Specific Dopamine Sensing Based on Short-Term Plasticity Behavior of a Whole Organic Artificial Synapse.

In this work, we demonstrate the ultra-sensitive and selec-tive detection of dopamine by means of a neuro-inspired device platform without the need of a specific recognition moiety. The sensor is a whole organic device featuring two electrodes made of poly(3,4-ethylenedioxythiophene):polystyrene sulfonate - PEDOT:PSS - patterned on a polydymethylsiloxane - PDMS - flexible substrate. One electrode is pulsed with a train of voltage square waves, to mimic the pre-synaptic neuron behavior, while the other is used to record the displacement current, mimicking the post-synaptic neuron. The current response exhibits the features of synaptic Short-Term Plasticity (STP) with facilitating or depressing re-sponse according to the stimulus frequency. We found that the response characteristic time υSTP depends on dopamine (DA) concentration in solution. The dose curve exhibits super-exponential sensitivity at the lowest concentrations below 1 nM. The sensor detects [DA] down to 1 pM range. We assess the sensor also in the presence of ascorbic acid (AA) and uric acid (UA). Our sensor does not respond to UA, while responds to AA only at concentration above 100 μM. Yet, it is still able to detect DA down to 1 pM range in the presence of [AA] = 100 μM and 100 pM in the presence of [UA] = 3 μM, these values for AA and UA being their physiological levels in the cerebrospinal fluid and the striatum respectively.