Ultraviolet-curable bionic meniscus and preparation method thereof

Abstract

The invention discloses an ultraviolet-curable bionic meniscus and a preparation method thereof, and relates to the technical field of meniscus tissue substitutes, the shape of the bionic meniscus is a C-shaped structure simulating a natural meniscus, and the C-shaped structure of the bionic meniscus is sequentially divided into a front part, a middle part and a rear part from front to back, the surface strength of the bionic meniscus increases in a gradient mode from the front portion to the middle portion and decreases in a gradient mode from the middle portion to the rear portion. The C-shaped knot of the bionic meniscus is sequentially divided into an inner side, a middle part and an outer side from inside to outside, and the surface strength of the bionic meniscus is increased in a gradient manner from the outer side to the middle in the front area and the middle area and is decreased in a gradient manner from the middle to the inner side; the surface strength of the bionic meniscus is gradually reduced from the outer side to the inner side in the rear area; the bionic meniscus is prepared by curing an ultraviolet light cross-linked material. The non-degradable bionic meniscus with gradient intensity distribution is prepared from an ultraviolet curing material, and the mechanical property of the bionic meniscus is similar to that of a natural meniscus.

Description

Technical Field

[0001] The present invention relates to the technical field of meniscus tissue substitutes, and further relates to a bio-mimetic meniscus curable by ultraviolet light and a preparation method thereof. Background Art

[0002] The knee meniscus is a C-shaped fibrocartilaginous structure located between the femoral plateau and the tibial plateau, which helps to increase the contact area between the femoral plateau and the tibial plateau and reduce the contact pressure. Meniscus injury is one of the most common injuries of the knee joint. Meniscus injury can occur through trauma and tearing, such as in sports activities, accidents, or due to the degeneration of the meniscus cartilage in the elderly. Although the meniscus tear can be repaired to a certain extent, due to the lack of sufficient blood supply, this cartilage tissue usually cannot heal normally. Therefore, especially in the case of complex tears, meniscus replacement is a viable treatment method, which can repair the surrounding tissues while replacing the damaged tissues.

[0003] During meniscus replacement, meniscus prostheses are essential and they play a role in restoring function. However, improper material selection is one of the reasons for the failure of meniscus implantation, which will ultimately lead to tissue wear, tearing and fracture. Therefore, extensive research has been carried out on various synthetic composite materials used as meniscus substitutes, including polytetrafluoroethylene, carbon fiber-polyurethane-poly(L-lactide), polyester and polyurethane / polylactic acid composite materials, etc. There have been attempts to produce meniscus substitutes made of polytetrafluoroethylene (Biomaterials, 1994, 15(3): 223-230.) and polyester-carbon fiber (Biomaterials, 1990, 11(1): 13-16.), but neither has achieved satisfactory results. The material wear of the implant will lead to a large amount of synovial inflammatory reaction and cartilage damage. There have also been studies testing polyester and polytetrafluoroethylene with polyurethane coatings (Biomaterials, 1994, 15(4): 243-250.). Although the coated implants have advantages over uncoated implants or meniscectomy alone, the overall effect of implants made of polyester or polytetrafluoroethylene is not satisfactory. Implants without polyurethane coatings are more prone to wear and deformation, while polyurethane-coated prostheses are more likely to cause synovitis.

[0004] A common limitation of these composite materials is that they cannot provide long-term protection for articular cartilage, so these solutions are not suitable for young and energetic patients. Other problems related to existing meniscus replacement include the inability to replicate the function of natural meniscus, prosthesis wear, and possible immune responses.

[0005] The natural meniscus can be regarded as a non - homogeneous collagen fiber - reinforced composite material. Polymer composite biomaterials are both anisotropic and non - homogeneous, which conform to the characteristics of the natural meniscus. Therefore, they can be used as ideal alternative materials for meniscus prostheses.

