Composite membrane material, biosensor

Abstract

This application relates to a composite membrane material and a biosensor, comprising a polymer material and a modified polymer. The polymer material includes at least one of a divalent copolymer, an acrylate polymer, and a urethane polymer. The composite membrane material has a molecular weight of 15,000–30,000 and a molecular weight distribution index (D) of 1.3–1.6. The polymer material in this application is non-toxic, non-irritating, and exhibits good biocompatibility. Mixing the polymer material with the modified polymer results in a composite membrane material that combines good biocompatibility with good permeability selectivity. When used in a biosensor, this composite membrane material improves the selective permeability of tissue fluid, allowing glucose, lactic acid, ketones, etc., to pass through while preventing other viscous substances from passing through. This avoids clogging of the composite membrane material during prolonged operation, thereby improving the sensitivity and efficiency of the biosensor.

Description

Technical Field

[0001] This application belongs to the field of biosensor technology, and in particular relates to a composite membrane material and a biosensor. Background Technology

[0002] Electrochemical sensors are increasingly used in the biomedical field. For example, a biosensor is an instrument that is sensitive to biological substances and converts their concentration into an electrical signal for detection. Examples include uric acid analyzers and blood glucose analyzers, which quickly assess an individual's physiological condition by monitoring the fluid in the skin's tissues, allowing people to monitor their health at home.

[0003] However, the complexity of human tissue fluid presents significant challenges to implanted medical biosensors. To ensure the normal, efficient, and long-term operation of implanted medical chemical sensors in this complex tissue fluid environment, the outer polymer membrane is crucial. This semi-permeable membrane allows substances smaller than its pore size, such as oxygen, carbon dioxide, inorganic salts, and nutrients, to pass freely, while substances larger than its pore size, such as bacteria and foreign bodies, cannot pass through. These impermeable tissue fluids accumulate on the surface of the semi-permeable membrane over time. This tissue fluid adhering to the membrane surface affects the implanted biosensor, reducing its sensitivity and shortening its continuous operating time.

[0004] Therefore, there is an urgent need for a biosensor that can operate efficiently and for extended periods in complex tissue fluid environments and has high sensitivity. Summary of the Invention

[0005] To overcome the above-mentioned deficiencies, this application provides a composite membrane material and a biosensor. Using this membrane material in a biosensor can improve the selective permeability of tissue fluid, thereby improving the sensitivity and working efficiency of the biosensor.

[0006] In a first aspect, this application provides a composite membrane material comprising a polymer material and a modified polymer, wherein the polymer material comprises at least one of a copolyester polymer, an acrylate polymer, and a urethane polymer, the composite membrane material has a molecular weight of 15,000 to 30,000, and in conjunction with the first aspect, the molecular weight distribution index D of the composite membrane material is 1.3 to 1.6.

[0007] In conjunction with the first aspect, the copolydiester polymer has the following structure:

[0008]

[0009] Wherein, R is selected from C1 to C12 alkyl groups, R1 is selected from any one of H and C1 to C5 alkyl groups, and n is an integer greater than 1.

[0010] In conjunction with the first aspect, the copolydivalent ester polymer includes at least one of polyhydroxy esters, polymalates, and polycaprolactone.

[0011] In conjunction with the first aspect, the acrylate polymer includes at least one of polyacrylate, polyethyl methacrylate, polybutyl methacrylate, and polymethyl methacrylate.

[0012] In conjunction with the first aspect, the urethane polymer includes at least one of polyether polyurethane and polyester polyurethane.

[0013] In conjunction with the first aspect, the modified polymer includes at least one of cellulose and silane polymers.

[0014] In conjunction with the first aspect, the cellulose includes at least one of cellulose acetate, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0015] In conjunction with the first aspect, the silane polymer includes at least one of tetraethyl orthosilicate and polydimethylsiloxane.

[0016] In conjunction with the first aspect, the mass ratio of the polymer material to the modified polymer is (1.1 to 1.5): 1.

[0017] In conjunction with the first aspect, the average thickness of the composite membrane material is 2 μm to 13 μm.

[0018] In conjunction with the first aspect, the porosity of the composite membrane material is 53% to 58%.

