Multiwalled Carbon Nanotubes/Nanofibrillar Cellulose/Nafion Composite-Modified Tetrahedral Amorphous Carbon Electrodes for Selective Dopamine Detection

We introduce a composite membrane comprised of multiwalled carbon nanotubes (MWCNTs) dispersed in a matrix of sulfated nanofibrillar cellulose (SNFC) and Nafion. The high negative charge densities of the SNFC and Nafion ionomers enhance the cationic selectivity of the composite. The composite is characterized by scanning electron (SEM) and transmission electron (TEM) microscopies as well as Fourier transform infrared (FTIR) and Raman spectroscopies. Tetrahedral amorphous carbon (ta-C) electrodes modified with the composite are investigated as potential dopamine (DA) electrochemical sensors. The composite-modified electrodes show significant selectivity and sensitivity toward DA in the presence of ascorbic acid (AA) and uric acid (UA) in physiologically relevant concentrations. A linear dopamine detection range of 0.05-100 μM with detection limits of 65 nM in PBS and 107 nM in interferent solution was determined using 100 mV/s cyclic voltammetry (CV) measurements. These results highlight the potential of the composite membrane for in vivo detection of neurotransmitters.