CN113717607A

CN113717607A - Biocompatible membrane, block polymer thereof and application

Info

Publication number: CN113717607A
Application number: CN202111027308.1A
Authority: CN
Inventors: 沈薇
Original assignee: Suzhou Zhongxing Medical Technology Co ltd
Current assignee: Suzhou Zhongxing Medical Technology Co ltd
Priority date: 2021-09-02
Filing date: 2021-09-02
Publication date: 2021-11-30
Anticipated expiration: 2041-09-02
Also published as: CN113717607B

Abstract

The invention discloses an electrochemical activation technology of oxidoreductase which is a third generation biosensing technology used for manufacturing various biosensors including a glucose biosensor used for an implanted continuous glucose monitoring system, which overcomes the defects of the first and second generation biosensing technologies, improves the sensitivity, accuracy, reproducibility, stability, specificity and anti-interference capability of dynamic detection of glucose, prolongs the service life of the implanted continuous glucose monitoring system, and greatly reduces the cost of the glucose biosensor.

Description

Biocompatible membrane, block polymer thereof and application

Technical Field

The invention relates to the technical field of biosensors, in particular to a biocompatible film, a block polymer thereof and application thereof.

Background

Diabetes has become a common disease worldwide, and about 4.25 hundred million adults suffer from diabetes in the world according to the statistical data of the international diabetes union, wherein Chinese diabetes patients reach 1.16 hundred million people and are the first diabetes patients in the world. For diabetic patients, blood sugar measurement is an indispensable daily matter, the most common blood sugar detection equipment at present is a blood glucose meter, but blood sugar measurement has great limitation because the blood sugar measurement equipment can only detect the blood sugar value of the patient at a certain time point and cannot continuously monitor the blood sugar level of the patient. Therefore, continuous blood glucose monitoring devices have come into existence, most typically implantable (minimally invasive) continuous glucose monitoring systems that indirectly reflect blood glucose levels by monitoring the concentration of glucose in interstitial fluid under the skin via a subcutaneously implanted miniature glucose biosensor. They can provide all-day blood sugar information and the relationship between the fluctuation of blood sugar and living habits, and discover hidden hyperglycemia and hypoglycemia which are difficult to detect by the traditional monitoring method, thereby effectively assisting the patient to carry out instant blood sugar regulation. The performance of the biocompatible membrane, which is used as a main component of a glucose biosensor of the implantable continuous glucose monitoring system and a unique interface in direct contact with a living body, directly determines the stability of the implantable continuous glucose monitoring system and the working life of the implantable continuous glucose monitoring system during living body monitoring. The existing implantable glucose continuous monitoring system is developed based on the first or second generation biosensing technology. Dexcom G5 and G6, available from Dekkon and iPro2 and Guardian available from Meidun, which continuously monitor glucose using the first generation biosensing technology, work by indirectly monitoring glucose through electrochemically detecting hydrogen peroxide generated when oxygen is reduced during the catalytic oxidation of glucose oxidase. Since the continuous glucose monitoring system developed based on the first generation biosensing technology relies on the natural mediator that is in the body fluid such as interstitial fluid or blood and the oxygen-glucose oxidase catalyzes and oxidizes the glucose, the glucose monitoring is realized, and the oxygen content (0.2-0.3 mmol/L) in the body fluid is far lower than the glucose (5-10 mmol/L), so that the oxidation reaction rate depends on the amount of oxygen rather than the amount of glucose, and the problem of narrow linear detection range of the sensor, namely 'oxygen starvation' is caused. Therefore, its biocompatible membrane must be able to maximally allow the passage of oxygen while effectively simulating the passage of glucose, on a highly biocompatible basis. It is well known that oxygen is hydrophobic compared to glucose, so its biocompatible membrane must also be highly hydrophobic. However, the requirement of high hydrophobicity presents a great challenge to the design of biocompatible membranes, although their performance has been far from meeting the requirements for continuous glucose monitoring after more than 20 years of exploration. For example, the Guirdian and iPro2 of Meidun also require two corrections per day, which also have a working life of only one week.

