A silk protein flexible electrode capable of monitoring muscle and nerve damage and a preparation method thereof

Abstract

The invention discloses a silk protein flexible electrode capable of monitoring muscle and nerve damage and a preparation method thereof. The method comprises: degumming, dissolving, filtering and ultrafiltration desalting silk to obtain a silk protein aqueous solution; adding a plasticizer to the silk protein aqueous solution, mixing evenly, and then spray drying with a granulator to obtain silk protein masterbatch; pressing the silk protein masterbatch to form a film to obtain a silk protein base film, or first adding the silk protein masterbatch to deionized water, mechanically stirring and beating to obtain a silk protein paste, and then forming a film with the silk protein paste by a coating method; plasma treating the silk protein base film; preparing a coatable conductive solution; attaching a mask plate to the plasma treated silk protein base film, then coating the coatable conductive solution, drying and removing the mask plate to obtain a silk protein flexible electrode.

Description

Technical Field

[0001] The invention belongs to the technical field of flexible electrodes, and in particular relates to a silk protein flexible electrode capable of monitoring muscle and nerve damage and a preparation method thereof. Background Art

[0002] Muscle contraction and relaxation are controlled by nerves. Once the nerve control is lost, not only can the contraction and relaxation functions not be completed, but also the muscles will atrophy due to lack of nerve nutrition. The location and characterization of nerve damage both require the use of abnormal potentials of electromyography to detect. The method of using external bonding electrodes to detect electromyography to detect muscle nerve potential can effectively pay attention to the health of muscle nerves. Electrodes are applied to the outer skin of the muscle, and the electromyographic potential can be measured through muscle relaxation and light contraction. However, the electrodes currently used are mostly metal solid electrodes. The electrodes are bonded to the skin surface and fixed by adhesion to collect bioelectric signals from the skin surface and measure them. This method has many shortcomings: first, the hair and keratin of the electrode bonding area need to be processed when used, and the materials used have poor air permeability and biocompatibility, are easy to adhere to the skin epidermis, and long-term wearing can easily irritate the skin and cause allergic reactions; second, the weight of metal electrode patches is often large, which will restrict the human body from performing other activities when worn. Therefore, higher performance electrodes are urgently needed to solve the above problems. Electrodes with soft, lightweight, breathable and skin-friendly properties have become the focus of research in this field.

[0003] Silk protein (the part of mulberry silk that remains after the sericin is removed, also known as silk fibroin SILK FIBROIN), as a natural polymer protein material extracted from silk, has good biocompatibility and non-immunogenicity. Various clinical experiments have shown that silk protein has good effects on tissue repair, anti-aging, skin whitening, etc. Therefore, biomaterials prepared with silk protein as raw material show excellent performance. Silk protein solution also has good film-forming properties, and has a certain ductility after film formation, and has a good application prospect in the preparation of flexible biological film materials.

[0004] Research on the use of silk protein film to make biological patches has been developing in depth in recent years, but due to the reduced flexibility after drying into a film and the long film production time, there are still certain difficulties in actual manufacturing. How to speed up the film formation rate of silk protein in the process and improve the ductility of the silk protein base film to prepare higher performance and more widely used electrode materials; and how to further improve the flexibility of the silk protein film, extend the life of the silk protein film, and enhance the bonding strength between the conductive material and the silk protein film are currently unresolved issues. Summary of the invention

[0005] The purpose of the present invention is to provide a silk protein skin-adhesive flexible electrode that can monitor electromyography and locate and diagnose nerve damage. The electrode has a simple structure, is easy to use, has good skin affinity, and can be worn for a long time. The second purpose of the present invention is to provide a method for manufacturing a silk flexible electrode for locating and diagnosing muscle and nerve damage. The electrode has high sensitivity, a simple manufacturing method, high preparation efficiency, and can be mass-produced.

[0006] The present invention provides a method for preparing a flexible silk protein electrode capable of monitoring muscle and nerve damage, comprising the following steps:

[0007] S1: Preparation of silk protein solution: Silk protein solution is prepared by degumming, dissolving, filtering and ultrafiltration desalting of mulberry silk;

[0008] S2: Preparation of silk protein masterbatch: Add plasticizer to the silk protein aqueous solution prepared in step S1, stir and mix thoroughly, and then use a granulator to spray dry and granulate in one step;

[0009] S3: Preparation of silk protein film: pressing the silk protein masterbatch prepared in step S2 to form a film to obtain a silk protein base film;

[0010] S4: Plasma treatment of the silk protein basement membrane: Plasma treatment is performed on the silk protein basement membrane obtained in step S3;

[0011] S5: preparing a coatable conductive solution;

[0012] S6: Preparation of conductive structure: stick a mask plate on the plasma-treated silk protein base film obtained in step S4, then apply the coatable conductive solution obtained in step S5, and remove the mask plate after drying.

