Ultra-small nano low-valence copper negative pressure drainage sponge and preparation method thereof

Abstract

The present application relates to a kind of ultra-small nano low copper negative pressure drainage sponge and its preparation method, including sponge matrix, and / or, also including the anti-sticking layer being arranged on sponge matrix;The raw material of sponge matrix includes by mass fraction:8~12 parts of polyester polyol, 0.1~0.2 parts of ultra-small nano low copper particles, 0.2~0.4 parts of foaming agent, 0.2~0.3 parts of silicon surfactant, 0.3~0.4 parts of catalyst, 1.5~2.5 parts of sodium alginate and 12~18 parts of hexamethylene diisocyanate;Ultra-small nano low copper particles are prepared with copper salt and phenolic reducing agent as raw material, which contains Cu2O and CuO.The ultra-small nano low copper particles used in the present application have enzyme catalytic properties, antioxidant activity and antibacterial properties, so the negative pressure drainage sponge of the present application can reduce the concentration of reactive oxygen species, has good antibacterial properties (bacteriostatic rate is more than 90%), and effectively promotes wound repair.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomedical materials, and in particular relates to an ultra-small nanometer low-cost copper negative pressure drainage sponge and a preparation method thereof. Background Art

[0002] Skin trauma is a global health issue, and effectively rebuilding the function and integrity of damaged tissue is the current focus of clinical treatment. The ideal condition for skin wound healing is a moist environment. At the same time, the body consumes carbohydrates to provide energy during wound healing, but this process also produces a large amount of reactive oxygen species (ROS), which play an important role in affecting the speed of wound healing. Generally, low concentrations of reactive oxygen species promote wound healing, while high concentrations of reactive oxygen species inhibit wound healing. An ideal sponge should have the following characteristics: good hydrophilicity, water retention, antibacterial ability, the ability to promote wound healing, and the ability to prevent granulation induction.

[0003] While traditional polyurethane medical negative pressure drainage sponges offer hydrophilic and water-retention properties, effectively addressing the problem of wound exudate storage and creating a relatively moist environment, this humid environment also provides attachment points for foreign bacteria and fails to address the issue of how to reduce reactive oxygen species (ROS) concentrations to promote wound healing. Therefore, the design of a medical negative pressure drainage sponge is an urgent challenge in this field, yet holds great promise. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above technical deficiencies, provide an ultra-small nano low-cost copper negative pressure drainage sponge and its preparation method, and solve the technical problems in the existing technology that the negative pressure drainage sponge is hydrophilic and water-retaining but has poor antibacterial properties and slow wound healing speed.

[0005] In order to achieve the above technical objectives, the technical solution provided by the present invention is:

[0006] In a first aspect, the present invention provides an ultra-small nano-low-valent copper negative pressure drainage sponge, comprising a sponge matrix and / or an anti-sticking layer disposed on the sponge matrix; the raw materials of the sponge matrix comprise, by weight, 8 to 12 parts of polyester polyol, 0.1 to 0.2 parts of ultra-small nano-low-valent copper particles, 0.2 to 0.4 parts of a foaming agent, 0.2 to 0.3 parts of a silicone surfactant, 0.3 to 0.4 parts of a catalyst, 1.5 to 2.5 parts of sodium alginate, and 12 to 18 parts of hexamethylene diisocyanate; the ultra-small nano-low-valent copper particles are prepared using copper salt and a phenolic reducing agent as raw materials, and contain Cu2O and CuO.

[0007] In a second aspect, the present invention provides a method for preparing an ultrasmall nano-low-valent copper negative pressure drainage sponge, comprising the following steps: S1, preparing ultrasmall nano-low-valent copper particles using copper salt and phenolic reducing agent as raw materials; S2, uniformly mixing polyester polyol, ultrasmall nano-low-valent copper particles, foaming agent, silicon surfactant, catalyst, sodium alginate and hexamethylene diisocyanate to obtain a mixture; foaming and curing the mixture to obtain a sponge matrix; and / or, S3, coating an anti-sticking layer on the sponge matrix to obtain an ultrasmall nano-low-valent copper negative pressure drainage sponge.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] The present invention prepares a sponge matrix by mixing ultrasmall nanometer low-valent copper particles with polyester polyol, hexamethylene diisocyanate, and sodium alginate as raw materials, followed by foaming and curing. The ultrasmall nanometer low-valent copper particles contain Cu2O and CuO, which have enzyme catalytic properties and antioxidant activity, as well as antibacterial properties. The sodium alginate effectively enhances the hydrophilicity of the negative pressure drainage sponge. Therefore, the negative pressure drainage sponge of the present invention can reduce the concentration of active oxygen, has good antibacterial properties (with an inhibition rate of over 90%), and effectively promotes wound repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is the XPS peak diagram of the ultra-small nano-low-cost copper particles obtained by the present invention. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0012] While conventional polyurethane medical negative pressure drainage sponges have good hydrophilicity and water retention, effectively addressing the problem of storing wound exudate and creating a relatively favorable humid environment, this humid environment also provides attachment points for foreign bacteria and fails to address the problem of how to reduce reactive oxygen species concentration to promote wound healing. This is why the present invention was developed.

