Preparation method and application of polyethylene glycol functionalized nano capsule-like gel

Abstract

The invention discloses a preparation method and application of polyethylene glycol functionalized nano capsule-like gel. The preparation method comprises the following steps: (1) extracting a nano capsule-like body; (2) preparing polyethylene glycol functionalized nano capsule-like gel; and (3) applying the polyethylene glycol functionalized nano capsule-like gel to mediating photodynamic tooth bleaching. The polyethylene glycol functionalized nano capsule-like gel is combined with a photodynamic reaction to interfere with an electron transport chain and promote ROS accumulation, and the nano capsule-like gel with a specific photoreaction oxidation function is constructed, so that the nano capsule-like gel can be used for equivalently bleaching teeth with a traditional bleaching agent, and meanwhile, the activity of the nano capsule-like gel is improved. The sensitive risk to tooth essence and the mechanical injury risk to enamel and cementum are remarkably reduced, and the composition can be applied to home care or clinical whitening treatment; and the preparation method is simple, is convenient to use, is mild and non-irritant, is high in biocompatibility, and has a good market application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of medical materials, and particularly relates to a preparation method and application of polyethylene glycol functionalized nanometer vesicular gel. BACKGROUND

[0002] In recent years, tooth bleaching technology is roughly divided into external bleaching and internal bleaching. The former is clinic bleaching, home bleaching, combined bleaching, etc., and the latter includes walking bleaching, heat catalytic bleaching, etc. Clinic bleaching is completed by oral professional personnel in the oral clinic, using high-concentration bleaching agents to achieve short-time and rapid bleaching. Home bleaching is completed by patients at home, usually needing to wear a tray containing low-concentration bleaching agents to achieve long-time, safe and stable bleaching.

[0003] At present, there are various materials for tooth bleaching, and the most widely used ones mainly include different concentrations of hydrogen peroxide, urea peroxide and sodium perborate. The mechanism of action is to form free radicals, reactive oxygen molecules (ROS), etc., to act as strong oxidizing agents. These reactive molecules enter the tooth structure, attack long-chain, dark-colored chromophore molecules, and split them into smaller, lighter-colored and more easily diffused molecules, thereby causing changes in the microstructure of the tooth surface and the tooth interior, achieving the effect of improving tooth bleaching.

[0004] Although the above-mentioned bleaching technology and bleaching agents have different degrees of improvement on tooth whitening, they inevitably bring a series of complications to tooth bleaching patients, such as gum and mucosa irritation, tooth sensitivity, root neck external absorption, damage to enamel and dentin, decrease in adhesion, change in mechanical properties, and possible carcinogenicity, which are not conducive to safe and efficient tooth bleaching. Therefore, it is a technical problem to be solved at present to develop a safe, mild and efficient tooth whitening product without hydrogen peroxide. SUMMARY

[0005] In order to solve the problems in the prior art, the present application aims to provide a preparation method and application of polyethylene glycol functionalized nanometer vesicular gel. The polyethylene glycol functionalized nanometer vesicular gel prepared by the present application can safely and efficiently achieve tooth bleaching while overcoming the deficiencies of tooth bleaching in the prior art.

