CN106901996B

CN106901996B - Invisible and removable silk fibroin nursing membrane substrate and preparation method thereof

Info

Publication number: CN106901996B
Application number: CN201710088689.1A
Authority: CN
Inventors: 王晓路; 王永峰
Original assignee: Suzhou Simeite Biotechnology Co ltd
Current assignee: Suzhou Simeite Biotechnology Co ltd
Priority date: 2017-02-20
Filing date: 2017-02-20
Publication date: 2021-04-06
Anticipated expiration: 2037-02-20
Also published as: CN106901996A

Abstract

The invention belongs to the field of silk fibroin application, and particularly relates to an invisible and removable silk fibroin nursing membrane substrate and a preparation method thereof; the nursing membrane substrate comprises 0.5-5% of silk fibroin, 5-50% of humectant, 1-6% of thickener and the balance of water which are uniformly mixed; the preparation method comprises the following steps: s1, adding a humectant into the silk fibroin solution in proportion, and uniformly mixing to obtain a mixed solution; s2, adding a thickening agent into the mixed solution, and uniformly mixing to obtain a nursing membrane substrate; the invisible and removable silk fibroin nursing membrane and the preparation method thereof have the advantages that the raw materials are pure natural, the preparation method and the steps are simple, the base is uniformly coated on the skin for about 10-15min, an invisible membrane with aesthetic effect can be formed in situ, the membrane material is similar to the skin, the stripping is convenient, and in addition, the base has better compatibility with active substances.

Description

Invisible and removable silk fibroin nursing membrane substrate and preparation method thereof

Technical Field

The invention relates to the field of silk fibroin application, in particular to a hidden and removable silk fibroin nursing membrane substrate and a preparation method thereof.

Background

The material prepared from natural high molecular weight (>100KDa) silk fibroin has good biocompatibility, biodegradability, no toxicity and good film-forming property, and can be used for preparing various silk fibroin-based biomaterials. The silk fibroin film has good moisture absorption and air permeability, and has been applied to tissue engineering and drug sustained release systems, such as artificial skin and the like. As for silk fibroin, natural high molecular fiber protein extracted from silk accounts for about 70% -80% of the silk, the silk fibroin contains 18 amino acids, wherein glycine (gly), alanine (ala) and serine (ser) account for more than 80% of the total composition, leucine can accelerate metabolism of cells, serine and threonine can delay skin aging, tryptophan and tyrosine can absorb ultraviolet rays, the silk fibroin has a prominent structure and composition and is very similar to human skin, and a film prepared from the silk fibroin has the beauty of human 'second skin', relatively, the silk nursing product has a wide prospect, and accords with the green consumption concept of new human beings.

The physiological structure of the skin is known to be complex, the skin is the largest organ of the human body, the human body can be prevented from being invaded by bacteria and dirt, the effect of protecting and maintaining the stable environment in the organism is achieved, but the normal skin is exposed to the outside and threatened by various factors including ultraviolet rays, sharp objects, environmental pollution and bacteria and the influence of the autogenous metabolic aging of the skin, so that the skin is damaged and infected or the skin cells lack elasticity and are loose, meanwhile, the phenomena that the skin is wrinkled and rough due to the reduction of oil secretion, the young skin is fine and glossy, and the skin care is especially important unlike the young, fine and healthy skin.

At present, the skin care products on the market are various in types and forms, such as powder, liquid or gel smearing products for whitening, wrinkle removal, water replenishing, skin repair and the like, removable sticking materials for sticking to the skin, dressings and the like, beauty medical instruments used by beauty institutions and the like. Nowadays, with the improvement of living standard and fast pace life of people and the pursuit of beauty of people, the disposable skin care product is important in daily care and hospital treatment. Most of the removable products are applied to the treatment and restoration care, while the daily care is mainly a facial mask, and the removable products include a traditional wet tissue facial mask and a removable facial mask (a removable film is formed after gel, spray or cream is applied to the face).

The existing materials face the challenge, the materials are green, and the materials do not stimulate and cause allergy to skin. In terms of product performance, the following characteristics are required: 1) coating property: the formed formula is easy to coat on the skin and forms a layer of safe film; 2) air permeability and moisture permeability: after being applied, the mask is tightly combined with the skin, but the skin at the application position can normally breathe and is kept to be breathable and permeable to certain extent with the external environment; 3) mechanical properties: the skin care product is matched with the original skin mechanical property, has certain strength and resilience, and ensures normal skin activity; 4) aesthetic properties: the skin type simulation device simulates normal skin or at least does not change the original skin type, and has universality, and the skin types of most people are suitable for use; 5) uncovering property: when not needed, the skin can be easily torn off, and the skin is not needed to be washed and removed, which is equivalent to adding another layer of skin on the skin of a human body.