[0013] In a first aspect, the present invention provides an ultra-small nano-low-valent copper negative pressure drainage sponge, comprising a sponge matrix and / or an anti-sticking layer disposed on the sponge matrix; the raw materials of the sponge matrix comprise, by weight, 8 to 12 parts of polyester polyol, 0.1 to 0.2 parts of ultra-small nano-low-valent copper particles, 0.2 to 0.4 parts of a foaming agent, 0.2 to 0.3 parts of a silicone surfactant, 0.3 to 0.4 parts of a catalyst, 1.5 to 2.5 parts of sodium alginate, and 12 to 18 parts of hexamethylene diisocyanate; the ultra-small nano-low-valent copper particles are prepared using copper salt and a phenolic reducing agent as raw materials, and contain Cu2O and CuO.

[0014] Copper (Cu) is an essential trace element for the human body and plays an important role in various enzymes such as tyrosinase. Therefore, copper-based nanomaterials can be used to remove ROS; and cuprous oxide (Cu2O) has good catalytic activity and can promote electron transfer reactions, thereby partially simulating peroxidase. Therefore, the present invention can simultaneously obtain enzyme catalytic performance and antioxidant activity by combining Cu2O and CuO nanoparticles. At the same time, as a low-valent copper, it will enter the interior of bacterial cells through charge attraction, destroying its cell wall and internal protein enzymes, thereby having antibacterial and anti-inflammatory effects. The ultra-small nano low-valent copper particles are foamed with polyester polyol, hexamethylene diisocyanate and sodium alginate to obtain a sponge matrix, and then an anti-sticking layer is coated on the sponge matrix to effectively achieve a series of purposes such as reducing the concentration of active oxygen, preventing external bacterial invasion, absorbing tissue exudate, preventing wound adhesion and thus preventing granulation growth.

[0015] Preferably, the ultra-small nano-sized low-valent copper particles contain a molar ratio of Cu2O to CuO of 1:(6-8). This low-valent copper mixture exhibits excellent performance, improving enzyme catalysis and antioxidant activity, thereby creating an environment most conducive to wound recovery.

[0016] Preferably, the mass ratio of polyester polyol to ultra-small nano low-valent copper particles is 10:(0.1-0.2).

[0017] Preferably, the molar ratio of the total hydroxyl value of the polyester polyol to the total isocyanate value of the hexamethylene diisocyanate is 1:(1.1-1.2).

[0018] Preferably, the foaming agent includes deionized water; the silicon surfactant includes a silane coupling agent; and the catalyst includes stannous octoate.

[0019] Preferably, the material of the anti-sticking layer includes polydimethylsiloxane; the thickness of the negative pressure drainage sponge is 24 to 32 mm, and the thickness of the anti-sticking layer is 1.5 to 6.5 mm.

[0020] In a second aspect, the present invention provides a method for preparing an ultra-small nano-low-cost copper negative pressure drainage sponge, comprising the following steps:

[0021] S1, preparing ultra-small nano low-valence copper particles from a copper salt and a phenolic reducing agent;

[0022] S2, uniformly mixing polyester polyol, the ultra-small nano low-valence copper particles, a foaming agent, a silicon surfactant, a catalyst, sodium alginate and hexamethylene diisocyanate to obtain a mixture; the mixture is foamed and solidified to obtain a sponge matrix; and / or,

[0023] S3, coating an anti-sticking layer on the sponge matrix to obtain the ultra-small nano low-valence copper negative pressure drainage sponge.

[0024] Preferably, in step S1, the preparation of the ultra-small nano low-valence copper particles specifically comprises: adding the copper salt and the phenolic reducing agent into deionized water, reacting at 75-95℃ for 12-18h, cooling to room temperature after the reaction is completed and standing to separate layers, taking the supernatant liquid and performing centrifugation, dialysis and drying to obtain the ultra-small nano low-valence copper particles. In the specific reaction temperature and time conditions of the copper salt and the phenolic reducing agent, when the temperature is lower than 75℃, the reduction reaction cannot be induced due to the low temperature. When the temperature is higher than 95℃, the nano copper clusters are aggregated in large quantities, and the dissolved oxygen is reduced. The control of the reaction time makes the overall reaction time greater than 12h, and a shorter reaction time will lead to incomplete reaction of tea polyphenols and copper chloride, and the overall reaction tends to be stable after 12h.