[0006] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions: A preparation method of polyethylene glycol functionalized nanometer vesicular gel, comprising the following steps: Step S1, extracting nanometer vesicular gel: first, select fresh spinach leaves, place them in the dark for 24 hours, and cut the spinach leaves into 2-3cm 2The fragments are mixed with a buffer solution pre-cooled to 4℃ at a mass-volume ratio of 1:5, the cells are broken by a high-speed homogenizer, and the initial extraction solution is obtained by filtering through a 200-mesh nylon screen. The initial extraction solution is centrifuged to obtain supernatant, and the supernatant is centrifuged again to obtain a thylakoid precipitate. The thylakoid precipitate is resuspended in a buffer solution to obtain a thylakoid solution. Finally, the thylakoid solution is mixed with a buffer solution on ice, and the nanometer thylakoid precipitate is obtained by centrifugation. The nanometer thylakoid precipitate is resuspended in a buffer solution containing 20% dimethyl sulfoxide and stored at -80℃, thereby obtaining the nanometer thylakoid precipitate. Step S2, preparation of temperature-sensitive polyethylene glycol functionalized nanometer thylakoid gel: first, polypropylene glycol-ethylene oxide triblock copolymer is weighed as a temperature-sensitive matrix and dissolved in a phosphate buffered saline solution to obtain a polypropylene glycol-ethylene oxide triblock copolymer solution; second, the polypropylene glycol-ethylene oxide triblock copolymer solution is obtained by gradient stirring at 4℃ to obtain a polypropylene glycol-ethylene oxide triblock copolymer gel; finally, polyethylene glycol and the nanometer thylakoid obtained in step S1 are added to the polypropylene glycol-ethylene oxide triblock copolymer gel, and light is irradiated for 1h to obtain a polyethylene glycol functionalized nanometer thylakoid gel.

[0007] Further, the preparation method of the buffer solution in step S1 is as follows: deionized water, magnesium chloride hexahydrate, bovine serum albumin, and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid are used as raw materials to prepare a buffer solution with a pH of 7.6.

[0008] Further, the temperature of the first centrifugation in step S1 is 4℃, the speed is 600rpm, and the time is 5min; the temperature of the second centrifugation is 4℃, the speed is 2000rpm, and the time is 10min; the temperature of the third centrifugation is 4℃, the speed is 8000rpm, and the time is 10min.

[0009] Further, the specific method of stirring on ice in step S1 is as follows: the thylakoid solution is added to a buffer solution and placed on ice under light-proof conditions, and stirred at 300rpm for 2h to disperse the nanometer thylakoid uniformly.

[0010] Further, the speed of the gradient stirring method in step S2 is 800rpm, and the stirring time is 2h.

[0011] Further, the intensity of the light irradiation in step S2 is 200000Lx, and the wavelength of the light irradiation is 600nm.

[0012] Further, the application discloses an application of the polyethylene glycol functionalized nanovesicle gel in mediating photodynamic tooth bleaching.

[0013] Further, the specific method of mediating the photodynamic tooth bleaching is as follows: the polyethylene glycol functionalized nanovesicle gel is applied on a coffee-stained human in-vitro tooth crown, and cold light irradiation is performed for 30 min per day, and the irradiation is continuously performed for 30 days.

[0014] Further, the specific method of the coffee staining is as follows: the human in-vitro tooth is soaked in sugar-free coffee for 21 days, so that a coffee-stained human in-vitro tooth research model is obtained.

[0015] Further, the mode of the cold light irradiation is as follows: a household cold light whitening instrument is used to irradiate the coffee-stained human in-vitro tooth crown with a light intensity of 20000 Lx.

[0016] Compared with the prior art, the application has the following positive beneficial effects: (1) The application selects fresh spinach leaves to extract nanovesicles, and polypropylene glycol-ethylene oxide triblock copolymer (F127) is used as a temperature-sensitive matrix, and the amphiphilic molecular structure of the polypropylene glycol-ethylene oxide triblock copolymer (F127) can form a three-dimensional gel network with temperature-responsive pores at low temperature; polyethylene glycol and nanovesicles are added into the polypropylene glycol-ethylene oxide triblock copolymer (F127) gel, and a polyethylene glycol functionalized nanovesicle gel is formed under light irradiation; through the unique design of the polyethylene glycol functionalized modification of the nanovesicles, the electron transfer of the photosynthetic electron transport chain of the nanovesicles is interfered, the generation of NADPH (reduced coenzyme II) is inhibited, the accumulation of ROS (reactive oxygen molecules) is promoted, and the photosynthetic oxidation reaction is strengthened; the polyethylene glycol functionalized nanovesicle gel applied in mediating photodynamic tooth bleaching can realize low-concentration slow-release of ROS and non-excessive oxidative damage of tooth bleaching, can precisely decompose pigment molecules in combination with a targeted oxidation mechanism, is not easy to cause enamel demineralization and surface microstructure damage, can reduce the sensitivity of tooth dentin and the mechanical property damage of enamel and cementum, can improve the biological safety of tooth bleaching, and can realize the dual balance of efficient degradation of pigments and protection of tissues.

