Preparation method and application of underwater drivable fibers based on recombinant spider silk protein

Abstract

A preparation method and application of underwater drivable fibers based on recombinant spider silk protein, forming a hydrogel through a crosslinking reaction of a recombinant spider silk protein solution and a silicotungstic acid solution, and then post-stretching the hydrogel to obtain an underwater drivable fiber. The present invention forms a hydrogel through the crosslinking of a recombinant spider silk protein solution and a silicotungstic acid solution, and then prepares a drivable fiber through post-stretching of the hydrogel. The actuator prepared using the fiber can not only suture wounds but also serve as an underwater micro engine.

Description

Technical Field

[0001] The present invention relates to a technology in the field of bioengineering, specifically a preparation method and application of underwater drivable fibers based on recombinant spider silk protein. Background Art

[0002] In recent years, underwater drivable soft materials have shown great application prospects in fields such as soft robotics and biomedicine. Among these soft materials, fibers have attracted much attention due to their light weight, simple one-dimensional structure and anisotropic driving performance. These characteristics enable fiber actuators to play a role in more special robotics and medical fields, including smart textiles, underwater micro engines, and wound sutures. However, most current fiber actuators cannot simultaneously have excellent driving performance and super strong mechanical properties in an aquatic environment. This defect seriously limits the application of underwater fiber actuators. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the present invention proposes a method for preparing underwater drivable fibers based on recombinant spider silk protein and its application, wherein a hydrogel is formed by cross-linking a recombinant spider silk protein solution and a silicotungstic acid solution, and then a drivable fiber is prepared by post-stretching the hydrogel. The actuator prepared by the fiber can not only suture wounds but also serve as an underwater micro-engine.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to a method for preparing underwater drivable fibers based on recombinant spider silk protein, wherein a hydrogel is formed by a cross-linking reaction between a recombinant spider silk protein solution and a silicotungstic acid solution, and then the hydrogel is post-stretched to obtain the underwater drivable fibers.

[0006] The recombinant spider silk protein is specifically composed of 4, 8, 16, 32 or 64 core repeating sequences of the Nephilasilk spider dragline silk protein MaSpI, and the amino acid sequence of the MaSpI core repeating sequence is shown in SEQ ID No.1.

[0007] The concentration of the recombinant spider silk protein solution is 5-30% (w / v), the concentration of the silicotungstic acid solution is 1-20% (w / v), and the volume ratio of the two is 1:2.

[0008] The cross-linking reaction is as follows: a 1 volume ratio recombinant spider silk protein solution is dripped dropwise into a 2 volume ratio silicotungstic acid solution, and the protein and silicotungstic acid are stirred to fully react to form a hydrogel, the cross-linking temperature is 25-40°C, the stirring rate is 1500-3000rpm, and the stirring time is 10-30min.

[0009] The post-stretching treatment refers to: manually kneading the hydrogel into a hydrogel with a length of 1-5 cm and a radius of 2-10 mm, and stretching it in a water bath at a temperature of 25-40°C to 8-30 times the initial length at a stretching speed of 500-2000 cm min -1 , and then transferred to 4-20℃ for fixation.

[0010] The invention relates to an underwater drivable fiber prepared by the above method, with a radius of about 50-250 μm, a strength of 71-141 MPa, a breaking strain of 114-270%, a Young's modulus of 223-643 MPa, and a toughness of 135-156 MJ m -3 .

[0011] The driving includes: contraction, torsion and / or rotation.

[0012] The shrinking means that a single underwater drivable fiber is quickly transferred from a 4-20°C condition to a 30-80°C water bath to achieve shrinkage of the fiber.

[0013] The twisting means: placing a bundle of 5-20 underwater drivable fibers in an environment at 20°C, with one end of the fiber bundle fixed and the other end connected to a rotator; when the ambient temperature is heated to 30°C, slowly rotating the rotator, the fiber bundle will twist immediately; when the twisting is completed, the rotator is quickly stopped, and the ambient temperature is reduced to 4-20°C, and the preparation of the twisted fiber bundle is completed.

