Flexible degradable lactic acid sensor as well as preparation method and application thereof

Abstract

The invention relates to a flexible degradable lactic acid sensor and a preparation method and application thereof, and the flexible degradable lactic acid sensor comprises a substrate, which is polyethylene glycol diacrylate / peptide dual-network hydrogel; the electrodes comprise a working electrode, a reference electrode and a counter electrode, the working electrode, the reference electrode and the counter electrode are Mo / MoOx electrodes, each Mo / MoOx electrode is provided with a Mo substrate and a MoOx passivation layer formed on the Mo substrate, and x is larger than or equal to 1 and smaller than or equal to 3; wherein the electrode is embedded in the substrate, the working electrode is provided with an enzyme liquid layer, and the enzyme liquid layer contains lactic dehydrogenase. The flexible degradable lactic acid sensor disclosed by the invention has high viscosity, biocompatibility, degradability and sensitivity, and can be used for stably monitoring myocardial lactic acid for a long time in body fluid.

Description

Technical Field

[0001] The invention relates to a flexible and degradable lactic acid sensor and a preparation method and application thereof, belonging to the technical field of biological detection and medical detection. Background Art

[0002] In clinical analysis, the determination of lactate content is of great significance for the identification of diseases such as acidosis, sepsis, intestinal infarction, brain damage, tissue hypoxia, respiratory failure, and septic shock. In highly oxidized myocardial tissue, lactate, glucose, and fatty acids are often used as the main energy substances, consuming a large amount of oxygen and completing energy metabolism to help the heart maintain its function. Among them, lactate contributes about 16.5% of the oxygen consumption of myocardial tissue, which is equivalent to glucose (17.9%). Once cardiovascular disease occurs, the utilization and metabolism of lactate will be disordered. For example, in cases of myocardial ischemia, acute heart failure, myocardial infarction, etc., the myocardial uptake and use of lactate increases significantly, leading to the accumulation of myocardial lactate. At the same time, in emergency conditions such as tension, excitement, and shock, myocardial cells can also produce a large amount of lactate and transport it to organs such as the brain to provide energy. Therefore, real-time monitoring of myocardial lactate is crucial for the diagnosis and treatment of cardiovascular diseases.

[0003] At present, the main medical method is to draw blood from the heart through cannulation to monitor myocardial lactate, but this may reduce patient compliance, and the discontinuity of lactate data will also lead to delayed feedback information. Myocardial microdialysis technology can continuously monitor lactate content during cardiac surgery, but myocardial microdialysis probes have not yet been commercialized. Implantable chemical sensors can achieve in situ real-time monitoring of myocardial lactate and extend clinical analysis to non-medical environments. In implantable lactate sensors, highly selective lactate oxidase (LOX) and lactate dehydrogenase (LDH) are often used as biological receptors to react specifically with lactate molecules. The converter usually adopts an electrochemical sensing strategy to convert chemical information into detectable electrical signals (such as voltage, current, capacitance, conductivity, impedance, etc.) on conductor or semiconductor electrodes. Electrochemical workstations or mobile, miniaturized devices are often used in analysis systems to process electrical signals, form a mathematical logical relationship with lactate concentration, and realize qualitative and quantitative analysis of lactate.

[0004] However, traditional lactate sensors are usually constructed of rigid materials, which have a mechanical mismatch with soft biological tissues, resulting in the inability of the device to adhere tightly to the tissue surface, affecting the stable transmission of signals. Mechanical mismatch may also cause tissue damage and inflammatory reactions, resulting in fibrosis or thrombus accumulation. Secondly, traditional sensors contain non-degradable components, which may cause sensor materials to be retained in biological systems or require secondary surgery to remove, increasing the risk of infection. In addition, traditional lactate sensors cannot perform long-term, stable and highly sensitive monitoring of dynamic organs (such as the heart, stomach, lungs, etc.) in body fluids. Therefore, the development of a lactate sensor with high adhesion, biocompatibility, degradability, high sensitivity and stability is an urgent problem to be solved in the prior art. Summary of the invention

[0005] Problem that the invention aims to solve

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a flexible and degradable lactic acid sensor and a preparation method and application thereof. The flexible and degradable lactic acid sensor of the present invention comprises a substrate and an electrode, wherein the electrode is embedded in the substrate; the substrate is polyethylene glycol diacrylate / peptide double network hydrogel; the electrode comprises a working electrode, a reference electrode and a counter electrode, which is Mo / MoO x The working electrode has an enzyme liquid layer, and the enzyme liquid layer contains lactate dehydrogenase. The flexible and degradable lactate sensor has high viscosity, biocompatibility, degradability and sensitivity, and can perform long-term and stable monitoring of myocardial lactate in body fluids.