[0017] (2) The temperature-sensitive semi-solid gel formed by the high-concentration polypropylene glycol-ethylene oxide tri-block copolymer (F127) can maintain the spatial directional arrangement of the nano-capsule, avoid the agglomeration of the nano-capsule, fully integrate the technology of material science and biological engineering, regulate the balance of the photo-oxidation product and the reduction product of the nano-capsule photo-reaction by combining the polyethylene glycol functionalized nano-capsule gel and the photodynamic reaction, interfere with the electron transport chain, promote the accumulation of reactive oxygen molecules (ROS), construct the photo-oxidation functionalized polyethylene glycol functionalized nano-capsule gel, and realize the tooth bleaching with high efficiency, which is equivalent to the pigment degradation efficiency of the traditional household tooth bleaching agent.

[0018] (3) The polyethylene glycol functionalized nano-capsule gel prepared by the application has flexible application scenarios and simple operation, and is suitable for both family and clinic, covering different user needs, combining oral medicine and material science, breaking through the limitations of traditional tooth bleaching, and promoting the development of safe and precise tooth whitening technology. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a process schematic diagram of the preparation method and application of the polyethylene glycol functionalized nano-capsule gel in the application; Figure 2 is a mechanism schematic diagram of the polyethylene glycol functionalized nano-capsule gel in the application applied to mediate photodynamic tooth bleaching; Figure 3 is a related characterization schematic diagram of the nano-capsule and the polyethylene glycol functionalized nano-capsule gel in the application; Figure 4 is a qualitative and quantitative effect schematic diagram of the polyethylene glycol functionalized nano-capsule gel in the application applied to mediate photodynamic tooth bleaching; Figure 5 is a schematic diagram of the degree of dentin sensitivity caused by the polyethylene glycol functionalized nano-capsule gel in the application; Figure 6 is a schematic diagram of the influence of the polyethylene glycol functionalized nano-capsule gel in the application on the mechanical properties of enamel and dentin; Figure 7 is a schematic diagram of the polyethylene glycol functionalized nano-capsule gel in the application staining live and dead cells and cell proliferation. DETAILED DESCRIPTION