[0019] Secondly, this application provides a biosensor, comprising:

[0020] Working electrode;

[0021] At least one counter electrode;

[0022] Reference electrode;

[0023] A detection layer that contacts the working electrode, the detection layer comprising the composite membrane material as described above and an enzyme that transfers electrons to and receives electrons from the working electrode.

[0024] In conjunction with the second aspect, the working electrode includes any one of gold, platinum, palladium, ruthenium, and carbon.

[0025] In conjunction with the second aspect, the counter electrode comprises any one of gold, platinum, palladium, ruthenium, and carbon.

[0026] In conjunction with the second aspect, the reference electrode includes any one of silver, gold, platinum, palladium, and ruthenium.

[0027] In conjunction with the second aspect, the enzyme includes any one of glucose oxidase, glutamate dehydrogenase, and galactose oxidase.

[0028] In conjunction with the second aspect, at least a portion of the surface of the working electrode is also covered with an electrode modification layer.

[0029] In conjunction with the second aspect, the electrode modification layer is prepared by coating the working electrode with a dispersion of at least one of graphene, carbon fiber and carbon quantum dots.

[0030] In conjunction with the second aspect, the median particle size of at least one of graphene, carbon fiber and carbon quantum dots in the dispersion is 30 nm to 50 nm.

[0031] Compared with existing technologies, this technical solution has at least the following technical effects: The composite membrane material of this application is a non-toxic and non-irritating polymer material with good biocompatibility. By mixing the polymer material with the modified polymer, the prepared composite membrane material has both good biocompatibility and good permeability selectivity. This allows the composite membrane material to improve the selective permeability of tissue fluid when used in biosensors, allowing glucose, lactic acid, ketones, etc., to pass through, while other viscous substances (proteins, macromolecular peptides, lipids, and phospholipids, etc.) in the tissue fluid cannot pass through. This avoids clogging of the composite membrane material during long-term operation, thereby improving the sensitivity and working efficiency of the biosensor.

[0032] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Detailed Implementation

[0033] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to specific implementation methods.

[0034] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0036] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0037] This application provides a composite membrane material comprising a polymer and a modified polymer, wherein the polymer material comprises at least one of a copolyester polymer, an acrylate polymer, and a urethane polymer.

[0038] In the above scheme, the polymer material selected in this application is non-toxic and non-irritating, and has good biocompatibility. The polymer material and the modified polymer are mixed to prepare a composite membrane material with a molecular weight between 15,000 and 30,000 and a molecular weight distribution index of 1.3 to 1.6. It has both good biocompatibility and good permeability selectivity. When used in biosensors, this composite membrane material can improve the selective permeability of tissue fluid, allowing blood glucose, lactic acid, and ketones to pass through, while other viscous substances (proteins, macromolecular peptides, lipids, and phospholipids, etc.) in the tissue fluid cannot pass through. This avoids clogging of the composite membrane material during long-term operation, thereby improving the sensitivity and working efficiency of the biosensor.

[0039] In some embodiments, the molecular weight of the composite membrane material is 15,000 to 30,000. The molecular weight of the composite membrane material can be 15,000, 17,000, 20,000, 25,000, 28,000 and 30,000, etc., and of course it can be other values ​​within the above range. This application does not limit it here.

[0040] In some embodiments, the molecular weight distribution index D of the composite membrane material is 1.3 to 1.6. The molecular weight index D of the composite membrane material can be 1.3, 1.4, 1.5 and 1.6, etc., and of course it can be other values ​​within the above range. This application does not limit it here.

[0041] In some embodiments, the copolyester polymer has the following core structure:

[0042]

[0043] Wherein, R is selected from C1 to C12 alkyl groups, R1 is selected from H and C1 to C5 alkyl groups, and n is an integer greater than 1, for example, n can be 2, 3, 4 and 5, etc.

[0044] The ester functional groups contained in the above-mentioned copolydivalent ester polymers have non-toxic and non-irritating effects and do not affect human tissue fluid.

[0045] In some embodiments, the copolydiester polymer includes at least one of polyhydroxy esters, polymalates, and polycaprolactone. Exemplarily, the polyhydroxy esters include at least one of poly(3-hydroxybutyrate) (PHB), poly(hydroxyvalerate) (PHV), and poly(3-hydroxyhexanoate); the polymalates include at least one of polybenzyl malate, poly(lactic-co-malolactone), and poly(β-benzyl malate-co-β-hydroxybutyrate); and the polycaprolactone (PCL) includes at least one of PCL-1000, PCL-1800, and PCL-2000.