In the preparation of the pull-off care products, there are several preparation methods: 1) the first is a traditional method, firstly, a sheet material such as a non-woven material is prepared, then a functional substance is combined on the sheet material, or the sheet material is soaked in the functional substance according to the principle of physical adsorption to prepare a common nursing product, or a composite bracket with special application is prepared by continuously coating, the most obvious characteristic of the material is that the material is a formed product before use, and the material can be used only by being stuck to a specific part to achieve the nursing effect, such as a facial mask, while other products for treatment and repair are still dependent on complicated dressing dressings, and often combined with external ointment for use, and the patient often fails due to poor compliance. 2) The second one is a frozen film, which is a facial mask added with colloids such as carbomer, aloe and the like, can be smeared on the face for sleeping like night cream, and is washed off the next day, but most of skin care products are easily stuck on pillows or bedclothes after being smeared on the face, and the use is not very convenient. 3) And a third is a gel or liquid product which is easy to apply and carry, and after application, gradually forms a film to protect the skin, for example, chinese patents CN201410537752.1 and CN201610601512.2 disclose peelable facial masks. Chinese patent CN201410537752.1 discloses a peelable mask substrate based on an aqueous polyurethane dispersion system, which is prepared by compounding an aqueous polyurethane dispersion as a main component with a thickening agent, an emulsifier, grease, a preservative, essence and the like, is completely attached to skin, becomes a transparent film after being dried thoroughly, does not fall off, and has the effects of tightening skin and removing dead skin dirt. Chinese patent CN201610601512.2 discloses a stripping mask, the formula of which consists of an agent A and an agent B, wherein the agent A consists of curdlan, glycerol, sodium hyaluronate and water, the agent B is a spray prepared from trehalose and water, when in use, the agent A is smeared on the face to form a uniform film, then the agent B is sprayed on the surface of the agent A, and the agent A is stripped after 15-20 min.

In addition to the above methods, researchers at the American society of labor, Massachusetts, Robert Langer, Betty Yu, have developed a "second skin" XPL, primarily in two steps, the first step being the application of a flowable, skin-friendly, reactive silicone gel. In a second step, the platinum-catalyzed silicone crosslinks and also deposits light scattering particles on the surface of the XPL to crosslink the silicone on the skin, thus forming a film that can be applied to the skin on the face or other areas of the body, and the resulting film can be applied to the skin in close proximity for more than 16 hours, as evidenced by studies. The specific principle is that the appearance of the youthful skin is approached by the surface optical particles and the bottom layer cross-linked polysiloxane network to generate mirror surface and scattering reflection, and the simulated skin is formed. Subsequent clinical tests show that the second skin can effectively restore the original mechanical property of the skin and can effectively eliminate the eye bags on the face of a user. Meanwhile, the existence of the polysiloxane film can also better help skin moisture retention, can be used for skin care products or cosmetics, and can also be applied to medical skin, but in the formulas of the first step and the second step, the raw materials are complex, the two-step operation is more complicated, the second layer is continuously coated after the first layer is uniformly coated, the time is longer, and the best scheme is that the film-forming material can be prepared by a one-step method.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide an invisible and peelable silk fibroin nursing film substrate which is prepared from pure natural raw materials, has simple preparation method and steps, is similar to skin in material, is convenient to peel and has better compatibility with active substances, and a preparation method thereof.

The invention provides a hidden and uncovered silk fibroin nursing membrane substrate, which comprises silk fibroin, a humectant and a thickener which are uniformly mixed, wherein the mass fraction of the silk fibroin is 0.5-5%, the mass fraction of the humectant is 5-50%, the mass fraction of the thickener is 1-6%, and the balance is water.

Further, the mass fraction of the silk fibroin is 1-3%.

Further, the functional active substance comprises one or more of vitamin E, vitamin C, epigallocatechin gallate, Glycyrrhrizae radix extract, arbutin, Bulbus Allii Cepae extract, Sargassum extract, and hyaluronic acid.

Further, the humectant comprises one or more of polyethylene glycol 400, polyethylene glycol 200, polyethylene glycol 300, polyethylene glycol 600, glycerin, 1-3 butanediol, sorbitol and hyaluronic acid.

Further, the thickener comprises one or more of hydroxyethyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, xanthan gum and carbomer.

Further, the nursing film substrate is a paste, a spray or a glue.