[0020] The technical solutions of the application will be further specifically described below through examples and drawings, and these examples and drawings are for the description of the application and are not a limitation of the application. Based on the examples in the application, all other examples obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0021] The experimental methods described in the examples are all conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0022] Embodiments Figure 1 A schematic diagram of a preparation method of a polyethylene glycol functionalized nanochylomebra gel and applications thereof, the preparation method of the polyethylene glycol functionalized nanochylomebra gel specifically includes the following steps: Step S1, extracting nanochylomebra, the specific steps are as follows: Step S1a, place fresh spinach leaves in the dark for 24 h to inhibit photosynthetic activity, peel the leaf veins of the spinach leaves, and cut them into 2-3 cm 2 fragments, add a buffer solution with a pH of 7.6 prepared from deionized water, magnesium chloride hexahydrate (MgCl2 6H2O), bovine serum albumin (BSA), and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), and the mass-volume ratio of the leaf vein fragments to the buffer solution is 1:5, use a high-speed homogenizer (at a speed of 20,000 rpm in pulse mode) to break the leaf vein fragment cells, filter the initial extract through a 200-mesh nylon screen, centrifuge the initial extract at 4°C, the centrifugal speed is 600 rpm, and the centrifugal time is 5 min, and obtain the supernatant; Step S1b, centrifuge the supernatant obtained in step S1a at 4°C, the centrifugal speed is 2000 rpm, and the centrifugal time is 10 min, obtain the chylomebra precipitate, resuspend the chylomebra by adding a buffer solution with a pH of 7.6 prepared from deionized water, magnesium chloride hexahydrate (MgCl2 6H2O), bovine serum albumin (BSA), and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), and obtain the chylomebra solution; Step S1c, add a buffer solution with a pH of 7.6 prepared from deionized water, magnesium chloride hexahydrate (MgCl2 6H2O), bovine serum albumin (BSA), and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) to the chylomebra solution obtained in step S1b, stir at a speed of 300 rpm on ice in the dark for 2 h, then centrifuge at 4°C, the centrifugal speed is 8000 rpm, and the centrifugal time is 10 min, obtain the nanochylomebra precipitate, resuspend the nanochylomebra precipitate by adding a buffer solution containing 20% dimethyl sulfoxide, store the nanochylomebra precipitate at-80°C, and obtain the nanochylomebra, the activity retention rate of the nanochylomebra is ≥95% within 6 months; Step S2, preparing a polyethylene glycol functionalized nanochylomebra gel, the specific steps are as follows: Step S2a, selecting polypropylene glycol-ethylene oxide triblock copolymer (F127) as a temperature-sensitive matrix, which can form a dynamic micellar network at low temperature. Take the appropriate amount of F127, dissolve it in an appropriate volume of phosphate buffered saline (PBS) to obtain a polypropylene glycol-ethylene oxide triblock copolymer (F127) solution. The polypropylene glycol-ethylene oxide triblock copolymer (F127) solution is subjected to gradient stirring on ice (800 rpm for 2 h) to achieve ordered arrangement of molecular chains and form a three-dimensional polypropylene glycol-ethylene oxide triblock copolymer gel with temperature-responsive channels; Step S2b, adding polyethylene glycol with a molecular weight of 800 Da and the nanocystid obtained in step S1 to the polypropylene glycol-ethylene oxide triblock copolymer gel obtained in step S2a. The mass ratio of polyethylene glycol and nanocystid is 10:1. The polyethylene glycol and nanocystid interfere with the photosynthetic electron transport chain, act as PSI and PSII inhibitors, inhibit the generation of (reduced coenzyme II), promote the accumulation of ROS (reactive oxygen molecules), and strengthen the photosynthetic oxidation reaction. At the same time, the polyethylene glycol functionalized nanocystid gel is irradiated with visible light with a light intensity of 200000 Lx and a wavelength of 600 nm for 1 h, so that the polyethylene glycol functionalized nanocystid is uniformly dispersed in the polypropylene glycol-ethylene oxide triblock copolymer (F127) gel network to form an injectable gel with a "F127 micelle-polyethylene glycol (PEG) interface-nanocystid core" three-level structure. The polyethylene glycol functionalized nanocystid gel is obtained. Figure 3 The related characterization of nanocystid and polyethylene glycol functionalized nanocystid gel is shown in FIG. 1; wherein, Figure 3 a is the particle size distribution of both; Figure 3 b is the charge distribution of both; Figure 3 c is the transmission electron microscopy (TEM) image of both; from Figure 3 a and Figure 3 b can be seen that polyethylene glycol changes the particle size and charge distribution of the nanocystid membrane surface, and Figure 3 c can be seen that polyethylene glycol changes the size and membrane structure of the nanocystid, and Figure 3 can help prove that polyethylene glycol has successfully functionalized nanocystid.