[0007] Solutions for solving problems

[0008] [1] A flexible and degradable lactic acid sensor comprising:

[0009] A substrate, wherein the substrate is a polyethylene glycol diacrylate / peptide double network hydrogel;

[0010] The electrodes include a working electrode, a reference electrode and a counter electrode, wherein the working electrode, the reference electrode and the counter electrode are Mo / MoO x The electrode, the Mo / MoO x The electrode comprises a Mo substrate and a MoO layer formed on the Mo substrate. x Passivation layer, wherein 1≤x≤3;

[0011] Wherein, the electrode is embedded in the substrate, the working electrode has an enzyme liquid layer, and the enzyme liquid layer contains lactate dehydrogenase.

[0012] [2] A method for preparing a flexible and degradable lactic acid sensor according to [1], comprising the following steps:

[0013] S1: Preparation of polyethylene glycol diacrylate / peptide double network hydrogel as substrate;

[0014] S2: Preparation of 3 Mo / MoO x The electrodes serve as working electrode, reference electrode, and counter electrode;

[0015] S3: Mo / MoO as working electrode x An enzyme solution layer is provided on the electrode, and then the working electrode, the reference electrode and the counter electrode are embedded in the substrate prepared in step S1, and encapsulated to obtain a flexible and degradable lactic acid sensor;

[0016] Wherein, the enzyme liquid layer contains lactate dehydrogenase.

[0017] [3] According to the preparation method described in [2], step S1 comprises the following steps:

[0018] S101: adding polyethylene glycol diacrylate powder, light curing agent powder and peptide powder into a solvent and mixing them evenly to obtain a precursor solution W1 of polyethylene glycol diacrylate / peptide double network hydrogel;

[0019] S102: Pour W1 into a mold containing electrode holes, and obtain a polyethylene glycol diacrylate / peptide double network hydrogel containing electrode holes after photocuring.

[0020] [4] According to the preparation method described in [3], in step S101,

[0021] Mass of polyethylene glycol diacrylate powder: Mass of photocuring agent powder: Mass of peptide powder: Volume of solvent = (200-400) mg: (0.2-0.4) mg: (10-20) mg: 1 mL.

[0022] [5] According to the preparation method described in [2] or [3], step S2 comprises the following steps:

[0023] S201: dissolving sodium chloride powder in a solvent to obtain an electrolyte solution W2;

[0024] S202: Mo foil is used as the working electrode, platinum electrode is used as the counter electrode, and silver / silver chloride electrode is used as the reference electrode and immersed in W2. An alternating voltage is applied to the Mo foil to generate MoO on the surface of the Mo foil. x Passivation layer;

[0025] S203: Repeat step S202 three times to obtain three Mo / MoO x electrode.

[0026] [6] According to the preparation method described in [5], in step S201,

[0027] The ratio between the mass of sodium chloride powder and the volume of the solvent is (0.04-0.07) g:1 mL.

[0028] [7] According to the preparation method described in [3], step S3 comprises the following steps:

[0029] S301: dissolving polyvinyl alcohol powder in a solvent to obtain a polyvinyl alcohol solution; adding lactate dehydrogenase powder to the polyvinyl alcohol solution and mixing well to obtain an enzyme-containing hydrogel W3;

[0030] S302: Coating W3 on Mo / MoO as the working electrode x The surface of the electrode, after refrigeration, obtains an enzyme liquid layer;

[0031] S303: Combine 3 Mo / MoO x The electrodes were embedded in polyethylene glycol diacrylate / peptide double network hydrogel;

[0032] S304: 3 Mo / MoO embedded in polyethylene glycol diacrylate / peptide double network hydrogel x The electrode surface is coated with W1 for packaging and then photocured to obtain the flexible and degradable lactic acid sensor.

[0033] [8] According to the preparation method described in [7], in step S301,

[0034] The mass of polyvinyl alcohol powder: the mass of lactate dehydrogenase powder: the volume of solvent = (10-50) mg: (1-5) mg: 1 mL.