Further, the water-soluble polyvinyl alcohol gel further comprises a cross-linking agent, wherein the cross-linking agent comprises one or more of polyvinyl alcohol, sodium alginate, calcium chloride and cationic hydroxyethyl cellulose.

The invention provides a preparation method of a hidden and uncovered silk fibroin nursing membrane substrate, which comprises the following steps:

s1, adding a humectant into the silk fibroin solution in proportion, and uniformly mixing to obtain a mixed solution;

and S2, adding a thickening agent into the mixed solution, and uniformly mixing to obtain the nursing membrane substrate.

Among them, it should be noted that the preparation method of the high molecular weight (>100KDa) fibroin solution should include various methods including, but not limited to, the preparation by the lithium bromide method or the denaturant dialysis method, wherein,

the lithium bromide method comprises the following steps:

soaking the degummed mature silk in 9.3M LiBr solution, heating and dissolving to obtain silk fibroin raw liquid, then pouring the silk fibroin raw liquid into a dialysis bag, dialyzing with deionized water, and centrifuging to remove insoluble impurities after dialysis to obtain the silk fibroin solution;

the denaturant dialysis method comprises the following steps:

dissolving degummed silk by using a calcium chloride-containing ternary solution to obtain a silk fibroin stock solution, dialyzing the silk fibroin stock solution by using a protein denaturant solution in sequence from high to low according to concentration gradient, and dialyzing by using water to obtain the silk fibroin solution.

Further, in step S1, a functional active substance is further added, wherein the functional active substance includes one or more of vitamin e (ve), vitamin c (vc), epigallocatechin gallate (EGCG), licorice extract, arbutin, onion extract, seaweed extract, and hyaluronic acid.

In step S1, the functional active material is mixed, and it is necessary to consider the film-forming property of the substrate, the appearance after film formation, and the content of the active material. For VC and VE, the components are water-soluble, and the content can be 3-20% when the components are commonly used in skin care products, and the activity of VC is unstable after the concentration is increased, so that an active substance needs to be mixed in step S1, and Silk fibroin has a certain protection effect on the activity (the literature sources are Luo T, Lei Y, Wu J, et al. EGCG (0.01% -3%) plays an important role in radiation protection, EGCG can be mixed into step S1 to prepare a removable nursing membrane with a certain radiation protection effect, and substances such as licorice extract (0.001% -3%), alpha-arbutin (1% -7%), onion extract (0.01% -5%), seaweed extract (0.5% -5%), hyaluronic acid (0.05% -0.1%) and the like can be directly added to obtain a whitening scar-inhibiting nursing membrane substrate.

Further, the nursing film substrate is a paste, a spray or a glue.

Further, a cross-linking agent is mixed in the step S1, and the cross-linking agent includes one or more of polyvinyl alcohol, sodium alginate, calcium chloride, and cationic hydroxyethyl cellulose. It should be noted that the care film base prepared in the above steps is easily changed in shape by contact with water after being applied to the skin to form a film, and partially begins to be lost, and in order to expand the use environment of the present invention, particularly in the case of contact with water, a cross-linking agent may be mixed to improve this phenomenon, but the greasy feeling, the application property, the film-forming property, and the film-forming invisibility of the base are not changed. Such a cross-linking agent may be chitosan, polyvinyl alcohol, sodium alginate, calcium chloride, or cationic hydroxyethyl cellulose. However, chitosan is water insoluble when incorporated into a substrate, and therefore it is necessary to formulate the chitosan into a solution prior to use, usually by dissolving the chitosan in 1-2% glacial acetic acid. The content of chitosan in the total substrate is 0.1-2%, the content of polyvinyl alcohol is 1-20%, the content of sodium alginate is 0.1-10%, and the content of cationic hydroxyethyl cellulose is 2-5%.

By the scheme, the invention at least has the following advantages:

1) the raw material is pure natural silk fibroin, the source is green, the whole preparation process is environment-friendly, and the mass production can be realized; 2) the preparation method and the steps of the substrate are simple; 3) the prepared substrate can be smeared on the skin only by one step, a film is formed in a short time after smearing, and the formed film can stay on the skin for more than 12 hours; 4) the formed film is transparent and glossy, looks similar to human skin, and has the function of shielding ultraviolet rays; 5) the film can be smoothly peeled off, and the skin cannot be torn when the film is peeled off; 5) the film has the mechanical property close to human skin; 6) the added silk fibroin has a certain water locking and moisturizing effect on the skin because the added silk fibroin has a plurality of hydrophilic groups in the side chain; 7) the matrix has good compatibility with active substances, active substances or medicines for whitening, resisting aging and the like can be added into the substrate, so that the matrix has a good slow release effect, and the silk fibroin material has a protection effect on some unstable active substances, so that the bioavailability of the active substances can be improved. The base can be smeared or sprayed on other parts of the body such as the face, the neck and the like for the daily care field of the skin and the fields of bedsore care, radiation protection and the like.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

