KR101084623B1 - Enzymatic biofuel cell comprising nanowire array - Google Patents

Abstract

The present invention provides an electrode comprising an array of nanowires containing an enzyme, a conductive polymer and an electron mediator, a method of manufacturing the electrode, an enzyme fuel cell including the electrode, and a living body implantation device including the enzyme fuel cell.

Nanowire array electrode according to the present invention can increase the reaction of the enzyme because the surface area of the electrode is significantly increased. In addition, by using a conductive polymer and an electron mediator, it is possible to manufacture an electrode in the form of a nanowire array in which an enzyme is immobilized stably and efficiently without using an electron conductor or a substance for fixing an enzyme to an electron conductor.

Enzyme Fuel Cells, Nanowire Arrays, Conductive Polymers, Electronic Mediators

Description

Enzymatic fuel cell comprising nanowire array {Enzymatic biofuel cell comprising nanowire array}

The present invention relates to an electrode comprising an array of nanowires containing an enzyme, a conductive polymer and an electron mediator, a method for producing the electrode, an enzyme fuel cell comprising the electrode and a living body implantation device comprising the enzyme fuel cell.

Enzyme fuel cells are electrochemical devices that convert biochemical energy into electrical energy using specific redox enzymes as catalysts. Electrons can be transferred through the substrate by using an enzyme that oxidizes the substrate to the anode and, conversely, by using an enzyme that reduces the substrate to the reduction electrode. Enzymes can be used to increase the energy density of enzymatic fuel cells due to their excellent catalytic action, but they are sensitive to the environment and can easily lose their activity. In addition, since the active site of the enzyme is usually buried deep inside the enzyme, direct electron transfer reaction with the electrode can be difficult, so a method for electrically connecting the enzyme with the electrode is required. In addition, the commercialization of the enzyme fuel cell requires the development of a technology that can increase the power density of the enzyme fuel cell.

An object of the present invention is to provide an electrode and an enzyme fuel cell including the same, which are electrically and efficiently connected between an electrode and an enzyme, and which can provide a high power density.

For this purpose, the present invention provides an electrode comprising an array of nanowires containing an enzyme, a conductive polymer and an electron mediator, a method of manufacturing the electrode, an enzymatic fuel cell comprising the electrode and an in vivo implant comprising the enzyme fuel cell. Provide a device.

Nanowire array electrode according to the present invention can increase the reaction of the enzyme because the surface area of the electrode is significantly increased. In addition, by using an all-solid polymer and an electron mediator, it is possible to manufacture an electrode in the form of a nanowire array in which an enzyme is immobilized stably and efficiently without using an electron conductor or a substance for fixing an enzyme to an electron conductor.

The present invention provides an electrode comprising an array of nanowires containing enzymes, conductive polymers and electron mediators.

In one embodiment of the present invention, the electrode may be used as an anode or a cathode.

In the present invention, the anode means an anode comprising an oxidoreductase that catalyzes the oxidation of the substrate. Through oxidation of the substrate, the anode supplies electrons to the electrical circuit. On the other hand, the cathode refers to a cathode including a oxidoreductase to reduce the substrate. The cathode receives electrons and serves to reduce the substrate.

Oxidoreductase refers to an enzyme that catalyzes the transfer of electrons from a reductant, ie hydrogen or electron donor, to an oxidant, ie hydrogen or electron acceptor. The oxidoreductase is preferably named 'donor: acceptor oxidoreductase', but is commonly referred to as 'donor dehydrogenase' or 'acceptor reductase'. In particular, when oxygen is a receptor, the oxidoreductase is sometimes referred to as 'donor oxidase'.

In one aspect of the present invention, the oxidoreductase included in the anode may be used as long as it is an oxidoreductase capable of supplying electrons by oxidizing a substrate. Although not limited thereto, the oxidoreductase included in the anode is, for example, glucose oxidase, glucose dehydrogenase, alcohol redox enzyme, aldehyde dehydrogenase, CH-CH redox enzyme, amino acid redox enzyme, CH -NH redox enzymes, lactate dehydrogenases, lactose dehydrogenases, pyruvate dehydrogenases, formate dehydrogenases and formaldehyde dehydrogenases. The type of enzyme may vary depending on the type of substrate to be used as fuel of the enzyme fuel cell. Substrates of enzymes are organic compounds such as sugars, carbohydrates, organic acids, alcohols, fatty acids, hydrocarbons, ketones, aldehydes, amino acids, proteins and nucleic acids. For example, when glucose is used as a fuel of an enzyme fuel cell, the oxidoreductase included in the anode may be a glucose oxidase. Glucose oxidase releases electrons by oxidizing glucose to gluconolactone.