[0046] In some embodiments, the acrylate polymer includes at least one of polyethyl methacrylate, polybutyl methacrylate, and polymethyl methacrylate.

[0047] In some embodiments, the urethane polymer includes at least one of polyether-type polyurethane and polyester-type polyurethane. For example, the polyether-type polyurethane may be... A78-P-4766 A78-P-4207 and At least one of 2103-85A, such as polyester-type polyurethane, may be 2355-80AE 58133 and At least one of A85-H-4656.

[0048] In some embodiments, the modified polymer includes at least one of cellulose and silane polymers.

[0049] In some embodiments, cellulose includes at least one of cellulose acetate, hydroxyethyl cellulose, and hydroxypropyl cellulose.

[0050] In some embodiments, the silane polymer includes at least one of tetraethyl orthosilicate and polydimethylsiloxane;

[0051] In some embodiments, the mass ratio of the polymer material to the modified polymer is (1.1 to 1.5):1. Specifically, the mass ratio of the polymer material to the modified polymer can be 1.1:1, 1.2:1, 1.3:1, 1.4:1, and 1.5:1, or other values ​​within the above range. This application does not limit this. A mass ratio of the polymer material to the modified polymer less than 1.1:1, or a mass ratio greater than 1.5:1, will lead to a decrease in the sensitivity of the composite membrane material as a biosensor and a shorter working time (less than 15 days).

[0052] In some embodiments, the average thickness of the composite membrane material is 2μm to 13μm. Specifically, the average thickness of the composite membrane material can be 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm and 13μm, etc. Of course, it can also be other values ​​within the above range. This application does not limit it here. Limiting the thickness of the composite membrane material to the above range is beneficial to the penetration of tissue fluid.

[0053] In some embodiments, the porosity of the composite membrane material is 53% to 58%. Specifically, the porosity of the composite membrane material can be 53%, 54%, 55%, 56%, 57%, and 58%, etc. Limiting the porosity of the composite membrane material to the above range is beneficial for the permeation and filtration of tissue fluid.

[0054] Controlling the molecular weight and molecular weight distribution index D of the composite membrane material within the above range is beneficial to improving the permeation selectivity of the membrane material.

[0055] This application also provides a method for preparing the above-mentioned composite membrane material, including the following steps:

[0056] Step 1: Dissolve the polymer and the modified polymer in a reaction vessel at a mass ratio of (1.1 to 1.5): 1, and stir at 70°C to 90°C for 60 to 75 minutes to obtain the membrane solution.

[0057] Step 2: Aging the membrane solution obtained in Step 1 at room temperature to prepare a membrane for later use.

[0058] In some implementations, room temperature refers to 20°C to 25°C under standard atmospheric pressure.

[0059] In some embodiments, aging treatment is beneficial for preparing a homogenized membrane. The aging time is 24h to 48h, and the aging time can be 24h, 25h, 28h, 30h, 36h, 42h and 48h, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0060] Step 3: The membrane obtained in Step 2 is subjected to steam treatment to obtain a composite membrane material.

[0061] In some embodiments, the steam treatment temperature is 95°C, 96°C, 97°C, 98°C, 99°C, and 100°C, etc. Of course, other values ​​within the above range are also possible, and this application does not limit them.

[0062] In some embodiments, the steam treatment time is 1h to 2h. The specific steam treatment time can be 1h, 80min, 9min, 100min, 110min and 2h, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0063] In this step, steam treatment refers to placing the membrane in a heating furnace and introducing supersaturated steam into the furnace at a temperature of 95-100°C. The purpose of steam treatment is to improve the membrane's permeability.

[0064] This application also provides a biosensor, comprising:

[0065] Working electrode;

[0066] At least one counter electrode;

[0067] Reference electrode;

[0068] The detection layer contacts the working electrode and includes the aforementioned composite membrane material and an enzyme that transfers electrons to and receives electrons from the working electrode.

[0069] In the above-mentioned scheme, the polymer material selected in this application is non-toxic and non-irritating, and has good biocompatibility. Mixing the polymer material with the modified polymer results in a composite membrane material that possesses both good biocompatibility and good permeability. This composite membrane material, when used in biosensors, can improve the selective permeability of tissue fluid, thereby enhancing the sensitivity and efficiency of the biosensor. Simultaneously, this composite membrane material can also serve as a protective membrane for the working electrode, reducing the damage to the biosensor caused by tissue immune responses and extending the lifespan of the biosensor.