[0025] Further preferably, the copper salt comprises copper chloride, and the phenolic reducing agent comprises tea polyphenols; the mass ratio of the copper salt to the phenolic reducing agent is 1:(2.4-2.6); and the mass ratio of the copper salt to deionized water is (4-6):100. When the amount of the phenolic reducing agent such as tea polyphenols is too small, the obtained nano copper clusters will have insufficient antioxidant capacity, and when the proportion of tea polyphenols is too high, the content of Cu2O in the obtained nano copper clusters will be too low to lose the enzyme-like effect.

[0026] Still further preferably, the tea polyphenols can be green tea and other substances rich in phenolic reducing agents, which are added into deionized water and rapidly stirred at 120-130℃ for 2-3h; the liquid phase is taken after cooling to room temperature and is subjected to drying treatment to obtain the phenolic substances in the green tea. The tea polyphenols or the phenolic substances in the tea leaves used as the raw materials of the present application are edible substances, the green preparation method improves the safety of the present application, and can provide a new idea for the development of medical negative pressure drainage sponges.

[0027] Further preferably, the centrifugation conditions include: a rotation speed of 3000-5000 r / min and a time of 20-30 min; and a dialysis bag with a molecular weight cutoff of 8000-10000 Da is used during dialysis. The dialysis bag preferably has a molecular weight cutoff (Mw cutoff) of 10000 Da, which can control the size of the copper to below 5 nm. A smaller size facilitates absorption by the body and subsequent metabolism through the kidneys.

[0028] Preferably, in step S2, the polyester polyol is first mixed evenly with the ultrasmall nano low-valent copper particles, and then the foaming agent, silicon surfactant, catalyst and sodium alginate are added, and stirred at a speed of 800 to 1200 r / min for 10 to 20 seconds, and finally hexamethylene diisocyanate is added and stirred at a speed of 1000 to 1500 r / min for 15 to 25 seconds to obtain a mixture.

[0029] Preferably, in step S2, the foaming conditions are: stirring and foaming with a stirring rod at room temperature, the stirring time is 20 to 30 seconds, and the speed is 600 to 1200 r / min; the curing temperature is 55 to 65° C., and the curing time is 18 to 24 hours.

[0030] The present invention is further described in detail below through specific examples.

[0031] Example 1

[0032] A method for preparing an ultra-small nano-low-cost copper negative pressure drainage sponge comprises the following steps:

[0033] S1, preparation of ultra-small nano-low-cost copper particles:

[0034] 5 g of copper chloride was dissolved in 100 mL of deionized water, 12 g of tea polyphenols was added, and the mixture was reacted at 85°C for 12 h. After the reaction was completed, the mixture was cooled for 6 h, and the mixture was cooled to room temperature and separated into layers. The supernatant was centrifuged at 4000 r / min for 25 min and the supernatant was collected again. The supernatant was dialyzed using a dialysis bag (molecular weight cutoff: 10000 Da) for 48 h to obtain the final solution. The final solution was freeze-dried for 48 h to obtain ultrasmall nano-low-valent copper particles.

[0035] The obtained ultra-small nano-low-cost copper particles were measured by XPS, and the peak fitting was performed using the Avantage software to obtain the peak diagram as shown below: Figure 1 As shown. Figure 1 It can be seen that the ultra-small nano-low-valent copper particles prepared in the present invention contain Cu2O and CuO, and the peak area ratio of the two is 1:7.7, that is, the molar ratio of Cu2O to CuO is 1:7.7.

[0036] S2, preparing a medical polyurethane negative pressure drainage sponge matrix:

[0037] After uniformly mixing 10g of polyester polyol (YSH908) and 0.1g of ultrasmall nano-low-valent copper particles, 0.4g of water, 0.3g of silane coupling agent KH-561, 0.4g of stannous octoate, and 2g of sodium alginate were added. The mixture was stirred at 1000 rpm for 15 seconds at room temperature. After adding 15g of hexamethylene diisocyanate, the mixture was stirred at 1200 rpm for 20 seconds. The mixture was then quickly poured into a mold for foaming. The prepared foam was placed in an oven and cured at 60°C for 20 hours to obtain a sponge matrix.

[0038] S3, preparing the anti-sticking layer:

[0039] The inner layer of the sponge matrix (the side to be in contact with the wound) after solidification was coated with polydimethylsiloxane (thickness of 2 mm), and then dried again for 12 hours to obtain a negative pressure drainage sponge.