[0035] [9] An application of the flexible and degradable lactate sensor described in [1] in myocardial lactate monitoring.

[0036] Effects of the Invention

[0037] The substrate of the flexible and degradable lactic acid sensor of the present invention is polyethylene glycol diacrylate / peptide double network hydrogel, which is a hydrophilic highly cross-linked network rich in water, and has the following advantages: 1) providing chemical and structural properties similar to biological tissues, which can alleviate foreign body reactions; 2) utilizing multiple mechanisms such as energy dissipation, interfacial bonding and topological entanglement to achieve long-term stable and firm adhesion; 3) realizing a functional bidirectional interface; and 4) being self-degradable after monitoring.

[0038] The electrodes of the flexible and degradable lactic acid sensor of the present invention include working, counter and reference electrodes, wherein the working electrode, reference electrode and counter electrode are Mo / MoO x Electrode with good electrochemical stability; MoO formed on Mo substrate xThe passivation layer can delay the decline in sensing performance caused by electrode degradation and ensure long-term monitoring of myocardial lactate. By adjusting the oxidation parameters of the electrode with the help of a controllable electrochemical oxidation strategy, the electrochemical properties such as open circuit voltage and conductivity can be optimized, which helps to improve the sensitivity, stability and selectivity of the sensor during lactate monitoring. After the monitoring is completed, the electrode slowly degrades together with the hydrogel substrate, and no secondary surgery is required to remove it, which improves patient compliance.

[0039] Therefore, the flexible and degradable lactate sensor of the present invention has the advantages of high viscosity, flexibility, stretchability, biocompatibility, biodegradability and sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A graph showing changes in underwater adhesion energy between the polyethylene glycol diacrylate / peptide double network hydrogel of Example 1 of the present invention and pig heart.

[0041] Figure 2 Scanning electron microscopic morphology of the polyethylene glycol diacrylate / peptide double network hydrogel of Example 1 of the present invention.

[0042] Figure 3 A physical picture of the flexible and degradable lactic acid sensor of Example 1 of the present invention and a diagram showing its bendability and stretchability.

[0043] Figure 4 A linear relationship diagram between the output current measured by the flexible and degradable lactic acid sensor of Example 1 of the present invention and the lactic acid content in PBS.

[0044] Figure 5 Schematic diagram of the in vitro degradation of the flexible and degradable lactate sensor of Example 1 of the present invention at different times.

[0045] Figure 6 Schematic diagram of the flexible and degradable lactate sensor of Example 1 of the present invention implanted on the surface of the myocardium of a mammal.

[0046] Figure 7 The test graph of the flexible and degradable lactate sensor of Example 1 of the present invention on lactate current, pulse rate and blood oxygen before and after myocardial vascular ligation in mammals during animal experiments.

[0047] Figure 8 A comparison chart of the flexible and degradable lactate sensor of Example 1 of the present invention and the commercial lactate sensor for measuring changes in lactate in mammals before and after myocardial vascular ligation.

[0048] Fig. 9 Schematic diagram of the sensing mechanism of the flexible and degradable lactic acid sensor of Example 1 of the present invention. DETAILED DESCRIPTION

[0049] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0050] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0051] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0052] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0053] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0054] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0055] The present invention provides a flexible and degradable lactic acid sensor, comprising:

[0056] A substrate, wherein the substrate is a polyethylene glycol diacrylate / peptide double network hydrogel;

[0057] The electrodes include a working electrode, a reference electrode and a counter electrode, wherein the working electrode, the reference electrode and the counter electrode are Mo / MoO x The electrode, the Mo / MoO x The electrode comprises a Mo substrate and a MoO layer formed on the Mo substrate. x Passivation layer, wherein 1≤x≤3;

[0058] Wherein, the electrode is embedded in the substrate, the working electrode has an enzyme liquid layer, and the enzyme liquid layer contains lactate dehydrogenase.

[0059] Electrochemical sensing mechanism

[0060] The electrochemical sensing principle of the flexible and degradable lactic acid sensor prepared in the present invention is as follows: Fig. 9 Mo / MoO as working electrode in flexible and degradable lactate sensor x An enzyme liquid layer is provided on the surface of the electrode, and the enzyme liquid layer contains lactate dehydrogenase (LDH). Fig. 9 As shown, lactic acid in the test solution generates pyruvate and NADH under the catalysis of LDH, and NADH is oxidized under the action of an applied voltage to generate electron transfer and generate current. The current has a linear logical relationship with lactic acid, thereby achieving qualitative and quantitative analysis of lactic acid.

