Preparation process of platelet-rich plasma and application of product thereof

Abstract

The application provides a preparation process of platelet-rich plasma and application of a product thereof. The process adds a hydrophobic agent to a separation gel to make the water contact angle of the separation gel reach 130-180 degrees, and cooperates with an operation mode of "firstly transferring the PPP in the upper PPP layer with a liquid volume of 70%-80% to a blood collection tube, and then gently shaking the blood collection tube to suspend the platelets and white blood cells in the remaining PPP", to finally obtain platelet-rich plasma, i.e. PRP. The application reduces the absorption of the separation gel to the platelet and white blood cell layer, provides favorable conditions for the platelets and white blood cells to separate from the separation gel and suspend in the PPP, simplifies the operation, is beneficial to improve the stability of the operation, meanwhile, improves the platelet recovery rate, and can stably obtain PRP with high recovery rate and high enrichment degree.

Description

Technical Field

[0001] This invention relates to the field of blood sampling and separation, and in particular to a process for preparing platelet-rich plasma and the application of its products. Background Technology

[0002] Platelet-rich plasma (PRP) is plasma obtained from peripheral blood through separation, which is rich in platelets. PRP contains various growth factors and other bioactive substances that are essential for cell growth, promoting cell proliferation, migration, and differentiation. In recent years, PRP has been widely used in the treatment of bone defects, skin wound repair, plastic surgery, and sports injuries, achieving good results in promoting tissue regeneration and repair.

[0003] Currently, there are two main processes for preparing PRP: two-stage centrifugation and one-stage centrifugation.

[0004] The double centrifugation process involves centrifuging whole blood once (at low speed) to remove some red blood cells and white blood cells. The supernatant from the first centrifugation is then transferred to another centrifuge container and centrifuged again (at high speed) to remove any remaining red blood cells and white blood cells. The resulting supernatant is platelet-rich plasma (PRP). This process is relatively complex, and because the centrifugal forces and times differ between the two centrifugations, it is difficult to control precisely. This results in a lower platelet recovery rate in the PRP and a higher likelihood of contamination with red blood cells. Furthermore, the double centrifugation requires changing containers, inevitably leading to repeated contact with the external environment and increasing the risk of PRP contamination.

[0005] One-step centrifugation involves centrifuging whole blood once to separate red blood cells, platelet-rich plasma (PPP), and platelet-rich plasma (PRP). However, the subsequent separation and injection still requires additional equipment, making the process cumbersome and posing a risk of contamination. Furthermore, this process typically requires specialized centrifuges and equipment, resulting in high production costs. Additionally, due to significant individual variations in blood concentration and viscosity among the different layers, the boundaries between the upper and lower layers are often unclear, demanding high operator skill and leading to inconsistent and low platelet recovery rates in the resulting PRP.

[0006] Some existing PRP preparation processes employ a separating gel plus a single centrifugation step, involving separate operations of blood collection centrifugation and separation injection. This is cumbersome and carries a certain risk of contamination. Furthermore, although serum separating gels can form an isolation layer between serum and blood clots, separating them, the existing separating gels have a certain degree of adhesion, causing platelets and leukocytes to adhere tightly to the surface. Simply shaking the centrifuge tube is insufficient to resuspend the platelets and leukocytes on the separating gel surface in the serum, resulting in low platelet recovery rates. Using a syringe to agitate the separating gel surface to resuspend the platelets and leukocytes in the serum not only increases the difficulty and complexity of the operation but also increases the risk of contamination. In addition, differences in agitation force, angle, and other operating conditions can lead to significant variations in platelet recovery rates, resulting in poor stability of platelet recovery rates.

[0007] Chinese patent CN 105820574 B discloses an organosilicon serum separating gel and its preparation method. It improves the thixotropy of the separating gel (thixotropy refers to the property of a substance to decrease in consistency when subjected to shear and increase in consistency when shearing stops) by synergistically using multiple organosilicon materials, thereby simultaneously solving the problems of unstable separation effect and poor storage stability of the separating gel. However, this patent does not mention the hydrophobicity of the separating gel (hydrophobicity refers to the repulsive force between a substance and water, i.e., the property of a substance not easily wetted, absorbed, or dissolved by water).