[0013] Preferably, in step S5, the conductive component in the coatable conductive solution is: one of metal nanowires such as silver nanowires, gold nanowires, gold-silver alloy nanowires, or one of carbon materials such as carbon nanotubes, graphene, carbon fiber, carbon ceramic conductive materials, or a material prepared by carbonizing a mixture of a carbon material and silk protein.

[0014] Furthermore, the coatable conductive solution prepared in step S5 is a reduced graphene oxide silk protein conductive solution, and the preparation method specifically comprises the following steps:

[0015] a. adding reduced graphene oxide to an aqueous solution of silk protein and stirring to dissolve to obtain a reduced graphene oxide silk protein suspension;

[0016] b. spray drying the reduced graphene oxide silk protein suspension obtained in step a to obtain a powder;

[0017] c. carbonizing the powder obtained in step b in a muffle furnace under a nitrogen atmosphere to obtain a porous reduced graphene oxide silk protein composite material;

[0018] d. dispersing the composite material obtained in step c in a potassium hydroxide solution to obtain a reduced graphene oxide silk protein conductive solution.

[0019] Preferably, the mass concentration of silk protein in the reduced graphene oxide silk protein suspension in step a is 3-10wt%.

[0020] Preferably, the specific method for preparing the silk protein masterbatch in step S2 is: a. adding a plasticizer to the silk protein aqueous solution prepared in step S1, stirring and mixing thoroughly and then passing the mixture into a spray drying system for spray drying, spray drying into a powdery state, at which time the powder particle size in the system is relatively small; b. simultaneously spraying a powder binder into the spray drying system so that smaller powders gradually combine into larger particles during the flying process.

[0021] Furthermore, the powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-40%, preferably 1-20%, and more preferably 1-10%.

[0022] Preferably, in the preparation of the silk protein masterbatch in step S2, the feed rate of the spray drying process is 10-500 mL / min, the spray drying inlet air temperature is 90-150°C, and the nozzle pressure is 0.1-1 MPa; preferably, the feed rate is 15-200 mL / min, the spray drying inlet air temperature is 100-130°C, and the nozzle pressure is 0.2-0.7 MPa.

[0023] Preferably, the plasticizer in step S2 is one or more of polyethylene glycol 300, polyethylene glycol 400 or polyethylene glycol 600.

[0024] Preferably, the particle size of the silk protein masterbatch prepared in step S2 is 10-100 μm, more preferably 10-50 μm.

[0025] Furthermore, the specific method of pressing the silk protein masterbatch into a film in step S3 is: taking a certain mass of silk protein masterbatch and placing it in a mold, and then placing the mold between two pressing plates of an oil press. The oil press is pressurized to 20-60MPa and maintained at this pressure for a certain period of time, and the mold is removed from the oil press and demoulded to prepare a silk protein film.

[0026] Furthermore, the specific conditions for plasma treatment of the silk protein base film in step S4 are: carried out in an atmospheric low-temperature plasma discharge experimental device, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 30-50V, a current intensity of 1-3A, and a plasma treatment time of 10-200 seconds.

[0027] Another method for preparing a silk protein flexible electrode capable of monitoring muscle and nerve damage proposed by the present invention comprises the following steps:

[0028] S1: Preparation of silk protein solution: Silk protein solution is prepared by degumming, dissolving, filtering and ultrafiltration desalting of mulberry silk;

[0029] S2: Preparation of silk protein masterbatch: Add plasticizer to the silk protein aqueous solution prepared in step S1, stir and mix thoroughly, and then use a granulator to spray dry and granulate in one step;

[0030] S3: Preparation of silk protein film: firstly, add the silk protein masterbatch prepared in step S2 into deionized water, and stir and beat it mechanically to obtain a silk protein paste; then, form a film with the silk protein paste by coating.

[0031] S4: Plasma treatment of the silk protein basement membrane: Plasma treatment is performed on the silk protein basement membrane obtained in step S3;

[0032] S5: preparing a coatable conductive solution;

[0033] S6: Preparation of conductive structure: attaching a mask plate to the plasma-treated silk protein base film obtained in step S4, then applying the coatable conductive solution obtained in step S5, and removing the mask plate after drying;

[0034] S7: Wet heat crosslinking treatment: Place the silk protein film containing the conductive structure in the above step S6 at a temperature of 70-120° C. and a relative humidity of 80-100% for 10-60 minutes to perform wet heat crosslinking.

[0035] Preferably, in step S3, the mass percentage of silk protein in the paste is 5-80%, preferably 20-60%, and the mixing temperature is 1-80°C, preferably 10-60°C.

[0036] Furthermore, in order to improve the solubility of the regenerated silk protein in water and the stability of the bubbles in the paste, additives are added during the mixing operation of step S2, and the additives are small molecule compounds, including amino acids, metal inorganic salts or alcohols.