At the end of the last century, Heller et al (Accounts of Chemical Research 23(1990)128-134) have found that by introducing a redox species, an artificial redox mediator (redox small molecules such as ferricyanide, ferrocene and derivatives thereof or redox polymers) into a biosensing membrane, glucose oxidase can exchange electrons with an electrode through the artificial mediator without oxygen participating in a reaction, thereby fundamentally solving the problem of oxygen shortage in interstitial fluid. Second generation biosensing technologies developed based on this principle are now widely used in biosensors, particularly glucose biosensors, including implantable glucose biosensors of continuous glucose monitoring systems, such as FreeStyle library and FreeStyle library 2 of yapei diabetes care. Because the second generation of biosensing technology realizes direct electrochemical detection of glucose by introducing an artificially synthesized redox mediator into the biosensor, the detection of glucose can be realized at a very low potential by molecular design and optimization of the redox mediator, thereby greatly improving the anti-interference capability of the implanted continuous glucose monitoring system. Because the glucose monitoring system directly and electrochemically detects glucose through the artificial redox mediator, the sensitivity of the glucose monitoring system is also remarkably improved. On the other hand, although direct electrochemical detection of glucose is realized by introducing an artificially synthesized redox mediator, oxygen, which is a natural mediator for catalyzing and oxidizing glucose by glucose oxidase, inevitably participates in catalytic oxidation of glucose, and becomes an important interference factor for glucose monitoring. In order to further improve the performance of the implantable continuous glucose monitoring system, various biocompatible membranes are introduced, so that the interference of oxygen is eliminated to the maximum extent, and the monitorable range of glucose is expanded. In view of the significant difference in hydrophilicity between glucose and oxygen, a high degree of hydrophilicity is an essential characteristic of such biocompatible membranes. Although they are very effective in eliminating oxygen interference, it is difficult to achieve effective and precise simultaneous regulation of oxygen and glucose. An excessively thick biocompatible film directly results in excessively long response time of the implanted continuous glucose monitoring system to glucose, a serious hysteresis phenomenon occurs, and the accuracy of the system is greatly reduced. For example, FreeStyle library for the treatment of diabetes mellitus, Yapezi, responds to glucose in PBS (pH 7.4) buffer for up to 8-10 minutes. In addition, the existing biocompatible membrane has a chemical crosslinking reaction in the formula, so that the service life of the biocompatible membrane solution is greatly shortened, and the production cost of the implantable continuous glucose monitoring system is invisibly increased. More seriously, as the using time is increased, the chemical crosslinking reaction is more and more, and the viscosity of the biocompatible film solution is more and more, thereby seriously influencing the consistency of the product.

Disclosure of Invention

In order to overcome the defects of the first and second generation biosensing technologies, improve the sensitivity, accuracy, reproducibility, stability, specificity and anti-interference capability of glucose dynamic detection, prolong the service life of an implanted continuous glucose monitoring system and greatly reduce the cost of a glucose biosensor, the invention successfully develops the electrochemical activation technology of the redox enzyme, which is the third generation biosensing technology and can be used for manufacturing various biosensors, including the glucose biosensor used in the implanted continuous glucose monitoring system.

In one aspect, the invention provides a block polymer, comprising the following components in parts by weight:

10-200 parts of hydrophobic framework compound

2-40 parts of hydrophilic group organic compound

2-50 parts of organic compound with biocompatible groups

Wherein the hydrophobic skeleton compound comprises an aromatic olefin compound or an olefin acid ester compound; the hydrophilic organic compound comprises brominated polyethylene glycol or brominated polypropylene oxide; the biocompatible organic compound includes one or more of methacryloyl ethyl sulfobetaine, amino acid with vinyl or acetyl, 3- [ [2- (methacryloyloxy) ethyl ] dimethyl ammonium ] propionate, choline with vinyl or acetyl, and vinylpyrrolidone.

In some embodiments, the brominated polyethylene glycol is prepared by the following method:

1) dissolving 2-100 parts by weight of polyethylene glycol in 5-500 parts by weight of organic solvent and 2-50 parts by weight of triethylamine, dropwise adding 0.2-8 parts by weight of bromoisobutyryl bromide after ice bath, and reacting overnight at 30-50 ℃ to obtain a reaction solution;

2) and pouring the reaction solution into 100-2000 parts by weight of ethyl glacial ether to obtain a precipitate, washing the precipitate for multiple times by using 50-500 parts by weight of ethyl glacial ether, and performing vacuum drying at 60-80 ℃ for 22-26 hours to obtain the brominated polyethylene glycol.

