Patent Application
20240252072
The present disclosure relates to a method for controlling a treatment apparatus using a reaction system containing a redox enzyme and a coenzyme and to a treatment apparatus using a reaction system containing a redox enzyme and a coenzyme.
Technology known in the related art uses a reaction system containing a redox enzyme and a coenzyme.
For example, PTL 1 describes a method for measuring glucose concentration by utilizing a reaction system containing an enzyme and an electron transport mediator. In the method, glucose dehydrogenase (CyGDH) to which cytochrome C is bonded is used as the enzyme, and a Ru compound is used as the electron transport mediator. In a glucose sensor including a reagent layer composed of the Ru compound and CyGDH in combination, a reaction with glucose is completed, and an end point of glucose concentration measurement is reached in a short time.
The present disclosure provides a method for controlling a treatment apparatus having advantages from the viewpoint of dealing with a change in a component contained in a treatment target while using a reaction system containing a redox enzyme and a coenzyme.
The present disclosure provides a method for controlling a treatment apparatus using a reaction system containing a redox enzyme and a coenzyme,
The method for controlling a treatment apparatus according to the present disclosure provides advantages from the viewpoint of dealing with a change in a component contained in a treatment target while using a reaction system containing a redox enzyme and a coenzyme.
It is considered that a treatment target such as a raw material for producing food is treated by a treatment apparatus using a reaction system containing a redox enzyme and a coenzyme. Regarding operation of such a treatment apparatus, it is considered that a voltage is applied to an electrode, and whether the treatment is completed is determined in accordance with the magnitude of a current generated when the voltage is applied.
Based on the investigation by the present inventor, it is assumed that components in the treatment target are not limited to being the same, and that the components in the treatment target are changed in accordance with the type of the treatment target. Therefore, it is considered that operating conditions of the treatment apparatus, such as a voltage applied to an electrode in the treatment apparatus and the magnitude of a current serving as an indicator of completion of treatment, are adjusted in accordance with the treatment target.
The present inventor performed an intensive investigation and, as a result, newly found that the operation conditions in accordance with the treatment target of the treatment apparatus can be specified on the basis of a relationship between a voltage applied to an electrode and a current value corresponding to the voltage when a treatment liquid stored in the treatment apparatus is in a predetermined state. The present inventor devised the method for controlling a treatment apparatus according to the present disclosure in accordance with the new finding.
The embodiments according to the present disclosure will be described below with reference to the drawings. In this regard, all the embodiments described below indicate comprehensive or specific examples. Numerical values, shapes, materials, constituents, arrangement positions of the constituents, connection forms, process conditions, steps, step sequence, and the like described in the following embodiments are exemplifications and are not intended to limit the present disclosure. In this regard, of the constituents in the following embodiments, the constituents not described in the independent claims indicating the highest conceptualization are described as optional constituents. In addition, each drawing is a schematic diagram and is not limited to being precisely drawn.
As illustrated in
As illustrated in
The first relationship R1 may include a relationship between the first voltage value and the first current value acquired by changing the first voltage value at a different rate in a specific voltage range. In such an instance, in Step S101, the first relationship R1 may be acquired by measuring a current in the third electrode 13 while a voltage between the first electrode 11 and the second electrode 12 is swept at a different rate in a predetermined voltage range.
The first relationship R1 may include a relationship between the first voltage value and the first current value in a voltage range corresponding to the treatment target in the treatment liquid 2. For example, when the treatment target is albumen, the first relationship R1 may include a relationship between the first voltage value and the first current value in the voltage range of 0.9 V to 1.1 V. In the first relationship R1, for example, the first current values corresponding to the first voltage values of 0.9 V, 1.0 V, and 1.1 V are specified.
Next, in Step S102, a redox enzyme and a coenzyme are added to the treatment liquid 2. The redox enzyme and the coenzyme may be manually added or automatically added.
Neither the redox enzyme nor the coenzyme is limited to a specific enzyme. When the treatment liquid 2 contains glucose, the redox enzyme is, for example, glucose dehydrogenase (GDH). In addition, the coenzyme is, for example, nicotinamide adenine dinucleotide (NAD).
