Device and method for detecting retention performance of liquid-phase solute of articular cartilage

Abstract

The invention relates to a device and a method for detecting the retention performance of a liquid-phase solute of articular cartilage. The method comprises the following steps: adhering and fixing a treated cartilage on a perforated rubber plug; the cartilage pasted with the rubber plug is placed in a retention device with a perforated plate at the bottom, and water is added till the cartilage completely exceeds an overflow opening; the retention pressing rod provided with the rubber plug is pressed into the retention device, and whether liquid leakage exists or not is detected in advance; discharging the water, adding a solution required by a retention experiment, and pressing the retention pressure rod again; the retention device is arranged in the cylindrical base, and the screws on the two sides are fastened; the base of the device is fixed on a lower disc of a testing machine; a retention compression bar of the device is fixed on an upper disc of a testing machine; and setting expected pressure and time, starting to load experimental pressure, and then starting a cartilage retention experiment. And after the retention experiment is finished, observing the retention state of the fluorescent solute molecules by using a slicing machine and a laser confocal microscope. The cartilage liquid phase solute retention performance is effectively detected, the problem that sealing performance is difficult in a retention experiment is solved, a cartilage mass transfer research method is expanded, and the detection precision and stability are improved. The method is expected to be popularized to become a standard test technology of cartilage retention performance, and plays a positive role in promoting cartilage in-vitro experiments.

Description

Technical Field

[0001] The invention relates to the fields of biomechanics, fluid mechanics and mass transfer, and in particular to a device and method for detecting the solute retention performance of cartilage liquid phase. Background Art

[0002] Articular cartilage is a special connective tissue whose main functions include providing smooth and low-friction properties on the joint surface, absorbing and dispersing the impact force during joint movement, and maintaining joint stability and normal movement posture. Since articular cartilage is a non-vascularized tissue, its nutrient supply mainly depends on the diffusion and osmotic effect of solutes in the synovial fluid, thereby maintaining its normal metabolic function and mechanical properties.

[0003] In the biomechanical study of articular cartilage, the retention properties of solutes in the permeate directly affect the absorption efficiency of the cartilage matrix for external solutes and their distribution characteristics within the cartilage tissue. This property is crucial for understanding the nutrient exchange of articular cartilage, the drug delivery mechanism, and the optimal design of tissue repair materials. Especially in the study and treatment of joint diseases, there is a close connection between the retention efficiency of solutes in cartilage and its metabolic function. Therefore, in-depth research on the retention properties of cartilage can provide an effective theoretical basis and technical support for improving drug delivery efficiency and carrying out functional integration of repair materials.

[0004] At present, there are still many problems with the devices and methods used to study the solute retention properties of articular cartilage. First, existing detection devices often focus on the permeability characteristics of cartilage, but there is little research on the retention effect of solutes during the permeation process, which makes it impossible to fully reflect the nutrient exchange capacity and related metabolic characteristics of cartilage. Secondly, due to the irregularity of the surface morphology of cartilage, many devices lack flexibility in achieving sample sealing, which may introduce experimental errors. Thirdly, conventional detection methods lack the accuracy to monitor changes in solute concentration during the experiment, making it difficult to accurately quantify the retention effect. Finally, such experimental devices are generally complex in design and cumbersome to operate, making it difficult to balance the repeatability and efficiency of the experiment.

[0005] While ensuring sealing and stability, the device and detection method greatly improve the detection accuracy and efficiency of solute retention performance, providing important technical support for basic research and clinical treatment related to articular cartilage. This innovation fills the technical gap in the field of solute retention performance detection and effectively promotes the in-depth development of articular cartilage biomechanics and drug delivery research.

[0006] SUMMARY OF THE INVENTION

[0007] In view of the deficiencies of the prior art, the present invention proposes a device and method for detecting the liquid phase solute retention performance of articular cartilage, which improves the detection accuracy and stability and simplifies the operation process.