In some embodiments, polyethylene oxide, copolymers containing polyethylene oxide, polypropylene oxide, copolymers containing polypropylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polylactic acid, hyaluronic acid and derivatives thereof, chitosan and derivatives thereof, cellulose and derivatives thereof, alginic acid and derivatives thereof are also included.

In some embodiments, polyvinyl pyridine, styrene and vinylpyridine copolymers, styrene and vinylpyrrole copolymers, styrene and acrylamide copolymers are also included.

In another aspect, the present invention also provides a method for preparing a block polymer, comprising the steps of:

1) adding 2-40 parts by weight of hydrophilic group organic compound and 2-50 parts by weight of biocompatible group organic compound into 20-500 parts by weight of organic solvent, and deoxidizing through argon;

2) adding 0.001-0.02 weight part of cuprous bromide and 0.002-0.05 weight part of 2, 2' -bipyridyl, and reacting under the protection of argon;

3) then adding 10-200 parts by weight of hydrophobic framework compound, and reacting under the protection of argon to obtain a block polymer

4) Adding water to precipitate the block polymer, and centrifugally separating and vacuum drying;

5) dissolving the dried block polymer in ethanol, adding water for precipitation, centrifuging again, vacuum drying, and repeating the steps for multiple times;

6) finally the block polymer was dried under vacuum for at least 12 hours.

In another aspect, the present invention also provides a biocompatible film, wherein the biocompatible film is formed by coating the block polymer solution on a biosensor and drying.

In some embodiments, the block polymer solution is applied to the biosensor by a drop coating method, spin coating method, spray coating method, or dip coating method.

In some embodiments, the block polymer solution further comprises one or more solutions of polyethylene oxide, a copolymer containing polyethylene oxide, polypropylene oxide, a copolymer containing polypropylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polylactic acid, hyaluronic acid and derivatives thereof, chitosan and derivatives thereof, cellulose and derivatives thereof, alginic acid and derivatives thereof.

In some embodiments, the block polymer solution is further added to a solution of one or more of polyvinyl pyridine, styrene and vinyl pyridine copolymer, styrene and vinyl pyrrole copolymer, styrene and acrylamide copolymer.

In another aspect, the invention also provides the use of a biocompatible membrane in a biosensor.

The third-generation biosensing technology is developed by direct electrochemistry using oxidoreductases (measurement technology, 2006, (volume 26, supplement) 92-96). Experiments show that: the glucose biosensor containing the electrochemically activated glucose oxidase, which is developed based on the third-generation biosensing technology, not only maintains the catalytic oxidation performance of the glucose biosensor on glucose, but also obviously improves the catalytic oxidation efficiency of the glucose on glucose through direct electrochemistry compared with the catalytic oxidation efficiency of natural glucose oxidase on glucose through oxygen. Compared with the second generation of biosensing technology, the direct electrochemistry of the glucose oxidase greatly simplifies the design and manufacture of the glucose biosensor, and also obviously improves the sensitivity, accuracy, stability, specificity and anti-interference capability of the glucose biosensor.

Drawings

FIG. 1 is a schematic diagram of the structure of a biocompatible block polymer;

FIG. 2 is a gel permeation chromatogram of a block polymer type biomaterial before (1) formation, (2) addition of methacryloylethyl sulfobetaine for reaction for 3 hours, and (3) addition of acrylate for reaction for 12 hours;

FIG. 3 is a cyclic voltammogram of (1) a biosensing membrane containing electrochemically activated glucose oxidase in PBS buffer and (2) after addition of 10 mmol/L glucose;

FIG. 4 is a cyclic voltammogram of (1) a glucose biosensor coated with a biocompatible membrane in PBS buffer and (2) after addition of 10 mmol/L glucose;

FIG. 5 is a graph showing the relationship between the current of a glucose biosensor and the number of dipping pulls in a PBS buffer solution containing 5 mM glucose;

FIG. 6 is a graph showing the corresponding current curves in a PBS buffer solution containing 20 mM glucose for (1) a glucose biosensor without a biocompatible membrane and (2) a glucose biosensor coated with a biocompatible membrane;

FIG. 7 is a graph showing the operation of a glucose biosensor (1) without a biocompatible membrane and (2) coated with a biocompatible membrane;

FIG. 8 is a graph of experimental results of a human body with a glucose biosensor coated with a biocompatible membrane in an implanted continuous glucose monitoring system.