Next, in Step S103, a voltage is applied between the first electrode 11 and the second electrode 12. In other words, a voltage is applied between the first electrode 11 and the second electrode 12 in a state where the treatment liquid 2 contains the redox enzyme and the coenzyme. In such an instance, a second relationship R2 between a second voltage value and a second current value is acquired. The second voltage value is a value of a voltage between the first electrode 11 and the second electrode 12. The second current value is a current value corresponding to the second voltage value. The second current value is, for example, a measurement value of a current in the third electrode 13. In Step S103, for example, the second relationship R2 is acquired by measuring a current in the third electrode 13 while the second voltage value is changed at a predetermined rate. For example, in Step S103, the second relationship R2 is acquired by measuring a current in the third electrode 13 while a voltage between the first electrode 11 and the second electrode 12 is swept in a predetermined voltage range at a predetermined rate.
In Step S103, for example, the controller 40 acquires data indicating the second current value from the voltage application apparatus 30. The controller 40 correlates the data with data indicating the second voltage value so as to produce data indicating the second relationship R2 and store the data indicating the second relationship R2 in predetermined memory.
Next, in Step S104 and Step S105, a voltage Vt for treating the treatment liquid 2 and a target current Ia serving as an indicator of completion of treatment of the treatment liquid 2 are determined in accordance with the first relationship R1 and the second relationship R2.
A voltage that is desirably applied to an electrode and the magnitude of a current serving as an indicator of completion of treatment in the treatment apparatus 1a may be changed in accordance with a change in the component of the treatment target contained in the treatment liquid 2. Since the voltage Vt and the target current Ia are determined in accordance with the first relationship R1 and the second relationship R2, the treatment apparatus 1a is readily operated under a predetermined condition in accordance with a change in the component of the treatment target.
In Step S104 and Step S105, for example, the controller 40 performs a predetermined calculation using the data indicating the first relationship R1 and the data indicating the second relationship R2 so as to determine the voltage Vt and the target current Ia.
Methods for determining the voltage Vt and the target current Ia are not limited to specific methods provided that the methods are in accordance with the first relationship R1 and the second relationship R2. For example, in Step S104, the voltage Vt is determined on the basis of a difference ΔI12 and a ratio ΔI2/ΔV2. The difference ΔI12 is a difference between the first current value in the first relationship R1 and the second current value in the second relationship R2. This difference is a difference between the first current value and the second current value corresponding to the first voltage value and the second voltage value, respectively, when the first voltage value in the first relationship R1 is equal to the second voltage value in the second relationship R2. The ratio ΔI2/ΔV2 is a ratio of an amount of the changed second current value to an amount of the changed second voltage value ΔV2. The treatment time of the treatment liquid 2 tends to be decreased by the difference ΔI12 being taken into consideration when the voltage Vt is determined. The treatment liquid 2 tends to be stably treated by the ratio ΔI2/ΔV2 being taken into consideration when the voltage Vt is determined.
In Step S104, for example, a voltage range in which the difference ΔI12 is greater than or equal to a predetermined lower limit value is specified. In addition, a voltage range in which the ratio ΔI2/ΔV2 is less than or equal to a predetermined upper limit value is specified. The voltage Vt is determined in the range in which these voltage ranges overlap with each other.
In Step S105, for example, the target current Ia is determined in accordance with the first current value corresponding to the voltage Vt determined in Step S104 in the first relationship R1. According to such a method, the target current Ia corresponding to the voltage Vt can be determined.
For example, when the first relationship R1 includes a relationship between the first voltage value and the first current value acquired by changing the first voltage value at a different rate in a specific voltage range, the current value corresponding to the voltage Vt is determined for each change rate of the first voltage value. Thereafter, the current value when the change rate of the first voltage value is zero may be determined by using an approximate formula denoting a relationship between the resulting current value and the change rate of the first voltage value, and the resulting current value may be determined to be the target current Ia.