[0008] Therefore, existing PRP preparation processes cannot simultaneously achieve both operational simplicity and consistently high platelet recovery rates. Furthermore, centrifuge tubes have limited size and a narrow range of blood volume adaptability; different blood volumes require different centrifuge sizes, or repeated preparations using the same size centrifuge, which is cumbersome. Summary of the Invention

[0009] The objective of this invention is to provide a process for preparing platelet-rich plasma. This process uses a unique separating gel formulation, which can simultaneously simplify operation and achieve a high platelet recovery rate.

[0010] A process for preparing platelet-rich plasma includes the following steps:

[0011] S1: Mix the separating gel with the blood sample in a blood collection tube and centrifuge; wherein the weight parts of each component in the separating gel formulation are as follows:

[0012] 90-110 parts of acrylate

[0013] 1-4 parts of benzoyl peroxide

[0014] 1-4 parts of silicon dioxide

[0015] 0.01–0.15 parts of silane coupling agent

[0016] 80-100 parts of organic solvent

[0017] And a hydrophobic agent, wherein the hydrophobic agent is any one or more of nano-polysiloxane, nano-fluorinated polyethylene, nano-perfluoroethylene propylene copolymer, and nano-fluorosilane, and the amount of the hydrophobic agent added is determined by the water contact angle of the separating adhesive reaching 130 to 180 degrees.

[0018] S2: After centrifugation, the blood collection tube forms four layers from top to bottom: anemic platelet layer (PPP layer), platelet and leukocyte layer, separating gel layer, and red blood cell layer. The platelet and leukocyte layer are attached to the surface of the separating gel layer. 70% to 80% of the liquid volume of the PPP layer is transferred, and the blood collection tube is gently shaken to suspend the platelets and leukocytes in the remaining PPP. The suspension formed by the remaining PPP, platelets, and leukocytes is the platelet-rich plasma (PRP).

[0019] Starting from reducing the absorption of platelets by the separating gel, the inventors increased the hydrophobicity of the separating gel by adding a hydrophobic agent. By limiting the type and amount of the hydrophobic agent, the water contact angle of the separating gel reached over 130 degrees, resulting in a superhydrophobic separating gel. This makes the boundaries between the layers after centrifugation clearer while reducing the absorption of platelets and leukocytes by the separating gel. This allows platelets and leukocytes to detach from the separating gel and remain suspended in the platelet-polypeptide (PPP) simply by gently shaking the blood collection tube, eliminating the need to use a syringe to blow the surface of the separating gel. This simplifies the operation, improves operational stability, and avoids the risk of contamination from blowing. At the same time, the platelets and leukocytes remain suspended in the remaining PPP, increasing the platelet recovery rate of the PRP and enabling the stable acquisition of PRP with high recovery rate and high enrichment.

[0020] The silane coupling agent is any one or more of hexamethyldisilazane, vinyltrimethoxysilane, and vinyltriethoxysilane.

[0021] The organic solvent is any one or more of dimethylpentane, 3-methylhexane, methylcyclohexane, n-heptane, and ethyl acetate.

[0022] The acrylate is any one or more of methyl methacrylate, ethyl acrylate, and butyl acrylate.

[0023] The silica mentioned is untreated silica with a specific surface area of ​​100-380 m². 2 / g, bulk density of 60-100kg / m, carbon atom mass percentage of 2.5-5.0%, and moisture content of 0.1-0.3wt%.

[0024] To achieve a water contact angle of 130 to 180 degrees for the separating adhesive, the amount of hydrophobic agent added is typically 1 to 3 parts.

[0025] Furthermore, in step S1 above, the volume ratio between the blood sample and the separating gel is controlled between 3:1 and 20:1, the centrifugal force during centrifugation is between 1000 and 3000 × g, and the centrifugation time is between 3 and 15 min. The platelet-rich plasma obtained by stratification has a high platelet concentration and a high platelet recovery rate (over 80%).

[0026] The second objective of this invention is to apply the platelet-rich plasma (PRP) prepared by the preparation process of platelet-rich plasma according to the first objective of this invention to the repair of skin wounds.