[0061] The present invention also provides a method for preparing a flexible and degradable lactic acid sensor, which comprises the following steps:

[0062] S1: Preparation of polyethylene glycol diacrylate / peptide double network hydrogel as substrate;

[0063] S2: Preparation of 3 Mo / MoO x The electrodes serve as working electrode, reference electrode, and counter electrode;

[0064] S3: Mo / MoO as working electrode x An enzyme solution layer is arranged on the electrode, and then the working electrode, the reference electrode and the counter electrode are embedded in the substrate prepared in step S1, and encapsulated to obtain a flexible and degradable lactic acid sensor;

[0065] Wherein, the enzyme liquid layer contains lactate dehydrogenase.

[0066] According to the preparation method of the present invention, step S1 comprises the following steps:

[0067] S101: adding polyethylene glycol diacrylate powder, light curing agent powder and peptide powder into a solvent and mixing them evenly to obtain a precursor solution W1 of polyethylene glycol diacrylate / peptide double network hydrogel;

[0068] S102: Pour W1 into a mold containing electrode holes, and obtain a polyethylene glycol diacrylate / peptide double network hydrogel containing electrode holes after photocuring.

[0069] According to the preparation method of the present invention, in step S101, polyethylene glycol diacrylate powder, photocuring agent powder and peptide powder can be dissolved in a solvent separately and then mixed; or they can be added into the solvent one by one to obtain a mixed solution.

[0070] According to the preparation method of the present invention, in step S101, the photocuring agent powder is I2959 powder.

[0071] According to the preparation method of the present invention, in step S101, the solvent is water, preferably deionized water.

[0072] According to the preparation method of the present invention, in step S101, the mass of polyethylene glycol diacrylate powder: the mass of photocuring agent powder: the mass of peptide powder: the volume of solvent = (200-400) mg: (0.2-0.4) mg: (10-20) mg: 1 mL.

[0073] According to the preparation method of the present invention, in step S102, the ultraviolet light irradiation time is 10-30 minutes, preferably 20 minutes.

[0074] According to the preparation method of the present invention, step S2 comprises the following steps:

[0075] S201: dissolving sodium chloride powder in a solvent to obtain an electrolyte solution W2;

[0076] S202: Mo foil is used as the working electrode, platinum electrode is used as the counter electrode, and silver / silver chloride electrode is used as the reference electrode and immersed in W2. An alternating voltage is applied to the Mo foil to generate MoO on the surface of the Mo foil. x Passivation layer;

[0077] S203: Repeat step S202 three times to obtain three Mo / MoO x electrode.

[0078] According to the preparation method of the present invention, in step S201, the solvent is water, preferably deionized water.

[0079] According to the preparation method of the present invention, in step S201, the ratio between the mass of sodium chloride powder and the volume of the solvent is (0.04-0.07) g: 1 mL.

[0080] According to the preparation method of the present invention, in step S202, an alternating voltage is applied to the Mo foil using the CV mode of the electrochemical workstation to generate MoO on the surface of the Mo foil. x Passivation layer; The specific parameters of the CV mode of the electrochemical workstation are: voltage range: 0-0.8V, number of scan cycles: 50-100 cycles, scan direction: positive or negative, scan rate: 0.1V / s.

[0081] According to the preparation method of the present invention, step S3 comprises the following steps:

[0082] S301: dissolving polyvinyl alcohol powder in a solvent to obtain a polyvinyl alcohol solution; adding lactate dehydrogenase powder to the polyvinyl alcohol solution and mixing well to obtain an enzyme-containing hydrogel W3;

[0083] S302: Coating W3 on Mo / MoO as the working electrode x The surface of the electrode, after refrigeration, obtains an enzyme liquid layer;

[0084] S303: Combine 3 Mo / MoO x The electrodes were embedded in polyethylene glycol diacrylate / peptide double network hydrogel;

[0085] S304: 3 Mo / MoO embedded in polyethylene glycol diacrylate / peptide double network hydrogel x The electrode surface is coated with W1 for packaging and then photocured to obtain the flexible and degradable lactic acid sensor.