Detailed Description

The invention is further described with reference to the accompanying drawings.

Similar to the second generation biosensing technology, oxygen, which is a natural mediator for catalyzing and oxidizing glucose by glucose oxidase, inevitably participates in the catalytic oxidation of glucose, and becomes an important interference factor for glucose monitoring. Although the efficiency of the catalytic oxidation of glucose by direct electrochemistry is much higher than the efficiency of the catalytic oxidation of glucose oxidase by oxygen as a natural mediator, the influence of oxygen is fundamentally eliminated, and a selective permeation membrane capable of effectively eliminating oxygen interference is coated on the glucose biosensor. In addition, this permselective membrane must also be able to effectively regulate glucose due to the high sensitivity of direct electrochemical detection of glucose. More importantly, this permselective membrane must be highly biocompatible or otherwise severely limits the useful life of the implantable continuous glucose monitoring system. This is why, although implantable continuous glucose monitoring systems have been developed for over 20 years, the service life of most implantable continuous glucose monitoring systems is less than satisfactory. That is, this permselective membrane must be bifunctional-on the one hand, the biocompatibility (lifetime) of the glucose biosensor should be greatly improved, and on the other hand, oxygen and glucose must be effectively regulated. We have greatly improved the biocompatibility of the glucose biosensor by selecting materials with high biocompatibility as raw materials for the preparation of a biocompatible membrane (permselective membrane) and optimally combining them. By adjusting the components of the selective biocompatible membrane and the ratio between the components, such as the type and ratio of hydrophobic and hydrophilic components, simultaneous control of oxygen and glucose can be achieved. In addition, by preparing a single component (no cross-linking agent) biocompatible membrane, the stability and lifetime of the biocompatible membrane solution can be greatly improved, thereby enabling us to prepare an implantable continuous glucose monitoring system with high consistency.

Through detailed research and experiments, the block polymer type biomaterial-biocompatible film developed by the invention is covered on a biosensor which is developed based on a third-generation biosensing technology and contains electrochemically activated glucose oxidase, so that the high biocompatibility of the glucose biosensor can be satisfactorily realized, and the accurate regulation and control of oxygen and glucose can be realized at the same time. Besides high biocompatibility, the biocompatible membrane can effectively regulate glucose to meet the requirement. Through detailed research and experiments, the block polymer type biological material film developed by the invention is covered on a biosensor containing electrochemically activated glucose oxidase, and as shown in figure 1, the block polymer is composed of three functional parts, namely a hydrophobic skeleton, a hydrophilic group (glucose regulating group) and a biocompatible group.

The details are as follows:

a block polymer comprising the following components:

10-200 g of hydrophobic skeleton compound

2-40 g of hydrophilic organic compound

2-50 g of organic compound with biocompatibility group

Wherein the hydrophobic skeleton compound comprises an aromatic olefin compound or an olefin acid ester compound; the hydrophilic organic compound comprises brominated polyethylene glycol or brominated polypropylene oxide; the biocompatible organic compound includes one or more of methacryloyl ethyl sulfobetaine, amino acid with vinyl or acetyl, 3- [ [2- (methacryloyloxy) ethyl ] dimethyl ammonium ] propionate, choline with vinyl or acetyl, and vinylpyrrolidone. The aromatic olefin compound or olefin acid ester compound comprises one or more of acrylate, styrene, vinylpyridine, vinyl acetate and butenoate.

The brominated polyethylene glycol is prepared by the following method:

1) dissolving 2-100 parts by weight of polyethylene glycol in 5-500 parts by weight of dichloromethane and 2-50 parts by weight of triethylamine, carrying out ice bath to zero degree, dropwise adding 0.2-8 parts by weight of dibromo isobutyryl bromide, and reacting at 30-50 ℃ overnight to obtain a reaction solution; .

2) Pouring the reaction solution into 100-2000 parts by weight of ethyl glacial ether to obtain a precipitate, washing the precipitate for multiple times by using 50-500 parts by weight of ethyl glacial ether, and carrying out vacuum drying at 60-80 ℃ for 22-26 hours to obtain brominated polyethylene glycol; the yield is 80-90%.