[0027] Furthermore, in step S2 above, 70%–80% of the liquid volume of the PPP layer at the top is transferred and collected to obtain PPP. The PPP is then mixed with the PRP in a specific ratio to obtain PRP diluted serum with platelet concentrations of 1%–5%, which is then used for skin wound repair. The inventors' CCK-8 assay results show that the proliferation rate of 3T3 cells corresponding to PRP diluted serum with platelet concentrations of 1%, 3%, and 5% is increased compared to the control group. Specifically, when the platelet concentration is 3%, the CCK-8 assay shows the highest 3T3 cell proliferation rate at 206.13%. Simultaneously, when the platelet concentration is 3%, the cell migration results show the optimal 3T3 cell migration rate after 48 hours of treatment, reaching 99.81%.

[0028] Preferably, the PRP, PPP, or diluted serum of the PRP are first activated before being used for skin wound repair. Furthermore, the activation process employs an activator or repeated freeze-thaw cycles. When using an activator, the activator is one or more of the following: a CaCl2 solution with a final concentration of 0.1–3%, or thrombin with a final concentration of 50–3000 U. When using repeated freeze-thaw cycles, the conditions for repeated freeze-thaw cycles are: -80–45°C, 1–5 cycles. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the water contact angle of the separating adhesive of the present invention without the addition of a hydrophobic agent;

[0030] Figure 2 This is a schematic diagram of the water contact angle of the separating adhesive of the present invention;

[0031] Figure 3 This is a three-dimensional structural diagram of the platelet-rich plasma preparation device of the present invention, wherein the centrifuge sleeve and needle storage compartment are in perspective view.

[0032] Figure 4 This is a three-dimensional structural diagram of the blood collection tube of the present invention, wherein the needle storage compartment is a perspective view;

[0033] Figure 5 This is a three-dimensional structural diagram of the blood collection tube of the present invention in the blood collection state;

[0034] Figure 6 This is a schematic diagram of the assembly structure of the blood collection tube of the present invention, wherein the dotted lines are assembly lines;

[0035] Figure 7 This describes the plasma stratification after centrifugation using the blood collection tube of the present invention;

[0036] Figure 8 The graph shows the cell proliferation rates of PRP diluted serum with platelet concentrations of 1%, 3%, and 5% and the blank control group, respectively, according to the present invention.

[0037] Figure 9 The graph shows the migration of 3T3 cells at 0h, 24h and 48h in serum diluted with PRP at platelet concentrations of 1%, 3% and 5% and in the blank control group, respectively. Detailed Implementation

[0038] The following detailed description, in conjunction with the accompanying drawings, illustrates the specific implementation methods for preparing platelet-rich plasma according to the present invention and the application of the product:

[0039] like Figures 3-7 As shown, a process for preparing platelet-rich plasma includes the following steps:

[0040] S1, Blood Collection: The separating gel and blood sample are mixed in a blood collection tube 20 and centrifuged; the weight proportions of each component in the separating gel formulation are as follows:

[0041] 90-110 parts of acrylate

[0042] 1-4 parts of benzoyl peroxide

[0043] 1-4 parts of silicon dioxide

[0044] 0.01–0.15 parts of silane coupling agent

[0045] 80-100 parts of organic solvent

[0046] And a hydrophobic agent, wherein the hydrophobic agent is any one or more of nano-polysiloxane, nano-fluorinated polyethylene, nano-perfluoroethylene propylene copolymer, and nano-fluorosilane, and the amount of the hydrophobic agent added is determined by the water contact angle of the separating adhesive reaching 130 to 180 degrees.

[0047] S2, after centrifugation, the blood collection tube 20 forms four layers from top to bottom: anemic platelet layer (i.e., PPP layer) 100, platelet and leukocyte layer 200, separating gel layer 300, and red blood cell layer 400. The platelet and leukocyte layer 200 is attached to the surface of the separating gel layer 300. The PPP liquid volume at the top of the PPP layer 100, which accounts for 70% to 80% of the total volume, is transferred. The blood collection tube is then gently shaken to suspend the platelets and leukocytes in the remaining PPP. The suspension formed by the remaining PPP, platelets, and leukocytes is the platelet-rich plasma (PRP).