[0006] Currently, the synthetic materials of popular meniscus substitutes mainly include polyurethane, polytetrafluoroethylene, etc., which have good biocompatibility. Among them, polyurethane materials with adjustable molecular structure and controllable material properties are the current research hotspots for preparing meniscus substitutes. Currently, there are three types of popular polyurethane - based menisci, the partial meniscus prostheses CMI and Aci - fit that can be used in the human body, and the permanent total meniscus prosthesis NUsurface for clinical trials. The main materials of Acifit and NUsurface are polyurethane. A degradable polycaprolactone / polyurethane meniscus scaffold prepared by the British company Orteq has been commercialized (trade name Atifit) (Biomaterials, 35, 3527 - 3540, 2014). In 2010, the R & D team of the Israeli company ActiveImplants developed a permanent polycarbonate meniscus substitute (Nusurface), which is the first meniscus prosthesis to enter phase I clinical trials. Nusurface is a non - anchored implant that fits the femur.

[0007] However, the existing meniscus tissue substitutes still have problems such as insufficient bionic effect of mechanical strength and poor fatigue resistance. They will be damaged and degraded within half a year or one year after being implanted in the body, so they are not conducive to long - term use. Summary of the Invention

[0008] To solve the problems existing in the prior art, the present invention provides a UV - curable bionic meniscus and its preparation method. By designing a mask plate with different light transmittances and irradiating with ultraviolet light, a polyurethane meniscus with different mechanical strength distributions is formed. This meniscus simulates the mechanical strength distribution of the natural meniscus, making its mechanical properties similar to those of the natural meniscus, having good bionic performance, bionic structure, good biocompatibility and in - vivo mechanical stability.

[0009] One of the purposes of the present invention is to provide a UV - curable bionic meniscus.

[0010] The shape of the ultraviolet-curable bionic meniscus described in the present invention is a C-shaped structure that mimics the natural meniscus. The C-shaped structure of the bionic meniscus is sequentially divided into a front part, a middle part, and a rear part from front to back. The surface strength of the bionic meniscus increases in a gradient along the direction from the front part to the middle part and decreases in a gradient along the direction from the middle part to the rear part; the C-shaped structure of the bionic meniscus is sequentially divided into an inner part, a middle part, and an outer part from inside to outside. The surface strength of the bionic meniscus increases in a gradient along the direction from the outer part to the middle part in the front part and middle part regions and decreases in a gradient along the direction from the middle part to the inner part; the surface strength of the bionic meniscus decreases in a gradient along the direction from the outer part to the inner part in the rear part region; the bionic meniscus is prepared by curing a material that can be crosslinked by ultraviolet light.

[0011] Preferably,

[0012] The surface strength of the bionic meniscus is different in different regions, and the overall surface nanoindentation Young's modulus strength ranges from 0.1 to 25 MPa, preferably from 0.5 to 15 MPa;

[0013] Preferably,

[0014] The gradient meniscus is divided into a front inner region, a front middle region, a front outer region, a middle inner region, a middle middle region, a middle outer region, a rear inner region, a rear middle region, and a rear outer region from front to back and from inside to outside;

[0015] The surface nanoindentation Young's modulus of the front inner region is 1 to 15 MPa, preferably 2 to 6 MPa;

[0016] The surface nanoindentation Young's modulus of the front middle region is 1 to 20 MPa, preferably 3 to 10 MPa;

[0017] The surface nanoindentation Young's modulus of the front outer region is 1 to 20 MPa, preferably 2 to 8 MPa;

[0018] The surface nanoindentation Young's modulus of the middle inner region is 1 to 20 MPa, preferably 2 to 8 MPa;

[0019] The surface nanoindentation Young's modulus of the middle middle region is 1 to 25 MPa, preferably 4 to 15 MPa;

[0020] The surface nanoindentation Young's modulus of the middle outer region is 1 to 25 MPa, preferably 3 to 15 MPa;

[0021] The surface nanoindentation Young's modulus of the rear inner region is 0.1 to 8 MPa, preferably 0.5 to 3 MPa;

[0022] The surface nanoindentation Young's modulus of the rear middle region is 1 to 10 MPa, preferably 1 to 5 MPa;

[0023] The surface nano-indentation Young's modulus of the posterior outer region is 1-10 MPa, preferably 1-4 MPa.

[0024] Preferably,

[0025] The ultraviolet light-crosslinkable material is prepared by mixing raw materials including the following components:

[0026] Polyurethane prepolymer and photoinitiator;

[0027] Based on the total amount of polyurethane prepolymer and photoinitiator being 100 parts by weight:

[0028] Polyurethane prepolymer 95-99 parts by weight;

[0029] Photoinitiator 1-5 parts by weight.