The specific embodiment is as follows: the brominated polyethylene glycol is prepared by the following method:

1) dissolving 50g of polyethylene glycol in 250 ml of dichloromethane and 25 ml of triethylamine, carrying out ice bath to zero degree, dropwise adding 4 ml of dibromo isobutyryl bromide, and reacting overnight at 30-50 ℃ to obtain a reaction solution; .

2) Pouring the reaction solution into 2L of ethyl glacial ether to obtain a precipitate, washing the precipitate for multiple times by using 500 ml of ethyl glacial ether in parts by weight, and performing vacuum drying at the temperature of 60-80 ℃ for 22-26 hours to obtain bromopolyethylene glycol; the yield was 89%.

The biocompatibility can be further optimized and adjusted by directly adding high molecular weight polymer with good hydrophilicity and high biocompatibility, namely the block polymer also comprises polyethylene oxide, copolymer containing polyethylene oxide, polypropylene oxide, copolymer containing polypropylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polylactic acid, hyaluronic acid and derivatives thereof, chitosan and derivatives thereof, cellulose and derivatives thereof, alginic acid and derivatives thereof.

Besides adjusting the content of acrylic ester in the copolymer, the mechanical property of the hydrophobic skeleton can also be adjusted by adding polymers with excellent mechanical property, such as polyvinyl pyridine, styrene and vinyl pyridine copolymer, styrene and vinyl pyrrole copolymer, and styrene and acrylamide copolymer into the copolymer solution.

A method for preparing a block polymer comprising the steps of:

1) adding 20 g of brominated polyethylene glycol and 10 g of methacryloyl ethyl sulfobetaine into 250 ml of methanol, and deoxidizing for 20-60 minutes by argon;

2) adding 10 mg of cuprous bromide and 25 mg of 2, 2' -bipyridyl, and reacting at room temperature for 2-4 hours under the protection of argon;

3) then adding 100 ml of acrylate, and reacting at room temperature for 6-24 hours under the protection of argon to obtain a block polymer

4) Adding 5 liters of water to precipitate the block polymer, and carrying out centrifugal separation and vacuum drying at 50-100 ℃ for 12-24 hours;

5) dissolving the dried block polymer with ethanol, adding 5 liters of water for precipitation, centrifuging again, drying in vacuum at 80 ℃ for 12-24 hours, and repeating the steps for 3-6 times;

6) and finally, drying the block polymer for at least 12 hours in vacuum at 50-100 ℃.

As shown in FIG. 2, before adding the methacrylethyl sulfobetaine, the polymerization system has only one brominated polyethylene glycol atom transfer radical polymerization initiator, and the gel permeation chromatogram thereof has only one macromolecular chromatogram peak (as shown in curve 1 of FIG. 2). On the other hand, when methacrylethyl sulfobetaine was added and reacted for 3 hours, gel permeation chromatography clearly showed a high molecular weight polymer (see curve 2 in FIG. 2), while the peak of the brominated polyethylene glycol photoinitiator almost completely disappeared. After 12 hours of further acrylate addition and reaction, the gel permeation chromatogram showed a higher molecular weight polymer (FIG. 2, curve 3).

Coating of biocompatible film: the block polymer solution (50-400 mg/ml ethanol solution) is uniformly coated on the biosensor by a dripping coating method, a spin coating method, a spraying method or a dip-coating method, and then dried to form a film at room temperature, and the steps are repeated for 2 to 6 times. For example, a solution of a block polymer is uniformly coated on glucose biosensors by a dip-coating method, and then the glucose biosensors are dried in a strictly controlled environment to form a film. After complete evaporation of the solvent, the glucose biosensor surfaces have been completely covered by a thin biocompatible film. In order to increase the thickness of the biocompatible film, the above process can be repeated for many times, and the required thickness can be achieved usually 3-4 times. Since the biocompatible film is formed through a plurality of film forming processes, the final glucose regulation and control performance of the biocompatible film can be conveniently and effectively optimized through the thickness (dipping and pulling times) of the film and the formula of the block polymer solution, so that the expected effect is achieved.