FIG. 1 is a graph of rheological data for three samples of a third embodiment of the present invention;

FIG. 2 is a graph of rheological data for a second skin xpl developed by the American Massachusetts;

FIG. 3 is a graph showing the results of a UV resistance test on a skin care film according to a fourth embodiment of the present invention;

FIG. 4 is a graph showing the results of stress-strain of sample 1 in a fifth example of the present invention;

FIG. 5 is a graph showing the results of stress-strain of sample 2 in a fifth embodiment of the present invention;

FIG. 6 is a graph showing the results of an observation of the invisibility and the peeling test of the skin care film in the sixth embodiment of the present invention;

FIG. 7 is a graph showing the observation result of the stability in water of the skin-care film in the eighth embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Example 1 preparation of silk fibroin solution

Weighing 30g of raw silk, putting the raw silk into boiling water containing 0.02M of anhydrous sodium carbonate, boiling for 30min, stirring once every 5min, then rubbing the degummed silk with deionized water for five times, transferring the silk to a fume hood, and drying overnight to obtain the cooked silk.

Immersing the dried cooked silk into a beaker containing 9.3M lithium bromide according to a bath ratio of 1g:4ml, and standing in an oven at 60 ℃ for 4 hours, wherein the solution in the beaker is stirred every other hour, and finally, a 20% (w/v) silk fibroin mixed solution can be obtained.

Transferring the solution into 3.5KDa dialysis bag, dialyzing in deionized water for 48h, and centrifuging the fibroin solution in 4 deg.C centrifuge at 9000r/min twice for 20min each time to remove undissolved substances.

Weighing 1ml of centrifuged silk fibroin solution, recording the mass value of the solution, then placing the solution in a 60-degree oven for drying until the mass ratio of the mass after drying to the mass before drying is the concentration (mass percentage, MW%) of silk fibroin, generally obtaining the concentration range of the silk fibroin about 6-9%, then diluting the obtained silk fibroin solution to 1-5%, then treating the solution in a high-temperature high-pressure sterilization pot for 20min, and after the solution is cooled, placing the solution in a refrigerator at 4 ℃ for later use.

Example 2 preparation of Soft and peelable Silk fibroin Care films

The embodiment provides a preparation method of a soft and peelable silk fibroin nursing film, which comprises the following steps:

s1, preparing a 3% silk fibroin solution according to the silk fibroin solution obtained in the embodiment 1;

s2, preparing 60% PEG400(400 represents the molecular weight of PEG, and the PEG grade is the medicine grade);

s3, taking a fibroin solution, a PEG400 solution and pure water according to the proportion of each component shown in the table 1, stirring and mixing, then respectively adding QP100 (hydroxyethyl cellulose, cellulose of Dow, purchased from Guangzhou feather hemerocallis Biotech Co., Ltd.) into the mixed solution, and stirring completely to obtain the fibroin nursing substrates with different film-forming properties. Smearing on the back of hand, observing indexes: extensibility, breathability, firmness, detachability, and film-forming (on five scales of good, medium, weak, and poor).

a. Ductility: the matrix is smeared on the skin of the back of the hand, whether the matrix can be smoothly smeared or not and whether a continuous film is formed or not are not uniformly distributed;

b. air permeability: the matrix is smeared on the skin of the back of the hand, and after the film is formed, the substrate feels that the skin has non-sticky feeling and air-tight feeling.

c. Compactness: the matrix is smeared on the skin of the back of the hand to form a film, and the feeling that the substrate is tight on the skin is felt.

d. Film forming property: the matrix is smeared on the skin of the back of the hand, and whether the film can be formed or not is observed, and whether the formed film is transparent or not is observed.

e. Uncovering property: the matrix is smeared on the skin of the back of the hand, and after the film is formed, whether the film can be smoothly torn off from the skin and is tightly combined with the skin or not and whether the skin has uncomfortable feeling or not when the film is torn off.

Table 1: mixing proportion of components in preparation of soft and peelable silk fibroin nursing film

Test specimen	3％SF(ml)	60％PEG(ml)	QP100(g)	Water (ml)
					1	1	1	0.12	4
2	1	2	0.15	3
					3	1	3	0.18	2
4	2	1	0.15	3
					5	2	2	0.18	2
6	2	3	0.12	1
					7	3	1	0.18	2
8	3	2	0.12	1
					9	3	3	0.15	0
10	0	1	0.18	5
					11	3	0	0.18	3
12	3	1	0	2

The test results are shown in table 2: as a result, it was found that the substrate was not uncomfortable in contact with the skin, was easily peeled off, and remained on the skin in the above test. SF, PEG and QP100 must all be present, and a certain proportion of the three must be matched.