[0014] The rotation means that the twisted fiber bundle stored at 4-20°C is quickly transferred to a water bath at 30-80°C, and the fiber will undergo rotational deformation.

[0015] The present invention relates to a wound suture based on the above-mentioned underwater actuatable fiber, with a radius of about 50-250 μm, a strength of 71-141 MPa, a breaking strain of ~114-270%, a Young's modulus of ~223-643 MPa, and a toughness of ~135-156 MJm -3 , when the temperature rises from below 20°C to above 30°C, the fiber can shrink by more than 50% within 2s.

[0016] The present invention relates to an underwater micro-engine based on the above-mentioned underwater drivable fiber, whose two ends are respectively connected to a hull and a propeller. By quickly transferring the hull from a 4-20°C environment to a 30-80°C water bath, the underwater micro-engine composed of the fiber bundle rotates to drive the propeller to rotate, thereby driving the model ship to move on the water surface.

[0017] The length of the fiber bundle of the underwater micro engine is 5-30 cm, the fiber torsion force can reach 40 N·m / kg, and the maximum rotation speed can reach 400 rpm when the temperature rises from below 20° C. to above 30° C.

[0018] Technical Effects

[0019] The recombinant spider silk protein hydrogel fiber of the present invention has a fiber driver that contracts and twists in response to light and heat, and the temperature response is around 20°C, which is within the physiological range, and has important application prospects in the field of biomedical materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a flow chart of the present invention;

[0021] Figure 2 This is a macroscopic photograph of a typical fiber prepared in the present invention;

[0022] Figure 3 The electronic scanning photos of fibers with different post-stretching ratios; RSS-8, RSS-12, RSS-16 and RSS-20 are fibers with stretching ratios of 8, 12, 16 and 20, respectively;

[0023] Figure 4 The curves of storage modulus, loss modulus and loss factor of different fibers as the temperature rises;

[0024] Figure 5 is the stress-strain curve of different fibers;

[0025] Figure 6 The photo of the load shrinkage process of RSS-20 fiber; scale bar: 1.5 cm;

[0026] Figure 7 This is a photo of the wound suturing process of RSS-20 fiber; scale bar: 5 mm;

[0027] Figure 8 The curves of the number of rotations and rotation rate of the RSS-20 torsion fiber bundle over time; the temperature before rotation is 20℃, and the thermal stimulation temperature is 50℃;

[0028] Fig. 9 This is a photo of a RSS-20 torsion fiber bundle used as a micro engine to propel a model boat forward on the water. The water bath temperature is 50°C. DETAILED DESCRIPTION

[0029] Example 1

[0030] like Figure 1As shown, this embodiment relates to a method for preparing underwater drivable fibers based on spider silk protein, comprising: dissolving recombinant spider silk protein in deionized water, then dripping it dropwise into a silicotungstic acid solution at a volume ratio of 1:2 and a flow rate of 0.05 mL / min, and stirring it with an automatic stirrer for more than 10 minutes, then a hydrogel can be obtained, and then the hydrogel is post-stretched to obtain Figure 2 The underwater actuatable fiber is shown.

[0031] The recombinant spider silk protein is composed of 4, 8, 16, 32 and 64 core repeating sequences of the golden web spider dragline silk protein MaSpI, respectively. The amino acid sequence of the MaSpI core repeating sequence is shown in SEQ ID No.1.

[0032] The concentration of the recombinant spider silk protein solution is 5-30% (w / v), the concentration of the silicotungstic acid solution is 1-20% (w / v), and the stirring rate is 1500-4000 rpm.

[0033] The post-stretching refers to stretching the cross-linked hydrogel into fibers at a certain multiple, specifically: stretching a cylindrical hydrogel with a length of 1-5 cm and a radius of 2-10 mm in a water bath at a temperature of 25-40°C to 8-30 times the initial length, and then transferring it to 4-20°C for fixation.

[0034] The underwater drive includes the contraction of the fiber and the rotation of the twisted fiber bundle. Contraction means that when a single fiber is quickly transferred from 4-20℃ to a 30-80℃ water bath, the fiber will shorten; while shrinkage means that when a twisted fiber bundle stored at 4-20℃ is quickly transferred to a 30-80℃ water bath, the fiber will rotate and deform.