For example, when the first relationship R1 includes a relationship between the first voltage value and the first current value in a voltage range corresponding to the treatment target in the treatment liquid 2, the target current Ia may be determined by using an approximate formula of the relationship between the first voltage value and the first current value. For example, the first current value corresponding to the voltage Vt may be specified from the approximate formula, and the resulting first current value may be determined to be the target current Ia.
Next, as illustrated in Steps S106, S107, S108, and S109, the treatment liquid is treated by applying the voltage Vt for treating the treatment liquid 2. In addition, application of the voltage Vt is stopped when a current value generated by application of the voltage Vt is less than or equal to the target current Ia.
In Step S106, treatment of the treatment liquid 2 is started by applying the voltage Vt to the first electrode 11. For example, the controller 40 controls the voltage application apparatus 30 so that the voltage Vt is applied to the first electrode 11. Subsequently, in Step S107, a value Imon of a current passing through the third electrode 13 is measured at a predetermined timing after starting treatment of the treatment liquid 2. For example, the controller 40 acquires data indicating the current value Imon. Next, in Step S108, it is determined whether the current value Imon is less than or equal to the target current Ia. For example, the controller 40 performs determination in Step S108.
When the determination result in Step S108 is No, the procedure returns to Step S107, the value Imon of a current passing through the third electrode 13 is measured again at a predetermined timing, and determination in Step S108 is performed.
When the determination result in Step S108 is Yes, the procedure advances to Step S109, and application of the voltage to the first electrode 11 is stopped so that a treatment series is completed.
As illustrated in
Each of the treatment liquid 2 and the second liquid 3 contains, for example, a phosphate buffer. In such a configuration, the pH of the treatment liquid 2 and the second liquid 3 can be prevented from rapidly changing, and accordingly, the treatment liquid 2 tends to be stably treated.
The treatment apparatus 1a further includes, for example, a membrane 16. The membrane 16 separates the inside of the reaction tank 10 from the inside of the second tank 20. For example, the membrane 16 hinders the redox enzyme and the coenzyme contained in the treatment liquid 2 from passing through and, in addition, has ionic conductivity. In such a configuration, the energy efficiency of the treatment apparatus 1a tends to be increased.
For example, when the treatment target contained in the treatment liquid 2 is D-glucose, the redox enzyme is GDH, and the coenzyme is NAD, a reaction represented by Formula (1) below occurs in the treatment apparatus 1a. GDH serving as a redox enzyme is involved in the reaction.
In the treatment apparatus 1a, reduced nicotinamide adenine dinucleotide (NADH) generated in accordance with Formula (1) is oxidized by the first electrode 11 serving as a working electrode. Consequently, oxidized nicotinamide adenine dinucleotide (NAD+) is generated. Since NAD+ is generated by continuous oxidation of NADH, glucose can be continuously decomposed even when a large amount of NAD is not contained in the treatment liquid 2.
The membrane 16 hinders the redox enzyme and the coenzyme from passing through. Consequently, the coenzyme present in the reaction tank 10 remains in the reaction tank 10 and is not readily introduced into the second tank 20. As a result, the treatment apparatus 1a tends to prevent the generation of a reduced coenzyme such as NADH due to reduction of an oxidized coenzyme such as NAD+ by the third electrode 13. Accordingly, the treatment apparatus 1a decomposes glucose while continuously oxidizing nicotinamide adenine dinucleotide and provides advantages from the viewpoint of energy efficiency. Since the membrane 16 has ionic conductivity, for example, ions of a predetermined type pass through the membrane 16 to maintain electrical neutrality of the treatment liquid 2 and the second liquid 3.
The material for forming the first electrode 11 is not limited to a specific material. The surface of the first electrode 11 is formed of, for example, platinum. In such a configuration, the reduced coenzyme tends to be directly oxidized by the first electrode 11, and the treatment target in the treatment liquid 2 may be efficiently treated. The material constituting the surface of the first electrode 11 may be gold (Au), a carbon material such as glassy carbon, graphite, or boron-doped diamond, or indium tin oxide (ITO).