[0023] The polyethylene glycol functionalized nanocystid gel prepared above is applied to mediate photodynamic tooth bleaching, and the specific steps of its application are as follows: Step (1), the human in vitro tooth is soaked for 21 days using sugar-free coffee to obtain a coffee-stained human in vitro tooth research model, the polyethylene glycol functionalized nanocystid gel is applied on the human in vitro tooth crown of the coffee-stained human in vitro tooth research model, a household cold light whitening instrument is used to irradiate the human in vitro tooth crown at a light intensity of 20000 Lx for 30 min / day, and the irradiation is continuously performed for 30 days; Step (2), the brightness L, red-green color a and yellow-blue color b of the tooth crown before and after the application of the polyethylene glycol functionalized nanocystid gel are measured, and the color difference ΔE before and after the application of the polyethylene glycol functionalized nanocystid gel is calculated. Step (3), the mechanical property change of the enamel and dentin and the dentin sensitivity change after the polyethylene glycol functionalized nanocystid gel is bleached for 30 days are detected, and the application effect of the polyethylene glycol functionalized nanocystid gel in mediating photodynamic tooth whitening is evaluated.

[0024] The mechanical property change of the enamel and dentin is detected: the polyethylene glycol functionalized nanocystid gel prepared by the application is used for bleaching the human in vitro tooth crown and root, a 2mm-thick tooth hard tissue slice is prepared through a hard tissue cutting system, the surface microstructure of the tooth hard tissue slice is observed by using a scanning electron microscope (SEM), and the surface porosity is calculated to evaluate the influence of the bleaching gel on the mechanical properties of the enamel and dentin.

[0025] The dentin sensitivity is detected: first, a 2mm-thick dentin slice is prepared through a hard tissue cutting system, the polyethylene glycol functionalized nanocystid gel prepared by the application is used for treating the dentin slice for 30 min, and the dentin tubular diameter and cross-sectional porosity are calculated by using a scanning electron microscope (SEM) combined with Image J; second, a SD rat dentin defect model is established, the polyethylene glycol functionalized nanocystid gel prepared by the application is used for treating the SD rat dentin defect model for 30 min, the pulp electrical activity and behavior score of the rat dentin defect model before modeling, after modeling and after gel treatment are recorded, and the degree of dentin sensitivity caused by the polyethylene glycol functionalized nanocystid gel prepared by the application is comprehensively evaluated.

[0026] The method for recording the pulp electrical activity is as follows: after the SD rat is anesthetized by 1% sodium pentobarbital, the rat is fixed on a rat fixing frame, the oral cavity is opened, the tooth surface is wiped dry with a sterile cotton ball, the probe of a pulp activity tester is placed on the labial surface of the upper incisor of the rat, the mode of the pulp activity tester is selected as High, the pulp activity value is recorded when the body of the rat shrinks, the pulp activity is tested for a total of 3 times, and the pulp activity is tested before modeling, after modeling and after gel treatment of the rat dentin defect model.

[0027] Method of recording the behavior score: the surface of the tooth defect is affected by cold water for 5s, and the reaction score of the animal is recorded, and the score is performed by two persons; the behavior score standard is: 0-no reaction; 0.5-body slight contraction; 1-body strong contraction; 2-body strong contraction with short vocalization; 3-body strong contraction with long vocalization.

[0028] By Figure 5 It can be seen that, compared with the control group (without any treatment), the 35% phosphoric acid group, the 40% hydrogen peroxide group and the 10% urea hydrogen peroxide group, the polyethylene glycol functionalized nanocystidium (Oxi-NT) gel causes a small degree of dentin tubule opening and a small dentin cross-sectional porosity; the pulp electrical activity of the SD rat is close to normal, and the behavior performance is better than that of the traditional bleaching agent treatment group (40% hydrogen peroxide group and 10% urea hydrogen peroxide group), which indicates that the polyethylene glycol functionalized nanocystidium (Oxi-NT) gel causes a small degree of dentin sensitivity; by Figure 6 It can be seen that, compared with the control group (without any treatment), the dental etching agent group, the erythritol sandblasting group, the 40% hydrogen peroxide group and the 10% urea hydrogen peroxide group, the polyethylene glycol functionalized nanocystidium (Oxi-NT) gel treatment causes a small change in the micro-morphology of enamel and cementum, which indicates that the polyethylene glycol functionalized nanocystidium (Oxi-NT) gel has a small damage to the mechanical properties of enamel and cementum.