[0035] The twisted fiber bundle is formed by twisting multiple fibers, specifically: a bundle of 5-20 fibers is placed in an environment at 20°C, one end of the fiber bundle is fixed, and the other end is connected to a rotator; when the ambient temperature is heated to 30°C, the rotator is slowly rotated, and the fiber bundle is twisted immediately; when the twisting is completed, the rotator is quickly stopped, and the ambient temperature is reduced to 4-20°C, and the preparation of the twisted fiber bundle is completed.

[0036] The microscopic surface structure of the underwater actuable fiber prepared by the above method was photographed and analyzed using a scanning electron microscope. The experimental results are as follows: Figure 3 As shown. The length of the sample is 1-4cm, and the effective diameter is 100-500μm. The samples must be gold-sprayed before testing.

[0037] The storage modulus, loss modulus and loss factor of the fiber at different temperatures were tested using a dynamic thermomechanical analyzer. Specifically, the two ends of the fiber with a length of 1-4 cm and an effective diameter of 100-500 μm were fixed using the analyzer's fixture, and the fiber was subjected to a dynamic temperature scanning measurement with a strain of 0.1%, a frequency of 1 Hz, and a preload of 0.1 N. The temperature was raised from 0°C to 80°C at a rate of 3°C / min. Figure 4 As shown in the figure, with the increase of temperature, the storage modulus and loss modulus of the fiber gradually decrease, while the loss factor first increases and then decreases.

[0038] The tensile mechanical properties of the fiber were analyzed using a universal tensile tester. Specifically, the two ends of a fiber with a length of 1-2 cm and an effective diameter of 100-500 μm were clamped using the clamp of the tensile tester, and the fiber was strained at a strain rate of 20 mm / min. -1 , tensile test with preload of 0.1N. Figure 5 As shown, the fiber strength is 71-141 MPa, the breaking strain is 114-270%, the Young's modulus is 223-643 MPa, and the toughness is 135-156 MJ m -3 .

[0039] The contraction actuation process of RSS-20 fiber was photographed and analyzed using a high-speed camera. Figure 6 As shown in the figure, specifically: a RSS-20 fiber with a length of 17 cm and a mass of 12 mg is fixed on the experimental frame, a metal weight with a mass of 0.2 g is hung at the bottom of the fiber, and the ambient temperature is 20°C; after the fiber is stable, a nozzle is used to spray 50°C hot water on the fiber sample, and the fiber shrinks rapidly, thereby lifting the weight.

[0040] Example 2

[0041] like Figure 7 In this embodiment, the fiber is repeatedly passed through a simulated wound placed in a water environment, and infrared light is used to remotely heat the fiber. The fiber shrinks due to the photothermal stimulation, and the shrinking fiber then sutures the wound tightly.

[0042] The initial environmental temperature of the wound is 20° C., the infrared light intensity is 600 W, and the distance between the infrared light source and the fiber is 10 cm.

[0043] Example 3

[0044] In this embodiment, the length of the twisted fiber bundle is 5 cm, and the mass of the twisted reference object is 200 mg.

[0045] like Figure 8As shown, the two ends of the twisted fiber bundle are fixed in the middle of a special square frame, and the end of the fiber is connected to a twisted reference object. The ambient temperature is 20°C. After the reference object is stable, the square frame is quickly immersed in a water bath at a temperature of 50°C. The twisted fiber bundle rotates rapidly, and then drives the reference object to rotate at high speed. The quantitative analysis results show that the fiber bundle rotates 45 times and the maximum rotation speed is 420rpm.

[0046] Example 4

[0047] In this embodiment, the twisted fiber bundle is composed of 5 RSS-20 single fibers, with a length of 15 cm and a mass of about 290 mg. The length of the model ship is 15 cm, the height is 5-10 cm, and the mass is 80 g.

[0048] like Fig. 9 As shown, the twisted fiber bundle is fixed to the bottom of the model ship, and the end of the fiber bundle near the stern is connected to the propeller. The model ship is quickly transferred from a 20°C environment to a 50°C water bath, and the fiber bundle rotates to drive the propeller to rotate at high speed, driving the model ship to move on the water surface.

