Wet-Spun Porous Carbon Microfibers for Enhanced Electrochemical Detection

Abstract

We present a novel copolymer-based, uniform porous carbon microfiber (PCMF) formed via wet-spinning for significantly improved electrochemical detection. Carbon fiber (CF), fabricated from a polyacrylonitrile (PAN) precursor, is commonly used in batteries or for electrochemical detection of neurochemicals due to its biplanar geometry and desirable edge plane sites with high surface free energy and defects for enhanced analyte interactions. Recently, the presence of pores within carbon materials has presented interesting electrochemistry leading to detection improvements; however, there is currently no method to uniformly create pores on a carbon microfiber surface impacting a broad range of electrochemical applications. Here, we synthesized controllable porous carbon fibers from a spinning dope of the copolymers PAN and poly(methyl methacrylate) (PMMA) in dimethylformamide via wet spinning for the first time. PMMA serves as a sacrificial block introducing macropores of increased edge-plane character on the fiber. Methods were optimized to produce porous CFs at similar dimensions to traditional CF. We prove that an increase in porosity enhances the degree of disorder on the surface, resulting in significantly improved detection capabilities with fast-scan cyclic voltammetry. Local trapping of analytes at porous geometries enables electrochemical reversibility with improved sensitivity, linear range of detection, and measurement temporal resolution. Overall, we demonstrate the utility of a copolymer synthetic method for PCMF fabrication, providing a stable, controlled macroporous fiber framework with enhanced edge plane character. This work will significantly advance fundamental investigations of how pores and edge plane sites influence electrochemical detection.

Editors’ Choice—Review—The Future of Carbon-Based Neurochemical Sensing: A Critical Perspective

“…4C). 25 Although recent innovations have proven to improve on CF's diminished temporal resolution, there are still limiting factors keeping researchers from discarding CF all together. Limitations & routes of addressing these challenges.-CF has remained a staple to neurochemical sensing for decades as its biocompatibility and non-invasive nature provides viable tissue implantation.…”

“…The phenomenon of locally trapping neurochemicals has continued to lead to the development of other novel carbon structures through processes like chemical vapor deposition (CVD) and spinning dope alterations during carbon fiber synthesis. 25 , 26 CVD has been used to deposit carbonaceous material within a nanocavity electrode (CNPEs) capable of locally trapping and amplifying the current of low concentrations of dopamine (Fig. 4 B).…”

“…Various carbon nanostructures have been developed through carbon surface treatments to manipulate the surface geometry/chemical connectivity, [16][17][18][19] modification additions of carbon nanostructures onto carbon fibers, [20][21][22][23] or the synthesis of new carbon materials to focus on sought after sensor attributes. [24][25][26][27] Nanomaterials possess innate properties (high surface area, electrical and mechanical properties, etc) capable of improving neurochemical measurement kinetics, sensitivity, and, at times, selectivity depending on the analytical technique of use. [28][29][30] Carbon-based nanomaterials are unique with elaborate nanoscale geometries and chemical structures providing numerous useful applications for enhancing electrochemical detection of neurochemicals.…”

“…Many recent advances have started to address these fundamental gaps and hindrances to the advancement of the neurochemical sensing field. [24][25][26][27]…”

Waste Coffee Ground-Derived Porous Carbon for Neurochemical Detection

“…Prior reports have modified the surface of CFMEs with new chemical functionalities, polymers, and carbon nanomaterials; , however, modification of these surfaces with nanoporous carbon materials is limited. The influence of surface geometries has been greatly examined, noting that porous geometries promote greater degrees of surface roughness and can even exhibit thin-layer cell characteristics for redox cycling amplification. , Novel nanoporous geometries have recent applications in microelectrode frameworks in the form of carbon nanotube (CNT) yarns , or CFME surface modifications with other carbon nanomaterials. ,− CNT yarns possess fast electron transfer characteristics, ease of functionalization, and high conductivity for ultrasensitive dopamine and serotonin detection. − Porous carbon nanofibers, nanospikes, nanohorns, and nanocavity pipettes have all been explored as surface geometry modifications exhibiting enhanced electron transfer rates, surface defect site abundance, and, in some cases, redox cycling. ,− Our lab fabricated porous carbon microfibers as a result of these materials with highly localized defect-dense macropores enhancing electrochemical reversibility with many of the aforementioned electrochemical properties . Although these materials have excellent properties, pore controllability is difficult and often involves rigorous synthesis procedures.…”