[0029] In the present application, the nanocystidium is functionalized by polyethylene glycol to obtain a polyethylene glycol functionalized nanocystidium (Oxi-NT) gel, which has a small degree of dentin sensitivity and a small damage to the mechanical properties of enamel and cementum. Figure 2 It can be seen that the polyethylene glycol functionalization can play a similar role to the PSI and PSII inhibitors in blocking the photosynthetic electron transport chain of the polyethylene glycol functionalized nanocystidium (Oxi-NT), generating more oxidizing substances such as ROS, O2⁻ and O2, and reducing reducing substances such as NADPH, which indicates that the preparation method of the present application successfully constructs the plant extract nanocystidium with oxidized functional specialization. 1 O2, reducing substances such as NADPH, which indicates that the preparation method of the present application successfully constructs the plant extract nanocystidium with oxidized functional specialization. 1O2) about 30%, the electron transport chain is better blocked, thereby inhibiting the reduction reaction, and the production of NADPH (reduced coenzyme II) is reduced; the polyethylene glycol functionalized nanocapsid (Oxi-NT) gel is applied to the human tooth crown of the coffee-stained human tooth ex vivo research model, a household cold light whitening instrument is used, the light intensity is 20000Lx, the human tooth crown is irradiated for 30min / day, after continuous irradiation for 30 days, the color difference DE of the tooth crown before and after the polyethylene glycol functionalized nanocapsid gel is applied is about 25, the whitening effect is close to 40% hydrogen peroxide group (2 times, 30min / time), and is higher than that of 10% urea peroxide group (30 days, 30min / day), which is consistent with the results of Figure 4 .

[0030] Figure 7 The live and dead cell and cell proliferation experiment schematic diagram of the polyethylene glycol functionalized nanocapsid gel for staining human dental pulp stem cells (HDPSCs) and human oral epithelial cells (HOK) is shown, and Figure 7 It can be seen that compared with the control group (without any treatment), 5% urea peroxide and 10% urea peroxide, after the polyethylene glycol functionalized nanocapsid (Oxi-NT) gel treatment, human dental pulp stem cells (HDPSCs) and human oral epithelial cells (HOK) still have more survival, and the proportion of living cells is close to the negative control group (only cell culture medium), and have excellent biological safety.

[0031] In summary, the polyethylene glycol functionalized nanocapsid Oxi-NT gel prepared by the application causes the degree of dentin sensitivity and the degree of damage to the mechanical properties of enamel and cementum much less than the traditional bleaching agent (hydrogen peroxide and urea peroxide), and the biological safety is much higher than that of the traditional bleaching agent (hydrogen peroxide and urea peroxide), which is conducive to realizing safe and efficient tooth bleaching.

[0032] Finally, it should be noted that although the embodiments of the application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the application, and any equivalent changes and improvements made within the scope of the application should still belong to the scope of the application.

