An intelligent visualization measuring film for cartilage / meniscus defects and a preparation method thereof

Abstract

The application provides an intelligent developing measurement film for cartilage / meniscus defects and a preparation method thereof, relates to the technical field of medicines, and comprises the following steps: performing low-temperature oxygen plasma treatment on one side of a medical flexible substrate to perform surface activation and form an activated layer; forming a biomimetic anchoring substrate on the activated layer; depositing MMP-responsive microcapsules on the biomimetic anchoring substrate, performing gas-phase crosslinking, and drying to obtain an MMP-response functional color developing layer; and printing a measurement grid on the other side of the medical flexible substrate. The technical problem that the prior art cartilage / meniscus defect measurement method with medical imaging and intraoperative auxiliary measurement as cores has poor adaptability to complex curved surfaces and irregular defects, high error rate, and cannot quickly and accurately obtain morphological parameters of defects in an operation is solved.

Description

Technical Field

[0001] This invention relates to the field of medical technology, and in particular to an intelligent imaging measurement film for cartilage / meniscus defects and its preparation method. Background Technology

[0002] Osteoarthritis (OA), a prevalent degenerative joint disease worldwide, severely damages the knee joint. In orthopedic clinical practice, the knee joint, as the most weight-bearing and frequently used joint in the human body, relies heavily on the integrity of its cartilage and meniscus for its functional status. Articular cartilage covers the bone ends, providing a low-friction sliding interface; while the meniscus plays a crucial protective role by increasing the contact area, distributing mechanical loads, absorbing shock, and enhancing joint stability. However, due to their inherent structural characteristics, the meniscus and cartilage have extremely limited intrinsic healing capacity after injury. Once injury occurs, if effective intervention is not provided in a timely manner, the disease will continue to progress, not only exacerbating symptoms such as joint pain and limited mobility but also accelerating cartilage degeneration, thereby inducing or worsening osteoarthritis.

[0003] Given the crucial supporting role of cartilage and the meniscus in knee joint function, precise repair after injury has become a key research focus in orthopedics and sports medicine. With the development of tissue engineering and regenerative medicine, various repair techniques have been applied in clinical practice. These include microfracture / microdrilling techniques for full-thickness cartilage injuries, autologous chondrocyte transplantation (ACT) and osteochondral grafting (OCT), as well as suture techniques and allogeneic meniscus transplantation for meniscus repair. However, the successful implementation of these advanced repair techniques largely depends on accurate morphological assessment of cartilage and meniscus defects. Studies have shown that parameters such as the area, geometric contour, depth, and specific location of the defect are key to developing individualized repair plans. For example, cartilage defects smaller than 2 cm² may be suitable for microfracture surgery, while larger or more complex defects require consideration of grafting techniques. Therefore, accurate morphological assessment not only affects the choice of surgical approach but also relates to the quality of graft preparation and matching, thus determining postoperative tissue integration and functional recovery.

[0004] Currently, cartilage / meniscus defect assessment methods centered on medical imaging and intraoperative auxiliary measurements have become clinical standards. Compared to purely visual estimation, these techniques have significant value in providing quantitative data and assisting preoperative planning. However, existing mainstream techniques each have inherent limitations, preventing them from achieving ideal accuracy, real-time performance, and convenience. While medical imaging measurements (such as MRI and CT) offer advantages in morphological visualization, their measurement errors (e.g., MRI's measurement error for cartilage defect area can reach 15%-20%) and their disconnect from the actual intraoperative defect morphology limit their reliability as a basis for precise intraoperative decision-making. Arthroscopic probe measurement techniques, although usable intraoperatively to some extent, rely on the operator's subjective estimation and have poor adaptability to complex surfaces and irregular defects, resulting in low repeatability and a high error rate. The "sterile packaging paper imprinting method," occasionally used as a non-standard technique, is relatively convenient, but lacks objectivity and standardization throughout the process, failing to provide digital, recordable results.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One of the objectives of this invention is to provide a method for preparing an intelligent imaging measurement film for cartilage / meniscus defects, in order to solve the technical problems of existing cartilage / meniscus defect measurement methods that rely on medical imaging and intraoperative auxiliary measurement, which have poor adaptability to complex curved surfaces and irregular defects and high error rates, and cannot quickly and accurately obtain the morphological parameters of the defects during surgery.

[0007] The second objective of this invention is to provide an intelligent imaging measurement film for cartilage / meniscus defects.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0009] In a first aspect, the present invention provides a method for preparing a smart imaging measurement film for cartilage / meniscus defects, comprising the following steps:

[0010] A. Surface activation is achieved by low-temperature oxygen plasma treatment on one side of the medical flexible substrate to form an activation layer;

[0011] B. The medical flexible substrate treated in step A is immersed in a first buffer solution containing 1.0~5.0 mg / mL of catecholamine compounds to carry out a self-polymerization reaction, forming a biomimetic anchoring substrate on the activation layer. MMP-responsive microcapsules are deposited on the biomimetic anchoring substrate, crosslinked in the gas phase, and dried to obtain an MMP-responsive functional colorimetric layer.