Preferably, the block polymer solution is further added with one or more than two solutions of 1-30% of polyethylene oxide, copolymer containing polyethylene oxide, polypropylene oxide, copolymer containing polypropylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polylactic acid, hyaluronic acid and derivatives thereof, chitosan and derivatives thereof, cellulose and derivatives thereof, alginic acid and derivatives thereof (i.e. before the block polymer solution is prepared and coated).

Preferably, the block polymer solution (i.e., before the block polymer solution is prepared for coating) is further added with one or more than two solutions of 1-25% of polyvinyl pyridine, styrene-vinyl pyridine copolymer, styrene-vinyl pyrrole copolymer and styrene-acrylamide copolymer.

All of the above formulations of biocompatible membranes are based on synthetic and purified polymers, provided that they are dissolved in a suitable organic solvent, such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, water, N-dimethylacrylamide, dimethylsulfoxide, sulfolane, tetrahydrofuran, dioxane, etc., and the prepared solutions can be used indefinitely.

The block polymer solution is uniformly coated on glucose biosensors containing electrochemically activated glucose oxidase by a dip-coating method, and then the glucose biosensors are dried to form a film in a strictly controlled environment. After complete evaporation of the solvent, the glucose biosensor surfaces have been completely covered by a thin biocompatible film. To increase the thickness of the biocompatible film, the above process can be repeated several times, usually 3-4 times to achieve the desired thickness. Since the biocompatible film is formed through a plurality of film forming processes, the final regulation and control performance on oxygen and glucose can be conveniently and effectively optimized through the thickness (dipping and pulling times) of the film and the formula of the biocompatible film solution, so as to achieve the expected effect.

We first characterized a biosensor comprising a sensor membrane covered with a biocompatible membrane and containing electrochemically activated glucose oxidase (as shown in figure 3) using cyclic voltammetry. FIG. 3, Curve 1, is a cyclic voltammogram of a biosensor containing only an electrochemically activated glucose oxidase sensing membrane in PBS buffer, which is a typical surface electrochemical phenomenon (peak potential difference is only 12 mV, much less than 59 mV). After 10 mmol/l glucose was added to the PBS buffer, the glucose biosensor cyclic voltammogram clearly shows a typical electrochemical catalysis process (FIG. 3, curve 2). The above experiment results show that the film forming process (including chemical reaction) of the electrochemically activated glucose oxidase does not have obvious influence on the catalytic activity center of the glucose oxidase, and further experiments show that the glucose oxidase not only maintains the catalytic oxidation performance of the glucose oxidase on glucose, but also remarkably improves the catalytic oxidation efficiency of the glucose oxidase on glucose through direct electrochemistry compared with the catalytic oxidation efficiency of the glucose oxidase on glucose through oxygen, thereby paving a way for the application of the glucose biosensor in an implantable continuous glucose monitoring system.

When a layer of biocompatible film is uniformly covered on the glucose biosensor by a dip-coating method, the cyclic voltammogram of the glucose biosensor is obviously changed. As shown in fig. 4, the peak potential difference of the glucose oxidase sensing membrane increased significantly from 12 mv to 160 mv. Obviously, the insulating biocompatible membrane provides a very large resistance to electron transfer in this glucose biosensor. Fortunately, although this biocompatible membrane greatly increases the resistance to electron transfer, its ability to catalyze the oxidation of glucose by direct electrochemistry remains, which allows for the development of implantable continuous glucose monitoring systems.

In addition, as shown in fig. 5, when the glucose biosensor is completely coated with the biocompatible membrane, the current of the glucose biosensor is reduced to less than 1% after four cycles of dip-coating and drying, in which the catalytic oxidation current of glucose by direct electrochemistry exponentially decreases sharply as the thickness of the membrane (dip-coating times, numbers) increases. The experimental result shows that the biocompatible membrane can effectively regulate and control glucose (the reaction is on the current of catalytic oxidation of glucose).