[0037] Preferably, in the step S3, the stirring rate in the whipping operation matches the viscosity of the paste, otherwise the material cannot be made uniform, and the whipping speed of the stirring device is 100rpm-2000rpm, preferably 200rpm-1200rpm; for a paste with a silk fibroin powder mass fraction of 40%, the preferred speed is 300rpm-500rpm; for a paste with a silk fibroin powder mass fraction of 30%, the preferred speed is 500rpm-700rpm; for a paste with a silk fibroin powder mass fraction of 20%, the preferred speed is 700rpm-1200rpm.

[0038] Preferably, in step S3, a silk protein film is prepared using a silk protein paste, and a coating film-forming method such as spin coating or scraping coating is selected.

[0039] Preferably, in step S5, the conductive component in the coatable conductive solution is one of metal nanowires such as silver nanowires, gold nanowires, gold-silver alloy nanowires, or one of carbon materials such as carbon nanotubes, graphene, carbon fiber, carbon / ceramic conductive materials, or the above carbon materials can be mixed with silk protein and then carbonized.

[0040] Furthermore, the coatable conductive solution prepared in step S5 is a reduced graphene oxide silk protein conductive solution, and the preparation method specifically comprises the following steps:

[0041] a. adding reduced graphene oxide to an aqueous solution of silk protein and stirring to dissolve to obtain a reduced graphene oxide silk protein suspension;

[0042] b. spray drying the reduced graphene oxide silk protein suspension obtained in step a to obtain a powder;

[0043] c. carbonizing the powder obtained in step b in a muffle furnace under a nitrogen atmosphere to obtain a porous reduced graphene oxide silk protein composite material;

[0044] d. dispersing the composite material obtained in step c in a potassium hydroxide solution to obtain a reduced graphene oxide silk protein conductive solution.

[0045] Preferably, the mass concentration of silk protein in the reduced graphene oxide silk protein suspension in step a is 3-10wt%.

[0046] Preferably, the specific method for preparing the silk protein masterbatch in step S2 is: a. adding a plasticizer to the silk protein aqueous solution prepared in step S1, stirring and mixing thoroughly and then passing the mixture into a spray drying system for spray drying, spray drying into a powdery state, at which time the powder particle size in the system is relatively small; b. simultaneously spraying a powder binder into the spray drying system so that smaller powders gradually combine into larger particles during the flying process.

[0047] Furthermore, the powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-40%, preferably 1-20%, and more preferably 1-10%.

[0048] Preferably, in the preparation of the silk protein masterbatch in step S2, the feed rate of the spray drying process is 10-500 mL / min, the spray drying inlet air temperature is 90-150°C, and the nozzle pressure is 0.1-1 MPa; preferably, the feed rate is 15-200 mL / min, the spray drying inlet air temperature is 100-130°C, and the nozzle pressure is 0.2-0.7 MPa.

[0049] Preferably, the plasticizer in step S2 is one or more of polyethylene glycol 300, polyethylene glycol 400 or polyethylene glycol 600.

[0050] Preferably, the particle size of the silk protein masterbatch prepared in step S2 is 10-100 μm, more preferably 10-50 μm.

[0051] Furthermore, the specific conditions for plasma treatment of the silk protein base film in step S4 are: carried out in an atmospheric low-temperature plasma discharge experimental device, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 30-50V, a current intensity of 1-3A, and a plasma treatment time of 10-200 seconds.

[0052] The beneficial effects of the present invention are as follows: a plasticizer with good biocompatibility is added during the preparation of silk protein masterbatch, thereby increasing the flexibility of silk protein; the method of pressing the silk protein masterbatch to form a film can significantly improve the efficiency of silk protein film formation. Usually, silk protein films are made by natural drying for more than 24 hours. The pressing method adopted by the present invention can form a film within a few minutes, greatly improving the preparation efficiency and enabling large-scale production; another coating film-forming method adopted by the present invention improves efficiency while preparing a porous silk protein film, which is more conducive to the volatilization of water vapor on the skin surface; a plasma surface pretreatment method is adopted to improve the bonding strength between the conductive material and the silk protein substrate by increasing the surface roughness of the silk protein substrate membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a schematic diagram of the structure of the silk protein flexible electrode according to Example 1 of the present invention;

[0054] Figure 2 is a graph of water vapor permeability of the silk protein flexible electrode according to Example 1 of the present invention;

[0055] Figure 3The electromyogram of the silk protein flexible electrode test of Example 1 of the present invention;

[0056] Figure 4 is a surface morphology of the plasma-treated silk protein film of Example 1 of the present invention;

[0057] Figure 5 Graph showing the tensile strength of the silk protein films prepared in Examples 1 to 4 of the present invention.

[0058] Figure 6 This is a scanning electron microscope image of the silk protein film prepared in Example 5 of the present invention. DETAILED DESCRIPTION

[0059] The present invention will be further described below in conjunction with specific embodiments. It should be understood that the embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention. In addition, it should be understood that after reading the contents disclosed in the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope of protection defined by the present invention.