[0012] The catecholamine compounds include at least one of dopamine, norepinephrine, and dopamine derivatives; the pH of the first buffer solution is 7.5 to 9.0;

[0013] C. Print a measurement grid on the other side of the medical flexible substrate.

[0014] Furthermore, the preparation method of the MMP responsive microcapsules includes adding the wall material solution to the core material oil phase at a volume ratio of 1:1.5 to 1:5 under high-speed homogenization, emulsifying to form an oil-in-water primary emulsion, adding the oil-in-water primary emulsion to a cold aqueous solution containing a stabilizer at a volume ratio of 1:5 to 1:20, stirring to form an oil-in-water complex emulsion, adding a curing agent to precipitate the wall material, adding a crosslinking agent, and collecting to obtain the MMP responsive microcapsules;

[0015] The wall material solution contains 3-10% w / v of MMP-responsive material;

[0016] The core material oil phase contains 0.1-2.0% w / v of pH-sensitive dye, 1-5% w / v of acid precursor compound and 1-5% w / v of emulsifier;

[0017] The concentration of stabilizer in the cold aqueous solution is 0.5~3.0% w / v;

[0018] The amount of curing agent added is 10-30% of the total system volume;

[0019] The final concentration of the crosslinking agent added is 0.1~0.2% w / v;

[0020] The rotational speed of the high-speed homogenizer is 5000~15000 rpm;

[0021] The emulsification time for forming an oil-in-water primary emulsion is 3-10 min;

[0022] The stirring speed for forming the water-in-oil-in-water complex emulsion is 1000~3000 rpm;

[0023] The stirring time for forming the water-in-oil-in-water complex emulsion is 5 to 20 minutes.

[0024] Furthermore, the MMP-responsive material includes at least one of gelatin, collagen, or MMP-specific substrate peptides;

[0025] The solvent of the wall material solution is a second buffer solution, and the pH of the second buffer solution is 6.5~8.0;

[0026] The second buffer is selected from phosphate buffer or Tris-HCl buffer;

[0027] The pH-sensitive dye is selected from at least one of bromocresol green, bromocresol purple, phenol red, or Congo red.

[0028] The acid precursor compound is selected from at least one of glucono-δ-lactone, gluconic acid, ascorbic acid, or citric acid.

[0029] The emulsifier is selected from at least one of Span 80, Span 60 or Tween 80;

[0030] The solvent for the core material oil phase is selected from at least one of octane, chloroform, ethyl acetate, and dichloromethane;

[0031] The stabilizer is selected from at least one of gum arabic, polyvinyl alcohol, or gelatin;

[0032] The crosslinking agent used in the preparation of MMP-responsive microcapsules is selected from at least one of glutaraldehyde, genipin, or tannic acid.

[0033] Furthermore, the deposition of MMP-responsive microcapsules on the biomimetic anchoring substrate includes uniformly depositing a suspension of MMP-responsive microcapsules onto the biomimetic anchoring substrate by coating.

[0034] The solid content of the MMP-responsive microcapsule suspension is 5-15% w / v;

[0035] The particle size distribution of the MMP-responsive microcapsule suspension is 10-50 μm;

[0036] The coating method includes at least one of atomized spraying, spin coating, or dip coating;

[0037] The ambient temperature for the gas-phase crosslinking is 20~50℃;

[0038] The time for gas-phase crosslinking is 2-8 hours;

[0039] The crosslinking agent for gas-phase crosslinking is selected from at least one of glutaraldehyde vapor, formaldehyde vapor, or genipin vapor.

[0040] The drying time is 12-48 hours.

[0041] Furthermore, the conditions for the self-polymerization reaction are: light protection at 20-30°C, and oscillation reaction at a rate of 40-80 rpm.

[0042] The self-polymerization reaction takes 10-36 hours;

[0043] The first buffer solution is selected from Tris-HCl buffer, phosphate buffer, or carbonate buffer;

[0044] Furthermore, the vacuum degree of the low-temperature oxygen plasma treatment is 5~50 Pa;

[0045] The radio frequency power of the low-temperature oxygen plasma treatment is 100~500W;

[0046] The duration of the low-temperature oxygen plasma treatment is 30~180s;

[0047] The material of the medical flexible substrate is selected from thermoplastic polyurethane, polycaprolactone, polylactic acid-glycolic acid copolymer or silicone rubber.

[0048] The gas used in the low-temperature oxygen plasma treatment is selected from at least one of oxygen, air, or argon.

[0049] Furthermore, the printing process includes printing and curing;

[0050] The printing method includes screen printing, with a screen mesh count of 200-600 mesh;

[0051] The curing includes ultraviolet curing, thermal curing, or photothermal dual curing, preferably ultraviolet curing;

[0052] The main wavelength of the ultraviolet light used for ultraviolet curing is 365~405nm, the light intensity is 300~800 mW / cm², and the irradiation time is 3~20s;

[0053] The line width of the measurement grid is 0.05~0.2mm;

[0054] The line material of the measurement grid is selected from at least one of UV-cured polyurethane ink, water-based polyurethane ink, or medical silicone ink.