[0030] Preferably,

[0031] Based on the total amount of polyurethane prepolymer and photoinitiator being 100 parts by weight:

[0032] Polyurethane prepolymer 95.5-98.5 parts by weight;

[0033] Photoinitiator 1.5-4.5 parts by weight.

[0034] Preferably,

[0035] The polyurethane prepolymer is a polyurethane-based photosensitive resin prepolymer, preferably polyurethane acrylate; and / or,

[0036] The photoinitiator is at least one of a cleavage-type initiator, a photosensitive initiator, a cationic photoinitiator, and a radical-cation hybrid photoinitiator.

[0037] The cleavage-type initiator is a commonly used photoinitiator in the art, such as: photoinitiator 1173, photoinitiator 184, photoinitiator 907, photoinitiator 369, photoinitiator 1490, photoinitiator 1700, etc.;

[0038] The photosensitive initiator is a commonly used photoinitiator in the art, such as: photoinitiator BP, etc.;

[0039] The cationic photoinitiator is at least one of an onium salt-based photoinitiator, a metal organic-based photoinitiator, and an organosilane-based photoinitiator;

[0040] The onium salt-based photoinitiator is a commonly used photoinitiator in the art, such as: at least one of diaryliodonium salt, triarylsulfonium salt, and alkylsulfonium salt;

[0041] The metal organic-based photoinitiator is a commonly used photoinitiator in the art, such as: iron arene salt, sulfonyloxy ketone, etc.;

[0042] The organosilane photoinitiator is a commonly used photoinitiator in the art, such as: triarylsiloxane, etc.;

[0043] The radical-cation hybrid photoinitiator is a commonly used photoinitiator in the art, such as: diazonium salt photoinitiator TPO, etc.

[0044] Preferably,

[0045] The bionic meniscus is prepared by 3D printing or casting process.

[0046] Specifically, the following scheme can be adopted:

[0047] After the 3D printing or casting process, ultraviolet light is irradiated through a mask plate with different light transmittances to make the sample present different gradient changes.

[0048] The second object of the present invention is to provide a preparation method of a bionic meniscus that can be cured by ultraviolet light.

[0049] The preparation method of the bionic meniscus that can be cured by ultraviolet light according to the present invention includes:

[0050] Simulating the surface strength distribution of the natural meniscus, and photocuring the ultraviolet-light crosslinkable material by designing a mask plate with a corresponding light transmittance distribution to obtain the bionic meniscus.

[0051] Preferably, the method includes:

[0052] (1) Design a mask plate with a corresponding gradient light transmittance according to the surface strength distribution of the natural meniscus, and the light transmittance of the mask plate increases with the increase of the surface strength of the meniscus at different positions;

[0053] (2) Photocuring the ultraviolet-light crosslinkable material by irradiating the mask plate with gradient light transmittance with ultraviolet light to obtain the bionic meniscus, and the surface strength of the ultraviolet-cured meniscus increases with the increase of the light transmittance of the mask plate.

[0054] Preferably,

[0055] The light transmittance of the mask plate is 1%-100%, preferably 20%-80%.

[0056] Specifically, the following technical scheme can be adopted:

[0057] A meniscus that can replace natural meniscus tissue and mimics the surface strength distribution of natural meniscus. The main body of this meniscus is made of materials such as ultraviolet-curable polyurethane. The curing degree of the ultraviolet-cured meniscus is controlled by regulating the content of the photoinitiator added. Through comparison of several groups containing different photoinitiators, the group with the most suitable photoinitiator content (the mechanics after curing is similar to that of natural meniscus) is selected to prepare the meniscus with gradient distribution.

[0058] Using materials such as ultraviolet-cured polyurethane as the raw materials for casting or 3D printing, and designing a mask plate with different light transmittances according to the gradient distribution of natural meniscus. After the polyurethane prepolymer and the photoinitiator are stirred and mixed evenly, they are put into the corresponding mold, and irradiated with ultraviolet light with a wavelength of 250 - 420 nm (the shorter the wavelength of ultraviolet light irradiation, the longer the irradiation time, and the faster the curing speed. The specific wavelength can be selected according to the best absorption band of the photoinitiator) through the mask plate with different light transmittances (or after 3D printing the meniscus sample, irradiating through the mask plate with different light transmittances with ultraviolet light with a wavelength of 250 - 420 nm). The ultraviolet light irradiates the materials such as ultraviolet-curable polyurethane through the mask plate, causing them to undergo ultraviolet curing, thereby forming a bionic meniscus with strength distribution.