[0049] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The protection scope of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. Each implementation scheme within its scope shall be subject to the constraints of the present invention.

Claims

1. A method for preparing underwater drivable fibers based on spider silk protein, characterized in that: A hydrogel is formed by a cross-linking reaction between a recombinant spider silk protein solution and a silicotungstic acid solution, and then the hydrogel is subjected to a post-stretching treatment to obtain an underwater actuable fiber; The recombinant spider silk protein is specifically composed of 4, 8, 16, 32 or 64 core repeating sequences of the Nephila silkspider dragline silk protein MaSpI, and the amino acid sequence of the MaSpI core repeating sequence is shown in SEQ ID No.

1.

2. The method for preparing underwater drivable fibers based on spider silk protein according to claim 1, characterized in that: The concentration of the recombinant spider silk protein solution is 5-30% w / v, the concentration of the silicotungstic acid solution is 1-20% w / v, and the volume ratio of the two is 1:

2.

3. The method for preparing underwater drivable fibers based on spider silk protein according to claim 1 or 2, characterized in that: The cross-linking reaction is as follows: dripping a 1 volume ratio recombinant spider silk protein solution dropwise into a 2 volume ratio silicotungstic acid solution, stirring to promote the protein and silicotungstic acid to fully react to form a hydrogel, the cross-linking temperature is 25-40°C, the stirring rate is 1500-3000 rpm, and the stirring time is 10-30 min.

4. The method for preparing underwater drivable fibers based on spider silk protein according to claim 1, characterized in that: The post-stretching treatment refers to: manually kneading the hydrogel into a hydrogel with a length of 1-5 cm and a radius of 2-10 mm, and stretching it in a water bath at a temperature of 25-40°C to 8-30 times the initial length at a stretching speed of 500-2000 cm min -1 , and then transferred to 4-20℃ for fixation.

5. An underwater drivable fiber, characterized in that: Prepared based on the method described in any one of claims 1-4; the driving includes: contraction, torsion and / or rotation.

6. The underwater drivable fiber according to claim 5, characterized in that: Its radius is 50-250 μm, strength is 71-141 MPa, fracture strain is 114-270%, Young's modulus is 223-643 MPa, and toughness is 135-156 MJ m -3 .

7. The underwater drivable fiber according to claim 5, characterized in that: The shrinking means: quickly transferring a single underwater drivable fiber from 4-20°C to a 30-80°C water bath to achieve shrinkage of the fiber; The twisting means: placing a bundle of 5-20 underwater drivable fibers in an environment at 20°C, with one end of the fiber bundle fixed and the other end connected to a rotator; when the ambient temperature is heated to 30°C, slowly rotating the rotator, the fiber bundle will be twisted; when the twisting is completed, the rotator is quickly stopped, and the ambient temperature is reduced to 4-20°C, and the preparation of the twisted fiber bundle is completed; The rotation means that the twisted fiber bundle stored at 4-20°C is quickly transferred to a water bath at 30-80°C, and the fiber will undergo rotational deformation.

8. An application of the underwater drivable fiber according to any one of claims 5 to 7, wherein the fiber is used to prepare wound sutures or underwater micro engines.

9. The use according to claim 8, characterized in that: The wound suture has a radius of 50-250 μm, a strength of 71-141 MPa, a breaking strain of 114-270%, a Young's modulus of 223-643 MPa, and a toughness of 135-156 MJ m -3 When the temperature rises from below 20°C to above 30°C, the fiber can shrink by more than 50% within 2 seconds.

10. The use according to claim 8, characterized in that: The underwater micro-engine is constructed by connecting the two ends of the underwater drivable fiber to the hull and the propeller respectively, and by quickly transferring the hull from a 4-20°C environment to a 30-80°C water bath, so that the underwater micro-engine composed of the fiber bundle rotates to drive the propeller to rotate, thereby driving the model ship to move on the water surface; The length of the fiber bundle of the underwater micro engine is 5-30 cm.

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