Temperature responsive carbon nanotubes/poly(N-isopropylacrylamide)-modified electrodes for electrochemical selective determination of dopamine, uric acid, and ascorbic acid

Poly(N-isopropylacrylamide)(PNIPAAm) with a lower critical solution temperature of about 32 °C was used as matrix to prepare temperature responsive carbon nanotubes (CNT) and functionalized CNT (fCNT) composites to modify glassy carbon electrode (GCE) as working electrode for electrochemical selective detection of dopamine, uric acid, and ascorbic acid. The GCE modification temperature (25 and 37 °C, denoted as 25f and 37f), working temperature (25 and 37 °C, denoted as 25aq and 37aq), and the type of CNT (CNT and fCNT) were found to significantly affect the electrocatalytic activity of the composites toward redox reactions of Fe(CN) ₆ ^3−/4− as a probe and the selective detection ability for the three analytes. The fCNT/PNIPAAm composite with the 25f–37aq temperature combination exhibited strong electrocatalytic activity and highly selective detection ability for the three analytes. In contrast, the same composite with the other three combinations (25f–25aq, 37f–25aq, and 37f–37aq) and the CNT/PNIPAAm composite with all four combinations exhibited insignificant electrocatalytic activity and no selective detection ability.