[0086] According to the preparation method of the present invention, in step S301, the solvent is water, preferably deionized water.

[0087] According to the preparation method of the present invention, in step S301, the mass of polyvinyl alcohol powder: the mass of lactate dehydrogenase powder: the volume of solvent = (10-50) mg: (1-5) mg: 1 mL.

[0088] According to the preparation method of the present invention, in step S304, ultraviolet light is used for photocuring, and the photocuring time is more than 20 minutes, so that the electrode and the hydrogel are tightly combined.

[0089] The flexible and degradable lactate sensor of the present invention can adhere to tissues in body fluids for at least 7 days.

[0090] The flexible and degradable lactic acid sensor of the present invention can be degraded in body fluids within 5-7 months.

[0091] The present invention also provides an application of the flexible and degradable lactate sensor according to the present invention in myocardial lactate monitoring.

[0092] Example

[0093] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0094] Example 1: Preparation of flexible and degradable lactic acid sensor

[0095] S1: Preparation of polyethylene glycol diacrylate / peptide double network hydrogel as substrate

[0096] Dissolve 200 mg of polyethylene glycol diacrylate (PEGDA) powder in 1 mL of deionized water to obtain solution W1-1;

[0097] Dissolve 0.2 mg of I2959 photocuring agent powder in solution W1-1 to obtain solution W1-2;

[0098] 10 mg of peptide powder was dissolved in solution W1-2 to obtain solution W1-3, and magnetic stirring was performed for 2 hours to mix the solution evenly to obtain the precursor solution W1 of polyethylene glycol diacrylate / peptide hydrogel. W1 was poured into a mold with electrode holes, irradiated with ultraviolet light for 20 minutes, and the liquid was solidified to obtain polyethylene glycol diacrylate / peptide double network hydrogel with electrode holes, which was stored in a constant temperature and humidity chamber.

[0099] S2: Preparation of 3 Mo / MoO x The electrodes are used as working electrode, reference electrode and counter electrode respectively.

[0100] 4 g of sodium chloride powder was dissolved in 100 mL of deionized water to obtain electrolyte solution W2. Mo foil was used as the working electrode, platinum electrode as the counter electrode, and silver / silver chloride electrode as the reference electrode and immersed in W2. An alternating voltage of 0-0.8 V was applied to the Mo foil in the CV mode of the electrochemical workstation. MoO was generated on the foil surface by forward scanning at a rate of 0.1 V / s for 50 cycles. x Passivation layer; repeated three times to obtain 3 Mo / MoO x electrode.

[0101] S3: Preparation of flexible and degradable lactate sensor

[0102] 20 mg of polyvinyl alcohol (PVA) powder was dissolved in 1 mL of deionized water to obtain a polyvinyl alcohol aqueous solution; 1 mg of lactate dehydrogenase powder was added to the polyvinyl alcohol aqueous solution and mixed evenly to obtain an enzyme-containing hydrogel solution W3; W3 was coated on the Mo / MoO x The surface of the electrode was refrigerated overnight to obtain an enzyme liquid layer; the working electrode, the counter electrode and the reference electrode were embedded in the polyethylene glycol diacrylate / peptide double network hydrogel; on the three Mo / MoO x The electrode surface was coated with W1 for encapsulation and cured by ultraviolet light for 20 minutes to tightly combine the electrode with the hydrogel substrate to obtain a flexible and degradable lactic acid sensor, which was recorded as sensor-I.

[0103] Performance Testing

[0104] Adhesion energy test

[0105] The polyethylene glycol diacrylate / peptide double network hydrogel prepared in Example 1 was tested for adhesion energy. The precursor liquid W1 of polyethylene glycol diacrylate / peptide hydrogel was poured into two polytetrafluoroethylene molds, and then irradiated with ultraviolet light for 20 minutes. The liquid solidified to obtain two sheets of hydrogels of 2cm×1cm×0.2cm. The two sheets of hydrogel had an adhesion overlapping joint of 0.5cm×0.5cm, and pig heart squares of the same area were embedded in the middle of the joint to form a sandwich structure hybrid of hydrogel-pig heart-hydrogel. An Instron tensile testing machine was used to apply axial forces in opposite directions to the two free ends of the hydrogel / pig heart / hydrogel at a stretching rate of 5mm / min, and stress and displacement were recorded at the same time. The adhesion energy is the maximum stress divided by the area of ​​the adhesion area. The hybrid was immersed in PBS at room temperature, and the adhesion energy of the overlap was tested every three days. The samples were tested in parallel 3 times, and the average value was calculated. The results are shown as follows. Figure 1 shown.

