Porous Carbon Nanofiber-Modified Carbon Fiber Microelectrodes for Dopamine Detection

Abstract

We present a method to modify carbon fiber microelectrodes (CFME) with porous carbon nanofibers (PCFs) to improve detection and to investigate the impact of porous geometry for dopamine detection with fast-scan cyclic voltammetry (FSCV). PCFs were fabricated by electrospinning, carbonizing, and pyrolyzing poly­(acrylonitrile)-b-poly­(methyl methacrylate) (PAN-b-PMMA) block copolymer nanofiber frameworks. Commonly, porous nanofibers are used for energy storage applications, but we present an application of these materials for biosensing, which has not been previously studied. This modification impacted the topology and enhanced redox cycling at the surface. PCF modifications increased the oxidative current for dopamine (2.0 ± 0.1)-fold (n = 33) with significant increases in detection sensitivity. PCFs are known to have more edge plane sites which we speculate lead to the 2-fold increase in electroactive surface area. Capacitive current changes were negligible, providing evidence that improvements in detection are due to faradaic processes at the electrode. The ΔE p for dopamine decreased significantly at modified CFMEs. Only a 2.2 ± 2.2% change in dopamine current was observed after repeated measurements and only 10.5 ± 2.8% after 4 h, demonstrating the stability of the modification over time. We show significant improvements in norepinephrine, ascorbic acid, adenosine, serotonin, and hydrogen peroxide detection. Lastly, we demonstrate that the modified electrodes can detect endogenous, unstimulated release of dopamine in living slices of rat striatum. Overall, we provide evidence that porous nanostructures significantly improve neurochemical detection with FSCV and echo the necessity for investigating the extent to which geometry impacts electrochemical detection.

Wet-Spun Porous Carbon Microfibers for Enhanced Electrochemical Detection

“…All prior studies demonstrating frequency independence with FSCV have been on carbon nanomaterials, while here, we demonstrate this phenomenon on carbon-fiber. Although absolute frequency independence is not achieved like previous reports on CNT-based materials, 5,16 we observed a significant improvement in electrochemical reversibility and frequency independence from previous CF porous material modifications 22 showing the impact of an entirely porous substrate used as a biosensing material. The improved temporal resolution of PCMF will ultimately enable more rapid detection of neurotransmitters when implanted as a biosensor.…”

“…These porous geometries also provide some electrocatalytic properties by enhancing the electron transfer kinetics of dopamine at these surfaces, reducing oxidation/reduction peak splitting to 0.95 ± 0.03 V. This concept is common with pores on the nanoscale, so we believe the distribution of pore sizes present in PCMF proves feasibility for kinetic improvements additional to redox improvements. Notably, PCMF microelectrodes exhibit stable capacitive behavior with maintained capacitive current of 2480 ± 300 nA, comparable to previous traditional CF work 22 (Figure 6C, n = 8). The surface area of PCMF is increased by the pore geometries present, but the resulting capacitive current increases can be combatted by reducing working electrode lengths.…”

“…This LOD is vastly improved from that of traditional CF, where the average LOD is reported in the range of 10−15 nM. 22 High waveform application frequency measurements are capable on PCMF microelectrodes with FSCV. Increases in application frequency are known to decrease the analyte preaccumulation time at the surface of the microelectrode.…”

The emergence of psychoanalytical electrochemistry: the translation of MDD biomarker discovery to diagnosis with electrochemical sensing

“…Electrochemical sensors can utilize the surfactant sodium dodecyl sulfate to improve the detection of dopamine and serotonin by creating surface charge effects to electrostatically promote sensitivity [ 72 ]. Use of carbon materials or fast-scan cyclic voltammetry has been shown to improve sensitivity toward and differentiation between dopamine and serotonin [ 73 – 75 ]. The design of dopamine-selective biosensors has integrated materials such as screen-printed electrodes, graphene-modified microfluidic paper-based analytical devices, and pencil-on-paper analytical devices to improve device cost and simplicity [ 72 , 76 ].…”

Mesoporous carbon-based materials and their applications as non-precious metal electrocatalysts in the oxygen reduction reaction

“…Carbon is a truly remarkable element and continues to deliver a host of new, interesting, and fascinating materials. Its unique ability to form a multitude of diverse nanostructures has led to the development of fullerenes [1,2], carbon nanotubes [2,3], including single and multi-walled carbon nanotubes, graphene [2], graphene oxide, reduced graphene oxide [4] and graphene quantum dots [5], carbon fibres [6] and various porous carbon-based materials [7,8]. These carbon based materials have been used in a myriad of applications, extending from medical [9], electrochemical sensors and biosensors [10], energy conversion and storage [11] to adsorbents for the treatment of wastewater [12].…”