Although the glucose biosensor is successfully regulated by covering the glucose biosensor with the biocompatible membrane, the glucose biosensor which has good accuracy, reproducibility and stability and can be used for an implantable glucose continuous monitoring system needs to be prepared, and the sensors need to have a wide linear response range and high stability, and the sensors can be realized by optimizing the biocompatible membrane on the glucose biosensor. For example, when the glucose biosensor is subjected to three cycles of dip-coating and drying in a solution of a biocompatible film, the current signal is well controlled by the biocompatible film even though the response time to glucose is extended from 1 minute to 3 minutes, and the stability of the glucose biosensor is significantly improved, as compared to the glucose biosensor without any biocompatible film coating (see fig. 6). At the same time, the monitorable range of glucose was successfully expanded from 10 mM to 60 mM (as shown in FIG. 7), fully meeting the glucose monitoring needs of diabetic patients.

Although all the above experimental results confirm that our biocompatible membrane exhibits superior performance in vitro, its performance when monitored in vivo is the most powerful proof of its biocompatibility. Therefore, we applied a glucose biosensor covered with a biocompatible membrane to an implantable continuous glucose monitoring system based on in vitro work, in which the first 23 days of human testing gave good results without significant sensitivity (baseline) decay (as shown in fig. 8), which is the longest working life of the glucose biosensor used for human monitoring so far. From day 24 post-implantation, there was a significant decay in sensor sensitivity, with the onset of a large difference in monitored glucose concentration from what was measured in the blood glucose level. Therefore, for insurance, we set the working life of this biocompatible membrane to 20 days.

In conclusion, the glucose biosensor developed based on the third-generation biosensing technology is covered with a biocompatible film developed by people, so that the glucose can be effectively and accurately regulated, more importantly, the existence of the biocompatible film obviously expands the monitoring range of the glucose, greatly improves the stability and the biocompatibility of the glucose biosensor in a human body, fully meets the requirements of a correction-free (factory correction) implantable continuous glucose monitoring system, and lays a solid foundation for the batch production of the correction-free implantable continuous glucose monitoring system. In addition, the biocompatible membrane can also be applied to other implanted continuous monitoring systems, such as monitoring of lactic acid and blood ketones.

Claims

1. A block polymer characterized by: comprises the following components in parts by weight:

10-200 parts of hydrophobic framework compound

2-40 parts of hydrophilic group organic compound

2-50 parts of organic compound with biocompatible groups

2. The block polymer according to claim 1, characterized in that: the brominated polyethylene glycol is prepared by the following method:

1) dissolving 2-100 parts by weight of polyethylene glycol in 5-500 parts by weight of organic solvent and 2-50 parts by weight of triethylamine, dropwise adding 0.2-8 parts by weight of dibromo isobutyryl bromide after ice bath, and reacting overnight at 30-50 ℃ to obtain a reaction solution;

3. The block polymer according to claim 1, characterized in that: also comprises polyethylene oxide, copolymer containing polyethylene oxide, polypropylene oxide, copolymer containing polypropylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polylactic acid, hyaluronic acid and derivatives thereof, chitosan and derivatives thereof, cellulose and derivatives thereof, alginic acid and derivatives thereof.

4. The block polymer according to claim 1, characterized in that: also included are polyvinylpyridine, styrene and vinylpyridine copolymers, styrene and vinylpyrrole copolymers, styrene and acrylamide copolymers.

5. A process for the preparation of a block polymer characterized by: the method comprises the following steps:

6) finally the block polymer was dried under vacuum for at least 12 hours.

6. A biocompatible film characterized by: coating the block polymer solution as described in claims 1 to 5 on a biosensor and drying to form the biocompatible film.

7. The biocompatible film according to claim 6, wherein: the block polymer solution is coated on the biosensor by a dripping coating method, a spin coating method, a spraying method or a dip-coating method.

8. The biocompatible film according to claim 6, wherein: the block polymer solution is also added with one or more than two solutions of polyethylene oxide, copolymer containing polyethylene oxide, polypropylene oxide, copolymer containing polypropylene oxide, polyvinylpyrrolidone, polyvinyl alcohol, polylactic acid, hyaluronic acid and derivatives thereof, chitosan and derivatives thereof, cellulose and derivatives thereof, and alginic acid and derivatives thereof.

9. The biocompatible film according to claim 8, wherein: the block polymer solution is also added with one or more than two solutions of polyvinyl pyridine, styrene and vinyl pyridine copolymer, styrene and vinyl pyrrole copolymer and styrene and acrylamide copolymer.

10. Use of the biocompatible film according to any one of claims 6 to 9 in a biosensor.