[0070] In some embodiments, a redox reaction occurs on the surface of the working electrode in the biosensor. The working electrode includes any one of gold, platinum, palladium, ruthenium, and carbon, and the reference electrode includes any one of silver, gold, platinum, palladium, and ruthenium. The reference electrode has a constant and well-known potential, and the counter electrode includes any one of gold, platinum, palladium, ruthenium, and carbon. The working electrode, counter electrode, and reference electrode selected in this application have good oxidation resistance. In some cases, the working electrode and reference electrode can be electrodes made of the same material, or electrodes made of different materials. For example, both the working electrode and the counter electrode are gold electrodes, and the reference electrode is a carbon electrode; alternatively, both the working electrode and the counter electrode can be carbon electrodes, and the reference electrode can be a gold electrode, etc.

[0071] In some embodiments, the biosensor further includes a substrate on which a working electrode, a counter electrode, and a reference electrode are disposed. The working electrode, the counter electrode, and the reference electrode are respectively connected to terminals of a measuring device via leads. The substrate is composed of an insulating material, and exemplaryly, the substrate includes glass, polyimide resin, and epoxy resin, etc.

[0072] The enzyme includes any one of glucose oxidase, glutamate dehydrogenase, and galactose oxidase. Preferably, the enzyme is glucose oxidase.

[0073] In some embodiments, the biosensor of this application is prepared by the following method: a working electrode, a counter electrode, and a reference electrode are formed on the surface of a substrate by physical vapor deposition (PVD) or chemical vapor deposition (CVD). The working electrode, the counter electrode, and the reference electrode can be prepared using the same material or different materials. Then, the enzyme and the composite membrane material of this application are placed on the working electrode to form the biosensor.

[0074] In some embodiments, at least a portion of the surface of the working electrode is coated with an electrode modification layer, which includes at least one of graphene, carbon fiber, and carbon quantum dots. The stable lattice structure and unique two-dimensional sheet structure of graphene are used to improve enzyme adhesion without affecting electronic signal transmission.

[0075] In some embodiments, the electrode modification layer is prepared by coating a dispersion of at least one of graphene, carbon fiber and carbon quantum dots onto the working electrode.

[0076] In some embodiments, the coating method includes at least one of vapor deposition, spraying, and immersion.

[0077] In some embodiments, the dispersion is prepared by ultrasonic dispersion of at least one of graphene, carbon fiber and carbon quantum dots.

[0078] In some embodiments, the particle size of at least one of graphene, carbon fiber and carbon quantum dots in the dispersion is 30 nm to 50 nm. Specific particle sizes can be, for example, 30 nm, 32 nm, 35 nm, 38 nm, 40 nm, 42 nm, 46 nm, 48 nm and 50 nm. Of course, other values ​​within the above range are also possible in this application and are not limited here. Controlling the particle size of at least one of graphene, carbon fiber and carbon quantum dots in the dispersion within the above range is beneficial to improving enzyme adhesion without affecting electronic signal transmission.

[0079] In some embodiments, the thickness of the electrode modification layer is 0.5 μm to 1 μm. Specifically, the thickness of the electrode modification layer can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm and 1 μm, etc. Of course, other values ​​within the above range can also be used in this application, which are not limited here.

[0080] In some embodiments, the biosensor of this application is also prepared by the following method: a working electrode, a counter electrode, and a reference electrode are formed on the surface of a substrate by physical vapor deposition (PVD) or chemical vapor deposition (CVD). The working electrode, the counter electrode, and the reference electrode can be prepared using the same material or different materials. Then, a dispersion of at least one of graphene, carbon fiber, and carbon quantum dots is coated on the working electrode to form an electrode modification layer. Finally, a detection layer is formed on the electrode modification layer, that is, the enzyme and the composite membrane material of this application are placed on the electrode modification layer.

[0081] The biosensor of this application can be any one of a glucose biosensor, a uric acid biosensor, a cholesterol biosensor, and a microbial sensor. For example, the glucose sensor uses glucose invertase to convert glucose into gluconolactone under oxygen conditions, generating hydrogen peroxide, which is detected and quantified on the surface of the working electrode of the biosensor.

