A nano zinc oxide / silk protein solution and preparation method thereof

Abstract

The present invention relates to a nano zinc oxide / silk protein solution and a preparation method thereof, and belongs to the technical field of nano zinc oxide. The nano zinc oxide / silk protein solution of the present invention comprises a silk protein nanobelt and nano zinc oxide attached to the silk protein nanobelt, wherein the crystallinity of the silk protein nanobelt is above 40%, the length is 100nm-3000nm, the width is 5nm-30nm, and the height is 0.3nm-5nm. The preparation method of the present invention realizes the preparation of a high-concentration nano zinc oxide aqueous solution by a simple physical method, and improves the fluidity and stability of nano zinc oxide in an aqueous solution, uses water as a solvent, has a simple and controllable process, and the obtained solution has no organic solvent, good biocompatibility, and has the prospect of large-scale preparation and application.

Description

Technical Field

[0001] The invention belongs to the technical field of nano zinc oxide, and in particular relates to a nano zinc oxide / silk protein solution and a preparation method thereof. Background Art

[0002] Nano zinc oxide has great potential for application in various fields such as sunscreen products, batteries, electronic devices, and biomedicine due to its excellent UV protection, optical properties, excellent biocompatibility, and antibacterial properties. In order to realize its application functions, it is necessary to use a high-concentration dispersible zinc oxide solution in the device preparation or product development process. However, due to the spontaneous aggregation behavior of nanomaterials, it is difficult to prepare a high-concentration zinc oxide aqueous solution that is stable for a long time through an effective method, which limits its effective application in different fields of sunscreen, optoelectronics, and medical products.

[0003] Although researchers have tried to improve the stable dispersion of zinc oxide in aqueous solution by controlling the viscosity of the solution to inhibit the aggregation of zinc oxide and chemically modifying zinc oxide to improve its water dispersibility, there is still a lack of effective methods for the preparation of high-concentration zinc oxide, especially high-concentration zinc oxide aqueous solutions with a concentration greater than 6%, which greatly limits its wider application. How to effectively inhibit the spontaneous aggregation of zinc oxide in aqueous solution is the key to achieving long-term stable dispersion of zinc oxide in aqueous solution. Although increasing the viscosity of the solution can inhibit the aggregation of zinc oxide to a certain extent, it also makes it difficult for zinc oxide to be fully dispersed in the system, and the increased viscosity makes it difficult for the solution to be compounded with other systems, further affecting its application. While the chemical modification method improves the water dispersibility, it inevitably affects its function, making it difficult for high-concentration zinc oxide aqueous solutions to achieve a balance between functionality, stability and operability. How to prepare high-concentration zinc oxide aqueous solutions that can achieve stable dispersion while ensuring fluidity and functionality has become a technical bottleneck that urgently needs to be solved.

[0004] Silk protein has excellent biocompatibility and structural designability, and has been successfully used in cosmetics / different tissue repair and drug carriers. Studies have found that by regulating the nanostructure of silk protein, its loading performance can be optimized. Using silk protein nanofibers as stabilizers and dispersants, a graphene solution with good water dispersibility has been prepared, proving its feasibility of loading and dispersing nanomaterials. However, the concentration of high-concentration graphene water-dispersible solution is mg / ml, which is far from the concentration requirement of more than 6% of nano zinc oxide. How to improve the adsorption and fixation ability of silk protein on nanomaterials has become the key to solving the preparation of high-concentration zinc oxide. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of poor dispersibility and stability of nano zinc oxide solutions in the prior art.

[0006] In order to solve the above technical problems, the present invention provides a nano zinc oxide / silk protein solution and a preparation method thereof. Silk protein nanobelts with special structures and hydrophilic and hydrophobic properties are used as carriers and stabilizers, nano zinc oxide is attached to the silk protein nanobelts through physical adsorption, and the aggregation is inhibited by the negative electric repulsion of the silk protein nanobelts themselves, and finally the aggregation and precipitation behavior of high-concentration nano zinc oxide is effectively inhibited to obtain a stable high-concentration zinc oxide solution. The excellent adsorption capacity of the silk protein nanobelts with special structures on nano zinc oxide is utilized to achieve the dispersion of high-concentration zinc oxide by physical means, avoiding the influence of chemical modification on the performance of zinc oxide, and at the same time, the high-concentration zinc oxide solution has good fluidity, and also avoids the adverse effects of the method of inhibiting the aggregation of zinc oxide by increasing the viscosity of the system on subsequent applications.