[0008] One of the above objects of the present invention is achieved by the following technical solution:

[0009] A device for detecting the retention performance of liquid phase solutes in articular cartilage is characterized by comprising a testing machine, a cylindrical base, a retention device, a retention pressure rod, a porous plate, and a syringe rubber plug.

[0010] The retainer is placed in the cylindrical base through the square hole and fixed by screws on both sides. It is used to load experimental samples and target solutions, provide space for the experiment, create certain sealing conditions and provide a passage for the permeation solution.

[0011] The cylinder base is fastened to the lower disc of the testing machine by bolts and nuts, and is used to support and fix the retention device to store the solution discharged by the permeation.

[0012] The retention pressure rod is fixed to the upper disc of the testing machine and is used to transfer the load output by the testing machine to the solution.

[0013] The multi-hole plate is placed under the sample to prevent abnormal deformation of the cartilage during the retention experiment.

[0014] The second objective of the present invention is achieved by the following technical solutions:

[0015] A method for detecting the liquid phase solute retention performance of articular cartilage comprises the following steps:

[0016] Step 1: Process the cartilage sample containing the underlying bone, remove the cartilage calcification layer and the tissue underneath, and ensure that the cartilage can be easily flattened;

[0017] Step 2: Make a hole in the syringe plug and cut off the 5ml syringe from the middle; put the plug with a hole into the cut-off syringe so that the bottom of the plug slightly protrudes from the outer edge of the syringe; use ethyl cyanoacrylate to initially bond the bottom of the plug to the cartilage; then apply pressure to the other end of the plug through the retention pressure rod to completely eliminate the gap between the plug and the cartilage. In addition, since the plug is confined by the syringe shell, it will not produce additional deformation due to extrusion; then cut the excess part of the cartilage along the edge of the plug so that it can just fit into the retention device; finally, evenly apply ethyl cyanoacrylate adhesive around the joint between the cartilage and the plug for further sealing and reinforcement, and wait for it to completely dry before the sample is ready;

[0018] Step 3: Place a porous plate at the bottom of the retention device, place the sample close to the porous plate, add water until it completely exceeds the overflow port, install a rubber plug on the end of the retention pressure rod and press it into the retention device, and continuously apply pressure to pre-detect whether the device and the sample are leaking; after the pre-detection is successful, drain all the water;

[0019] Step 4: Fill the retention vessel with the solution required for the experiment, push the retention pressure rod back in, place it into the penetration base, fix the bolts on both sides, place the whole on the testing machine, fix the penetration base to the lower disc of the testing machine, fix the retention pressure rod to the upper disc of the testing machine, set the appropriate pressure and time, and then start the experiment.

[0020] Step 5: After the experiment, based on Darcy's law, the displacement-time curve data of the stable section can be extracted and calculated according to the following formula:

[0021]

[0022] Where K is the permeability coefficient; Δh is the height of the liquid level drop during the permeation stability period; A t is the cross-sectional area of ​​the liquid column; Δt is the duration of the osmotic stability period; h c is the average height of cartilage; A c is the effective contact area between cartilage and liquid column; Δp is the pressure difference.

[0023] Step 6: After the permeability coefficient is calculated, separate the cartilage sample from the perforated rubber plug; use an 8mm round steel punch to take a sample from the center of the cartilage sample; immediately place the removed sample in OCT embedding medium for fixation and store at -80°C; after it is completely hardened, dig out the sample and use a slicer to cut a 5μm thick cartilage slice. Use a laser confocal microscope to observe the retention distribution state of fluorescent solute molecules in the slice.

[0024] The advantages and positive effects of the present invention are:

[0025] 1. The present invention utilizes the closed-loop pressure control system of the testing machine and combines it with a high-precision pressure detector to achieve a stable supply of pressure. The previous method of applying pressure to the liquid column by gas is replaced by a mechanical metal pressure head directly applying pressure to the liquid column, thus avoiding the problems of poor pressure stability caused by gas compression. At the same time, the extremely small liquid level displacement is monitored in real time by the high-precision displacement sensor of the testing machine, which effectively improves the accuracy of permeability detection.