TABLE 2 Soft removable Silk fibroin nursing film test results statistics

1

2

3

4

5

6

7

8

9

10

11

12

Ductility of the alloy

Superior food

Good wine

Superior food

Good wine

In

Good wine

In

Superior food

Air permeability

Good wine

Superior food

Good wine

In

Good wine

Compactness

Weak (weak)

In

Good wine

In

Good wine

In

Superior food

Good wine

Superior food

Weak (weak)

Difference (D)

Film forming property

Weak (weak)

In

Good wine

Weak (weak)

Superior food

In

Superior food

Good wine

Weak (weak)

Difference (D)

Can be uncovered

Difference (D)

Weak (weak)

Good wine

Weak (weak)

Superior food

In

Superior food

In

Good wine

Weak (weak)

Difference (D)

Example 3 spreadability (extensibility) testing of skin care films

The embodiment provides a method for testing the smearing performance (ductility) of a soft and removable silk fibroin nursing film, which comprises the following steps:

s3, taking a fibroin solution PEG400 solution and pure water according to the proportion of each component shown in the table 3, stirring and mixing, then respectively adding QP100 (hydroxyethyl cellulose, cellulose tawny, purchased from Guangzhou feather hemerocallis Biotech Co., Ltd.) into the mixed solution, and stirring completely to obtain the fibroin nursing substrates with different smearing performances.

S4, test the ductility of the three substrates in table 3 on a rheometer.

Using an instrument: rheometer (AR2000, TA instruments, usa), using the parameters: the diameter of the conical plate is 20mm, the conical angle is 1 degree, and the heating temperature is as follows: the viscosity was tested at 37 ℃ as a function of shear rate, with the rate varying from 0.1 to 100 (1/s).

Table 3: mixing ratio of each component in smearing performance test of skin care film

Test specimen	3％SF(ml)	60％PEG(ml)	QP100(g)	Water (ml)
					1	3	1	0.18	2
2	3	2	0.18	1
					3	3	3	0.18	0

The results are shown in fig. 1, which is data of viscosity variation with shear rate of

samples

1, 2 and 3 provided in this example, wherein 1, 2 and 3 in the picture represent

samples

1, 2 and 3, and the viscosity (ordinate) decreases with increasing shear rate (abscissa), indicating that the substrate of the present invention is a shear thinning matrix, which is easy to spread, has good thixotropy, and the less the PEG content (sample 1), the easier to spread; as shown in FIG. 2, the rheological data of the skin care film of the present invention, which was the second skin xpl rheological data developed by American Massachusetts, was similar to the results (from Yu, B., et al, "An elastic second skin," Nature Materials 15.8(2016)),

besides the mixing proportion, the smearing performance can be optimized from the aspect of the content of the hydroxyethyl cellulose QP100, the more the content of the hydroxyethyl cellulose QP100 is, the more viscous the texture is, in the invention, the range is selected to be within the range of 1-3%, in addition, experiments show that the control (1-4%) of the content of the Silk Fibroin (SF) shows that the influence of the content of the silk fibroin on the smearing performance is not obvious by the hydroxyethyl cellulose QP 100.

Example 4 uv resistance testing of skin Care films

The embodiment provides a method for testing the ultraviolet resistance of a soft and peelable silk fibroin nursing film, which comprises the following steps:

s3, taking a fibroin solution PEG400 solution and pure water according to the proportion of each component shown in Table 4, stirring and mixing, then respectively adding QP100 (hydroxyethyl cellulose, cellulose tawny, purchased from Guangzhou feather hemerocallis Biotech Co., Ltd.) into the mixed solution, and stirring completely to obtain the fibroin nursing substrates with different film-forming properties.