Claims

1. A method for preparing polyethylene glycol functionalized nanothylakoid gel, characterized in that: The steps include: Step S1, extracting nanothylakoids: First, fresh spinach leaves were selected and placed in the dark for 24 hours. The spinach leaves were peeled off the veins and cut into 2-3 cm 2 fragments; secondly, the fragments were mixed with a buffer solution precooled to 4° C. at a mass-to-volume ratio of 1:5, the cells were disrupted using a high-speed homogenizer, and the primary extract was obtained by filtering through a 200-mesh nylon mesh. The primary extract was centrifuged to obtain a supernatant, and the supernatant was centrifuged again to obtain a thylakoid precipitate. Buffer was added to the thylakoid precipitate to resuspend the thylakoids to obtain a thylakoid solution; finally, buffer was added to the thylakoid solution, and the mixture was stirred on ice for uniform mixing. After centrifugation, a nanothylakoid precipitate was obtained, and a buffer solution containing 20% ​​dimethyl sulfoxide was added to the nanothylakoid precipitate to resuspend the precipitate, and the nanothylakoid precipitate was stored at -80° C. to obtain nanothylakoids; Step S2, preparing a thermosensitive polyethylene glycol-functionalized nanothylakoid gel: first, weighing a polypropylene glycol-ethylene oxide triblock copolymer as a thermosensitive matrix and dissolving it in phosphate buffered saline to obtain a polypropylene glycol-ethylene oxide triblock copolymer solution; second, subjecting the polypropylene glycol-ethylene oxide triblock copolymer solution to a gradient stirring method at 4°C to obtain a polypropylene glycol-ethylene oxide triblock copolymer gel; finally, adding polyethylene glycol and the nanothylakoids obtained in step S1 to the polypropylene glycol-ethylene oxide triblock copolymer gel, and irradiating the mixture with light for 1 hour to obtain a polyethylene glycol-functionalized nanothylakoid gel.

2. The method for preparing a polyethylene glycol functionalized nanothylakoid gel according to claim 1, characterized in that: The preparation method of the buffer solution in step S1 is as follows: using deionized water, magnesium chloride hexahydrate, bovine serum albumin, and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid as raw materials to prepare a buffer solution with a pH of 7.

6.

3. The method for preparing a polyethylene glycol functionalized nanothylakoid gel according to claim 1, characterized in that: In step S1, the first centrifugation temperature is 4°C, the speed is 600 rpm, and the time is 5 min; the second centrifugation temperature is 4°C, the speed is 2000 rpm, and the time is 10 min; the third centrifugation temperature is 4°C, the speed is 8000 rpm, and the time is 10 min.

4. The method for preparing a polyethylene glycol functionalized nanothylakoid gel according to claim 1, characterized in that: The specific method of stirring on ice in step S1 is as follows: adding a buffer solution to the thylakoid solution under light-proof conditions, placing the solution on ice, and stirring at 300 rpm for 2 hours to uniformly disperse the nanothylakoids.

5. The method for preparing a polyethylene glycol functionalized nanothylakoid gel according to claim 1, characterized in that: The rotation speed of the gradient stirring method in step S2 is 800 rpm, and the stirring time is 2 h.

6. The method for preparing a polyethylene glycol functionalized nanothylakoid gel according to claim 1, characterized in that: The intensity of the light in step S2 is 200,000 Lx, and the wavelength of the light is 600 nm.

7. A use of polyethylene glycol functionalized nanothylakoid gel in mediating photodynamic tooth bleaching, characterized in that: The polyethylene glycol functionalized nano thylakoid gel is prepared by the preparation method of the polyethylene glycol functionalized nano thylakoid gel according to any one of claims 1 to 6.

8. The use of a polyethylene glycol functionalized nanothylakoid gel in mediating photodynamic tooth bleaching according to claim 7, characterized in that: The specific method of mediating photodynamic tooth bleaching is: applying the polyethylene glycol functionalized nanothylakoid gel to coffee-stained human in vitro tooth crowns, and irradiating with cold light for 30 minutes per day for 30 consecutive days.

9. The use of a polyethylene glycol functionalized nanothylakoid gel in mediating photodynamic tooth bleaching according to claim 8, characterized in that: The specific method of coffee staining is: soaking human ex vivo teeth in sugar-free coffee for 21 days to obtain a research model of coffee-stained human ex vivo teeth.

10. The use of a polyethylene glycol functionalized nanothylakoid gel in mediating photodynamic tooth bleaching according to claim 8, characterized in that: The cold light irradiation method is: using a household cold light whitening device to irradiate the coffee-stained human ex vivo tooth crown with a light intensity of 20,000 Lx.

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