Tuning the properties of paper-based electrodes for neurochemical analysis

Analysis of neurotransmitters such as dopamine (DA) is essential to better understand brain-related mechanisms. In this context, paper-based electroanalytical devices are promising alternatives to the current techniques for affordable, user-friendly molecular quantitation. Conductive carbon-based and polymer-based inks such as carbon nanotubes (CNT) and polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) have shown several advantageous properties, such as resistance to the DA fouling occurring during the elec-trochemical detection. Here, the electrical and electrochemical properties of paper devices prepared from mix-tures of the inks were investigated, as well as their DA detection performance (limit of detection and fouling resistance). The properties of these paper electrodes were found to be directly impacted by the choice of ink. CNT-based electrodes are more resistive than the PEDOT:PSS based ones, which are more capacitive. Also, electrodes with undercoats of CNT and overcoats of PEDOT:PSS, doped with organic solvents, better resist DA fouling and have lower limits of detection. The combination of carbon-based and polymer-baser inks allowed for optimizing DA detection, and highlights the versatility and adaptability of paper-based electrode fabrication.