[0055] The measurement grid is a square grid;

[0056] The square grid has a size of 1.0mm × 1.0mm;

[0057] The measurement grid includes coordinate scales and numerical labels.

[0058] Furthermore, the MMP includes at least one of MMP-1, MMP-2, MMP-8, MMP-9, or MMP-13.

[0059] Secondly, the present invention provides an intelligent imaging measurement film for cartilage / meniscus defects, which is prepared by the above-described preparation method.

[0060] Furthermore, it includes an MMP-responsive colorimetric layer disposed on one side of the medical flexible substrate and a measurement grid disposed on the other side of the medical flexible substrate;

[0061] The MMP-responsive colorimetric layer includes a biomimetic anchoring substrate and MMP-responsive microcapsules fixed on the biomimetic anchoring substrate.

[0062] The MMP-responsive microcapsules are used to specifically recognize MMPs and release chromogenic dyes;

[0063] The biomimetic anchoring substrate is used for in-situ deposition and immobilization of colorimetric dyes released from MMP-responsive microcapsules.

[0064] The intelligent imaging measurement film for cartilage / meniscus defects provided by this invention involves preparing an activation layer on a medical flexible substrate through plasma treatment. This allows catecholamine compounds to undergo a self-polymerization reaction in a weakly alkaline environment, forming a biomimetic anchoring substrate with the activation layer substrate through covalent bonds, hydrogen bonds, π-π stacking, and coordination bonds. Simultaneously, the surface of the biomimetic anchoring substrate contains active groups that provide abundant binding sites for the fixation of MMP-responsive microcapsules. The MMP-responsive microcapsules are then anchored to the anchoring layer via gas-phase crosslinking, avoiding the problems of easy detachment and unstable signal associated with traditional physical coatings or simple embedding materials. The reliability of intraoperative measurements was compromised. The MMP-responsive microcapsules, with a W / O / W structure, encapsulate hydrophobic chromogenic materials. Under the action of MMP, they promptly release the chromogenic materials and deposit them in situ onto the surface of the biomimetic anchoring substrate. This allows for precise chromogenic imaging of complex curved or irregular defect areas, enabling rapid and accurate acquisition of morphological parameters of the defects. This solves the technical problem that existing cartilage / meniscus defect measurement methods, which rely on medical imaging and intraoperative auxiliary measurements, have poor adaptability to complex curved and irregular defects and high error rates, making it impossible to quickly and accurately acquire morphological parameters of the defects during surgery. Detailed Implementation

[0065] Unless otherwise defined herein, the scientific and technical terms used in conjunction with this invention shall have the meanings commonly understood by one of ordinary skill in the art. The meaning and scope of terms shall be clear; however, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or foreign definitions. In this application, unless otherwise stated, the use of "or" means "and / or". Furthermore, the use of the term "comprising" and other forms is non-limiting.

[0066] Unless otherwise stated, the methods and techniques of the present invention are generally carried out according to conventional methods well known in the art and as described in various general and more specific references, which are cited and discussed throughout this specification.

[0067] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0068] This invention provides a method for preparing a smart imaging measurement film for cartilage / meniscus defects, comprising the following steps:

[0069] A. Surface activation is achieved by low-temperature oxygen plasma treatment on one side of the medical flexible substrate to form an activation layer;

[0070] B. The medical flexible substrate treated in step A is immersed in a first buffer solution containing 1.0~5.0 mg / mL of catecholamine compounds to carry out a self-polymerization reaction, forming a biomimetic anchoring substrate on the activation layer. MMP-responsive microcapsules are deposited on the biomimetic anchoring substrate, crosslinked in the gas phase, and dried to obtain an MMP-responsive functional colorimetric layer.

[0071] The catecholamine compounds include at least one of dopamine, norepinephrine, and dopamine derivatives; the pH of the first buffer solution is 7.5 to 9.0;

[0072] C. Print a measurement grid on the other side of the medical flexible substrate.

[0073] An activation layer was prepared on a medical flexible substrate through plasma treatment, enabling catecholamine compounds to undergo self-polymerization in a weakly alkaline environment. This forms a biomimetic anchoring substrate with the activation layer substrate, composed of covalent bonds, hydrogen bonds, π-π stacking, and coordination bonds. Simultaneously, the surface of the biomimetic anchoring substrate contains active groups, providing abundant binding sites for the fixation of MMP-responsive microcapsules. MMP-responsive microcapsules are then anchored to the anchoring layer via gas-phase crosslinking, avoiding the problems of easy detachment and signal instability associated with traditional physical coatings or simple embedding materials, thus ensuring the reliability of intraoperative measurements. P-responsive microcapsules have a W / O / W structure, encapsulating hydrophobic chromogenic materials. Under the action of MMP, they promptly release the chromogenic materials and deposit them in situ onto the surface of a biomimetic anchoring substrate. This allows for precise chromogenic imaging of complex curved or irregular defect areas, enabling rapid and accurate acquisition of defect morphological parameters. This solves the technical problem of existing cartilage / meniscus defect measurement methods, which rely on medical imaging and intraoperative auxiliary measurements, having poor adaptability to complex curved and irregular defects and high error rates, and failing to rapidly and accurately acquire defect morphological parameters intraoperatively.