[0106] from Figure 1 It can be seen that the adhesion energy between the hydrogel and the pig heart gradually decreases with the increase of the number of days of immersion in PBS. After more than 15 days, the adhesion energy value is too small to be measured by the tensile tester.

[0107] Scanning electron microscope test

[0108] The microscopic properties of the polyethylene glycol diacrylate / peptide double network hydrogel prepared in Example 1 were analyzed. The hydrogel and the hydrogel, and the hydrogel and the pig heart were adhered together and pressed for 5 minutes at room temperature to obtain two hybrids. The size of the hydrogel and the pig heart was 2cm×1cm×0.2cm. The two hybrids were placed in a -20℃ refrigerator and frozen overnight, and then placed in a freeze dryer for 24 hours to remove moisture and reduce the size. The adhesion interface was observed using a scanning electron microscope. The results are as follows: Figure 2 shown.

[0109] from Figure 2 It can be seen that the polyethylene glycol diacrylate / peptide double network hydrogel has a micron-level porous structure, and the interfaces between the hydrogels and between the hydrogels and the pig heart are tightly adhered to form a complete network.

[0110] Bending and tensile testing

[0111] Figure 3 This is a physical picture of the flexible and degradable lactic acid sensor prepared in Example 1. Figure 3 The size and dimensions of the device can be seen in a. Figure 3 It can be seen from the bd that it has excellent bending and stretching capabilities.

[0112] In vitro lactate sensing performance testing

[0113] The flexible and degradable lactic acid sensor prepared in Example 1 was subjected to an in vitro lactic acid sensing experiment. The It mode in the electrochemical workstation was used to detect the dissolution of lactic acid solutions of different concentrations (0, 1, 2, 3, 4, 5, 6, 7, 8 mM) in 0.01 M PBS (pH 7.4) solution. The initial potential of It detection of lactic acid was -0.65 V. The experimental results are shown in Figure 2. Figure 4 shown.

[0114] from Figure 4 It can be seen that in the range of 0-8mM, as the lactate concentration increases, the output current of the sensor increases accordingly. In this range, the lactate concentration and the current are linearly related, and the linear relationship is y(μA)=-0.85×(μM)-24.58(R 2 =0.987). This indicates that the flexible and degradable lactate sensor can reliably monitor myocardial lactate.

[0115] In vitro degradation test

[0116] The flexible and degradable lactic acid sensor prepared in Example 1 was subjected to an in vitro degradation experiment. The flexible and degradable lactic acid sensor was immersed in a 0.01M PBS (pH 7.4) solution and kept warm in a 55°C water bath. The sensor was photographed at specific intervals. The experimental results are shown in FIG. Figure 5 shown.

[0117] from Figure 5 It can be seen that the polyethylene glycol diacrylate / peptide double network hydrogel is basically degraded within 20 days. Within 170 days, including Mo / MoO x The flexible and degradable lactate sensor including the foil electrode was substantially degraded, demonstrating the degradability of the sensor without producing any residual material.

[0118] Implantation testing on mammalian myocardial surface

[0119] The flexible and degradable lactate sensor prepared in Example 1 was subjected to an in vivo animal experiment. The New Zealand white rabbits used in the experiment were anesthetized and the left thorax was opened and fixed with hemostatic forceps. The flexible and degradable lactate sensor was embedded between the beating heart and the pericardium, and the second diagonal branch of the anterior descending branch of the heart was ligated with sutures to simulate myocardial infarction. The experimental schematic diagram is shown in FIG. Figure 6 The response current is recorded during the whole process and Figure 4 The linear calibration curve in was converted into lactate concentration, and the difference of lactate concentration before and after ligation was calculated. The pulse rate and blood oxygen before and after ligation were monitored using a commercial pulse oximeter (brand: RocSea, model: BM1000A). The experimental results are shown in Figure 7A commercial lactate sensor (brand: Bayford, model: YST-I) was used to detect the myocardial lactate concentration before and after ligation, and the difference before and after was compared with the flexible degradable lactate sensor. The experimental results are shown in Figure 8 shown.