[0026] 2. The improvement in sealing of the present invention has greatly improved the accuracy of cartilage permeability testing. In previous studies, the pressure applied to cartilage samples was often far lower than the mechanical environment of cartilage under normal working conditions. The reason is that the greater the pressure, the more stringent the test of airtightness. The inability to efficiently achieve sealing of the edge seams of irregular cartilage has greatly limited the development of cartilage retention performance testing.

[0027] 3. The present invention pays great attention to the related performance of cartilage retention and detects the permeability of cartilage at the same time, which enhances the depth of cartilage liquid phase related research and provides a broader idea for cartilage mass transfer research. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 yes Figure 1 Front view of the cartilage clamp in;

[0030] Figure 3 It is a schematic diagram of the cylindrical base of the present invention;

[0031] Figure 4 is a schematic diagram of the retainer of the present invention;

[0032] Figure 5 It is a schematic diagram of a porous plate of the present invention; DETAILED DESCRIPTION

[0033] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0034] A device for testing the solute retention properties of articular cartilage, see Figure 1 The invention point is: it includes a computer 1, a testing machine 2, an upper disc of the testing machine 3, a retention pressure rod 4, a fastening screw 5, a cylindrical base 6, a lower disc of the testing machine 7, a complete rubber ring 8, a retention device 9, a perforated rubber ring 10, a cartilage sample 11, and a porous plate 12.

[0035] The retainer 9 is fixed to each other by tightening screws 5 and internal nuts on both sides of the cylindrical base 6. It is used to load experimental samples and solutions, provide space for the experiment, create certain sealing conditions and provide a passage for the permeation solution.

[0036] The cylindrical base 6 is fixed to the lower disc 7 of the testing machine 2 by fastening bolts, and is used to support and fix the retention device 9 to store the solution discharged by the osmosis.

[0037] The retention pressure rod 4 is fixed to the upper disc 3 of the testing machine by fastening bolts, and the pressure generated by the downward pressure mechanism of the testing machine 2 is transmitted through the upper disc 3. At the same time, the downward pressure mechanism of the testing machine 2 includes a high-precision displacement sensor, which can accurately detect the descending height of the retention pressure rod and obtain the descending distance of the liquid level of the infiltrated cartilage.

[0038] The porous plate 12 is placed below the cartilage sample 11 to prevent abnormal deformation of the cartilage due to water pressure during the retention experiment.

[0039] In the present invention, the upper limit of detection of the pressure sensor of the testing machine 2 is 100N, the accuracy is 0.0001N; the displacement sensing accuracy is 0.0001mm.

[0040] The processing methods of the cylindrical base 6, the retainer 9, and the porous plate 12 include but are not limited to additive manufacturing or subtractive molding, and the processing materials include but are not limited to high-transparency resins, engineering plastics, and polymer materials.

[0041] The processing methods of the retention pressure rod 4 include but are not limited to casting or subtractive molding, and the processing materials include but are not limited to titanium alloy, zirconium-niobium alloy, stainless steel or aluminum alloy.

[0042] Based on the above-mentioned detection method for the liquid phase solute retention performance of articular cartilage, the method comprises the following steps:

[0043] Step 1: Process the cartilage sample containing the underlying bone, remove the cartilage calcification layer and the tissue underneath, and ensure that the cartilage can be easily flattened;

[0044] Step 2: Make a hole in the syringe plug and cut off the 5ml syringe from the middle; put the plug with a hole into the cut-off syringe so that the bottom of the plug slightly protrudes from the outer edge of the syringe; use ethyl cyanoacrylate to initially bond the bottom of the plug to the cartilage; then apply pressure to the other end of the plug through the retention pressure rod to completely eliminate the gap between the plug and the cartilage. In addition, since the plug is confined by the syringe shell, it will not produce additional deformation due to extrusion; then cut the excess part of the cartilage along the edge of the plug so that it can just fit into the retention device; finally, evenly apply ethyl cyanoacrylate adhesive around the joint between the cartilage and the plug for further sealing and reinforcement, and wait for it to completely dry before the sample is ready;