[0074] In some specific embodiments, the first buffer is selected from Tris-HCl buffer, phosphate buffer, or carbonate buffer.

[0075] Because MMP-responsive materials are hydrophilic while the colorimetric core material is hydrophobic, encapsulation is difficult and core material leakage is prone to occur, leading to non-specific background color development. In some specific embodiments, the preparation method of the MMP-responsive microcapsules includes adding the wall material solution to the core material oil phase at a volume ratio of 1:1.5 to 1:5 under high-speed homogenization to emulsify and form an oil-in-water primary emulsion; adding the oil-in-water primary emulsion to a cold aqueous solution containing a stabilizer at a volume ratio of 1:5 to 1:20; stirring to form an oil-in-water complex emulsion; adding a curing agent to precipitate the wall material; adding a crosslinking agent; and collecting the MMP-responsive microcapsules. The wall material solution contains 3-10% w / v of MMP-responsive material; the MMP-responsive material includes at least one of gelatin, collagen, or MMP-specific substrate peptides. By combining the complex emulsification process with crosslinking, the MMP-responsive material is transformed into a wall material with high stability and specificity, which can accurately respond to and release the colorimetric core material.

[0076] In some specific embodiments, the core material oil phase contains 0.1-2.0% w / v of a pH-sensitive dye, 1-5% w / v of an acid precursor compound, and 1-5% w / v of an emulsifier. In some specific embodiments, the pH-sensitive dye is selected from at least one of bromocresol green, bromocresol purple, phenol red, or Congo red; in some specific embodiments, the acid precursor compound is selected from at least one of glucono-δ-lactone, gluconic acid, ascorbic acid, or citric acid; in some specific embodiments, the emulsifier is selected from at least one of Span 80, Span 60, or Tween 80. In some specific embodiments, the solvent of the core material oil phase is selected from at least one of octane, chloroform, ethyl acetate, and dichloromethane.

[0077] In some specific embodiments, the rotation speed of the high-speed homogenizer is 5000~15000 rpm; in some specific embodiments, the emulsification time for forming the water-in-oil primary emulsion is 3~10 min; in some specific embodiments, the stirring speed for forming the water-in-oil-in-water complex emulsion is 1000~3000 rpm; in some specific embodiments, the stirring time for forming the water-in-oil-in-water complex emulsion is 5~20 min.

[0078] In some specific embodiments, the concentration of the stabilizer in the cold aqueous solution is 0.5-3.0% w / v; in some specific embodiments, the stabilizer is selected from at least one of gum arabic, polyvinyl alcohol, or gelatin.

[0079] In some specific implementations, the amount of curing agent added is 10-30% of the total system volume;

[0080] In the preparation of MMP-responsive microcapsules, in some specific embodiments, the final concentration of the crosslinking agent is 0.1~0.2% w / v, and the crosslinking agent is selected from at least one of glutaraldehyde, genipin, or tannic acid to achieve precise crosslinking.

[0081] In some specific embodiments, the solvent of the wall material solution is a second buffer solution, and the pH of the second buffer solution is 6.5 to 8.0; in some specific embodiments, the second buffer solution is selected from phosphate buffer solution or Tris-HCl buffer solution.

[0082] In some specific embodiments, depositing MMP-responsive microcapsules on a biomimetic anchoring substrate includes uniformly depositing a suspension of MMP-responsive microcapsules onto the biomimetic anchoring substrate through coating. In some specific embodiments, the solid content of the MMP-responsive microcapsule suspension is 5-15% w / v.

[0083] In some specific embodiments, the particle size distribution of the MMP-responsive microcapsule suspension is 10-50 μm.

[0084] In some specific embodiments, the coating method includes at least one of atomized spraying, spin coating, or dip coating.

[0085] In some specific embodiments, the ambient temperature for gas-phase crosslinking is 20~50℃; in some specific embodiments, the gas-phase crosslinking time is 2~8h; in some specific embodiments, the crosslinking agent for gas-phase crosslinking is selected from at least one of glutaraldehyde vapor, formaldehyde vapor, or genipin vapor. Stable covalent connections are formed between the microcapsules and the biomimetic anchoring substrate through glutaraldehyde vapor crosslinking.

[0086] In some specific embodiments, the drying time is 12 to 48 hours.

[0087] In some specific embodiments, the conditions for the self-polymerization reaction are: 20-30°C in the dark, with oscillation at a rate of 40-80 rpm; in some specific embodiments, the time for the self-polymerization reaction is 10-36 hours.

