Electrochemical dopamine sensor based on the use of a thermosensitive polymer and an nanocompositeprepared from multiwalled carbon nanotubes and graphene oxide

An electrochemical dopamine sensor with a temperature-controlled switch was constructed by using a mixture of thermo-sensitive block copolymers (type tBA-PDEA-tBA), graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs). If the temperature is below 26 degrees C, the polymer on the glassy carbon electrode (GCE) is stretched, the distance between the MWCNTs is large, and the charge transfer resistance (R-ct) of the composite also is large. In the presence of dopamine, the electron transfer at theelectrode is strongly retarded and in the off state. At above 38 degrees C, the polymer is shrunk and the R-ct is much smaller. The presence of dopamine results in a rapid electron transfer at the GCE, and this is referred to as the on state. At temperatures between 26 and 38 degrees C, the polymer shrinks slightly and has a spring-like state. There is a linear relationship between the response current (typically measured at a potential as low as 0.16V vs. Ag/AgCl) and temperature. The response to dopamine is linear in the 0.06 to 4.2M and 4.2 to 18.2M concentration range, and the detection limit is 42nM. Conceivably, this approach provides a novel approach towards the design of electrochemical sensors based on the use of thermo-sensitive polymers.