Table 4 uv resistance of skin care film mixing ratio of ingredients in testing

Test specimen	3％SF(ml)	60％PEG(ml)	QP100(g)	Water (ml)
					1	3	1	0.18	2
2	0	1	0.18	5

Sunscreen performance instrumental testing (in vitro method): the sunscreen cosmetic is smeared on a quartz glass slide, and the absorbance value of a sample is measured by using an ultraviolet spectrophotometer, which is the basic principle of the measurement method of all instruments at home and abroad at present, in the embodiment, the used instrument is an ultraviolet visible near-infrared spectrophotometer (Cary 5000, Agilent, USA), and the experimental steps are as follows:

a. the substrate was uniformly coated on the quartz slide (25mm by 25mm), the coating area was the same, and 3 different thicknesses were coated, and since the thickness measurement was inconvenient, the thickness was indirectly reflected by the total weight of the slide and the substrate in the present invention, and the thicker the coating, the more the weight relatively increased. In the scheme, 20mg of (A), 50mg of (B) and 100mg of (C) substrates are weighed on a glass slide according to the material of the substrates, five parallel samples are arranged on each group of weight, and the total weight of the three samples is 15. When in smearing, a part of a substrate is taken away by a finger, a sample remained on the glass slide is weighed again after smearing, when in weighing, the total weight of the substrate and the glass slide is weighed, then the weight of the initial glass slide is subtracted, the residual quantity of the substrate (A1, A2, A3, A4, A5, B1, B2, B3, B4, B5, C1, C2, C3, C4 and C5) is obtained, then the absorbance values (Abs) at the wavelengths of 285nm, 290nm, 300nm, 310nm, 315nm and 320nm are respectively measured for samples with each thickness, the absorbance values of five parallels with the thickness of A are obtained under each wavelength by taking the thickness of A as an example, then the average value of the absorbance of the five parallels under each wavelength is calculated, the Abs (285nm, A), Abs (290nm, A) Abs (300nm, A) Abs (310nm, A) and Abs (315nm, and the absorbance of the wavelength of 6A) is obtained, A) the sum of (a) and (b) is divided by 6 to obtain the absorbance of the final thickness A, which is used to evaluate the sunscreen effect. The calculation methods of B and C are the same as those of A.

Absorbance < 1.0: no sun-screening effect.

Absorbance 1.0: low sunscreen effect.

Absorbance > 1.0, and < 2.0: middle grade sunscreen effect.

Absorbance > 2.0: high sunscreen effect.

Results are shown in fig. 3, which are absorbance values (sample 1 and sample 2) of the uv resistance test of the skin care film in the present example, and the abscissa in fig. 3 represents the residual amounts (14mg, 37mg and 87.5mg) of the slide glass in which 20mg, 50mg and 100mg of the substrate were weighed, and the ordinate represents the final absorbance values Abs at each thickness, and sample 1 and sample 2 are distinguished in that sample 2 does not contain fibroin. It can be seen from the figure that, after silk fibroin is added (sample 1), the absorbance value is significantly greater than that of the sample without silk fibroin (sample 2), and when the coating thickness is thicker (87.5 mg), the absorbance value is greater than 1, in this embodiment, the concentration of silk fibroin is lower, and when the concentration of silk fibroin is increased, the coating thickness is increased, so that a better sunscreen effect is achieved.

Example 5 mechanical property test of skin care film

The embodiment provides a method for testing mechanical properties of a soft and peelable silk fibroin nursing membrane, which comprises the following steps:

s3, taking a fibroin solution, a PEG400 solution and pure water according to the proportion of each component shown in the table 5, stirring and mixing, then respectively adding QP100 (hydroxyethyl cellulose, purchased from Hemerocallis fulva, Guangzhou) into the mixed solution, and stirring completely to obtain the silk fibroin nursing substrates with different mechanical properties after film formation.

S4, sample preparation: the substrate was smeared in a sample bath of 4cm x 1.27cm (equivalent to 4cm x 0.5 inch, second skin XPL test standard developed at the university of majordomo, astm d5083), 5 replicates of each sample were tested, and after drying, the test was taken off, the test environment: temperature 25 ℃, relative humidity: and 65% of standard environment.

S5, the instrument used for testing the mechanical property is a material tester (INSTRON-3365, American INSTRON corporation, USA)

Main parameters at the time of testing: clamping distance: 20 mm; stretching speed: 20 mm/min; pre-tension: 0.2 CN; width of the sample: 0.5 inch.