[0007] The first object of the present invention is to provide a nano zinc oxide / silk protein solution, comprising a silk protein nanobelt and nano zinc oxide attached to the silk protein nanobelt, wherein the silk protein nanobelt has a crystallinity of more than 40%, a length of 100nm-3000nm, a width of 5nm-30nm, and a height of 0.3nm-5nm.

[0008] In one embodiment of the present invention, the particle size of the nano zinc oxide is 5nm-800nm.

[0009] In one embodiment of the present invention, the mass concentration of nano zinc oxide in the nano zinc oxide / silk protein solution is 6%-25%.

[0010] In one embodiment of the present invention, the mass concentration of the silk protein nanoribbons in the nano zinc oxide / silk protein solution is 0.1%-5%. The silk protein nanoribbons serve as a carrier on the one hand and a dispersant on the other hand.

[0011] In one embodiment of the present invention, the nano zinc oxide / silk protein solution is stored at room temperature for 6 months without stratification, the solution has good fluidity, and is easy to compound with other materials or solvents, meeting the needs of sunscreen products, medical devices, photovoltaic products, etc. for high-concentration nano zinc oxide solutions.

[0012] The second object of the present invention is to provide a method for preparing the nano zinc oxide / silk protein solution, comprising the following steps:

[0013] S1, adding nano zinc oxide to the silk protein nanobelt solution, mixing to make the nano zinc oxide fully dispersed in the solution and attached to the silk protein nanobelt, to obtain a mixed solution; the mixing method is one or more of stirring, ultrasound and homogenization;

[0014] S2. The mixed solution described in S1 is allowed to stand and then centrifuged to remove the unattached zinc oxide to obtain the nano zinc oxide / silk protein solution.

[0015] In one embodiment of the present invention, in S1, the stirring rate is 100 rpm-1000 rpm, and the stirring time is 10 min-24 h.

[0016] In one embodiment of the present invention, in S1, the power of the ultrasound is 50W-200W, and the time of the ultrasound is 10min-24h.

[0017] In one embodiment of the present invention, in S1, the homogenization rate is 1000 rpm-5000 rpm, and the homogenization time is 1 min-30 min.

[0018] In one embodiment of the present invention, in S2, the standing time is 30 min-24 h, so that the free nano zinc oxide is fully aggregated or stratified.

[0019] In one embodiment of the present invention, in S2, the centrifugal speed is 800rpm-5000rpm, and the time is 5min-2h, while ensuring the stable dispersion of the silk protein nanobelt / nano zinc oxide aggregates, the free zinc oxide is fully separated to obtain a high-concentration nano zinc oxide solution.

[0020] The technical solution of the present invention has the following advantages over the prior art:

[0021] (1) The nano zinc oxide / silk protein solution of the present invention enables the nano zinc oxide to be firmly attached to the silk protein nano ribbons through the strong physical interaction between the silk protein nano ribbons with specific conformation and nano structure and the nano zinc oxide. At the same time, the special morphology of the surface of the silk protein nano ribbons is utilized to further promote the loading of more doses of nano zinc oxide, thereby breaking through the concentration limitation of nano zinc oxide, and the maximum mass concentration can reach 25%.

[0022] (2) The nano-zinc oxide loaded on the silk protein nanobelts in the nano-zinc oxide / silk protein solution of the present invention does not affect the negative charge of the silk protein nanobelts, thereby maintaining the strong negative charge repulsion of the silk protein nanobelts. The aggregation of high-concentration nano-zinc oxide is inhibited by silk protein, and the nano-zinc oxide is endowed with good water dispersibility, thus successfully solving the technical problem of long-term stable dispersion of high-concentration zinc oxide.

[0023] (3) The preparation method described in the present invention improves the dispersibility of nano-zinc oxide and promotes its better interaction with silk protein through process optimization. At the same time, the well-dispersed nano-zinc oxide forms aggregates with silk protein nanobelts, which can effectively reduce the viscosity of the system and improve the fluidity of high-concentration nano-zinc oxide aqueous solution, providing convenience for subsequent industrial applications.

