 mol L^-1, a sensitivity of 4.5 × 10⁴ (±1.0×10³) μA L mol^-1, and detection and quantification limits of 4.6 × 10^-6 and 1.4 × 10^-5 mol L^-1, respectively. The reproducibility of the sensor response evaluated by the analysis of three replicates, indicated a RSD of 3.91%.

The excellent response of the MWCNT-COOH/SDS/SPE cisplatin sensor allowed it to be test in samples of human blood serum whose levels of added cisplatin had been monitored by the HPLC. The average error % (sensor/HPLC) of 0.95 indicates that the combined methodology of MWCNT-COOH modified SPCE and the addition of a surfactant such as dodecyl sulfate is a convenient alternative for the use of HPLC for cisplatin quantitative determination in biological samples.