[0059] The third object of the present invention is to provide a bionic meniscus obtained by the preparation method of the ultraviolet-curable bionic meniscus.

[0060] The present invention uses specific ultraviolet-curable materials such as polyurethane to prepare a non-degradable bionic meniscus with gradient strength distribution through 3D printing technology or casting process, making its mechanical properties similar to those of natural meniscus, and having a specific bionic structure, with good biocompatibility and in-vivo mechanical stability. The bionic meniscus of the present invention simulates the gradient distribution of the natural meniscus structure. By analyzing the mechanical properties of the natural meniscus, a mechanical strength distribution model simulating the natural meniscus is designed. The purpose is to improve the problem that the mechanical property distribution of existing products does not match that of natural meniscus, and to design an artificial meniscus substitute with a more bionic mechanical strength distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is the front view of the bionic meniscus of the present invention;

[0062] Among them, 1 - anterior medial area, 2 - anterior central area, 3 - anterior lateral area, 4 - middle medial area, 5 - middle central area, 6 - middle lateral area, 7 - posterior medial area, 8 - posterior central area, 9 - posterior lateral area;

[0063] Figure 2 It is the structural schematic diagram of the mask plate of the present invention;

[0064] According to the strength distribution of the natural meniscus, it is designed and divided into 9 regions with different light transmittances, and the light transmittance of each region can be adjusted according to the strength requirements of the bionic meniscus;

[0065] Figure 3 It is the tensile test result of the ultraviolet cross-linked materials with different photoinitiator contents prepared in Example 5;

[0066] Figure 4 It is the cross-linking density test result of the ultraviolet cross-linked materials with different photoinitiator contents prepared in Example 5;

[0067] Figure 5 It is the surface Young's modulus obtained by nanoindentation test of the ultraviolet cross-linked materials with different initiator contents prepared in Example 5;

[0068] From Figure 3 , Figure 4 and Figure 5 's results, it can be seen that the increase in the photoinitiator content can increase the tensile strength, cross-linking density and surface Young's modulus of the ultraviolet cross-linkable materials. Therefore, the tensile strength, cross-linking density and surface strength of the bionic meniscus can be controlled by adjusting the photoinitiator content;

[0069] Figure 6 It is the surface Young's modulus obtained by nanoindentation test of the bionic meniscus prepared in Example 1 divided into the anterior inner region, anterior middle region, anterior outer region, middle inner region, middle middle region, middle outer region, posterior inner region, posterior middle region, and posterior outer region as shown in Figure 1 ;

[0070] From Figure 6 's results, it can be seen that by changing the light transmittance of the photomask, the surface strength of the sample can be changed: the higher the light transmittance of the photomask, the higher the modulus of the sample. Therefore, the surface strength at different positions of the bionic meniscus can be adjusted by changing the light transmittance of the photomask;

[0071] Figure 7 It is the surface Young's modulus obtained by nanoindentation test of the natural meniscus of a pig divided into the anterior inner region, anterior middle region, anterior outer region, middle inner region, middle middle region, middle outer region, posterior inner region, posterior middle region, and posterior outer region as shown in Figure 1 ;

[0072] Compare Figure 6 with Figure 7From the results, it can be seen that the trend of the surface Young's modulus of the ultraviolet-curable bionic meniscus prepared by the present invention is similar to the trend and range of the surface strength of the natural meniscus. Its surface Young's modulus increases in a gradient along the anterior to middle direction and decreases in a gradient along the middle to posterior direction; the surface Young's modulus increases in a gradient along the lateral to middle direction and decreases in a gradient along the middle to medial direction in the anterior and middle regions; and it decreases in a gradient along the lateral to medial direction in the posterior region. Detailed implementation mode

[0073] The present invention will be specifically described below in conjunction with specific drawings and embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art according to the content of the present invention still fall within the protection scope of the present invention.