[0060] The first method for preparing a silk protein flexible electrode proposed by the present invention comprises the following steps:

[0061] S1: Preparation of silk protein solution:

[0062] a) degumming: placing the silk of the mulberry silk into a boiling sodium carbonate, sodium bicarbonate aqueous solution or a mixed solution of sodium carbonate and sodium bicarbonate with a mass fraction of 0.1-5%, heating and boiling for 10-120 minutes, taking out and washing with purified water to remove the sericin protein and leave the silk protein, drying the silk protein at 25-100° C. to obtain the dried silk protein for later use;

[0063] b) Dissolving: dissolving the dried silk protein in a 9.3M lithium bromide (LiBr) aqueous solution at a mass volume ratio of less than or equal to 1:1, and placing the mixture in a water bath at 25-100° C. for 10-120 minutes until the silk protein is fully dissolved, to obtain a mixed solution containing the silk protein and a small amount of insoluble particles;

[0064] c) Filtration: The mixed solution is first filtered through a 50-200 mesh filter bag to remove insoluble particulate impurities, and then filtered through glass fiber filter paper and PES filter paper in sequence to obtain a clarified lithium bromide protein solution;

[0065] d) Ultrafiltration: Take the clarified solution and dilute it with one times of pure water, then pass it into the ultrafiltration system for desalination. After desalination, collect the solution for later use;

[0066] e) Concentration determination: The purified silk protein aqueous solution was dried in a flat dish, and the mass concentration of the silk protein aqueous solution was measured by mass difference method to be 10%, and the number average molecular weight was 80-200 kDa. The silk protein aqueous solution was stored at 4°C for later use.

[0067] S2: Preparation of silk protein masterbatch:

[0068] A plasticizer, such as one or more of polyethylene glycol 300, polyethylene glycol 400 or polyethylene glycol 600, is added to the silk protein aqueous solution prepared in step S1, and the mixture is stirred and mixed thoroughly, and then granulated by a one-step granulation method of spray drying using a granulator.

[0069] S3: Preparation of silk protein membrane:

[0070] The silk protein masterbatch prepared in step S2 is pressed into a film to obtain a silk protein basement membrane. The specific method is: a certain mass of silk protein masterbatch is placed in a mold, and then the mold is placed between two pressing plates of an oil press. The oil press is pressurized to 20-60MPa and maintained at this pressure for 5 minutes. The mold is removed from the oil press and demoulded to prepare a silk protein membrane.

[0071] S4: Plasma treatment of silk protein basement membrane:

[0072] The silk protein base film obtained in step S3 is placed in an atmospheric low-temperature plasma discharge experimental device for plasma treatment. A gas-solid reactor is used as a container, helium is used as a carrier gas, the voltage is selected to be 30-50V, and the current intensity is 1-3A. The plasma treatment time is 10-200 seconds.

[0073] S5: Preparation of reduced graphene oxide silk protein conductive solution, specifically comprising the following steps:

[0074] a) adding reduced graphene oxide to an aqueous solution of silk protein and stirring to dissolve, to obtain a reduced graphene oxide silk protein suspension, wherein the mass ratio of reduced graphene oxide to silk protein is 1:50-10:50, and the mass concentration of silk protein in the mixed solution is 3-10wt%.

[0075] b) spray drying the reduced graphene oxide silk protein suspension obtained in the above step to obtain powder, wherein the air inlet temperature of the spray drying is selected to be 100-150°C.

[0076] c) placing the powder obtained in step b in a muffle furnace under a nitrogen atmosphere for carbonization to obtain a porous reduced graphene oxide silk protein composite material, wherein the carbonization temperature is 500-800° C. and the carbonization time is 1-4 hours.

[0077] d) dispersing the composite material obtained in step c in a potassium hydroxide solution with a mass concentration of 1-10 wt % to obtain a reduced graphene oxide silk protein conductive solution.

[0078] S6: Conductive structure preparation:

[0079] The mask plate is attached to the plasma-treated silk protein base film obtained in step S4, and then the reduced graphene oxide silk protein conductive solution obtained in step S5 is coated, and the mask plate is removed after drying.

[0080] The structure of the silk protein flexible electrode prepared according to the above method can be in various forms, such as Figure 1 The structure shown.

[0081] The water vapor permeability of the silk protein flexible electrode prepared according to the above method was tested according to the test method specified in YY / T 0148-2006. The results are as follows: Figure 2 As shown, the water vapor permeability at 25°C is 57g.m -2 .h -1 The water vapor permeability at 37°C is 116 g.m -2 .h -1 The standard stipulates that the water vapor permeability of the membrane applied to the skin surface should be no less than 500g / m per 24 hours. 2 ·24h, it can be determined that the water vapor permeability of the silk protein flexible electrode prepared by the above method meets the standard.

[0082] The electromyogram measured by attaching the silk protein flexible electrode prepared according to the above method to the skin is as follows Figure 3 As shown, the collection of electromyographic signals can be realized.

[0083] The surface morphology of the silk protein film treated by the plasma method is as follows Figure 4 As shown, the surface of the silk protein film after plasma treatment is relatively rough, which is more conducive to close bonding with conductive materials.