[0045] Step 3: Place a porous plate at the bottom of the retention device, place the sample close to the porous plate, add water until it completely exceeds the overflow port, install a rubber plug on the end of the retention pressure rod and press it into the retention device, and continuously apply pressure to pre-detect whether the device and the sample are leaking; after the pre-detection is successful, drain all the water;

[0046] Step 4: Fill the retention vessel with the solution required for the experiment, push the retention pressure rod back in, place it into the penetration base, fix the bolts on both sides, place the whole on the testing machine, fix the penetration base to the lower disc of the testing machine, fix the retention pressure rod to the upper disc of the testing machine, set the appropriate pressure and time, and then start the experiment.

[0047] Step 5: After the experiment, the following derivation can be made based on Darcy's law:

[0048] Darcy's law is often used to describe the ease with which a fluid passes through a porous medium. The classic Darcy's law states that the flow rate of a liquid is proportional to the pressure gradient applied to the porous material and inversely proportional to the viscosity of the liquid, so:

[0049]

[0050] in: is the volume flow rate of the porous medium as a whole;

[0051] k is the permeability of the test material;

[0052] μ is the concentration of the target solution;

[0053] A pressure gradient to drive the target solution to flow;

[0054] In one-dimensional flow direction, the volume flow rate It can be regarded as the volume flow rate Q of the incompressible fluid and the cross-sectional area A of the fluid passing through the porous material c The ratio of the permeability k of the detection material to the concentration μ of the target solution can be regarded as the overall K (permeability coefficient); the above formula can be changed to:

[0055]

[0056] Where: Q is the volume flow rate of the incompressible fluid;

[0057] A c is the effective contact area between the cartilage and the liquid column;

[0058] K is the permeability coefficient;

[0059] In the retentate, the volume flow rate Q of the incompressible fluid is related to the pressure gradient driving the target solution flow. The following conversions are possible:

[0060]

[0061] Rearranging the above formula yields:

[0062]

[0063] Where: Δh is the height of liquid level drop during the stable permeation period;

[0064] A t is the cross-sectional area of ​​the liquid column;

[0065] Δt is the duration of the permeation stability period;

[0066] h c is the average height of cartilage;

[0067] Δp is the pressure difference;

[0068] Step 6: After the permeability coefficient is calculated, separate the cartilage sample from the perforated rubber plug; use an 8mm round steel punch to take a sample from the center of the cartilage sample; immediately place the removed sample in OCT embedding medium for fixation and store at -80°C; after it is completely hardened, dig out the sample and use a slicer to cut a 5μm thick cartilage slice. Use a laser confocal microscope to observe the retention distribution state of fluorescent solute molecules in the slice.

[0069] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A device for detecting the liquid phase solute retention performance of articular cartilage, characterized in that: It includes a testing machine, a cylinder base, a retention device, a retention pressure rod, a porous plate, and a syringe stopper; The cylinder base is fastened to the lower disc of the testing machine by bolts and nuts, and is used to support and fix the retention device to store the solution discharged by the permeation; The retainer is placed in the cylindrical base through the square hole and fixed by screws on both sides, and is used to load the experimental sample and the target solution, provide a space for the experiment, create a certain sealing condition and provide a passage for the permeation solution; The porous plate is placed at the bottom of the retention device, and the sample to be tested is placed on the porous plate, and the surface of the cartilage sample must be completely bonded to the bottom of the open-pore rubber plug; The retention pressure rod is fixed to the upper disc of the testing machine, a complete rubber plug is installed at the end of the retention pressure rod, the retention pressure rod is pressed into the retention device, and the pressure head of the testing machine applies pressure to the retention pressure rod, and the descending height of the retention pressure rod is obtained at the same time.

2. A device for detecting the liquid phase solute retention performance of articular cartilage according to claim 1, characterized in that: The rubber plug is a rubber plug used in a 5 ml medical syringe, has an outer diameter of 12.5 mm, and the diameter of the inner hole of the perforated rubber plug is 8 mm.