[0120] from Figure 7 It can be seen that the myocardial lactate content increased significantly before and after ligation, while the pulse rate and blood oxygen value showed no obvious pattern. Therefore, the lactate value monitored by the flexible and degradable lactate sensor can be used as one of the markers for myocardial infarction.

[0121] from Figure 8 It can be seen that the difference in lactate before and after ligation measured by the commercial sensor is comparable to that of the flexible and degradable sensor, proving the practicality of the flexible and degradable lactate sensor.

[0122] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0123] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A flexible and degradable lactic acid sensor, characterized in that: include: A substrate, wherein the substrate is a polyethylene glycol diacrylate / peptide double network hydrogel; The electrodes include a working electrode, a reference electrode and a counter electrode, wherein the working electrode, the reference electrode and the counter electrode are Mo / MoO x The electrode, the Mo / MoO x The electrode comprises a Mo substrate and a MoO x Passivation layer, wherein 1≤x≤3; Wherein, the electrode is embedded in the substrate, the working electrode has an enzyme liquid layer, and the enzyme liquid layer contains lactate dehydrogenase.

2. A method for preparing the flexible and degradable lactic acid sensor according to claim 1, comprising the following steps: S1: Preparation of polyethylene glycol diacrylate / peptide double network hydrogel as substrate; S2: Preparation of 3 Mo / MoO x The electrodes serve as working electrode, reference electrode, and counter electrode; S3: Mo / MoO as working electrode x An enzyme solution layer is provided on the electrode, and then the working electrode, the reference electrode and the counter electrode are embedded in the substrate prepared in step S1, and encapsulated to obtain a flexible and degradable lactic acid sensor; in, The enzyme liquid layer contains lactate dehydrogenase.

3. The preparation method according to claim 2, characterized in that: Step S1 includes the following steps: S101: adding polyethylene glycol diacrylate powder, light curing agent powder and peptide powder into a solvent and mixing them evenly to obtain a precursor solution W1 of polyethylene glycol diacrylate / peptide double network hydrogel; S102: Pour W1 into a mold containing electrode holes, and obtain a polyethylene glycol diacrylate / peptide double network hydrogel containing electrode holes after photocuring.

4. The preparation method according to claim 3, characterized in that: In step S101, Mass of polyethylene glycol diacrylate powder: Mass of photocuring agent powder: Mass of peptide powder: Volume of solvent = (200-400) mg: (0.2-0.4) mg: (10-20) mg: 1 mL.

5. The preparation method according to claim 2 or 3, characterized in that: Step S2 includes the following steps: S201: dissolving sodium chloride powder in a solvent to obtain an electrolyte solution W2; S202: Mo foil is used as the working electrode, platinum electrode is used as the counter electrode, and silver / silver chloride electrode is used as the reference electrode and immersed in W2. An alternating voltage is applied to the Mo foil to generate MoO on the surface of the Mo foil. x Passivation layer; S203: Repeat step S202 three times to obtain three Mo / MoO x electrode.

6. The preparation method according to claim 5, characterized in that: In step S201, The ratio between the mass of sodium chloride powder and the volume of the solvent is (0.04-0.07) g:1 mL.

7. The preparation method according to claim 3, characterized in that: Step S3 includes the following steps: S301: dissolving polyvinyl alcohol powder in a solvent to obtain a polyvinyl alcohol solution; adding lactate dehydrogenase powder to the polyvinyl alcohol solution and mixing well to obtain an enzyme-containing hydrogel W3; S302: Coating W3 on Mo / MoO as the working electrode x The surface of the electrode, after refrigeration, obtains an enzyme liquid layer; S303: Combine 3 Mo / MoO x The electrodes were embedded in polyethylene glycol diacrylate / peptide double network hydrogel; S304: 3 Mo / MoO embedded in polyethylene glycol diacrylate / peptide double network hydrogel x The electrode surface is coated with W1 for packaging and then photocured to obtain the flexible and degradable lactic acid sensor.

8. The preparation method according to claim 7, characterized in that: In step S301, The mass of polyvinyl alcohol powder: the mass of lactate dehydrogenase powder: the volume of solvent = (10-50) mg: (1-5) mg: 1 mL.

9. Use of the flexible and degradable lactate sensor according to claim 1 in myocardial lactate monitoring.

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