[0084] The mechanical properties of the silk protein flexible electrode prepared according to the above method are as follows Figure 5 As shown, after plasma treatment, the silk protein film has better flexibility, is more suitable for adhering to the skin, and is not easy to fall off.

[0085] Example 1

[0086] S1: Preparation of silk protein solution: degumming, dissolving, clarifying and filtering, ultrafiltration and desalting, and concentrating mulberry silk to obtain a silk fibroin aqueous solution, the concentration of which is 10%.

[0087] S2: Preparation of silk protein masterbatch: a) Add plasticizer polyethylene glycol 600 to the silk protein aqueous solution prepared in step S1, and the mass fraction of polyethylene glycol 600 in the mixed solution is 0.3%. After fully stirring and mixing, pass it into the spray drying system for spray drying. The feeding rate is 100mL / min, the spray drying inlet air temperature is 130℃, and the nozzle pressure is 0.2MPa. Spray drying into a powdery state, at this time the powder particle size in the system is small; b) At the same time, 10% of the silk protein solution is sprayed into the spray drying system as a powder binder, so that the smaller powders gradually combine into larger particles during the flying process, and the final prepared silk protein masterbatch particle size is about 50μm.

[0088] S3: Preparation of silk protein film: 10g of silk protein masterbatch is placed in a mold, and then the mold is placed between two pressing plates of a hydraulic press. The hydraulic press is pressurized to 20-60MPa and maintained at this pressure for 5 minutes. The mold is removed from the hydraulic press and demoulded to prepare a silk protein film.

[0089] S4: Plasma treatment of silk protein base film: The above silk protein base film is placed in an atmospheric low-temperature plasma discharge experimental device for plasma treatment, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 45V, a current intensity of 2A, and a plasma treatment time of 20 seconds.

[0090] S5: The preparation method of the reduced graphene oxide silk protein conductive solution is as follows:

[0091] a) adding reduced graphene oxide to a solution of silk protein and stirring to dissolve the mixture to obtain a reduced graphene oxide silk protein suspension, wherein the mass ratio of reduced graphene oxide to silk protein is 1:50, and the mass concentration of silk protein in the mixed solution is 10 wt %.

[0092] b) spray drying the reduced graphene oxide silk protein suspension obtained in step (a) to obtain a powder, and selecting an air inlet temperature of 120° C.

[0093] c) placing the powder obtained in step (b) in a muffle furnace under a nitrogen atmosphere for carbonization to obtain a porous reduced graphene oxide silk protein composite material at a carbonization temperature of 700° C. and a carbonization time of 3 hours.

[0094] d) dispersing the composite material obtained in step (c) in a potassium hydroxide solution with a mass concentration of 1 wt% to obtain a reduced graphene oxide silk protein conductive solution.

[0095] S6: Preparation of conductive structure: stick a mask plate on the silk protein base film after the plasma treatment, and then apply the reduced graphene oxide silk protein conductive solution obtained in step S5, and remove the mask plate after drying.

[0096] Example 2

[0097] S1: Preparation of silk protein solution: same as step S1 in Example 1.

[0098] S2: Preparation of silk protein masterbatch: same as step S2 in Example 1.

[0099] S3: Preparation of silk protein film: 10g of silk protein particles are placed in a mold, and then the mold is placed between two pressing plates of a hydraulic press. The hydraulic press is pressurized to 20-60MPa and maintained at this pressure for 5 minutes. The mold is removed from the hydraulic press and demoulded to prepare a silk protein film.

[0100] S4: Plasma treatment of silk protein base film: The above silk protein base film is placed in an atmospheric low-temperature plasma discharge experimental device for plasma treatment, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 45V, a current intensity of 2A, and a plasma treatment time of 100 seconds.

[0101] S5: The method for preparing the reduced graphene oxide silk protein conductive solution is the same as step S5 in Example 1.

[0102] S6: Preparation of conductive structure: stick a mask plate on the silk protein base film after the plasma treatment, and then apply the reduced graphene oxide silk protein conductive solution obtained in step S5, and remove the mask plate after drying.

[0103] Example 3

[0104] S1: Preparation of silk protein solution: same as step S1 of Example 1.

[0105] S2: Preparation of silk protein masterbatch: basically the same as step S2 in Example 1, except that the plasticizer polyethylene glycol 600 is replaced by polyethylene glycol 400.

[0106] S3: Preparation of silk protein film: 10 g of silk protein particles are placed in a mold, and then the mold is placed between two pressing plates of a hydraulic press. The hydraulic press is pressurized to 20-60 MPa and maintained at this pressure for 5 minutes. The mold is removed from the hydraulic press and demoulded to prepare a silk protein film.

[0107] S4: Plasma treatment of silk protein base film: The above silk protein base film is placed in an atmospheric low-temperature plasma discharge experimental device for plasma treatment, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 45V, a current intensity of 2A, and a plasma treatment time of 20 seconds.

