Abstract
Poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrene sulfonate) (PSS) is the most commonly used conducting polymer in organic bioelectronics. However, electrochemical capacitances exceeding the current state-of-the-art are required for enhanced transduction and stimulation of biological signals. The long-term stability of conducting polymer films during device operation and storage in aqueous environments remains a challenge for routine applications. In this work, we electrochemically synthesize a PEDOT composite comprising the water dispersible two-dimensional conducting material Ti3C2 MXene. We find that incorporating MXene as a co-dopant along with PSS leads to PEDOT:PSS:MXene films with remarkably high volumetric capacitance (607.0 ± 85.3 F cm−3) and stability (capacity retention = 78.44% ± 1.75% over 500 cycles), outperforming single dopant-comprising PEDOT films, i.e., PEDOT:PSS and PEDOT:MXene electropolymerized under the same conditions on identical surfaces. The stability of microfabricated PEDOT:PSS:MXene electrodes is evaluated under different conditions, i.e., when the films are exposed to sonication (∼100% retention over 6 min), upon immersion in cell culture media for 14 days (∆|Z| = 2.13%), as well as after continuous electrical stimulation. Furthermore, we demonstrate the use of a PEDOT:PSS:MXene electrode as an electrochemical sensor for sensitive detection of dopamine (DA). The sensor exhibited an enhanced electrocatalytic activity toward DA in a linear range from 1 µM to 100 μM validated in mixtures containing common interferents such as ascorbic acid and uric acid. PEDOT:PSS:MXene composite is easily formed on conductive substrates with various geometries and can serve as a high performance conducting interface for chronic biochemical sensing or stimulation applications.
Highlights
Organic bioelectronics involves the development of electronic devices that rely on organic electronic materials for communication with living systems
We find that incorporating MXene as a co-dopant along with poly(styrene sulfonate) (PSS) leads to PEDOT:PSS:MXene films with remarkably high volumetric capacitance (607.0 ± 85.3 F cm−3) and stability, outperforming single dopant-comprising PEDOT films, i.e., PEDOT:PSS and PEDOT:MXene electropolymerized under the same conditions on identical surfaces
The PEDOT:PSS:MXene electrode surpassed the performance of the standard PEDOT:PSS as a DA sensor by detecting a few tens of μM of DA in aqueous solutions comprising hundreds of μMs of uric acid (UA) and ascorbic acid (AA), two common electro-oxidizable interferents
Summary
Organic bioelectronics involves the development of electronic devices that rely on organic electronic materials (e.g., conjugated polymers) for communication with living systems. For both of these films, the high resolution XPS spectra of S 2p showed signals of PEDOT (162 eV– 166 eV) and, for PEDOT:PSS:MXene, a third peak around 169 eV was found, which is attributed to sulfur atoms of PSS [Fig. 2(b)].47,48 We performed contact angle measurements to investigate the effect of Ti3C2 MXene on the wettability of the films.
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