[0074] All raw materials used in the embodiments of the present invention are commercially available products.

[0075] Example 1

[0076] 9.9 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.1 g of photoinitiator 184 (Guangdong Boxin New Materials Technology Co., Ltd.) were stirred and mixed evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 1%.

[0077] The above-prepared UV-crosslinkable material was transferred into a meniscus mold. Ultraviolet light (wavelength 365 nm, power 30 W) passed through a mask plate with a gradient change in light transmittance. As Figure 2 shown, the light transmittance in the A-I region is 50%, the light transmittance in the A-M region is 70%, the light transmittance in the A-O region is 60%, the light transmittance in the C-I region is 60%, the light transmittance in the C-M region is 80%, the light transmittance in the C-O region is 70%, the light transmittance in the P-I region is 20%, the light transmittance in the P-M region is 30%, and the light transmittance in the P-O region is 40%. The material was cured for 5 minutes to prepare a bionic meniscus with a gradient change in surface strength.

[0078] Example 2

[0079] 9.7 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.3 g of photoinitiator TPO (Guangdong Boxin New Materials Technology Co., Ltd.) were stirred and mixed evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 3%.

[0080] Transfer the UV-crosslinkable material prepared above into a meniscus mold. Pass ultraviolet light (wavelength 365 nm, power 30 W) through a mask plate with a gradient light transmittance change, such as Figure 2 shown. The light transmittance of area A-I is 40%, the light transmittance of area A-M is 70%, the light transmittance of area A-O is 60%, the light transmittance of area C-I is 60%, the light transmittance of area C-M is 80%, the light transmittance of area C-O is 70%, the light transmittance of area P-I is 20%, the light transmittance of area P-M is 30%, and the light transmittance of area P-O is 40%. Cure the material for 5 minutes to prepare a biomimetic meniscus with a gradient change in surface strength.

[0081] Example 3

[0082] Stir and mix 9.5 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.5 g of photoinitiator 1173 (Guangdong Boxin New Materials Technology Co., Ltd.) evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 5%.

[0083] Transfer the UV-crosslinkable material prepared above into a meniscus mold. Pass ultraviolet light (wavelength 285 nm, power 30 W) through a mask plate with a gradient light transmittance change, such as Figure 2 shown. The light transmittance of area A-I is 50%, the light transmittance of area A-M is 70%, the light transmittance of area A-O is 60%, the light transmittance of area C-I is 60%, the light transmittance of area C-M is 80%, the light transmittance of area C-O is 70%, the light transmittance of area P-I is 20%, the light transmittance of area P-M is 30%, and the light transmittance of area P-O is 40%. Cure the material for 3 minutes to prepare a biomimetic meniscus with a gradient change in surface strength.

[0084] Example 4

[0085] Stir and mix 9.7 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.3 g of photoinitiator 184 (Guangdong Boxin New Materials Technology Co., Ltd.) evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 3%.

[0086] Add the UV-crosslinkable material prepared above into the cartridge of a 3D printer and perform printing. After printing is completed, pass ultraviolet light (wavelength 365 nm, power 30 W) through a photomask plate, such as Figure 2As shown, the light transmittance of the A-I region is 50%, the light transmittance of the A-M region is 70%, the light transmittance of the A-O region is 60%, the light transmittance of the C-I region is 60%, the light transmittance of the C-M region is 80%, the light transmittance of the C-O region is 70%, the light transmittance of the P-I region is 20%, the light transmittance of the P-M region is 30%, and the light transmittance of the P-O region is 40%. The printing accuracy is 0.1 mm per layer, the total thickness is 6 mm, and the irradiation time per layer is 10 s, and a bionic meniscus with a gradient change in surface strength is prepared.

[0087] Example 5

[0088] 9.9 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.1 g of photoinitiator TPO (Guangdong Boxin New Materials Technology Co., Ltd.) were stirred and mixed evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 1%.

[0089] 9.8 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.2 g of photoinitiator TPO (Guangdong Boxin New Materials Technology Co., Ltd.) were stirred and mixed evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 2%.