[0048] The silane coupling agent in the formulation of the separating gel can be any one or more of hexamethyldisilazane, vinyltrimethoxysilane, and vinyltriethoxysilane; the organic solvent can be any one or more of dimethylpentane, 3-methylhexane, methylcyclohexane, n-heptane, and ethyl acetate; the acrylate can be any one or more of methyl methacrylate, ethyl acrylate, and butyl acrylate; and the silica is untreated silica with a specific surface area of ​​100-380 m². 2 / g, bulk density of 60-100kg / m, carbon atom mass percentage of 2.5-5.0%, and moisture content of 0.1-0.3wt%.

[0049] In the preparation process of platelet-rich plasma of the present invention, the water contact angle of the separating gel used reaches 130 degrees or more (e.g., Figure 2 (As shown). Meanwhile, the inventor's separating adhesive has a water contact angle of less than 80 degrees without the addition of the hydrophobic agent (e.g., Figure 1 (As shown). The platelet-rich plasma (PRP) preparation process of the present invention involves removing 70%–80% of the liquid volume of the PPP layer 100 obtained by layering. Platelets and leukocytes can be detached from the separating gel and suspended within the PPP layer simply by gently shaking the blood collection tube. This eliminates the need for blowing the separating gel surface with a syringe to detach platelets and leukocytes, simplifying the operation and improving operational stability. It also avoids the risk of contamination associated with blowing. Furthermore, with platelets and leukocytes suspended within the remaining PPP layer, the platelet recovery rate of the PRP can reach over 80%, ensuring a stable high recovery rate and high enrichment of PRP.

[0050] The platelet-rich plasma (PRP) preparation apparatus of the present invention for implementing the above-described platelet-rich plasma (PRP) preparation process includes a centrifuge sleeve 10 and a blood collection tube 20, wherein the blood collection tube 20 is coaxially and detachably mounted inside the centrifuge sleeve 10; the blood collection tube 20 is a syringe; the piston 21 and the core rod 22 of the syringe 20 are detachably connected (in combination). Figures 3-6 ).

[0051] When using the platelet-rich plasma (PRP) preparation device, the blood collection tube 20 is removed from the centrifuge sleeve 10 for blood collection. After blood collection, the blood collection tube 20 is then inserted into the centrifuge sleeve 10, and the blood collection tube 20 and the centrifuge sleeve 10 are placed together in a centrifuge for centrifugation. After centrifugation, the blood collection tube 20 is removed from the centrifuge sleeve 10 for separation and collection. Because this invention uses a syringe-type blood collection device, after centrifugation, the inside of the syringe 20 is divided into four layers from top to bottom: a PPP layer 100 (platelet-rich plasma layer), a platelet and leukocyte layer 200, a separating gel layer 300, and an RBC layer 400 (red blood cell layer) (e.g., ...). Figure 7 As shown, when intravenous PRP injection is required, remove the intravenous puncture needle assembly used for blood collection and replace it with a new sterile intravenous puncture needle assembly (medical disposable intravenous puncture needle assembly). Push the core rod 22 upward to first discharge 70% to 80% of the liquid volume of the uppermost layer of the syringe 20 (PPP). Then, gently shake the syringe from side to side to allow the platelets, white blood cells, and other active ingredients adhering to the upper surface of the separating adhesive layer 300 to mix into the remaining PRP layer to form PRP. Continue to push the core rod 22 to apply the PRP to the wound site. When spraying the wound surface, after 70% to 80% of the liquid volume of the PPP layer is discharged, gently shake the syringe 20 from side to side, and then directly spray the tip of the syringe 20 onto the wound surface. The unique structure of the platelet-rich plasma (PRP) preparation device of this invention allows blood collection, centrifugation, and separation injection to be completed through the same blood collection tube 20. This simplifies operation, eliminates the need for transferring the sample solution, and provides convenience for clinical medical workers applying PRP. It also avoids contamination and loss during sample transfer, facilitating further improvement in the recovery rate of active ingredients such as platelets. Furthermore, the detachable connection between the piston 21 and the core rod 22 of the syringe 20 prevents increased space occupation when the core rod 22 is withdrawn, making the PRP preparation device compatible with conventional centrifuges and reducing costs. Simultaneously, it has a wide sample compatibility range (for centrifuges with 50ml tubes, the corresponding sample volume range is 2–30 mL).