[0088] In some specific embodiments, the vacuum degree of the low-temperature oxygen plasma treatment is 5~50 Pa; in some specific embodiments, the radio frequency power of the low-temperature oxygen plasma treatment is 100~500 W; in some specific embodiments, the duration of the low-temperature oxygen plasma treatment is 30~180 s; in some specific embodiments, the gas used in the low-temperature oxygen plasma treatment is selected from at least one of oxygen, air or argon.

[0089] In some specific embodiments, the material of the medical flexible substrate is selected from thermoplastic polyurethane, polycaprolactone, polylactic acid-glycolic acid copolymer or silicone rubber.

[0090] In some specific embodiments, the printing includes printing and curing; in some specific embodiments, the printing method includes screen printing with a mesh count of 200-600 mesh; in some specific embodiments, the curing includes ultraviolet curing, thermal curing, or photothermal dual curing, preferably ultraviolet curing; in some specific embodiments, the dominant wavelength of the ultraviolet light used in the ultraviolet curing is 365-405 nm, the light intensity is 300-800 mW / cm², and the irradiation time is 3-20 s.

[0091] In some specific embodiments, the line width of the measuring grid is 0.05~0.2mm; in some specific embodiments, the line material of the measuring grid is selected from at least one of UV-curable polyurethane ink, water-based polyurethane ink, or medical silicone ink.

[0092] In some specific embodiments, the measurement grid is a square grid; in some specific embodiments, the size of the square grid is 1.0mm × 1.0mm; in some specific embodiments, the measurement grid includes coordinate scales and numerical markings.

[0093] In some specific embodiments, the MMP includes at least one of MMP-1, MMP-2, MMP-8, MMP-9, or MMP-13.

[0094] According to another aspect of the present invention, a smart imaging measurement film for cartilage / meniscus defects is also provided, which is prepared by the above-described preparation method.

[0095] The measurement film provided by this invention features an integrated design, facilitating convenient measurement and enabling a streamlined intraoperative workflow. The medical-grade flexible substrate offers excellent flexibility and maneuverability, making it easy to apply within narrow joint cavities. The measurement grid allows surgeons to directly estimate morphology after color development without any additional tools. The entire measurement process is simplified to three steps: "application-waiting-reading," completing a measurement task that traditionally takes tens of minutes within one minute, significantly improving surgical efficiency and greatly reducing the operational threshold. The built-in measurement grid can be used as a scale for high-precision image analysis, seamlessly converting images into digital archives. This provides a solid technical foundation for establishing standardized surgical databases, achieving objective quantitative assessment of postoperative efficacy, and conducting multi-center clinical research.

[0096] In some specific embodiments, the invention includes an MMP-responsive chromogenic layer disposed on one side of a medical flexible substrate and a measurement grid disposed on the other side of the medical flexible substrate; the MMP-responsive chromogenic layer includes a biomimetic anchoring substrate and MMP-responsive microcapsules fixed on the biomimetic anchoring substrate; the MMP-responsive microcapsules are used to specifically recognize MMPs and release chromogenic dyes; the biomimetic anchoring substrate is used to deposit and fix the chromogenic dyes released by the MMP-responsive microcapsules in situ.

[0097] In some specific implementations, post-processing, sterilization, or packaging steps are also included.

[0098] Post-processing includes cutting and / or performance verification. Cutting involves cutting the film to a size suitable for surgery. Performance verification criteria include that after the film comes into contact with a solution containing matrix metalloproteinases, a clear color change and distinct boundary should appear within 10–30 seconds. The concentration of matrix metalloproteinases should be 0.05–0.5 μg / μL. Sterilization methods include, but are not limited to, ethylene oxide sterilization, gamma ray sterilization, or electron beam sterilization. Packaging is aseptic packaging.

[0099] This invention constructs an intelligent colorimetric system with cascade amplification capabilities through a combination of biomimetic anchoring and controlled release. Its core lies in utilizing gelatin as a specific substrate for MMP enzymes and co-encapsulating pH indicator dyes and acid precursor compounds within microcapsules. When exposed to a high concentration of MMPs at the defect site, enzymatic cleavage triggers precise release of the contents from the microcapsule; hydrolysis of the acid precursor causes a sudden change in local pH, thereby driving a significant color change in the dye. This achieves a high-gain conversion from "biomolecular recognition" to "macroscopic visual signals," producing high-contrast color development of the defect area that is visible to the naked eye within 15 seconds, with sensitivity and specificity far exceeding traditional physical measurement methods.

[0100] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0101] Example 1

[0102] A smart imaging measurement film for cartilage / meniscus defects includes an MMP-responsive functional colorimetric layer disposed on one side of a medical flexible substrate and a measurement grid disposed on the other side of the medical flexible substrate; the MMP-responsive functional colorimetric layer includes a biomimetic anchoring substrate and MMP-responsive microcapsules fixed on the biomimetic anchoring substrate.

[0103] Prepare according to the following steps:

[0104] 1. A 100 μm thick medical-grade thermoplastic polyurethane (TPU) was selected as the flexible substrate. The film was first cleaned and surface-activated.