In one aspect of the present invention, the oxidoreductase included in the cathode may be used as long as it can reduce the substrate. Although not limited thereto, the oxidoreductase included in the cathode may be, for example, one or more oxidoreductases selected from the group consisting of laccase, bilirubin oxidase, superoxide dismutase and peroxidase. For example, when using a laccase as an oxidoreductase included in the cathode, the laccase reduces oxygen to water using the transferred electrons. As another example, when bilirubin oxidase is used as an oxidoreductase included in the cathode, bilirubin oxidase oxidizes bilirubin to biliverdine and reduces oxygen to water.

The electrode according to the present invention stably and efficiently fixes the enzyme to the electrode by using a conductive polymer and an electron mediator without using an electron conductor or a substance for fixing the enzyme to the electron conductor.

In the present invention, any conductive polymer may be used as long as it has a high conductivity and mediates the movement of electrons.

In one embodiment of the invention, the conductive polymer is polypyrrole; Polyacetylene; Polyaniline; Polythiophene; Polysulfurite; Polyfluorene; Poly (3-alkylthiophene); Polytetrathiafulvalene; Polynaphthalene; Poly (p-phenylene sulfide); At least one polymer selected from the group consisting of poly (para-phenylene vinylene) and derivatives thereof. Alternatively, a polymer in which a metal or metal oxide is combined may be used as the conductive polymer. In the following example, a nanowire-type electrode is formed using polypyrrole as the conductive polymer.

In the present invention, the electrolyte solution in which the enzyme is mixed with the conductive polymer and the electron mediator is polymerized by electrochemical polymerization to form a nanowire electrode without using an electron conductor such as a metal or a carbon-based material. By using the conductive polymer and the electron mediator, it is possible to manufacture the electrode to which the enzyme is immobilized stably and efficiently without using an electron conductor or a substance for fixing the enzyme to the electron conductor.

Electron mediators are used to provide high power density to enzyme fuel cells. In the present invention, the electron mediator can be used as long as the compound can accept or donate electrons. However, the electron mediator may be selected in consideration of reaction affinity with an enzyme used in an enzyme fuel cell, an electron exchange rate with a conductive polymer, and structural stability.

In one embodiment of the invention, the electron mediator is HQS (8-hydroxyquinoline-5-sulfonic acid hydrate), quinone compounds, vitamin K3 (2-methyl-1,4-naphthoquinone), biorogen-based Compound, nicotinamide compound, riboflavin compound, ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate), Os, Ru, Fe and Co metal complex (metal complex) For example, ABTS may be usefully used as an electron mediator when using a laccase as an oxidoreductase included in a cathode.

The invention also

Attaching a mold for forming a nanowire array on a metal-coated substrate,

Preparing an electrolyte solution containing a conductive polymer, an electron mediator and an enzyme,

Forming an electrode in the form of a nanowire array by polymerizing the electrolyte solution in a mold by electrochemical polymerization and then removing the mold.

It provides a method for producing the electrode.

Electrode according to the present invention takes the form that the nanowire array is formed on the substrate for fixing the nanowire array.

In one embodiment of the invention, the substrate may be made of a polymer compound, such as silicon, glass, quartz, and PET.

The metal coated on the substrate may be a conductive metal including gold, silver, platinum, and copper.

The mold for forming a nanowire array used in the present invention has a pore of a nano size, and any one can be used as long as it can be easily removed after synthesis of the nanowire array. In one embodiment of the present invention, the nanowire array forming mold may be a nano-size pore mold made of a metal oxide or polycarbonate having a nano-sized pore, a mold using a block copolymer, or the like. . In the following example, the nanowire array is synthesized using an aluminum oxide film template, and the nanowire array electrode is formed by partially removing the aluminum oxide film using phosphoric acid after the synthesis.

