Entrapment of Enzymes and Carbon Nanotubes in Biologically Synthesized Silica: Glucose Oxidase‐Catalyzed Direct Electron Transfer

Ivnitski, Dmitri; Artyushkova, Kateryna; Rincón, Rosalba A.; Atanassov, Plamen; Luckarift, Heather R.; Johnson, Glenn R.

doi:10.1002/smll.200700725

Cited by 180 publications

(123 citation statements)

References 34 publications

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“…To obtain direct electron transfer between the redox center of GOx and electrode surface we have exploited the combination of the excellent properties of carbon nanotubes in terms of dimension, stability and electrical conductivity [8,23,24] with the unique structure and transport properties of Nafion [25,26] as immobilizing matrix. The combined use of spectroscopy and electrochemistry was used as a tool for investigating structure property relationship of the enzyme electrode.…”

Section: Introductionmentioning

confidence: 99%

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

et al. 2012

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We fabricated an enzyme fuel cell (EFC) device based on glucose as fuel and glucose oxidase (GOx) as biocatalyst. As a strategy to improve GOx stability, preserving at the same time the enzyme catalytic activity, we propose an immobilization procedure to entrap GOx in a polymer matrix based on Nafion and multiwalled carbon nanotubes. Circular dichroism (CD) spectra were recorded to study changes in the 3D structure of GOx that might be generated by the immobilization procedure. The comparison between the CD features of GOx immobilized and free in solution indicates that the shape of the spectra and position of peaks do not significantly change. The bioelectrocatalytic activity toward glucose oxidation of immobilized GOx was studied by cyclic voltammetry and chronoamperometry experiments. Such electrochemical experiments allow monitoring the rate of GOx-catalyzed glucose oxidation and extrapolating GOx kinetic parameters. Results demonstrate that immobilized GOx has high catalytic efficiency, due the maintaining of regular and well-ordered structure of the immobilized enzyme, as indicated by spectroscopic findings. Once investigated the electrode structure-property relationship, an EFC device was assembled using the GOx-based bioanode, and sulfonated poly ether ether ketone as electrolyte membrane.Polarization and power density curves of the complete EFC device were acquired, demonstrating the suitability of the immobilization strategy and materials to be used in EFCs.

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Section: Introductionmentioning

confidence: 99%

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

et al. 2012

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“…These slopes were compatible with the theoretical slopes (−58.6 mV pH − 1 ) for the two-electron and two-proton redox reactions, indicating that the FADs of these catalyst structures participated in the desirable two-electron and two-proton redox reactions. 32 Performances and stability of the EBCs using the catalysts including PCA and PEI We investigated the performances and stability of the EBCs using CNT/PEI/GOx, CNT/[PCA/GOx] and CNT/PEI/[PCA/GOx] as anodic catalysts by measuring their polarization curves. Additionally, we evaluated the effects of enzyme catalyst and glucose fuel on the EBC performance.…”

Section: Resultsmentioning

confidence: 99%

A new biocatalyst employing pyrenecarboxaldehyde as an anodic catalyst for enhancing the performance and stability of an enzymatic biofuel cell

2017

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A new enzyme catalyst consisting of pyrenecarboxaldehyde (PCA) and glucose oxidase (GOx) immobilized on polyethyleneimine (PEI) and a carbon nanotube supporter (CNT/PEI/[PCA/GOx]) is suggested, and the performance and stability of an enzymatic biofuel cell (EBC) using the new catalyst are evaluated. Using PCA, the amount of immobilized GOx increases (3.3 U mg − 1 ) and the electron transfer rate constant of the CNT/PEI/[PCA/GOx] is promoted (11.51 s − 1 ). Also, the catalyst induces excellent EBC performance (maximum power density (MPD) of 2.1 mW cm − 2 ), long-lasting stability (maintenance of 93% of the initial MPD after 4 weeks) and superior catalytic activity (flavin adenine dinucleotide redox reaction rate of 0.62 mA cm − 2 and Michaelis-Menten constant of 0.99 mM). These characteristics are ascribed to effects of (i) electron collection due to hydrophobic interactions, (ii) electron transfer pathways due to π-conjugated bonds and (iii) enzyme stabilization due to π-hydrogen bonds that are newly induced by the PCA/GOx composite. The existence of such positive interactions is properly verified using X-ray photoelectron spectroscopy and enzyme activity measurements. NPG Asia Materials (2017) 9, e386; doi:10.1038/am.2017.75; published online 2 June 2017 INTRODUCTIONThe demand for clean electrical energy is increasing as a result of weather changes caused by the greenhouse effect and depletion of fossil fuels. 1 To meet this demand, related research and development efforts are being eagerly pursued. As one of the efforts, enzymatic biofuel cells (EBCs) that convert bioenergy into electrical energy are being considered. 2,3 In particular, EBC systems employing glucose oxidase (GOx) as a biocatalyst have emerged because of their advantageous properties, such as biocompatibility, excellent selectivity toward specific substrates and strong activity near neutral pH and room temperature. 2 In addition, because EBC systems use human body-friendly fuels, such as glucose, glycerol, water and oxygen, for electricity generation, they can be embedded as power generators for the operation of artificial internal organs, such as artificial hearts and brains, insulin pumps or bone stimulators. [4][5][6][7][8] However, in spite of such promising facets of EBC systems, the commercialization of EBCs using GOx has been limited because of their low EBC performance and poor durability. 9 The disadvantages are attributed to the low immobilization ratio of GOx molecules, slow GOx-related reaction rate, low GOx activity and easy GOx denaturation. Of them, low GOx immobilization has been considered the main problem.