[0105] Cleaning: Immerse the film in anhydrous ethanol and deionized water in sequence, and ultrasonically clean each for 15 min to remove surface contaminants. Then dry for later use.

[0106] Surface activation: Low-temperature oxygen plasma treatment was used. The cleaned film was placed in the plasma treatment chamber, oxygen was introduced (flow rate 60 sccm), and the treatment was carried out for 90 s under the conditions of vacuum degree 30 Pa and radio frequency power 300 W.

[0107] 2. Construction of the biomimetic anchoring layer

[0108] The pretreated TPU film was completely immersed in a biomimetic adhesion precursor solution (dopamine solution) and reacted at room temperature (25°C) in the dark with gentle shaking (60 rpm) for 18 h to allow a polydopamine layer to form uniformly on the film surface. After the reaction, the film was removed, rinsed with plenty of deionized water to remove physically adsorbed monomers and oligomers, and dried with nitrogen to obtain a biomimetic anchoring substrate with abundant active groups on its surface.

[0109] Preparation of biomimetic adhesion precursor solution: Dopamine was dissolved in 10 mM Tris-HCl buffer (pH=8.5) to prepare a solution with a concentration of 3.0 mg / mL.

[0110] 3. Preparation of MMP-responsive gelatin microcapsules

[0111] (1) Preparation of gelatin wall material solution

[0112] Gelatin was selected as the wall material and prepared into a 5% (w / v) solution with phosphate buffered saline (PBS, pH 7.4), which was then dissolved by stirring at 50°C.

[0113] (2) Preparation of core material oil phase

[0114] pH-sensitive dyes, acid precursor compounds, and emulsifiers are dissolved together in an organic solvent to form the core material oil phase;

[0115] The pH-sensitive dye is bromocresol green with a concentration of 1.0% (w / v); the acid precursor compound is gluconate-δ-lactone with a concentration of 3.0% (w / v); the emulsifier is Span 80 with a concentration of 2.0% (w / v); and the organic solvent is ethyl acetate.

[0116] (3) Microcapsule preparation: The preheated gelatin wall material solution was slowly added to the core material oil phase at a volume ratio of 1:3 under high-speed homogenization (10,000 rpm), and emulsified for 5 minutes to form a W / O primary emulsion. The primary emulsion was then rapidly poured into a 1% (w / v) polyvinyl alcohol aqueous solution at 10°C at a volume ratio of 1:12, and stirred at 2000 rpm for 10 minutes to form a W / O / W secondary emulsion. The system was cooled to 4°C, and acetone (20% by volume) was added to allow the gelatin to precipitate and solidify. Glutaraldehyde aqueous solution was then added to a final concentration of 0.5% (v / v), and crosslinked at 4°C for 12 h. The microcapsules were collected by centrifugation, washed repeatedly, and redispersed to obtain a microcapsule suspension with a solid content of 10% and a particle size of approximately 30 μm.

[0117] (4) Functional layer construction: The above microcapsule suspension was uniformly deposited on the biomimetic anchoring substrate by ultrasonic atomization (frequency 120 kHz). Subsequently, the film was placed in a sealed container filled with crosslinking agent vapor and subjected to secondary vapor-phase crosslinking at 35°C for 4 h (using glutaraldehyde vapor) to form covalent bonds between the microcapsules and the anchoring layer, thereby enhancing the bonding strength. Finally, the film was dried at room temperature for 24 h to obtain a functionalized film integrating an MMP-responsive color development layer.

[0118] 4. Printing and post-processing of precision measuring grids

[0119] On the back of the film, a standard square grid of 1.0 mm × 1.0 mm (0.1 mm line width) is printed using screen printing technology (400 mesh) and UV-curable ink, along with coordinate scales. It is then immediately cured by UV light (dominant wavelength 365 nm, intensity 500 mW / cm²) for 10 seconds. The film is then cut to a size suitable for arthroscopic surgery (e.g., 10–30 mm in length and 10–30 mm in width), cleaned, and ready for use.

[0120] Comparative Example 1

[0121] The difference from Example 1 is that no biomimetic anchoring layer is constructed. Instead, a chitosan coating is obtained by dip coating with a 2% (w / v) chitosan acetic acid solution.

[0122] Comparative Example 2

[0123] The difference from Example 1 is that in step 3, the microcapsules are produced using a W / O single emulsion method, specifically following these steps:

[0124] (3) Microcapsule preparation: The preheated gelatin wall material solution was slowly added to the core material oil phase at a volume ratio of 1:3 under high-speed homogenization (10,000 rpm), and emulsified for 5 minutes to form a W / O primary emulsion. The system was cooled to 4°C, and acetone (20% by volume) was added to allow the gelatin to precipitate and solidify. Then, glutaraldehyde aqueous solution was added to a final concentration of 0.5% (v / v), and crosslinked at 4°C for 12 h. The microcapsules were collected by centrifugation, washed a series of times, and redispersed to obtain a microcapsule suspension.