The mold can be formed on the substrate in any way. The mold may be formed directly on the substrate, or a separately manufactured mold may be attached on the substrate. In one embodiment of the present invention, the attachment of the mold on the substrate can be performed using a metal paste. The metal used in the metal paste may be a conductive metal including gold, silver, platinum, and copper.

When the electrolyte solution containing the conductive polymer, the electron mediator and the enzyme is polymerized by electrochemical polymerization in the template, nanowires are formed in the pores of the template, and the nanowire array can be obtained by removing a portion of the template.

The nanowire array, which is a collection of nanowires, has a very large surface area of the electrode, which allows the enzymatic reaction to increase the current density significantly compared to the film-type electrode that occurs only on the film surface. In addition, since the nanowire array electrode of the present invention is a form in which an enzyme is immobilized on an electrode made of a conductive polymer, the electrode and the enzyme are electrically connected more efficiently than the electrode immobilized on the electric conductor using carbon or metal. Will provide an increase in power density.

The present invention also provides an enzyme fuel cell comprising the electrode.

The fuel to be used in the enzyme fuel cell may be any organic compound used as the substrate by the enzyme. In one embodiment of the invention, the organic compound is one or more organic compounds selected from the group consisting of, but not limited to, sugars, carbohydrates, organic acids, alcohols, fatty acids, hydrocarbons, ketones, aldehydes, amino acids, proteins and nucleic acids Can be.

In one embodiment of the invention, the electrode may be provided in the fluid channel. Since the fluid channel allows the supply of fuel fluid to be made continuously, it can provide an increase in energy density and current density as compared to when fuel is present in a closed space. The fuel fluid is continuously provided to the enzyme fuel cell through the inlet and the outlet, thereby smoothly supplying the oxidizing agent and the reducing agent of the enzyme. In addition, compared with the case where fuel is present in the closed space, the enzyme of the anode or the enzyme of the cathode has an advantage of preventing the reaction efficiency from being lowered by oxidants or reducing agents other than their substrates. In particular, the use of microfluidic channels not only increases the operating time of the enzymatic fuel cell, but also enables miniaturization of the cell.

The present invention also provides a living body implantation device comprising the enzyme fuel cell. The enzyme fuel cell may be used in an electronic device other than a living body implantation device, but for efficient use thereof, the enzyme fuel cell should be used in a living body implantation device rather than a general electronic device because conditions such as an in vivo environment must be provided.

When used in a living body implantation device, the enzyme fuel device is very useful because it does not require a separate fuel supply and can use organic compounds supplied in vivo as fuel.

The living body implantation device may be any device as long as it is a device requiring implantation in vivo. In one embodiment of the present invention, the living implant device is a pacemaker, a nerve stimulator, a drug delivery pump, a living transplant sensor (eg, real time glucose sensor) or nano It may be a microscopic biological device such as a robot.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims.

[Example]

Example 1 Fabrication of Electrodes in the form of Nanowire Arrays

1 is a schematic diagram of an electrode including a nanowire array according to the present invention, Figure 2 is a schematic diagram showing a method of manufacturing an electrode according to the present invention.

First, as a template for forming a nanowire array, an aluminum oxide film template (AAO) template was manufactured. To fabricate the aluminum oxide mold, the aluminum plate was oxidized twice. When oxidizing for the first time, the 0.3 M oxalic acid solution was cooled to 0 ° C., and the carbon electrode and aluminum plate were immersed in the oxalic acid solution. Then, the oxide film formed on the aluminum plate was melted at 60 ° C. for 24 hours with a mixed solution of 6 wt% phosphoric acid and 1.8 wt% chromic acid, and then oxidized by controlling the time to a desired thickness under the same conditions as the primary oxidation. Thereafter, 45 V was applied in a 1: 1 mixture of perchloric acid and ethanol to separate the aluminum oxide film template from the aluminum plate. The mold thus obtained was placed in 6 wt% phosphoric acid to enlarge the pore size. Chrome and gold were deposited on one side for use in the electrode, making it easy to attach to the substrate.

