A dopamine sensor based on a carbon paste electrode modified with DNA-doped poly(3,4-ethylenedioxythiophene)

An electrochemical dopamine sensor was developed by electrochemical modification of a carbon paste electrode with a biocomposite made from poly(3,4-ethylenedioxythiophene) (PEDOT) that was doped with double stranded or single stranded DNA. The resulting conducting biocomposite displays excellent electrocatalytic activity towards the oxidation of dopamine (DA) which is attributed to the presence of the DNA dopant. Under optimum conditions and at a working potential of 300 mV, the modified electrode is capable of detecting DA in the 0.25 to 66 μM concentration range. The detection limit is 74 nM. The sensor is not interfered by uric acid and ascorbic acid. PEDOT biocomposites doped with dsDNA (left) and ssDNA (right) can be electrochemically prepared and used for the sensitive and selective detection of dopamine owing to their excellent catalytic activity towards dopamine oxidation.