[0125] Comparative Example 3

[0126] The difference from Example 1 is that in step 3, the concentration of the crosslinking agent in the microcapsule preparation is 0.05% (v / v).

[0127] Experiment 1: Determination of Physicochemical Parameters

[0128] 1. Determination of MMP enzyme-triggered colorimetric performance

[0129] Specific response time: 2 μL of MMP-13 enzyme solution (0.2 μg / μL) was dropped onto the surface of the membrane, and the time it took for a clear boundary to appear from yellow to blue was recorded using a high-speed camera as the response time.

[0130] Color contrast and stability: The color difference (ΔE) between the colorimetric area and the background area is measured using a colorimeter and continuously monitored.

[0131] Enzyme response specificity verification: Three parallel experiments were designed for verification: Group A (0.2 μg / μL MMP-13), Group B (phosphate buffer, pH 7.4), and Group C (0.1% trypsin).

[0132] 2. Interface bonding strength

[0133] Wet adhesion: After immersing the film in PBS, the functional layer detachment was tested using the cross-cut adhesion tester / tape method.

[0134] Dynamic scouring test: Simulated synovial fluid is used to scour the surface of the film at a certain flow rate, and the integrity of the functional layer and background color are observed.

[0135] 3. Clarity of color boundaries

[0136] High-resolution imaging was performed on the thin film after MMP-triggered color development, and the boundary diffusion width of the color development area was measured using image analysis software.

[0137] 4. Biocompatibility and Chemical Safety

[0138] The membrane extract was prepared according to GB / T 16886.5, and the relative cell proliferation rate (RGR) was measured after co-culturing with L929 mouse fibroblasts. The hemolysis rate of the membrane extract was measured according to GB / T 16886.4.

[0139] The results of the physicochemical parameter measurements are shown in Table 1.

[0140] Table 1

[0141]

[0142] The results showed that Example 1 met the performance requirements for accurate intraoperative measurement, while Comparative Examples 1-3 exhibited varying degrees of low response time efficiency, non-specific color development, unclear boundaries, or detachment, all failing to meet the performance requirements for accurate intraoperative measurement. Specifically, Comparative Example 1, using a chitosan coating, resulted in poor wet adhesion, causing the functional layer to easily detach in simulated synovial fluid. Furthermore, its loose structure could not effectively constrain the color development material, leading to blurred boundaries of the color development area (diffusion width approximately 0.8 mm) and non-specific background color development, failing to achieve the clear and stable contour delineation required during surgery. This demonstrates that conventional adhesive materials cannot replace the strong interfacial bonding and background "locking" function of the polydopamine layer of this invention. Comparative Example 2 omitted the core W / O / W multi-emulsification process, using a simple W / O single-emulsification method to prepare gelatin microcapsules, resulting in severe defects in their structural integrity. The resulting microcapsules exhibited extremely low encapsulation efficiency. The core material (chromogenic dye and acid precursor) rapidly and nonspecifically leaked upon contact with a humid environment, manifesting as an excessively fast response time (approximately 3.8 seconds) and complete loss of control. The buffer control group showed strong color development with diffuse color boundaries (diffusion width ≥ 2.0 mm). This demonstrates that without a specific re-emulsification process to construct a complete core-shell structure, controllable release of the core material is impossible, rendering the measurement function completely ineffective. Comparative Example 3 significantly reduced the cross-linking degree of the gelatin microcapsules (final glutaraldehyde concentration 0.05%), disrupting the controllability of release. The low cross-linking degree led to excessive swelling of the microcapsule wall in a wet state and insufficient mechanical strength, resulting in continuous and slow leakage of the core material under non-target conditions. This manifested as unstable response time, moderate nonspecific color development in the buffer control group, and decreased clarity of the color boundary (diffusion width approximately 1.5 mm). This demonstrates that an appropriate degree of cross-linking in the gelatin wall material can achieve targeted triggering and rapid release, balancing encapsulation stability and enzyme responsiveness.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a smart imaging measurement film for cartilage / meniscus defects, characterized in that, Includes the following steps: A. Surface activation is achieved by low-temperature oxygen plasma treatment on one side of the medical flexible substrate to form an activation layer; B. The medical flexible substrate treated in step A is immersed in a first buffer solution containing 1.0~5.0 mg / mL of catecholamine compounds to carry out a self-polymerization reaction, forming a biomimetic anchoring substrate on the activation layer. MMP-responsive microcapsules are deposited on the biomimetic anchoring substrate, crosslinked in the gas phase, and dried to obtain an MMP-responsive functional colorimetric layer. The catecholamine compound is dopamine; the pH of the first buffer solution is 7.5~9.0; C. Print a measurement grid on the other side of the medical flexible substrate; The method for preparing the MMP-responsive microcapsules includes adding a wall material solution to the core material oil phase at a volume ratio of 1:1.5 to 1:5 under high-speed homogenization, emulsifying to form an oil-in-water primary emulsion, adding the oil-in-water primary emulsion to a cold aqueous solution containing a stabilizer at a volume ratio of 1:5 to 1:20, stirring to form an oil-in-water complex emulsion, adding a curing agent to cause the wall material to precipitate, adding a crosslinking agent to a final concentration of 0.5% (v / v), and collecting to obtain the MMP-responsive microcapsules; The wall material solution contains 3-10% w / v of MMP-responsive material; The MMP-responsive material is gelatin.