In order to fabricate an electrode including a nanowire array, an aluminum oxide film mold made of silver paste was attached to a gold-coated silicon wafer and then dried. After the silver paste was dried, the remaining portion except for the AAO portion was passivated using a polymer compound such as epoxy.

In order to synthesize the nanowire array in the template, an electrolyte solution for preparing an anode and an electrolyte solution for a cathode were prepared and formed into a nanowire array by using an electrochemical polymerization method (L. Brunel et al. / Electrochemistry Communications 9 (2007) 331-336, J. Wang et al. / Journal of Electroanalytical Chemistry 575 (2005) 139-146, Manoj Kumar Ram et al. / Nanotechnology 11 (2000) 112-119). Specifically, electrochemical polymerization method in AAO using an electrolyte made by dissolving 0.1 M pyrrole and 0.01 M HQS (8-hydroxyquinoline-5-sulfonic acid hydrate) in distilled water and then dissolving 200 U / ml of glucose oxidase. A nanowire array was fabricated and used as an anode. In addition, 0.1 M pyrrole and 0.025 M ABTS (2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate)) are dissolved in distilled water, and then made by dissolving 150 U / ml of laccase. A nanowire array was fabricated in AAO by the method, which was used as a cathode. In the electrochemical polymerization method, the counter electrode was platinum and the reference electrode was Ag / AgCl electrode. The potential of the anode was 1.5 V and that of the cathode was 0.8 V until the potentials reached 3.5-4.0 C / cm ² and 625 mC / cm ² , respectively. An anode and a cathode were prepared by partially removing AAO using 10% wt phosphoric acid to expose the nanowires formed by electrochemical polymerization out of AAO.

FIG. 3 is a photograph showing a cross section (a) of a template for manufacturing a nanowire array used for manufacturing an electrode of the present invention, a cross section (b) and a side surface (c) of a nanowire array synthesized using the same. FIG. Illustrates an electrochemical polymerization process for the synthesis of the nanowire array.

Example 2 Current Measurement of Enzyme Fuel Cell Including Nanowire Array Electrode

FIG. 5 is a diagram exemplarily illustrating an enzyme fuel cell of the present invention including an anode including a nanowire array and a cathode including a nanowire array.

After maintaining the fuel fluid made by adding 15 mM glucose to PBS solution (Phospate buffer saline solution) at 37 ° C., the anode and the cathode prepared in Example 1 were immersed in the fuel fluid, and the voltage was measured by applying external resistances. The current was measured by looking at. As a control, the current was measured in the same manner by immersing a film electrode prepared by electrochemical polymerization on a gold-coated substrate under the same conditions except for an aluminum oxide film template. As a result, as can be seen in Figure 6 (graph in the log scale), the case of the anode having a nanowire diameter of 200 nm showed the largest energy density and current density. In practice, this is thought to be due to the increased frequency of enzymes and glucose. In the case of an anode made of nanowires with a diameter of 80 nm, the electrode having a diameter of less than 200 nm was found to be higher than that of a film electrode. In addition, the energy density was lower at the anode (80 nm diameter) made by depositing aluminum directly on a silicon wafer and growing on AAO made by oxidizing in a similar manner as that of an aluminum plate (denoted as 80 nm nanowire (Si-based)). The length of the directly grown nanowires (0.5 to 1 μm) is smaller than the nanowires (30 to 40 μm) made by pasting metal pastes. In the case of OCV (open circuit voltage), nanowires grown directly on silicon wafers were high. This is because electron transfer is easier for nanowires grown directly on silicon wafers, resulting in less voltage drop.

In addition, the same current was measured while flowing the same fuel fluid using the fluid channel. 7 is a schematic diagram illustrating an enzyme fuel cell using a fluid channel. As a result, as can be seen in Figure 8, the enzyme fuel cell using the fluid channel as a whole showed a higher energy density and current density than the enzyme fuel cell made by soaking the electrode. This is because when the fluid channel is used, the concentration of glucose used as fuel and the concentration of oxygen required at the reduction electrode are maintained, and oxygen is consumed at the reduction electrode, thereby reducing the decrease in efficiency due to oxygen at the anode. The same result as in Fig. 8 was obtained (the graph in the log scale). However, overall, OCV was found to be reduced, which is thought to be caused by a different ion distribution in the fuel as it flows through the fluid channel. In addition, FIG. 9 shows that the maintenance time of energy density increases with time when using a fluid channel (log scale).