[0082] In some embodiments, the biosensor of this application is placed in a prepared tissue fluid (e.g., glucose solution), and its sensitivity K value for 1–30 days is measured using a constant potential voltammetry method, ranging from 1.0 nA / mM to 9.57 nA / mM. Specific sensitivity values ​​can be 1.0 nA / mM, 1.5 nA / mM, 2 nA / mM, 2.8 nA / mM, 3.5 nA / mM, 4.6 nA / mM, 5.5 nA / mM, 6.15 nA / mM, 7.12 nA / mM, 8.0 nA / mM, 8.58 nA / mM, 9.20 nA / mM, and 9.57 nA / mM, etc. Of course, other values ​​within the above range are also possible and are not limited herein. Compared with existing biosensors, the biosensor of this application has higher sensitivity.

[0083] Those skilled in the art will understand that the composite membrane materials and biosensors described above are merely embodiments. Other methods commonly used in the art can be employed without departing from the disclosure of this application.

[0084] The embodiments of this application will be further described below with reference to several examples. However, the embodiments of this application are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of the main claims.

[0085] Example 1

[0086] (1) A gold electrode is used as the working electrode, a gold electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The working electrode, counter electrode and reference electrode are arranged on a glass substrate.

[0087] (2) Graphene was prepared into a dispersion by ultrasonic dispersion and coated onto the working electrode to obtain an electrode modification layer. The median particle size of graphene in the dispersion was 50 nm and the thickness of the electrode modification layer was 1 μm.

[0088] (3) Polycaprolactone PCL-2000 and tetraethyl orthosilicate were mixed at a mass ratio of 1.2:1 to obtain a composite membrane material. The prepared composite membrane material was coated on the outer surface of the electrode modification layer and the enzyme layer to obtain a biosensor. The biosensor was placed in a glucose solution at 37±0.5℃ and its sensitivity K was tested by constant potential voltammetry. The thickness, porosity and molecular characteristics (molecular weight and distribution index D) of the membrane were characterized. The test results are shown in Table 1.

[0089] Example 2

[0090] (1) A gold electrode is used as the working electrode, a gold electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The working electrode, counter electrode and reference electrode are arranged on a glass substrate.

[0091] (2) Graphene was prepared into a dispersion by ultrasonic dispersion and coated onto the working electrode to obtain an electrode modification layer. The median particle size of graphene in the dispersion was 50 nm and the thickness of the electrode modification layer was 1 μm.

[0092] (3) Poly(lactic acid-co-malolactone) (PMSL, Xi'an Ruixi Biotechnology Co., Ltd.) and cellulose acetate were mixed at a mass ratio of 1.2:1 to obtain a composite membrane material. The prepared composite membrane material was coated on the outer surface of the electrode-modified layer and the enzyme layer. The sensor was placed in a glucose solution at 37±0.5℃. Its sensitivity K was tested by constant potential voltammetry. The thickness, porosity and molecular characteristics (molecular weight and distribution index D) of the membrane were characterized. The test results are shown in Table 1.

[0093] Example 3

[0094] (1) A gold electrode is used as the working electrode, a gold electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The working electrode, counter electrode and reference electrode are arranged on a glass substrate.

[0095] (2) Graphene was prepared into a dispersion by ultrasonic dispersion and coated onto the working electrode to obtain an electrode modification layer. The median particle size of graphene in the dispersion was 50 nm and the thickness of the electrode modification layer was 1 μm.

[0096] (3) Poly(lactic acid-co-malolactone) (PMSL) and cellulose acetate were mixed at a mass ratio of 1.5:1 to obtain a composite membrane material. The prepared composite membrane material was coated on the outer surface of the electrode-modified layer and the enzyme layer. The sensor was placed in a glucose solution at 37±0.5℃ and its sensitivity K was tested by constant potential voltammetry. The thickness, porosity and molecular characteristics (molecular weight and distribution index D) of the membrane were characterized. The test results are shown in Table 1.

[0097] Example 4

[0098] (1) A gold electrode is used as the working electrode, a gold electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The working electrode, counter electrode and reference electrode are arranged on a glass substrate.

[0099] (2) Graphene was prepared into a dispersion by ultrasonic dispersion and coated onto the working electrode to obtain an electrode modification layer. The median particle size of graphene in the dispersion was 50 nm and the thickness of the electrode modification layer was 1 μm.