[0090] 9.7 g of polyurethane-based photosensitive resin prepolymer of type B2116 (Guangdong Boxin New Materials Technology Co., Ltd.) and 0.3 g of photoinitiator TPO (Guangdong Boxin New Materials Technology Co., Ltd.) were stirred and mixed evenly to prepare a UV-crosslinkable material with a photoinitiator mass fraction of 3%.

[0091] The above-prepared UV-crosslinkable materials with different photoinitiator mass fractions were respectively transferred into a meniscus casting mold. Ultraviolet light (wavelength 365 nm, power 30 W) passed through a mask plate with a gradient change in light transmittance, as Figure 2 shown, the light transmittance of the A-I region is 50%, the light transmittance of the A-M region is 70%, the light transmittance of the A-O region is 60%, the light transmittance of the C-I region is 60%, the light transmittance of the C-M region is 80%, the light transmittance of the C-O region is 70%, the light transmittance of the P-I region is 20%, the light transmittance of the P-M region is 30%, and the light transmittance of the P-O region is 40%, to cure the material, and the curing time is 4 min, and a bionic meniscus with a gradient change in surface strength is prepared.

[0092] The bionic menisci with photoinitiator mass fractions of 1%, 2%, and 3% prepared in the above Example 5 were subjected to relevant tensile tests to characterize the tensile strength of the materials. The test method is as follows:

[0093] Test conditions for the tensile test: The test was carried out according to GB / T 528-2009, and 5 splines were tested in each group of experiments. Three samples were analyzed in each test. All results were calculated as mean ± standard deviation. Stress (σ) and strain (ε) were calculated using (1) and (2) respectively.

[0094] σ = F / L 0 (1)

[0095] ε = (L - L 0 / L 0 ) × 100% (2)

[0096] where F is the force used, L is the height between the fixtures, S0 and L0 are the initial cross-sectional area and height respectively, and the test results are as Figure 3 shown.

[0097] The crosslinking density of the biomimetic menisci with photoinitiator mass fractions of 1%, 2%, and 3% prepared in Example 5 above was tested to characterize the crosslinking density of the material. The test method is as follows:

[0098] First, place the sample in the test tube, put on the sealing ring, and adjust the sealing ring; then place the test tube at the bottom of the coil so that its distance from the bottom of the coil is about 1 mm; finally, tighten the lid of the coil and the ejector rod at the top of the test tube (the ejector rod cannot push the test tube to the bottom of the coil). The test temperature is 90 °C, and wait for the temperature control to stabilize (about 20 min), and the specific test results are as Figure 4 shown.

[0099] For the biomimetic menisci with photoinitiator mass fractions of 1%, 2%, and 3% prepared in Example 5 above, the biomimetic meniscus with a photoinitiator mass fraction of 1% prepared in Example 1, and the natural meniscus of a miniature pig (Note: Since it is difficult to obtain fresh, healthy and intact natural tissue samples of human menisci, the knee joint menisci of adult miniature pigs, which are similar in shape and mechanical properties to human menisci, are selected for testing to provide a reference for the mechanical strength distribution trend of natural menisci.), relevant nanoindentation tests were carried out to characterize the surface strength. The test method is as follows:

[0100] According to the nanoindentation method disclosed by J.T. Moyer et al. in Journal of Biomechanics 45(2012)2230–2235 and Acta Biomaterialia 9(2013)6624–6629, the surface strength was tested. The specific method was as follows: Using a nanoindentation mechanical tester, the surface strength of the material was detected. 15 indentations were made on each sample at randomly spaced indentation positions in space, perpendicular to the surface, with an indentation spacing of at least 250 μm to avoid the influence of subsequent indentations. The nanoindentation mechanical tester adopted a trapezoidal loading sequence with a rise time of 5 s and a holding of 1 mN for 70 s. These test parameters were adaptively adjusted according to the preliminary test results, and the surface penetration was limited to approximately 10 μm. Curve fitting was performed on the generated load-displacement data to determine the instantaneous Young's modulus, and then the average value was obtained. The specific test results are as Figure 5 、 Figure 6 、 Figure 7 shown.