The shape of the first electrode 11 is not limited to a specific shape. The first electrode 11 may be a linear shape, a tabular shape, a mesh, or a fiber assembly. From the viewpoint of efficiency of treatment of the treatment liquid 2, it is advantageous that the first electrode 11 have a large surface area.
The material for forming the third electrode 13 is not limited to a specific material. The surface of the third electrode 13 is formed of, for example, platinum. In such a configuration, since electrons are readily released from the third electrode 13 to maintain electrical neutrality of the treatment liquid 2 and the second liquid 3 in response to oxidization of the coenzyme, the treatment liquid 2 may be efficiently treated. The material constituting the surface of the third electrode 13 may be gold (Au), a carbon material such as glassy carbon, graphite, or boron-doped diamond, or indium tin oxide (ITO).
The shape of the third electrode 13 is not limited to a specific shape. The third electrode 13 may be a linear shape, a tabular shape, a mesh, or a fiber assembly. From the viewpoint of efficiency of treatment of the treatment liquid 2, it is advantageous that the third electrode 13 have a large surface area.
The material for forming the membrane 16 is not limited to a specific material provided that the material hinders the redox enzyme and the coenzyme from passing through and, in addition, has ionic conductivity. The membrane 16 contains, for example, a polymer having a perfluoro side chain including a sulfonic acid group. In such a configuration, ions such as protons or the like readily pass through the membrane 16, and the treatment liquid 2 may be efficiently treated. Known examples of such a polymer include Nafion (registered trademark). The material for forming the membrane 16 may be porous glass or porous silicon.
As illustrated in
In the treatment apparatus 1a, the second tank 20 and the membrane 16 may be omitted, and the third electrode 13 may be disposed in contact with the treatment liquid 2 in the reaction tank 10.
The treatment liquid 2 may contain food or a raw material for producing food. A component serving as the treatment target is contained in the food or the raw material for producing the food, and specific examples of the component include saccharides such as glucose and alcohols such as ethanol.
The method for controlling a treatment apparatus according to the present disclosure will be described in more detail with reference to Examples. In this regard, the method for controlling a treatment apparatus and the treatment apparatus according to the present disclosure are not limited to Examples below.
An apparatus corresponding to the treatment apparatus 1a illustrated in
Phosphate-buffered saline (PBS) having a pH of 7.4 provided by NIPPON GENE CO., LTD. was stored in the second tank in which the counter electrode was disposed. In the second tank, a portion of the counter electrode was in contact with the PBS. The amount of liquid PBS stored in the second tank was 8.1 milliliters (mL).
Albumin was manually separated from the yolk of a commercially available egg. The resulting albumin was manually agitated by using chopsticks in such a manner that the amount of a highly viscous portion was reduced to the extent of not causing foaming. Thereafter, the albumin was filtered with gauze to remove a solid portion so as to obtain an albumin liquid. Albumin commonly contains about 0.7% glucose on a mass basis at an albumin glucose concentration of about 22×10−3 [mol/L]. As a treatment liquid, 7.2 mL of the albumin liquid was stored in the first tank serving as the reaction tank.
The potential of the reference electrode was taken as a reference potential, a voltage applied to the working electrode was swept in a predetermined range, and the value of a current passing through the counter electrode, the current value corresponding to the voltage value applied to the counter electrode, was measured and stored. A control computer and control software were used to adjust the potential difference between the reference electrode and the working electrode and to measure the value of a current passing through the counter electrode. Electronic data of the current-voltage characteristics 1 and the current-voltage characteristics 2 which indicate a relationship between the value of a voltage applied to the working electrode and the value of a current passing through the counter electrode were stored in the control computer memory.
Regarding acquisition of the current-voltage characteristics 1 and the current-voltage characteristics 2, the range of the voltage applied to the working electrode was −0.6 V to +1.3 V. The voltage applied to the working electrode was started at −0.6 V, increased to +1.3 V at 10-mV intervals, and, thereafter, decreased from +1.3 V to −0.6 V at 10-mV intervals. The current-voltage characteristics 1 were acquired at a sweep rate of 100 mV/sec. On the other hand, the current-voltage characteristics 2 were acquired at a sweep rate of 10 mV/sec.