[0100] (3) After mixing polyethyl methacrylate and cellulose acetate at a mass ratio of 1.5:1, a composite membrane material was obtained. The prepared composite membrane material was coated on the outer surface of the electrode-modified layer and the enzyme layer. The sensor was placed in a glucose solution at 37±0.5℃. Its sensitivity K was tested by constant potential voltammetry. The thickness, porosity and molecular characteristics (molecular weight and distribution index D) of the membrane were characterized. The test results are shown in Table 1.

[0101] Example 5

[0102] (1) A gold electrode is used as the working electrode, a gold electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The working electrode, counter electrode and reference electrode are arranged on a glass substrate.

[0103] (2) Graphene was prepared into a dispersion by ultrasonic dispersion and coated onto the working electrode to obtain an electrode modification layer. The median particle size of graphene in the dispersion was 50 nm and the thickness of the electrode modification layer was 1 μm.

[0104] (3) A78-P-4766 and cellulose acetate were mixed at a mass ratio of 1.5:1 to obtain a composite membrane material. The prepared composite membrane material was coated on the outer surface of the electrode-modified layer and the enzyme layer. The sensor was placed in a glucose solution at 37±0.5℃, and its sensitivity K was tested using the constant potential voltammetry method. The thickness, porosity, and molecular characteristics (molecular weight and distribution index D) of the membrane were characterized. The test results are shown in Table 1.

[0105] Example 6

[0106] Unlike Example 1, in step (3), the mass ratio of polycaprolactone PCL-2000 to tetraethyl orthosilicate is 1.1:1.

[0107] Example 7

[0108] Unlike Example 1, in step (3), the mass ratio of polycaprolactone PCL-2000 to tetraethyl orthosilicate is 1.5:1.

[0109] Example 8

[0110] Unlike Example 1, in step (3), the mass ratio of polycaprolactone PCL-2000 to tetraethyl orthosilicate is 1:1.

[0111] Example 9

[0112] Unlike Example 1, in step (3), the mass ratio of polycaprolactone PCL-2000 to tetraethyl orthosilicate is 1.8:1.

[0113] Example 10

[0114] Unlike Example 1, tetraethyl orthosilicate is not added in step (3).

[0115] Example 11

[0116] Unlike Example 1, the median particle size of graphene in the dispersion in step (2) is 25 nm, and the thickness of the electrode modification layer is 0.4 μm.

[0117] Example 12

[0118] Unlike Example 1, the median particle size of graphene in the dispersion in step (2) is 30 nm, and the thickness of the electrode modification layer is 0.7 μm.

[0119] Example 13

[0120] Unlike Example 1, the median particle size of graphene in the dispersion in step (2) is 60 nm, and the thickness of the electrode modification layer is 1.1 μm.

[0121] Example 14

[0122] Unlike Example 1, step (2) is omitted.

[0123] Comparative Example 1

[0124] (1) A gold electrode is used as the working electrode, a gold electrode is used as the counter electrode, and an Ag / AgCl electrode is used as the reference electrode. The working electrode, counter electrode and reference electrode are arranged on a glass substrate.

[0125] (2) The existing polyvinylidene fluoride (PVDF) high-throughput membrane was coated on the outer surface of the electrode-modified layer and the enzyme layer. The sensor was placed in a glucose solution at 37±0.5℃ and its sensitivity K was tested by constant potential voltammetry. The test results are shown in Table 1.

[0126] Performance testing

[0127] 1. The sensitivity K of the biosensor was tested using the constant potential voltammetry method.

[0128] 2. The thickness of the composite membrane material was determined using a step meter.

[0129] 3. The porosity of the composite membrane material was determined using the hexadecane absorption method (GB / T 33052-2016), a method for determining the porosity of microporous functional membranes.

[0130] 4. The molecular weight and molecular weight distribution index of the composite membrane material were determined by gel permeation chromatography (GPC).