[0052] Of course, the platelet-rich plasma preparation apparatus of the present invention for implementing the above-mentioned platelet-rich plasma preparation process may be, but is not limited to, the specific structure shown in the figures. It may also adopt existing platelet-rich plasma preparation apparatus (e.g., centrifugal blood collection tube with authorization announcement number CN207734170U).

[0053] The inventors investigated the effects of adding a hydrophobic agent to the separating gel (with or without adding a hydrophobic agent) on platelet enrichment fold and recovery rate under constant conditions of separating gel addition (i.e., blood sample to separating gel volume ratio) and centrifugation conditions. The experimental results are shown in Table 1.

[0054] Table 1

[0055]

[0056] Furthermore, the inventors investigated the effects of different amounts of separating gel and centrifugation conditions on the platelet recovery rate in the prepared PRP when nano-perfluoroethylene propylene copolymer was added to the separating gel. The specific experimental design conditions and experimental results are shown in Table 2 below:

[0057] Table 2

[0058]

[0059] The experimental results in Table 2 show that: in step S2, the centrifugal force is 1500–2000 × g, the centrifugation time is 5–10 min, and the ratio of blood sample to separating gel (V) is [missing information]. 血 / V 胶 When the ratio of blood sample to separating gel is 20 / 3 to 20 / 1, the platelet recovery rate in the PRP prepared by this invention can reach over 80%; especially when the ratio of blood sample to separating gel is 20 / 3 to 20 / 1. 血 / V 胶 When the ratio of blood sample to separating gel is 10 / 1, the platelet recovery rate of the PRP prepared by this invention is the highest, reaching 94%. Of course, the ratio of blood sample to separating gel (V) in this invention... 血 / V 胶 It can also be less than 20 / 3, but in order to achieve a basic separation effect, it needs to be at least 3 / 1.

[0060] Three replicate experiments were conducted according to the experimental conditions of Example 8. The blood routine results (as shown in Table 3) showed that the mean enrichment of platelet count (PLT) in the prepared PRP was 8.73 times with a standard deviation of 0.56, and the mean recovery rate was 94.27±0.39% with a standard deviation of 0.4. The platelet recovery rate in the PRP prepared in different batches of experiments was stable.

[0061] Table 3

[0062]

[0063] In step S2 of the present invention, 70% to 80% of the liquid volume in the upper part of the PPP layer obtained by layering is transferred and collected to obtain PPP. The inventors also mixed the prepared PRP with the PPP in different proportions to obtain PRP with different enrichment levels (specifically: PRP diluted with serum at platelet concentrations of 1%, 3%, and 5%, i.e., 1% PRP, 3% PRP, and 5% PRP), and performed cell proliferation assays. The purpose was to study the effect of PRP with different enrichment levels on cell growth. The specific experimental steps were as follows: 3T3 cells in logarithmic growth phase were taken, 1 ml of trypsin was added, and digestion was carried out for 1 min to obtain a single-cell suspension. The suspension was seeded in 96-well plates at a density of 2 × 10³ cells / well and incubated at 37°C for 24 hours in a 5% CO2 incubator. The culture medium was discarded, and PRP with different enrichment levels was dissolved in serum-free culture medium. The solution was added to the wells, with 5 parallel wells for each group. A blank control group (without PRP) was also established. Each drug group had 5 parallel wells and a blank control group was set up. After incubation for 24 hours, the wells were discarded, and 10% CCK-8 solution was added to each well. After incubation for 1-2 hours, the 450 nm value was measured using an enzyme marker. Absorbance at nm. For example Figure 8 As shown in the CCK-8 results, the proliferation rates of 3T3 cells after activation with 1% PRP, 3% PRP, and 5% PRP were 162.09%, 217.39%, and 180.08%, respectively, compared to the control group. Compared to the control group, the proliferation capacity of 3T3 cells was significantly enhanced in all sample groups after 24 h of culture. Furthermore, the proliferation effect of low-enriched PRP was significantly higher than that of high-enriched PRP, and the PRP plasma with a platelet concentration of 3% had the most significant effect on the proliferation of 3T3 cells.