When the anode is made of nanowires, like the anode, it is expected that water will be reduced by reacting with oxygen, resulting in more energy density and current density, and fuel cell operation for longer periods of time. .

1 is a schematic diagram of an electrode including a nanowire array according to the present invention.

2 is a schematic view showing an example of a method for manufacturing an electrode according to the present invention.

Figure 3 is a photograph showing a cross-section (a) of the mold for preparing a nanowire array used for the production of the electrode of the present invention, a cross section (b) and a side (c) of the nanowire array synthesized using the same.

4 is a diagram exemplarily illustrating an electrochemical polymerization process for synthesizing a nanowire array.

FIG. 5 is a diagram exemplarily illustrating an enzyme fuel cell of the present invention including an anode including a nanowire array and a cathode including a nanowire array.

Figure 6 is a graph showing the results of measuring the power density of the enzyme fuel cell of the present invention and the enzyme fuel cell having a film-shaped electrode.

7 is a diagram illustrating an enzyme fuel cell in which an electrode according to the present invention is provided in a microfluidic channel.

FIG. 8 is a graph showing that an enzyme fuel cell using a fluid channel has a higher energy density as compared to an enzyme fuel cell made by soaking an electrode.

9 is a graph showing that the maintenance time of energy density increases with time when the fluid channel is used.

Claims (15)

An electrode comprising an array of nanowires containing an enzyme, a conductive polymer and an electron mediator, The nanowire array is formed by electrochemical polymerization of an electrolyte solution containing enzymes, conductive polymers and electron mediators. The method of claim 1, The electrode is used as an anode electrode. The method of claim 1, The electrode is used as a reduction electrode. 3. The method of claim 2, Enzymes included in the anode are glucose oxidase, glycos dehydrogenase, alcohol redox enzyme, aldehyde dehydrogenase, CH-CH redox enzyme, amino acid redox enzyme, CH-NH redox enzyme, lactate dehydrogenase, An electrode which is at least one redox enzyme selected from the group consisting of lactose dehydrogenase, pyruvate dehydrogenase, formate dehydrogenase and formaldehyde dehydrogenase. The method of claim 3, The enzyme included in the cathode is at least one redox enzyme selected from the group consisting of laccase, bilirubin oxidase, superoxide dismutase and peroxidase. The method of claim 1, The conductive polymer is polypyrrole, polyacetylene, polyaniline, polythiophene, polysulfurtritride, polyfluorene, poly (3-alkylthiophene), polytetrathiafulvalene, polynaphthalene, poly (p-phenylene sulfide) , Poly (para-phenylene vinylene) and derivatives thereof. The method of claim 1, The electron mediators are HQS (8-hydroxyquinoline-5-sulfonic acid hydrate), quinone compounds, vitamin K3 (2-methyl-1,4-naphthoquinone), biorogen compounds, nicotinamide compounds, riboflavin System compound, ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonate), metal complex of Os, Ru, Fe and Co electrode. Forming a mold for forming a nanowire array on a metal-coated substrate, Preparing an electrolyte solution containing a conductive polymer, an electron mediator and an enzyme, Forming an electrode in the form of a nanowire array by polymerizing the electrolyte solution in a mold by electrochemical polymerization and then removing the mold. The manufacturing method of the electrode of Claim 1. The method of claim 8, The substrate is made of silicon, glass or polymer polymer. The method of claim 8, The manufacturing method for forming the nanowire array is a metal oxide having a pore of nano size. An enzyme fuel cell comprising the electrode of claim 1. The method of claim 11, The enzyme fuel cell is an enzyme fuel cell that uses at least one of organic compounds including sugars, carbohydrates, organic acids, alcohols, fatty acids, hydrocarbons, ketones, aldehydes, amino acids, proteins and nucleic acids as fuel. The method of claim 11, The electrode is an enzyme fuel cell is provided in the fluid channel. A living body implantation device comprising the enzyme fuel cell of claim 11. The method of claim 14, The living body implantation device is an artificial pacemaker, a nerve stimulator or drug delivery pump, a living body implantation sensor or a nanorobot implantation device.

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