Flotation Assembly of Large-Area Ultrathin MWCNT Nanofilms for Construction of Bioelectrodes.

Andrew Gross,Serge Cosnier,Jules Hammond,Michael Holzinger

doi:10.3390/nano7100342

Andrew Gross, Serge Cosnier + Show 2 more

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https://doi.org/10.3390/nano7100342

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Abstract

We report a simple, versatile, and rapid method for the fabrication of optically-transparent large-area carbon nanotube (CNT) films via flotation assembly. After solvent-induced assembly, floating films were transferred to a flat supporting substrate to form conductive and transparent CNT film electrodes. The resulting electrodes, with uniform 40 ± 20 nm multi-walled CNT (MWCNT) layers, were characterized by electrochemical and microscopy methods. The flotation method does not require specialized thin-film instrumentation and avoids the need for surfactants and pre-oxidized CNTs which can hamper electrochemical performance. A proof-of-concept nanostructured bioelectrode demonstrating high sensitivity for glucose was developed with an electropolymerized poly(pyrene-adamantane) layer for host–guest immobilization of active β-cyclodextrin tagged GOx enzymes. The polymer provides pyrene groups for cross-linking to CNTs and pendant adamantane groups for binding the β-cyclodextrin groups of the tagged enzyme. This demonstration offers a new approach for the preparation of stable and transparent CNT film electrodes with attractive electrochemical properties towards future photobio- and bio-electrochemical fuel cells, electrochemical sensors, and electroanalysis.

Highlights

The use of carbon nanotubes (CNTs) has garnered plenty of interest within the nanoscience community for interfacing soft biological systems due to their chemical stability, high electrical/thermal conductivity [1], appealing mechanical properties [2] and biocompatibility [3]
The high specific surface area [4] and unique geometry make multi-walled CNTs (MWCNTs) an ideal candidate for the construction of highly-porous three-dimensional electrodes, especially given the ability to attach a plethora of functionalities [5,6,7]
CNT films with sub-100 nm thicknesses can exhibit high optical transparency which could be exploited for light-driven photoelectrochemical devices [15,16]

Summary

Introduction

The use of carbon nanotubes (CNTs) has garnered plenty of interest within the nanoscience community for interfacing soft biological systems due to their chemical stability, high electrical/thermal conductivity [1], appealing mechanical properties [2] and biocompatibility [3]. CNT electrodes can provide a powerful platform for the immobilization of enzymes with high biomolecular activities [8,9] and have consistently demonstrated excellent performance for the electrical wiring of enzymes via direct and mediated electron transfer processes [10,11]. Use of nanoscale thin films can enhance mass transport of substrates/products and facilitate fast electron transfer with immobilized enzymes, opening up the possibility to improve bioelectrode performance for biofuel cell and biosensor devices [10,13,14]. CNT films with sub-100 nm thicknesses can exhibit high optical transparency which could be exploited for light-driven photoelectrochemical devices [15,16]

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