[0064] Furthermore, the inventors also investigated the promoting effect of serum diluted with PRP at platelet concentrations of 1%, 3%, and 5% on 3T3 cell migration using an in vitro wound healing model. The specific experimental steps were as follows: 3T3 cells (2 × 10⁵ cells / well) were seeded into 24-well plates and cultured until a confluent monolayer was formed. Next, the monolayer was scraped along a straight line using a sterile pipette tip, followed by rinsing with PBS to remove any cell debris. Subsequently, 1 mL of serum-free culture medium containing PRP diluted with 1%, 3%, and 5% platelet concentrations were added to establish a blank control group (no PRP added). Cell migration was observed under a microscope at 0 h, 24 h, and 48 h. Figure 9 As shown, the results indicate that at 0h, the distribution of 3T3 cells in each group remained basically consistent. At 24h and 48h, the migration rate of 3T3 cells corresponding to 1%PRP, 3%PRP, and 5%PRP was significantly faster than that of the control group. Furthermore, 3%PRP was more effective in promoting 3T3 cell migration than other groups.

[0065] The preparation process of this invention yields platelet-rich plasma (PRP) with high platelet enrichment and high recovery rate. Cellular experiments have verified that the prepared PRP significantly promotes the proliferation, growth, and migration of 3T3 cells. The PRP prepared using this platelet-rich plasma preparation process has good application value in skin wound repair.

[0066] Preferably, the PRP, PPP, or diluted PRP serum are first activated before being used for skin wound repair; that is, the PRP and PPP are first activated and then mixed to obtain diluted PRP serum for skin wound repair. Alternatively, the PRP and PPP are first mixed to obtain diluted PRP serum, and then the diluted PRP serum is activated before being used for skin wound repair. Activation enables platelets to release growth factors. Furthermore, the activation process uses an activator or repeated freeze-thaw cycles. When using an activator, the activator is any one or more of a CaCl2 solution with a final concentration of 0.1–3% or thrombin with a final concentration of 50–3000 U. When using repeated freeze-thaw cycles, the conditions for repeated freeze-thaw cycles are -80–45°C, 1–5 cycles. Of course, the activation process of the present invention can be, but is not limited to, activator activation and repeated freeze-thaw activation, and can also use any existing type of platelet activation method.

[0067] In addition, the platelet-rich plasma preparation device of the present invention can be improved as follows:

[0068] (1) such as Figure 3 , Figure 4 As shown, the front end of the syringe 20 is connected to a needle assembly 30; the needle assembly 30 is an intravenous puncture needle assembly, and the outer wall of the syringe 20 is provided with a needle storage compartment 40 for storing the needle of the intravenous puncture needle assembly. The needle storage compartment 40 realizes the storage of the needle of the intravenous puncture needle assembly, so that the intravenous puncture needle assembly does not need to be removed immediately after blood collection, reducing the contact between blood and the outside world and reducing the risk of contamination.

[0069] (2) Combination Figure 5 , Figure 6The piston 21 has a piston connecting shaft 23 fixedly connected to its tail end. The piston connecting shaft 23 has a screw-in groove 230. The outer peripheral wall of the front end of the core rod 22 has an external thread 220. The external thread 220 of the core rod 22 engages with the inner thread of the screw-in groove 230 to achieve connection. After the syringe 20 is inserted into the centrifuge sleeve 10, the core rod 22 is removed for centrifugation. After centrifugation, when preparing to remove the syringe 20 from the centrifuge sleeve 10, the core rod 22 is reinstalled. This design avoids increasing the space occupied when the core rod 22 is removed, thus making the platelet-rich plasma preparation device suitable for conventional centrifuges and reducing costs.

[0070] Of course, the shape of the centrifuge sleeve, the shape of the blood collection tube, the detachable connection between the centrifuge sleeve and the blood collection tube, and the detachable connection between the core rod and the piston in the platelet-rich plasma preparation device of the present invention are not limited to the specific structures shown in the drawings.