3. A device for detecting the liquid phase solute retention performance of articular cartilage according to claim 2, characterized in that: The single hole diameter of the porous plate is 1 mm, 4 holes are arranged on the inner circumference, and 8 holes are arranged on the outer circumference; the pore size is much larger than the pores of the cartilage itself, which can not only ensure the passage of the cartilage permeation solution, but also avoid unnecessary deformation of the cartilage under the action of water pressure.

4. A device for detecting the liquid phase solute retention performance of articular cartilage according to claim 3, characterized in that: The retainer is provided with a square hole at one half, so as to discharge the excess solution and air without inverting the retainer; a circular hole is provided at the bottom of the retainer, and the diameter of the circular hole is the distribution diameter of the outer circular holes of the porous plate, so as to realize the positioning and installation of the porous plate and the discharge of the permeate.

5. A device for detecting the liquid phase solute retention performance of articular cartilage according to claim 4, characterized in that: The upper part of the cylindrical base is provided with a cubic slot hole, which can realize the support of the retention device; the lower part of the cylindrical base is provided with a circular hole, the inner diameter of the hole is larger than the outer diameter of the retention device, and the height of the hole can meet the discharge of all solutions in the retention device.

6. A device for detecting the liquid phase solute retention performance of articular cartilage according to claim 5, characterized in that: The cylindrical base, the retention device, and the porous plate are all made of highly transparent materials, thus realizing full dynamic observation of the cartilage retention experiment.

7. A device and method for detecting the liquid phase solute retention performance of articular cartilage based on claims 1-6, characterized in that: The steps include: Step 1: Process the cartilage sample containing the underlying bone, remove the cartilage calcification layer and the tissue underneath, and ensure that the cartilage can be easily flattened; Step 2: Make a hole in the syringe plug and cut off the 5 ml syringe in the middle; put the plug with a hole into the cut syringe so that the bottom of the plug slightly protrudes from the outer edge of the syringe; use ethyl cyanoacrylate to preliminarily bond the bottom of the plug to the cartilage; Then, the pressure is applied to the other end of the rubber plug through the retention pressure rod to completely eliminate the gap between the rubber plug and the cartilage. In addition, since the rubber plug is surrounded by the syringe shell, it will not produce additional deformation due to squeezing. Then, the excess part of the cartilage is cut along the edge of the rubber plug so that it can fit into the retention device. Finally, ethyl cyanoacrylate adhesive is evenly applied around the joint between the cartilage and the rubber plug for further sealing and reinforcement. After it is completely dried, the sample is ready. Step 3: Place a porous plate at the bottom of the retention device, place the sample close to the porous plate, add water until it completely exceeds the overflow port, install a rubber plug on the end of the retention pressure rod and press it into the retention device, and continuously apply pressure to pre-detect whether the device and the sample are leaking; after the pre-detection is successful, drain all the water; Step 4: Fill the retention vessel with the solution required for the experiment, push the retention pressure rod back in, place it into the penetration base, fix the bolts on both sides, place the whole on the testing machine, fix the penetration base to the lower disc of the testing machine, fix the retention pressure rod to the upper disc of the testing machine, set the appropriate pressure and time, and then start the experiment. Step 5: After the experiment, based on Darcy's law, the displacement-time curve data of the stable section can be extracted and calculated according to the following formula: Where K is the permeability coefficient; Δh is the height of the liquid level drop during the permeation stability period; A t is the cross-sectional area of ​​the liquid column; Δt is the duration of the osmotic stability period; h c is the average height of cartilage; A c is the effective contact area between cartilage and liquid column; Δp is the pressure difference. Step 6: After the permeability coefficient is calculated, separate the cartilage sample from the perforated rubber plug; use an 8mm round steel punch to take a sample from the center of the cartilage sample; immediately place the removed sample in OCT embedding medium for fixation and refrigerate at -80℃; after it is completely hardened, dig out the sample and use a slicer to cut 5μm thick cartilage slices. The retention and distribution state of fluorescent solute molecules in the slice was observed using laser confocal microscopy.

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