[0024] (4) The preparation method described in the present invention realizes the preparation of high-concentration nano zinc oxide aqueous solution by simple physical means, and improves the fluidity and stability of nano zinc oxide in aqueous solution. Water is used as solvent, the process is simple and controllable, and the obtained solution is free of organic solvent and has good biocompatibility, which has the prospect of large-scale preparation and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 Characterization diagram of the silk protein nanoribbon in Example 1 of the present invention; wherein (a) is an infrared spectrum diagram, and (b) is an AFM morphology and height diagram;

[0027] Figure 2 Graph showing the particle sizes of the nano zinc oxide powder, silk protein nanobelts and nano zinc oxide / silk protein in Example 1 of the present invention;

[0028] Figure 3 These are the relevant test images of the nano zinc oxide / silk protein solution in Example 1 of the present invention; wherein (a) is a macroscopic image, (b) is an inverted image (fluidity), and (c) is a scanning electron microscope image;

[0029] Figure 4 These are macroscopic images of the nano zinc oxide / silk protein solution in Example 1 of the present invention and the pure nano zinc oxide solution in Comparative Example 1; wherein, a is a macroscopic image of the nano zinc oxide / silk protein solution placed at room temperature for 1 day, b is a macroscopic image of the nano zinc oxide / silk protein solution placed at room temperature for 28 days, c is a macroscopic image of the pure nano zinc oxide solution placed at room temperature for 2 hours, and d is a macroscopic image of the pure nano zinc oxide solution placed at room temperature for 24 hours. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0031] Example 1

[0032] A nano zinc oxide / silk protein solution and a preparation method thereof, specifically comprising the following steps:

[0033] (1) 10 g of nano zinc oxide powder (ZnO) was mixed with 100 g of a 2% mass concentration of silk nanoribbon (SNF) aqueous solution, and the mixture was stirred at a rate of 600 rpm for 30 min using a high-speed magnetic stirrer to fully disperse the nano zinc oxide powder and combine with the silk nanoribbon to form aggregates, thereby obtaining a mixed solution;

[0034] (2) The treated mixed solution was allowed to stand at room temperature for 8 h, and then centrifuged at 1500 rpm for 20 min to remove free zinc oxide to obtain a nano zinc oxide / silk protein (SNF@ZnO) solution.

[0035] Example 2

[0036] A nano zinc oxide / silk protein solution and a preparation method thereof, specifically comprising the following steps:

[0037] (1) 20 g of nano zinc oxide powder (ZnO) was mixed with 100 g of a 4% mass concentration of silk protein nanobelt (SNF) aqueous solution, and the mixture was homogenized by a homogenizer at a rate of 4000 rpm for 15 min to fully disperse the nano zinc oxide powder and combine with the silk protein nanobelt to form aggregates, thereby obtaining a mixed solution;

[0038] (2) The treated mixed solution was allowed to stand at room temperature for 24 hours and then centrifuged at 3000 rpm for 40 minutes to remove free zinc oxide to obtain a nano zinc oxide / silk protein (SNF@ZnO) solution.

[0039] Example 3

[0040] A nano zinc oxide / silk protein solution and a preparation method thereof, specifically comprising the following steps:

[0041] (1) 8 g of nano zinc oxide powder (ZnO) was mixed with 100 g of a 1% mass concentration of silk nanoribbon (SNF) aqueous solution, and the mixture was ultrasonicated for 15 min at 60 W power by a cell ultrasonic pulverizer to fully disperse the nano zinc oxide powder and combine with the silk nanoribbon to form aggregates, thereby obtaining a mixed solution;

[0042] (2) The treated mixed solution was allowed to stand at room temperature for 1 hour and then centrifuged at 800 rpm for 10 minutes to remove free zinc oxide and obtain a nano zinc oxide / silk protein (SNF@ZnO) solution.

[0043] Comparative Example 1

[0044] Add 5 g of nano zinc oxide powder (ZnO) into 100 g of water and mix well to obtain a pure nano zinc oxide solution.

[0045] Test Example 1

[0046] The nano zinc oxide powder (ZnO), silk protein nanobelt (SNF) and nano zinc oxide / silk protein (SNF@ZnO) of Example 1 were characterized. Figure 1-2 As shown. Figure 1-2It can be seen that the infrared spectrum shows that its conformation is mainly a beta-sheet crystal structure with a crystallinity of about 40%. The length of SNF is between 100nm-3000nm, the width is between 10nm-20nm, and the height is between 1nm-4nm; the particle size of ZnO is between 100nm-400nm; and the particle size of SNF@ZnO is about 1000nm.