A NAD solution was prepared by dissolving, at a concentration of 40×10−3 [mol/L], reduced nicotinamide adenine dinucleotide into the same type of phosphate buffer as the phosphate buffer stored in the second tank. P-Nicotinamide adenine dinucleotide disodium (reduced form) provided by NACALAI TESQUE, INC. was used as reduced nicotinamide adenine dinucleotide. A GDH solution was prepared by dissolving, at a concentration of 80 [unit/mL], glucose dehydrogenase into the same type of phosphate buffer as the phosphate buffer stored in the second tank. Glucose dehydrogenase (GDH) provided by FUJIFILM Wako Pure Chemical Corporation was used as glucose dehydrogenase. Addition of 0.8 mL of NAD solution and 0.1 mL of GDH solution to the treatment liquid stored in the first tank was performed.
Thereafter, a voltage applied to the working electrode was swept in a predetermined range under the same condition as the voltage range and the sweep rate when the current-voltage characteristics 1 were acquired, and the value of a current passing through the counter electrode, the current value corresponding to the voltage value applied to the counter electrode, was measured. The thus acquired current-voltage characteristics 3 were then stored.
As illustrated in
The selection range of the voltage applied to the working electrode to treat the treatment liquid was determined to be a range of +0.9 V to +1.05 V in which the range 1 overlapped the range 2. Subsequently, the voltage Vt applied to the working electrode to treat the treatment liquid in the apparatus according to Example was determined to be +1.0 V.
Next, the target current Ia serving as an indicator of completion of treatment of the treatment liquid was determined as described below. Regarding the current-voltage characteristics 1, each time the voltage applied to the working electrode was increased or decreased, a current value corresponding to the voltage Vt was specified, and a current value α that was the average value of the current values was determined. In Example, the current value a was 5.1×10−4 A.
Regarding the current-voltage characteristics 2, in the manner akin to that of determining the current value α, each time the voltage applied to the working electrode was increased or decreased, a current value corresponding to the voltage Vt was specified, and a current value β that was the average value of the current values was determined. In Example, the current value β was 6.2×10−5 A. It was assumed that a relationship between the sweep rate of the voltage applied to the working electrode when the current-voltage characteristics 1 and the current-voltage characteristics 2 were acquired and each of the current value α and the current value β was a linear relationship, and a current value when the sweep rate was zero in the linear relationship was determined to be the target current Ia. In Example, the target current Ia was 1.2×10−5 A.
Next, the treatment of the treatment liquid was started by continuously applying a voltage of +1.0 V between the working electrode and the reference electrode. In addition, the value Imon of the current passing through the counter electrode was measured. The treatment liquid was treated at room temperature (15° C. to 27° C.). The treatment liquid was agitated by using a stirrer during treatment of the treatment liquid.
When checking that the value Imon of the current passing through the counter electrode became less than or equal to the target current Ia, application of the voltage to the working electrode was stopped.
The treatment liquid was sampled at a predetermined timing during continuous application of the voltage of +1.0 V to the working electrode. Dripping of 50 microliters (L) of the sampled treatment liquid on a urine glucose inspection portion of a urine test paper New Uriace BT produced by Terumo Corporation was performed, and a change in the color of the urine glucose inspection portion was visually examined so as to check for the presence or absence of decomposed glucose and the degree thereof. Regarding the present urine test paper, it was found that when the concentration of glucose was less than or equal to 0.1×10−3 [mol/L], the color of the urine glucose inspection portion was almost unchanged even when the treatment liquid was dripped. In addition, it was found that when the concentration of glucose was higher than 0.1×10−3 [mol/L], the color of the urine glucose inspection portion changed to navy blue, and it was found that the two samples were visually distinguishable.
An electrochemical reaction apparatus according to the present disclosure is useful for electrochemical decomposition of, for example, glucose.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-176185 | Oct 2021 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2022/038667 | Oct 2022 | WO |
| Child | 18633575 | US |
