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In this work, we demonstrate the ultrasensitive and selective 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):polystyrenesulfonate-PEDOT:PSS-patterned on a polydymethylsiloxane-PDMS-flexible substrate. One electrode is pulsed with a train of voltage square waves, to mimic the presynaptic neuron behavior, while the other is used to record the displacement current, mimicking the postsynaptic neuron. The current response exhibits the features of synaptic Short-Term Plasticity (STP) with facilitating or depressing response according to the stimulus frequency. We found that the response characteristic time υ STP depends on dopamine (DA) concentration in solution. The dose curve exhibits superexponential 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, but responds to AA only at concentration above 100 μM. However, 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 the physiological levels in the cerebrospinal fluid and the striatum, respectively.

Specific detection of dopamine (DA) is achieved with organic neuromorphic devices with no specific recognition function in an electrolyte solution. The response to voltage pulses consists of amplitude‐depressed current spiking mimicking the short‐term plasticity (STP) of synapses. An equivalent circuit hints that the STP timescale of the device arises from the capacitance and resistance of the poly(3,4‐ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) in series with the electrolyte resistance. Both the capacitance and resistance of PEDOT:PSS change with solution compositions. Dose curves are constructed from the STP timescale for each DA metabolite from pM to mM range of concentrations. The STP response of DA is distinctive from the other metabolites even when differences are by one functional group. Both STP and sensitivity to DA are larger across the patho‐physiological range with respect to those to DA metabolites. Density functional theory calculations hint to a stronger hydrogen bond pattern of DA ammonium compared to cationic metabolites. The exponential correlation between STP and the binding energy of DA metabolites interacting with PEDOT:PSS indicates that the slow dynamics of ionic species in and out PEDOT:PSS is the origin of the neuromorphic STP. The sensing framework discriminates differences of nonspecific interactions of few kcal mol−1, corresponding to one functional group in the molecule. [ABSTRACT FROM AUTHOR]

Neuromorphic Organic Devices: Neuromorphic Organic Devices that Specifically Discriminate Dopamine from Its Metabolites by Nonspecific Interactions (Adv. Funct. Keywords: biosensors; neuromorphic devices; organic bioelectronics; PEDOT:PSS; short-term plasticity EN biosensors neuromorphic devices organic bioelectronics PEDOT:PSS short-term plasticity 1 1 1 07/11/20 20200709 NES 200709 In article number 2002141, Fabio Biscarini and co-workers demonstrate that the current response of a device made of two PEDOT:PSS electrodes is selective for dopamine even without specific recognition moieties. Biosensors, neuromorphic devices, organic bioelectronics, PEDOT:PSS, short-term plasticity. [Extracted from the article]