[0108] S5: The method for preparing the reduced graphene oxide silk protein conductive solution is the same as step S5 in Example 1.

[0109] S6: Preparation of conductive structure: stick a mask plate on the above-mentioned plasma-treated silk protein base film, then apply reduced graphene oxide silk protein conductive solution, and remove the mask plate after drying.

[0110] Example 4

[0111] S1: Preparation of silk protein solution: same as step S1 of Example 1.

[0112] S2: Preparation of silk protein masterbatch: The steps are the same as step S2 of Example 3.

[0113] S3: Preparation of silk protein film: 10 g of silk protein particles are placed in a mold, and then the mold is placed between two pressing plates of a hydraulic press. The hydraulic press is pressurized to 20-60 MPa and maintained at this pressure for 5 minutes. The mold is removed from the hydraulic press and demoulded to prepare a silk protein film.

[0114] S4: Plasma treatment of silk protein base film: The above silk protein base film is placed in an atmospheric low-temperature plasma discharge experimental device for plasma treatment, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 45V, a current intensity of 2A, and a plasma treatment time of 100 seconds.

[0115] S5: The preparation method of the reduced graphene oxide silk protein conductive solution is the same as that in Example 1.

[0116] S6: Preparation of conductive structure: stick a mask plate on the above-mentioned plasma-treated silk protein base film, then apply reduced graphene oxide silk protein conductive solution, and remove the mask plate after drying.

[0117] In Examples 1 to 4, two plasticizers, polyethylene glycol 400 and polyethylene glycol 600, were used, and the plasma treatment was performed for 20 seconds and 100 seconds. Figure 5 It can be seen that the addition of polyethylene glycol 400 and polyethylene glycol 600 has no significant effect on the tensile strength of the silk protein membrane, but after being treated with plasma for 100 seconds, the flexibility of the silk protein membrane is significantly better than that of the silk protein membrane treated with plasma for 20 seconds.

[0118] Example 5

[0119] The present invention proposes another method for preparing a silk protein flexible electrode, which is different from the first method for preparing a silk protein flexible electrode in that, in step S3, the method for preparing the silk protein film is different. The implementation of the method specifically includes the following steps:

[0120] S1: Preparation of silk protein solution: same as step S1 in Example 1.

[0121] S2: Preparation of silk protein masterbatch: same as step S2 in Example 1;

[0122] S3: Preparation of silk protein film, the specific method is as follows:

[0123] a) Preparation of silk protein paste: Add the silk protein masterbatch prepared in step S2 to deionized water, the mass ratio of silk protein masterbatch to deionized water is 3:7, and stir mechanically at a speed of 700 rpm for 5 minutes to obtain silk protein paste; b) Preparation of silk protein film: Form the above silk protein paste into a film by scraping.

[0124] S4: Plasma treatment of silk protein basement membrane: same as S4 in Example 1;

[0125] S5: preparing a reduced graphene oxide silk protein conductive solution: the same as S5 in Example 1;

[0126] S6: Preparation of conductive structure: same as S6 in Example 1.

[0127] S7: Wet heat crosslinking treatment: Place the silk protein film containing the conductive structure in the above step S6 at a temperature of 70-120° C. and a relative humidity of 80-100% for 10-60 minutes for wet heat crosslinking.

[0128] The silk protein film prepared in Example 6 was observed by scanning electron microscopy, and the results were as follows: Figure 6 As shown, the prepared silk protein membrane is a porous membrane, which is more conducive to the volatilization of water vapor on the skin surface as a material applied to the skin surface.

[0129] The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a silk protein flexible electrode capable of monitoring muscle and nerve damage, characterized in that: The following steps are involved: S1: Preparation of silk protein solution: Silk protein solution is prepared by degumming, dissolving, filtering and ultrafiltration desalting of mulberry silk; S2: Preparation of silk protein masterbatch: Add plasticizer to the silk protein aqueous solution prepared in step S1, stir and mix thoroughly, and then use a granulator to spray dry and granulate in one step; S3: Preparation of silk protein film: pressing the silk protein masterbatch prepared in step S2 to form a film to obtain a silk protein base film; S4: Plasma treatment of the silk protein basement membrane: Plasma treatment is performed on the silk protein basement membrane obtained in step S3; S5: preparing a coatable conductive solution; S6: Preparation of conductive structure: stick a mask plate on the plasma-treated silk protein base film obtained in step S4, then apply the coatable conductive solution obtained in step S5, and remove the mask plate after drying.

2. The method for preparing a silk protein flexible electrode according to claim 1, characterized in that: In step S5, the conductive component in the coatable conductive solution is a metal nanowire, a carbon material, or a material prepared by carbonizing a mixture of a carbon material and silk protein; wherein the metal nanowire includes silver nanowire, gold nanowire, and gold-silver alloy nanowire; and the carbon material includes carbon nanotube, graphene, carbon fiber, and carbon ceramic conductive material.