[0047] Test Example 2

[0048] The nano zinc oxide / silk protein solution of Example 1 was observed and characterized, and the results were as follows: Figure 3 As shown. Figure 3 It can be seen from a that the nano zinc oxide / silk protein solution is a uniform solution without stratification. Figure 3 b It can be seen that the high concentration zinc oxide prepared by the present invention has good fluidity; Figure 3 c It can be seen that nano-ZnO is evenly loaded on the silk protein nanofibers to form aggregates of 1000 nm.

[0049] Test Example 3

[0050] The nano zinc oxide / silk protein solution of Example 1 and the pure nano zinc oxide solution of Comparative Example 1 were observed at rest. Figure 4 As shown. Figure 4 It can be seen that the pure nano zinc oxide solution of Comparative Example 1 undergoes obvious aggregation and stratification after 2 hours, while the nano zinc oxide / silk protein solution of Example 1 remains stably dispersed after being placed at room temperature for 28 days.

[0051] In summary, the scheme of the present application can achieve long-term stable dispersion of nano zinc oxide with a mass concentration of more than 6% in aqueous solution. This is because the diameter of the silk protein nanobelt used is between 5nm-30nm, the height is between 0.3nm-5nm, the length is between 100nm-3000nm, the crystallinity is more than 40%, the nanobelt structure is stable, and it can be dispersed in water. The highly crystalline conformation composition gives it excellent interaction with nano zinc oxide, and the special nanobelt structure can significantly improve its loading capacity for nano zinc oxide, and ultimately achieve a great improvement in concentration and stability. In addition, the combination of silk protein nanobelt and nano zinc oxide is a physical combination, and the dispersion of nano zinc oxide powder in the silk protein nanobelt aqueous solution is achieved by a simple physical method. The preparation method and process are simple, and the obtained product is free of organic solvents and has good biocompatibility.

[0052] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A nano zinc oxide / silk protein solution, characterized in that: The invention comprises a silk protein nanobelt and nano zinc oxide attached to the silk protein nanobelt, wherein the crystallinity of the silk protein nanobelt is above 40%, the length is 100nm-3000nm, the width is 5nm-30nm, and the height is 0.3nm-5nm; the mass concentration of the nano zinc oxide in the nano zinc oxide / silk protein solution is 6%-25%; the mass concentration of the silk protein nanobelt in the nano zinc oxide / silk protein solution is 0.1%-5%.

2. The nano zinc oxide / silk protein solution according to claim 1, characterized in that: The particle size of the nano zinc oxide is 5nm-800nm.

3. A method for preparing the nano zinc oxide / silk protein solution according to any one of claims 1 to 2, characterized in that: The following steps are included: S1, adding nano zinc oxide to the silk protein nanobelt solution, mixing to make the nano zinc oxide fully dispersed in the solution and attached to the silk protein nanobelt, to obtain a mixed solution; the mixing method is one or more of stirring, ultrasound and homogenization; S2. The mixed solution described in S1 is allowed to stand and then centrifuged to remove the unattached zinc oxide to obtain the nano zinc oxide / silk protein solution.

4. The method for preparing the nano zinc oxide / silk protein solution according to claim 3, characterized in that: In S1, the stirring rate is 100 rpm-1000 rpm, and the stirring time is 10 min-24 h.

5. The method for preparing the nano zinc oxide / silk protein solution according to claim 3, characterized in that: In S1, the power of the ultrasound is 50W-200W, and the time of the ultrasound is 10min-24h.

6. The method for preparing the nano zinc oxide / silk protein solution according to claim 3, characterized in that: In S1, the homogenization rate is 1000 rpm-5000 rpm, and the homogenization time is 1 min-30 min.

7. The method for preparing the nano zinc oxide / silk protein solution according to claim 3, characterized in that: In S2, the standing time is 30 min-24 h.

8. The method for preparing the nano zinc oxide / silk protein solution according to claim 3, characterized in that: In S2, the centrifugal speed is 800 rpm-5000 rpm, and the time is 5 min-2 h.

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