Figure 3. Differential pulse voltammograms obtained for (a) GCE, (b) MWCNT/GCE, (c) NIP/MWCNT/GCE, and (d) MIP/MWCNT/GCE applied in PBS (at pH 3) in the presence of 100 μmol L−1 methotrexate. Figure 4. Possible mechanism involving the electroreduction of methotrexate. 3.3. Op...