3. The method for preparing a silk protein flexible electrode according to claim 2, characterized in that: The coatable conductive solution prepared in step S5 is a reduced graphene oxide silk protein conductive solution, and the preparation method specifically comprises the following steps: a. adding reduced graphene oxide to an aqueous solution of silk protein and stirring to dissolve to obtain a reduced graphene oxide silk protein suspension; b. spray drying the reduced graphene oxide silk protein suspension obtained in step a to obtain a powder; c. carbonizing the powder obtained in step b in a muffle furnace under a nitrogen atmosphere to obtain a porous reduced graphene oxide silk protein composite material; d. dispersing the composite material obtained in step c in a potassium hydroxide solution to obtain a reduced graphene oxide silk protein conductive solution.

4. The method for preparing a silk protein flexible electrode according to any one of claims 1 to 3, characterized in that: The specific method for preparing silk protein masterbatch in step S2 is as follows: a. adding plasticizer to the silk protein aqueous solution prepared in step S1, stirring and mixing thoroughly, and then passing it into a spray drying system for spray drying, spray drying into a powder state, at which time the powder particle size in the system is small; b. spraying a powder binder into the spray drying system at the same time, so that smaller powders gradually combine into larger particles during the flying process.

5. The method for preparing a silk protein flexible electrode according to claim 4, characterized in that: The powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-40%.

6. The method for preparing a silk protein flexible electrode according to claim 4, characterized in that: The powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-20%.

7. The method for preparing a silk protein flexible electrode according to claim 4, characterized in that: The powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-10%.

8. The method for preparing a silk protein flexible electrode according to claim 7, characterized in that: In the preparation of silk protein masterbatch in step S2, the feed rate of the spray drying process is 10-500 mL / min, the spray drying air inlet temperature is 90-150° C., and the nozzle pressure is 0.1-1 MPa.

9. The method for preparing a silk protein flexible electrode according to claim 7, characterized in that: In the preparation of the silk protein masterbatch in step S2, the feed rate of the spray drying process is 15-200 mL / min, the spray drying air inlet temperature is 100-130° C., and the nozzle pressure is 0.2-0.7 MPa.

10. The method for preparing a silk protein flexible electrode according to claim 9, characterized in that: The plasticizer in step S2 is one or more of polyethylene glycol 300, polyethylene glycol 400 or polyethylene glycol 600.

11. The method for preparing a silk protein flexible electrode according to claim 10, characterized in that: The specific conditions for plasma treatment of the silk protein base film in step S4 are: carried out in an atmospheric low-temperature plasma discharge experimental device, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 30-50V, a current intensity of 1-3A, and a plasma treatment time of 10-200 seconds.

12. The method for preparing a silk protein flexible electrode according to claim 11, characterized in that: The specific method of pressing the silk protein masterbatch into a film in step S3 is: taking a certain mass of silk protein masterbatch and placing it in a mold, and then placing the mold between two pressing plates of a hydraulic press; pressurizing the hydraulic press to 20-60MPa and maintaining this pressure for a certain period of time, taking the mold out of the hydraulic press and demoulding it, and then preparing a silk protein film.

13. A method for preparing a silk protein flexible electrode capable of monitoring muscle and nerve damage, characterized in that: The following steps are involved: S1: Preparation of silk protein solution: Silk protein solution is prepared by degumming, dissolving, filtering and ultrafiltration desalting of mulberry silk; S2: Preparation of silk protein masterbatch: Add plasticizer to the silk protein aqueous solution prepared in step S1, stir and mix thoroughly, and then use a granulator to spray dry and granulate in one step; S3: Preparation of silk protein film: first, add the silk protein masterbatch prepared in step S2 into deionized water, and stir and beat it mechanically to obtain a silk protein paste; then, form a film with the silk protein paste by coating; S4: Plasma treatment of the silk protein basement membrane: Plasma treatment is performed on the silk protein basement membrane obtained in step S3; S5: Preparation of coatable conductive solution: S6: Preparation of conductive structure: attaching a mask plate to the plasma-treated silk protein base film obtained in step S4, then applying the coatable conductive solution obtained in step S5, and removing the mask plate after drying; S7: Wet heat crosslinking treatment: Place the silk protein film containing the conductive structure in the above step S6 at a temperature of 70-120° C. and a relative humidity of 80-100% for 10-60 minutes to perform wet heat crosslinking.

14. The method for preparing a silk protein flexible electrode according to claim 13, characterized in that: In step S3, the mass percentage of silk protein in the paste is 5-80%, and the mixing temperature is 1-80°C.

15. The method for preparing a silk protein flexible electrode according to claim 13, characterized in that: In step S3, the mass percentage of silk protein in the paste is 20-60%.

16. The method for preparing a flexible silk protein electrode according to claim 13, characterized in that: In step S3, the mixing temperature is 10-60°C.