Claims

1. A UV-curable bionic meniscus, characterized in that: the shape of the bionic meniscus is a C-shaped structure that mimics the natural meniscus. The C-shaped structure of the bionic meniscus is divided into a front part, a middle part, and a rear part in sequence from front to back. The surface strength of the bionic meniscus increases in a gradient along the direction from the front part to the middle part and decreases in a gradient along the direction from the middle part to the rear part. The C-shaped structure of the bionic meniscus is divided into an inner side, a middle part, and an outer side in sequence from inside to outside. The surface strength of the bionic meniscus increases in a gradient along the direction from the outer side to the middle part and decreases in a gradient along the direction from the middle part to the inner side in the front part and the middle part regions. The surface strength of the bionic meniscus decreases in a gradient along the direction from the outer side to the inner side in the rear part region. The bionic meniscus is prepared by curing a UV-crosslinkable material.

2. The bionic meniscus according to claim 1, characterized in that: the surface strength of the bionic meniscus is different in different regions, and the overall surface nanoindentation Young's modulus ranges from 0.1 to 25 MPa, preferably from 0.5 to 15 MPa; preferably, the gradient meniscus is divided into a front inner region, a front middle region, a front outer region, a middle inner region, a middle middle region, a middle outer region, a rear inner region, a rear middle region, and a rear outer region from front to back and from inside to outside; the surface nanoindentation Young's modulus of the front inner region is 1 to 15 MPa, preferably 2 to 6 MPa; the surface nanoindentation Young's modulus of the front middle region is 1 to 20 MPa, preferably 3 to 10 MPa; the surface nanoindentation Young's modulus of the front outer region is 1 to 20 MPa, preferably 2 to 8 MPa; the surface nanoindentation Young's modulus of the middle inner region is 1 to 20 MPa, preferably 2 to 8 MPa; the surface nanoindentation Young's modulus of the middle middle region is 1 to 25 MPa, preferably 4 to 15 MPa; the surface nanoindentation Young's modulus of the middle outer region is 1 to 25 MPa, preferably 3 to 15 MPa; the surface nanoindentation Young's modulus of the rear inner region is 0.1 to 8 MPa, preferably 0.5 to 3 MPa; the surface nanoindentation Young's modulus of the rear middle region is 1 to 10 MPa, preferably 1 to 5 MPa; the surface nanoindentation Young's modulus of the rear outer region is 1 to 10 MPa, preferably 1 to 4 MPa.

3. The bionic meniscus according to claim 1, characterized in that: the UV-crosslinkable material is prepared by mixing raw materials including the following components: a polyurethane prepolymer and a photoinitiator; calculated based on the total amount of the polyurethane prepolymer and the photoinitiator being 100 parts by weight: 95 - 99 parts by weight of the polyurethane prepolymer; 1 - 5 parts by weight of the photoinitiator.

4. The bionic meniscus according to claim 3, characterized in that: calculated based on the total amount of the polyurethane prepolymer and the photoinitiator being 100 parts by weight: 95.5 - 98.5 parts by weight of the polyurethane prepolymer; 1.5 - 4.5 parts by weight of the photoinitiator.

5. The bionic meniscus according to claim 3, characterized in that: the polyurethane prepolymer is a polyurethane-based photosensitive resin prepolymer, preferably polyurethane acrylate; and / or, The photoinitiator is at least one of a cleavage-type initiator, a photosensitive initiator, a cationic photoinitiator, and a radical-cation hybrid photoinitiator.

6. The bionic meniscus according to claim 1, characterized in that: The bionic meniscus is prepared by a 3D printing or casting process.

7. A method for preparing a bionic meniscus according to any one of claims 1-6, characterized in that the method comprises: simulating the surface strength distribution of the natural meniscus, and performing photocuring on a UV-crosslinkable material by designing a mask plate with a corresponding light transmittance distribution to obtain the bionic meniscus.

8. The preparation method according to claim 7, characterized in that the method comprises: (1) Designing a mask plate with a corresponding gradient light transmittance according to the surface strength distribution of the natural meniscus; (2) Performing photocuring on a UV-crosslinkable material by irradiating the mask plate with gradient light transmittance with ultraviolet light to obtain the bionic meniscus.

9. The preparation method according to claim 8, characterized in that: The light transmittance of the mask plate is 1%-100%, preferably 20%-80%.

10. A UV-curable bionic meniscus obtained by the preparation method according to any one of claims 7-9.

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