[0071] For those skilled in the art, without departing from the concept of this invention, several simple deductions or substitutions can be made, and all such deductions or substitutions should be considered to fall within the scope of protection of this invention.

Claims

1. A process for preparing platelet-rich plasma, comprising the following steps: S1: mixing a separation gel with a blood sample in a blood collection tube and centrifuging; characterized in that: the weight percentage of each component in the formula of the separation gel is as follows: acrylic ester 90-110 parts, benzoyl peroxide 1-4 parts, silicon dioxide 1-4 parts, silane coupling agent 0.01-0.15 parts, organic solvent 80-100 parts, and a hydrophobic agent, which is one or more of nano polysiloxane, nano fluorinated polyethylene, nano perfluoroethylene propylene copolymer, and nano fluorosilane, and the addition amount of the hydrophobic agent is determined by the water contact angle of the separation gel reaching 130-180 degrees; S2: after centrifugation, four layers of PPP layer, platelet and white blood cell layer, separation gel layer, and red blood cell layer are formed in the blood collection tube from top to bottom, and the platelet and white blood cell layer is attached to the surface of the separation gel layer; the volume of the PPP in the layered PPP layer is 70-80% of the upper liquid, which is transferred, and the blood collection tube is gently shaken to suspend the platelet and white blood cell in the remaining PPP, and the suspension formed by the remaining PPP and the platelet and white blood cell is the platelet-rich plasma, i.e. PRP. The silane coupling agent is one or more of hexamethyldisilazane, vinyltrimethoxysilane, and vinyltriethoxysilane. The organic solvent is one or more of dimethylpentane, 3-methylhexane, methylcyclohexane, n-heptane, and ethyl acetate. The acrylic ester is one or more of methyl methacrylate, ethyl acrylate, and butyl acrylate. The addition amount of the hydrophobic agent is 1-3 parts. In step S1, the volume ratio between the blood sample and the separation gel is controlled between 3:1 and 20:1, the centrifugal force during centrifugation is between 1000 and 3000 x g, and the centrifugation time is 3-15 min. The platelet-rich plasma is the PRP prepared by the process for preparing platelet-rich plasma according to any one of claims 1-7; in the application, the volume of the PPP in the upper liquid in the layered PPP layer in step S2 of any one of claims 1-7 is 70-80%, which is transferred and collected to obtain the PPP; and the PPP and the PRP are mixed in proportion to obtain PRP diluted serum with a platelet concentration of 1-5%, and the PRP diluted serum is used for skin wound repair.

2. The process for preparing platelet rich plasma as claimed in claim 1 wherein: Any one of the PRP, the PPP, or the PRP diluted serum is activated before being used for skin wound repair.

3. The process for preparing platelet rich plasma as claimed in claim 1 wherein: The activation is performed by using an activator or by repeated freezing and thawing, and when the activation is performed by using an activator, the activator is one or both of a CaCl2 solution with a final concentration of 0.1-3% and a thrombin with a final concentration of 50-3000 U; when the activation is performed by repeated freezing and thawing, the repeated freezing and thawing is performed under the following conditions: -80-45°C, 1-5 cycles.

4. The process for preparing platelet rich plasma as claimed in claim 1 wherein: ​ 5. The process for preparing platelet rich plasma as claimed in claim 1 wherein: The silica is a silica which has not been subjected to hydrophobic pre-treatment, has a specific surface area of 100-380 m 2 / g, a bulk density of 60-100 kg / m, a carbon mass percentage of 2.5-5.0%, and a moisture content of 0.1-0.3 wt%.

6. The process for preparing platelet rich plasma as claimed in claim 1 wherein: ​ 7. The process for preparing platelet rich plasma as claimed in claim 1 wherein: ​ 8. Use of platelet-rich plasma in the repair of skin wounds, characterized in that: ​ 9. Use of platelet rich plasma according to claim 8 for skin wound repair, characterized in that: ​ 10. The use of platelet rich plasma according to claim 9 for skin wound repair, characterized in that: ​

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