17. The method for preparing a silk protein flexible electrode according to claim 14, characterized in that: In step S3, the stirring rate in the whipping operation matches the viscosity of the paste, otherwise the material cannot be made uniform, and the whipping speed of the stirring device is 100rpm-2000rpm.

18. The method for preparing a silk protein flexible electrode according to claim 17, characterized in that: In step S3, the whipping speed of the stirring device is 200 rpm-1200 rpm.

19. The method for preparing a silk protein flexible electrode according to claim 18, characterized in that: In the step S3, for the paste with a silk fibroin powder mass fraction of 40%, the rotation speed is 300 rpm-500 rpm.

20. The method for preparing a silk protein flexible electrode according to claim 18, characterized in that: In the step S3, for the paste with a silk fibroin powder mass fraction of 30%, the rotation speed is 500 rpm-700 rpm.

21. The method for preparing a silk protein flexible electrode according to claim 18, characterized in that: For a paste with a silk fibroin powder mass fraction of 20%, the rotation speed is 700 rpm-1200 rpm.

22. The method for preparing a silk protein flexible electrode according to claim 18, characterized in that: In the step S3, a silk protein film is prepared using a silk protein paste, and the coating method is spin coating or scraping coating.

23. The method for preparing a silk protein flexible electrode according to claim 22, characterized in that: In order to improve the solubility of the regenerated silk protein in water and the stability of the bubbles in the paste, an additive is added during the mixing operation in step S2, and the additive is a small molecule compound.

24. The method for preparing a silk protein flexible electrode according to claim 23, characterized in that: The additives are amino acids, metal inorganic salts or alcohols.

25. The method for preparing a silk protein flexible electrode according to any one of claims 13 to 24, characterized in that: In step S5, the conductive component in the coatable conductive solution is a metal nanowire, a carbon material, or a material prepared by carbonizing a mixture of a carbon material and silk protein; wherein the metal nanowire includes silver nanowire, gold nanowire, and gold-silver alloy nanowire; and the carbon material includes carbon nanotube, graphene, carbon fiber, and carbon ceramic conductive material.

26. The method for preparing a silk protein flexible electrode according to claim 25, characterized in that: The coatable conductive solution prepared in step S5 is a reduced graphene oxide silk protein conductive solution, and the preparation method specifically comprises the following steps: a. adding reduced graphene oxide to an aqueous solution of silk protein and stirring to dissolve to obtain a reduced graphene oxide silk protein suspension; b. spray drying the reduced graphene oxide silk protein suspension obtained in step a to obtain a powder; c. carbonizing the powder obtained in step b in a muffle furnace under a nitrogen atmosphere to obtain a porous reduced graphene oxide silk protein composite material; d. dispersing the composite material obtained in step c in a potassium hydroxide solution to obtain a reduced graphene oxide silk protein conductive solution.

27. The method for preparing a flexible silk protein electrode according to claim 26, characterized in that: The specific method for preparing silk protein masterbatch in step S2 is as follows: a. adding plasticizer to the silk protein aqueous solution prepared in step S1, stirring and mixing thoroughly, and then passing it into a spray drying system for spray drying, spray drying into a powder state, at which time the powder particle size in the system is small; b. spraying a powder binder into the spray drying system at the same time, so that smaller powders gradually combine into larger particles during the flying process.

28. The method for preparing a silk protein flexible electrode according to claim 27, characterized in that: The powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-40%.

29. The method for preparing a silk protein flexible electrode according to claim 27, characterized in that: The powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-20%.

30. The method for preparing a flexible silk protein electrode according to claim 27, characterized in that: The powder binder sprayed into the spray drying system is a silk protein solution with a concentration of 1-10%.

31. The method for preparing a flexible silk protein electrode according to claim 30, characterized in that: In the preparation of silk protein masterbatch in step S2, the feed rate of the spray drying process is 10-500 mL / min, the spray drying air inlet temperature is 90-150° C., and the nozzle pressure is 0.1-1 MPa.

32. The method for preparing a flexible silk protein electrode according to claim 30, characterized in that: In the preparation of the silk protein masterbatch in step S2, the feed rate of the spray drying process is 15-200 mL / min, the spray drying air inlet temperature is 100-130° C., and the nozzle pressure is 0.2-0.7 MPa.

33. The method for preparing a flexible silk protein electrode according to claim 24, characterized in that: The plasticizer in step S2 is one or more of polyethylene glycol 300, polyethylene glycol 400 or polyethylene glycol 600.

34. The method for preparing a flexible silk protein electrode according to claim 33, characterized in that: The specific conditions for plasma treatment of the silk protein base film in step S4 are: carried out in an atmospheric low-temperature plasma discharge experimental device, with a gas-solid reactor as a container, helium as a carrier gas, a voltage of 30-50V, a current intensity of 1-3A, and a plasma treatment time of 10-200 seconds.

35. A silk protein flexible electrode capable of monitoring muscle and nerve damage, characterized in that: The flexible silk protein electrode is prepared by the method for preparing the flexible silk protein electrode as described in claims 1-34.

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