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“…9 The silica gel surrounding the TPCNTs surface formed a 3D CNTs network-gel matrix which is highly conductive, porous, and stable allowing the bilirubin oxidase enzyme …”

Section: 17mentioning

confidence: 99%

“…Although there are many different ways to design an enzymatic electrode, the general procedure requires deposition of the enzyme onto a conductive material which then should be immobilized in a matrix such as chitosan, 14 nafion, 15 or silica gel in order to retain enzyme structure and function. 9,16,17 The objective of this research was to design a stable air "breathing" enzymatic cathode by improving the available surface area and 3D matrix of enzyme entrapment at the nanoscale for: a) higher enzyme loading on the biocathode and improved kinetic activity of the system and, b) decrease of oxygen and proton mass transfer limitations while retaining the active enzymatic 3D structure.Previous research has made it known that the design of a viable enzymatic gas-diffusional cathode has to satisfy the following main requirements: 1) consist of a porous hydrophobic layer that allows the flow of oxygen to feed the catalytic layer; 2) have a porous thin catalytic layer with enzyme-air-electrolyte three-phase interface, 18,19 and 3) preserve enzymatic activity. At the three phase interface oxygen molecules from air meet at the active site of the enzyme as well as protons (H + ) from the electrolytic solution.…”

mentioning

confidence: 99%

Gas-Diffusion Cathodes Integrating Carbon Nanotube Modified-Toray Paper and Bilirubin Oxidase

Garcia

Villarrubia

Falase

et al. 2014

J. Electrochem. Soc.

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This research introduces the design of a gas-diffusional cathode employing bilirubin oxidase (BOx) immobilized on a complex matrix composed of carbon nanotube (CNT) modified Toray paper (TP) and, encapsulated in silica-gel. The developed enzymatic cathode consists of two layers. One is the hydrophobic gas-diffusional layer (GDL) and the other a hydrophilic catalytic layer (CL) which were combined by pressing at 1000 psi for five minutes. The GDL (35% weight teflonized Vulcan carbon powder (XC35)) that is exposed to air has hydrophobic and porous properties that facilitate oxygen diffusion. The CL consists of a thin, high surface area, 3D CNT/silica-gel matrix where the 3D-enzymatic structure is immobilized and preserved. The nanostructured architecture of the CL was designed to improve conductivity and surface area. Such a design was achieved by modifying the TP surface with CNTs. CNTs are grown on TP by chemical vapor deposition which is possible by electrodepositing Ni seeds via pulse chronoamperometry. Entrapment of BOx was achieved by using tetramethyl orthosilicate (TMOS), a highly volatile compound that results in a polymeric condensation reaction with H 2 O at room temperature. TMOS polymerization of the cathode surface was performed in a chemical vapor deposition process to form a silica-gel matrix. The gas diffusional cathode was assembled to a capillary driven microfluidic system to be electrochemically characterized. The characterization was performed from electrolyte pH 5 to pH 8 with increments 0.5 in pH. The best performance was observed at pH 5.5 showing a current output of 655.07 ± 146.18 μA.cm −2 and 345.36 ± 30.04 μA.cm −2 at 0 V and 0.3 V, respectively. At a pH of 7.5 the current generated was 287.05 ± 20.37 μA.cm −2 and 205.37 ± 1.57 μA.cm −2 at 0 V and 0.3 V, respectively. The results show the stability of the enzymatic structure, subject to various pH, is maintained within the 3D-CNT silica-gel matrix for pH lower than 8. Future work will focus on storage life and stability over time. Interest in biofuel cells has increased in the past decade in pursue of self energetically-sustained biomedical devices and also small, portable electrical devices capable of work by harvesting energy from natural fuel sources. Such interests exist due to the low temperature and neutral pH operating range of biofuel cells.1-3 Depending on the mechanism of the enzyme, either direct or mediated electron transfer (DET and MET, respectively) reflects the electron transfer distance between enzyme active site and electrode interface. One must couple mediators/cofactors for the latter in order to have electrons transferred to the electrode and further to an external circuit therefore subjecting electrons to a diffusion distance.2,4-13 On the other hand DET works under an electron tunneling distance. Further design considerations are centered on the three main regions of inherent energetic losses in fuel cells known as kinetic, ohmic and mass transfer limits. Although there are many different ways to design an enzymat...

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Entrapment of Enzymes and Carbon Nanotubes in Biologically Synthesized Silica: Glucose Oxidase‐Catalyzed Direct Electron Transfer

Cited by 180 publications

References 34 publications

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

A new biocatalyst employing pyrenecarboxaldehyde as an anodic catalyst for enhancing the performance and stability of an enzymatic biofuel cell

Gas-Diffusion Cathodes Integrating Carbon Nanotube Modified-Toray Paper and Bilirubin Oxidase

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