[0131] Table 1. Performance tests of Examples 1-14 and Comparative Examples

[0132]

[0133]

[0134] Examples 1-13 of this application describe the preparation of biosensors with molecular weights between 15,000 and 30,000 and molecular weight distribution indexes between 1.3 and 1.6. This improves the selective permeability to tissue fluid, allowing glucose, lactic acid, and ketones to pass through, while preventing other viscous substances (proteins, large polypeptides, lipids, and phospholipids) from passing through. This avoids clogging of the composite membrane material during prolonged operation, thereby improving the sensitivity and efficiency of the biosensor. In contrast, Comparative Example 1 used conventional polyvinylidene fluoride to prepare the membrane material, resulting in no response from the biosensor.

[0135] In Example 8, the amount of copolymer material added was too small, or in Example 9, the amount of copolymer material added was too large, resulting in a decrease in the sensitivity of the biosensor and a shortening of its working time.

[0136] In Example 10, without the addition of modified polymer, the biosensor prepared there showed decreased sensitivity and no response.

[0137] In Examples 1 and 11-13, if the graphene particle size in the electrode modification layer is too large, the graphene layer is easy to fall off and the sensor has no response. If the graphene particle size is too small, it is not conducive to the dispersion of the graphene solution and the coating layer is uneven, resulting in poor sensor sensitivity.

[0138] In Example 14, no electrode modification layer was prepared. After working for a period of time, the enzyme layer was easily detached and separated from the electrode, causing the biosensor to fail.

[0139] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A composite film material, characterized by, The composite membrane material comprises a polymer material and a modified polymer, wherein the polymer material comprises at least one of a copolyester polymer, an acrylate polymer, and a urethane polymer, the mass ratio of the polymer material to the modified polymer is (1.1 to 1.5):1, the modified polymer comprises at least one of a cellulose polymer and a silane polymer, the molecular weight of the composite membrane material is 15,000 to 30,000, and the molecular weight distribution index D of the composite membrane material is 1.3 to 1.

6.

2. The composite membrane material according to claim 1, characterized in that, The copolydiester polymer has the following structure: Wherein, R is selected from C1 to C12 alkyl groups, R1 is selected from any one of H and C1 to C5 alkyl groups, and n is an integer greater than 1.

3. The composite membrane material according to claim 1 or 2, characterized in that, The copolydivalent ester polymer includes at least one of polyhydroxy acid esters, polymalic acid esters, and polycaprolactone.

4. The composite membrane material according to claim 1, characterized in that, The acrylate polymer includes at least one of polyacrylate polymer, polyethyl methacrylate, polybutyl methacrylate, and polymethyl methacrylate.

5. The composite membrane material according to claim 1, characterized in that, The urethane polymer includes at least one of polyether polyurethane and polyester polyurethane.

6. The composite membrane material according to claim 1, characterized in that, The modified polymer includes at least one of the following features (1) and (2); (1) The cellulose includes at least one of cellulose acetate, hydroxyethyl cellulose and hydroxypropyl cellulose; (2) The silane polymer includes at least one of tetraethyl orthosilicate and polydimethylsiloxane.

7. The composite membrane material according to claim 1, characterized in that, The composite membrane material includes at least one of the following features (1) to (2): (1) The average thickness of the composite membrane material is 2 μm to 13 μm; (2) The porosity of the composite membrane material is 53% to 58%.

8. A biosensor, characterized in that, include: Working electrode; At least one counter electrode; Reference electrode; A detection layer that contacts the working electrode, the detection layer comprising the composite membrane material according to any one of claims 1 to 7 and an enzyme that transfers electrons to and receives electrons from the working electrode.

9. The biosensor according to claim 8, characterized in that, The biosensor includes at least one of the following features (1) to (3): (1) The working electrode includes any one of gold, platinum, palladium, ruthenium and carbon; (2) The counter electrode includes any one of gold, platinum, palladium, ruthenium and carbon; (3) The reference electrode includes any one of silver, gold, platinum, palladium and ruthenium.

10. The biosensor according to claim 8, characterized in that, The enzyme includes any one of glucose oxidase, glutamate dehydrogenase, and galactose oxidase.

11. The biosensor according to claim 8, characterized in that, At least a portion of the surface of the working electrode is also covered with an electrode modification layer.

12. The biosensor according to claim 11, characterized in that, The electrode modification layer is prepared by coating the working electrode with a dispersion of at least one of graphene, carbon fiber and carbon quantum dots.

13. The biosensor according to claim 12, characterized in that, The median particle size of at least one of graphene, carbon fiber and carbon quantum dots in the dispersion is 30 nm to 50 nm.

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