TABLE 5 mixing ratio of ingredients in mechanical Properties test of skin Care film

Test specimen	3％SF(ml)	60％PEG(ml)	QP100(g)	Water (ml)
					1	3	1	0.18	2
2	3	2	0.18	1

Normal skin stress strain values are 0.5-1.95MPa and 140% -180% (literature source: Annaidh, a.n.et al j.mech.behav.biomed.mater.5,139148 (2012)). The stress strain values of second skin XPL at the university of majordomo are 0.51 ± 0.01MPa and 250 ± 82% (from Yu, b., et al, "An elastic second skin," Nature Materials 15.8(2016)). the stress strain values of sample 1 and sample 2 in this example are shown in fig. 4 and 5, respectively, where 10% and 20% of the abscissa in the graph represent the proportion of PEG in the whole substrate, respectively, and where the stress strain value of sample 2 is 1.08 ± 0.55MPa and 91.89 ± 18.5%, respectively, the stress value is close to that of human skin, so that the substrate has better compliance with skin and does not feel uncomfortable after being smeared on the skin. The strain value of the No. 1 sample reaches 83.38 +/-43.98 percent, the stress value is 6.64 +/-3 MPa, the strain value is large, and the sample has tight feeling after being attached to normal skin and certain shielding effect on wrinkles. The proportion is only part of the test of the case, and the

test numbers

1 and 2 have certain mechanical properties after film formation, so that a basis is further provided for optimizing the mechanical properties of the skin care film by optimizing the proportion of silk fibroin (1-4%), PEG (10-50%) and QP100 (1.5-3.5%).

EXAMPLE 6 stealth Performance testing of skin Care films

s3, taking the fibroin solution, the PEG400 solution and pure water according to the proportion of each component shown in the table 6, stirring and mixing, then respectively adding QP100 (hydroxyethyl cellulose, purchased from Hemerocallis fulva, Guangzhou) into the mixed solution, and stirring completely to obtain the fibroin nursing substrates with different stealth performances.

S4, smearing the prepared substrate on the skin, and observing whether the film is invisible after the substrate is dried.

TABLE 6 mixing ratio of ingredients in stealth Performance test of skin Care films

Test specimen	3％SF(ml)	60％PEG(ml)	QP100(g)	Water (ml)
					1	2	1	0.18	3
2	3	1	0.18	2
					3	1	1	0.18	4
4	2	2	0.18	2
					5	3	2	0.18	1
6	1	2	0.18	3
					7	2	3	0.18	1
8	3	3	0.18	0
					9	1	3	0.18	2

Results as shown in fig. 6, which is the results of the invisibility observation and the releasability test of the skin-care film in this example (sample 1), the first and second rows in the figure are an optical photograph and the releasability test of sample 1 at 20min after the film formation of the base on the outer skin of the arm and the inner skin of the arm, respectively. Test results show that after the care substrate is coated on the skin, a film can be formed after about 10-15min, and the film can be easily torn off without tearing the skin. The base of sample 1 was substantially invisible on the skin, and when removed by hand, a thin film was found, sample 1 in this example being invisible. For special requirements, such as long-time application on the skin, the relevant test results of the invention show that the invisible application can be performed on the skin for more than 12 hours, the skin can be smoothly torn off, and the skin can not be torn off and has no uncomfortable feeling in the process. It should be noted that other samples 2-9 are also the release samples, and the content of PEG and Silk Fibroin (SF) mainly affects the invisibility of the film formed by the substrate after film formation. The more PEG content, the brighter. When the content of the Silk Fibroin (SF) is increased, the uncovering property of the membrane is facilitated.

EXAMPLE 7 Studies of preparation of Care substrates with different thickeners

The embodiment provides a method for analyzing results after different thickening agents are added into a soft and peelable silk fibroin nursing film, which comprises the following steps:

s3, mixing the fibroin solution, PEG400 solution and pure water at the ratio shown in table 7, stirring, and adding HPMC (hydroxypropylmethylcellulose, available from bio-engineering (shanghai) gmbh, high viscosity (H), medium viscosity (M), low viscosity (L)), HEC (hydroxyethylcellulose, available from bio-engineering (shanghai) gmbh, high viscosity (H), medium viscosity (M), low viscosity (L)) and polyvinyl alcohol (pva) (1788 type, available from alatin) to the mixture.

HEC differs from QP100 in purity and viscosity, and in this case, purity has little effect on the substrate and viscosity has a large effect, so in order to further investigate the effect of different thickeners on the performance of the substrate, hydroxyethyl cellulose (HEC), hydroxypropyl methyl cellulose (HPMC) and hydroxyethyl cellulose (QP100) were used in this example. In addition, since polyvinyl alcohol is a good film former, this example also introduces polyvinyl alcohol as a contrast to existing substrates.

S4, and after stirring completely, obtaining the silk fibroin nursing substrates with different film-forming properties.

S5, coating the prepared substrate on the back of the hand, and observing indexes: the specific evaluation contents of extensibility, air permeability, compactness, detachability, film forming property and the like (divided into five grades of good and weak), can refer to the standard of the embodiment 2.