2. The preparation method according to claim 1, characterized in that, The core material oil phase contains 0.1-2.0% w / v of pH-sensitive dye, 1-5% w / v of acid precursor compound and 1-5% w / v of emulsifier; The concentration of stabilizer in the cold aqueous solution is 0.5~3.0% w / v; The amount of curing agent added is 10-30% of the total system volume; The rotational speed of the high-speed homogenizer is 5000~15000 rpm; The emulsification time for forming an oil-in-water primary emulsion is 3-10 min; The stirring speed for forming the water-in-oil-in-water complex emulsion is 1000~3000 rpm; The stirring time for forming the water-in-oil-in-water complex emulsion is 5 to 20 minutes.

3. The preparation method according to claim 2, characterized in that, The solvent of the wall material solution is a second buffer solution, and the pH of the second buffer solution is 6.5~8.0; The second buffer is selected from phosphate buffer or Tris-HCl buffer; The pH-sensitive dye is selected from at least one of bromocresol green, bromocresol purple, phenol red, or Congo red. The acid precursor compound is selected from at least one of glucono-δ-lactone, gluconic acid, ascorbic acid, or citric acid. The emulsifier is selected from at least one of Span 80, Span 60 or Tween 80; The solvent for the core material oil phase is selected from at least one of octane, chloroform, ethyl acetate, and dichloromethane; The stabilizer is selected from at least one of gum arabic, polyvinyl alcohol, or gelatin; The crosslinking agent used in the preparation of MMP-responsive microcapsules is selected from at least one of glutaraldehyde, genipin, or tannic acid.

4. The preparation method according to claim 1, characterized in that, The deposition of MMP-responsive microcapsules on a biomimetic anchoring substrate includes uniformly depositing a suspension of MMP-responsive microcapsules onto the biomimetic anchoring substrate by coating. The solid content of the MMP-responsive microcapsule suspension is 5-15% w / v; The particle size distribution of the MMP-responsive microcapsule suspension is 10-50 μm; The coating method includes at least one of atomized spraying, spin coating, or dip coating; The ambient temperature for the gas-phase crosslinking is 20~50℃; The time for gas-phase crosslinking is 2-8 hours; The crosslinking agent for gas-phase crosslinking is selected from at least one of glutaraldehyde vapor, formaldehyde vapor, or genipin vapor. The drying time is 12-48 hours.

5. The preparation method according to claim 1, characterized in that, The conditions for the self-polymerization reaction are: 20-30°C in the dark, with oscillation at a rate of 40-80 rpm. The self-polymerization reaction takes 10-36 hours; The first buffer is selected from Tris-HCl buffer, phosphate buffer, or carbonate buffer.

6. The preparation method according to claim 1, characterized in that, The vacuum degree of the low-temperature oxygen plasma treatment is 5~50 Pa; The radio frequency power of the low-temperature oxygen plasma treatment is 100~500W; The duration of the low-temperature oxygen plasma treatment is 30~180s; The material of the medical flexible substrate is selected from thermoplastic polyurethane, polycaprolactone, polylactic acid-glycolic acid copolymer or silicone rubber. The gas used in the low-temperature oxygen plasma treatment is selected from at least one of oxygen, air, or argon.

7. The preparation method according to claim 1, characterized in that, The printing process includes printing and curing; The printing method includes screen printing, with a screen mesh count of 200-600 mesh; The curing process includes ultraviolet light curing, thermal curing, or photothermal dual curing. The main wavelength of the ultraviolet light used for ultraviolet curing is 365~405nm, the light intensity is 300~800 mW / cm², and the irradiation time is 3~20s; The line width of the measurement grid is 0.05~0.2mm; The line material of the measurement grid is selected from at least one of UV-cured polyurethane ink, water-based polyurethane ink, or medical silicone ink. The measurement grid is a square grid; The square grid has a size of 1.0mm × 1.0mm; The measurement grid includes coordinate scales and numerical labels.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The MMP includes at least one of MMP-1, MMP-2, MMP-8, MMP-9, or MMP-13.

9. A smart imaging measurement film for cartilage / meniscus defects, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The intelligent developing and measuring film according to claim 9, characterized in that, It includes an MMP-responsive colorimetric layer on one side of the medical flexible substrate and a measurement grid on the other side of the medical flexible substrate; The MMP-responsive colorimetric layer includes a biomimetic anchoring substrate and MMP-responsive microcapsules fixed on the biomimetic anchoring substrate. The MMP-responsive microcapsules are used to specifically recognize MMPs and release chromogenic dyes; The biomimetic anchoring substrate is used for in-situ deposition and immobilization of colorimetric dyes released from MMP-responsive microcapsules.

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