Effect of Carbon Nanotubes on Direct Electron Transfer and Electrocatalytic Activity of Immobilized Glucose Oxidase

Abstract

Carbon nanotubes (CNTs) are excellent supports for electrocatalysts because of their large surface area, excellent electronic conductivity, and high chemical and structural stability. In the present study, the activity of CNTs on direct electron transfer (DET) and on immobilized glucose oxidase (GOX) is studied as a function of number of walls of CNTs. The results indicate that the GOX immobilized by the CNTs maintains its electrocatalytic activity toward glucose; however, the DET and electrocatalytic activity of GOX depend strongly on the number of inner tubes of CNTs. The GOX immobilized on triple-walled CNTs (TWNTs) has the highest electron-transfer rate constant, 1.22 s–1, for DET, the highest sensitivity toward glucose detection, 66.11 ± 5.06 μA mM–1 cm–2, and the lowest apparent Michaelis–Menten constant, 6.53 ± 0.58 mM, as compared to GOX immobilized on single-walled and multiwalled CNTs. The promotion effect of CNTs on the GOX electrocatalytic activity and DET is most likely due to the electron-tunneling effect between the outer wall and inner tubes of TWNTs. The results of this study have general implications for the fundamental understanding of the role of CNT supports in DET processes and can be used for the better design of more effective electrocatalysts for biological processes including biofuel cells and biosensors.

Multicomponent bionanocomposites based on clay-nanoarchitectures for electrochemical devices

“…In fact, with the addition of 0.1 M glucose, a clear increase (blue line) of the anodic current appears compared to that in PBS without glucose. For the here designed mediator-less cell, this behaviour is correlated to a direct electron transfer (DET) at the interface between the active site (FAD) of the enzyme and the conducting elements of the electrode surface, confirming that a DET mechanism is involved [68][69]. The current increase is predominant at a voltage of 0.35 V, which is higher than the typical FAD/FADH2 standard voltage (i.e., −0.460 V in pH 7.0 at 25.8 °C) probably due to the presence of carbon nanotubes that can influence the electrochemical response [56].…”

Intrinsic Effect of Carbon Supports on the Activity and Stability of Precious Metal Based Catalysts for Electrocatalytic Alcohol Oxidation in Fuel Cells: A Review

“…Most significantly, the distinctive volcano‐type dependence of the activity of Pd–CNTs for AORs on the number of CNT walls is similar to the electrocatalytic activity of pristine CNTs for ORR, the O 2 evolution reaction (OER), and the H 2 evolution reaction (HER), dye‐functionalized CNTs for photoelectrochemical water splitting, and CNT‐immobilized glucose oxidase . The electrocatalytic activity of double‐walled CNTs (DWCNTs) and TWCNTs is significantly higher than that of SWCNTs and MWCNTs.…”

Challenges and Opportunities of Carbon Nanomaterials for Biofuel Cells and Supercapacitors: Personalized Energy for Futuristic Self-Sustainable Devices

“…PTCA-DA/GCE in the cathode was able to output a power density of 112 µW cm -2 , indicating that 3D-GNs are a viable carbon substrate in retaining high enzymatic activity. Nanomaterials such as CNTs can enable direct contact to the enzymatic reaction center [54,59,60]. Because of this, more favorable electron transference between the CNTs and enzymes can be achieved, e.g., within the mediatorless carbon GOx bioelectrodes [59].…”

“…Particularly, these CNTs establish electrical communication with enzymes due to their intrinsic conductivity, or via electrons hopping to enzymes between immobilized redox locations. Regarding their miniscule scale, CNTs can accurately approach the prosthetic enzyme site with close proximity, therefore directly wiring the enzymes and the bulk electrode [60,83]. Note that some articles discuss that there is no clear indication to uphold the assertions of DET for native GOx at CNT-or graphene-based electrodes [84].…”