Table 7 mixing ratio table of each component in skin care film and test results thereof

The base formulations in Table 7, with three viscosities of cellulose selected, and concentrations between 3% and 5% were chosen because when the viscosity was too high, the concentration was not too high or the dispersion in water and stirring did not work well. In view of the whole, QP100, HPMC and HEC have good film forming property, HMPC needs shorter time for film forming than HEC and QP100, and is easy to form the film, but after the film forming, water absorption is very fast, the phenomenon of whitening and drying crack is generated very fast, the phenomenon of white crumbs is generated like scurf and a substrate added with PVA, but when HEC and QP100 are added, the QP100 or HEC is preferred if a invisible and beautiful film is to be obtained.

Example 8 stability of Care films in Water

The embodiment provides a stability result of a soft and peelable silk fibroin nursing film in water, which comprises the following steps:

s3, preparing a 2% glacial acetic acid solution (containing 3% of chitosan), mixing the chitosan solution according to the mixing ratio of the table 8, mixing hydroxyethyl cellulose QP100 (hydroxyethyl cellulose, purchased from Hemerocallis guangzhou, Hemerocallis fulva Biotech Co., Ltd.), and uniformly mixing to obtain the nursing substrate.

S4, after the obtained base was applied to the inner skin and outer skin of the arm, and after forming a film, the film was peeled off and placed in a petri dish containing water, and the stability of the film in water was observed at regular time intervals.

Table 8 mixing ratio of ingredients in stability test of skin care film in water

Test specimen	3％SF(ml)	60％PEG(ml)	QP100(g)	3% Chitosan (ml)	Water (ml)
						1	1	3	0.18	1.5	0.5
2	2	1	0.18	0	3

The results of the observation of the stability of the skin care film in water in this example are shown in fig. 7, which shows that the film becomes significantly more stable in water with a stabilization time >5h after chitosan addition. Besides adding chitosan, cationic hydroxyethyl cellulose (JR400, purchased from Guangzhou Shiming chemical Co., Ltd.) can be optionally added, alcohol is sprayed, sodium alginate, calcium chloride and the like are added, the water solubility problem can be partially solved, wherein the cationic cellulose JR400 is added, a film prepared by the substrate can collapse in water for about 40min and can be completely dissolved and lost after 90min, the original shape cannot be kept, the final result is the same as the last picture in figure 7, the problem of partial water solubility can be solved by spraying alcohol, adding sodium alginate, calcium chloride and the like, but the chitosan and the JR400 cationic hydroxyethyl cellulose are not lasting during the stabilization time, so the chitosan or the JR400 cationic hydroxyethyl cellulose is preferably selected.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, it should be noted that, for those skilled in the art, many modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.

Claims

1. A silk fibroin nursing membrane substrate which is invisible and can be uncovered is characterized in that: the silk fibroin-based water-based composite material is prepared by uniformly mixing a silk fibroin solution with the mass fraction of 3% of silk fibroin, a polyethylene glycol 400 solution with the mass fraction of 60% of polyethylene glycol 400, hydroxyethyl cellulose and water, wherein the mass fractions of the silk fibroin solution, the polyethylene glycol 400 solution and the water are as follows, and the weight ratio of the silk fibroin solution to the water is 3 mL: 1mL of: 2mL or 3 mL: 2mL of: 1mL, and the amount of hydroxyethylcellulose added was 0.18 g.

2. The invisible and removable silk fibroin care film substrate of claim 1, wherein: the functional active substance comprises one or more of vitamin E, vitamin C, epigallocatechin gallate, Glycyrrhrizae radix extract, arbutin, Bulbus Allii Cepae extract, Sargassum extract, and hyaluronic acid.

3. The invisible and removable silk fibroin care film substrate of claim 1, wherein: also comprises a cross-linking agent, wherein the cross-linking agent comprises chitosan or cationic hydroxyethyl cellulose.

4. The method for preparing the invisible and removable silk fibroin care film substrate as claimed in any one of claims 1 to 3, wherein: the method comprises the following steps:

s1, adding a polyethylene glycol 400 solution into the silk fibroin solution in proportion, and uniformly mixing to obtain a mixed solution;

and S2, adding hydroxyethyl cellulose into the mixed solution, and uniformly mixing to obtain the nursing membrane substrate.

5. The method of claim 4, wherein: the step S1 is further added with functional active substances, wherein the functional active substances comprise one or more of vitamin E, vitamin C, epigallocatechin gallate, licorice extract, arbutin, onion extract, seaweed extract and hyaluronic acid.

6. The method of claim 4, wherein: a cross-linking agent is also mixed in the step S1, and the cross-linking agent comprises chitosan or cationic hydroxyethyl cellulose.