[0040] Example 2

[0041] The only difference from Example 1 is that step S2 is different, and steps S1 and S3 are the same as those in Example 1; the difference is that:

[0042] S2: Mix 10g of polyester polyol (YSH908) and 0.15g of ultrasmall nano-low-valent copper particles. Add 0.2g of water, 0.2g of silane coupling agent KH-561, 0.3g of stannous octoate, and 2g of sodium alginate. Stir at 1000 rpm for 15 seconds at room temperature. Add 15g of hexamethylene diisocyanate and stir at 1200 rpm for 20 seconds. Then pour the mixture into a mold and allow it to foam. The prepared foam is placed in an oven and cured at 60°C for 20 hours to obtain a sponge matrix.

[0043] Example 3

[0044] The only difference from Example 2 is that the amount of ultrasmall nano-low-valent copper particles in step S2 is adjusted to 0.2 g, and the other steps and conditions are the same as those in Example 2.

[0045] Example 4 (without release layer)

[0046] S1, preparation of ultra-small nano-low-cost copper particles:

[0047] 5 g of copper chloride was dissolved in 100 ml of deionized water, 12 g of tea polyphenols was added, and the mixture was reacted at 85°C for 12 hours. After the reaction was completed, the mixture was cooled for 6 hours, and the mixture was cooled to room temperature and separated into layers; the supernatant was taken and centrifuged at 4000 r / min for 25 minutes, and the supernatant was collected again; the supernatant was dialyzed using a dialysis bag (molecular weight cutoff: 10000 Da) for 48 hours to obtain the final solution; the final solution was freeze-dried for 48 hours to obtain ultrasmall nano-low-valent copper particles.

[0048] S2, preparation of medical polyurethane negative pressure drainage sponge:

[0049] After uniformly mixing 10g of polyester polyol (YSH908) and 0.1g of ultrasmall nano-low-valent copper particles, 0.4g of water, 0.2g of silane coupling agent KH-561, 0.3g of stannous octoate, and 2g of sodium alginate were added, stirring at 1000 rpm for 15 seconds at room temperature. Add 15g of hexamethylene diisocyanate (the molar ratio of the total hydroxyl group of the polyester polyol to the isocyanate group in the hexamethylene diisocyanate was 1:1.1), stir at 1200 rpm for 20 seconds, and then quickly pour into a mold for foaming. The prepared foam was placed in an oven for curing to obtain a medical sponge.

[0050] Comparative Example 1 (non-hydrophilic control group)

[0051] The only difference from Example 1 is that sodium alginate is removed in step S2, and the other steps and conditions are the same as those in Example 1.

[0052] Comparative Example 2 (low copper content control group)

[0053] The only difference from Example 2 is that the amount of ultra-small nano-low-valent copper particles in step S2 is adjusted to 0.02 g, and the other steps and conditions are the same as those in Example 2.

[0054] Comparative Example 3 (low copper content control group)

[0055] The only difference from Example 2 is that the amount of ultra-small nano-low-valent copper particles in step S2 is adjusted to 0.08 g, and the other steps and conditions are the same as those in Example 2.

[0056] Performance Testing

[0057] Hydrophilicity: The contact angle of the anti-adhesive layer of the obtained negative pressure drainage sponge was tested using a contact angle meter (Dataphysics DCAT21).

[0058] Antibacterial properties: Using the oscillation method, dry negative pressure drainage sponge samples were added to liquid culture medium and swelled to swelling equilibrium. Then, the samples were transferred to 50 mL of fresh beef peptone liquid culture medium, inoculated with bacterial solution, and incubated at 37°C for 24 h. The experimental group (bacterial solution concentration was 10 6 The inhibitory rate was calculated by comparing the absorbance of the sample group (absorbance of 0.05 μg / mL) and the absorbance of the blank group (bacterial solution without sample), and the inhibitory rate was calculated as (absorbance of sample - absorbance of blank group) / absorbance of blank group × 100%. The test results are shown in Table 1 below.

[0059] ROS scavenging ability test: The antioxidant capacity (ROS scavenging ability) of the negative pressure drainage sponge sample of the present invention was evaluated using the DPPH antioxidant test. First, 4 mg of DPPH was dispersed in 100 ml of methanol. Then, 3 mL of DPPH solution was taken and added to the same volume of sample solution containing different amounts (0, 300, 500, 1000 μg / mL). Finally, the reaction solution was taken out at 120 min, and the absorbance value of the mixed solution at 516 nm was detected, and the scavenging rate was calculated using the formula [1-(A i -A j ) / A c ],in:

[0060] A i : absorbance of DPPH solution at 516 nm;

[0061] A j : absorbance of sample solution + DPPH solution at 516 nm;

[0062] A c : Absorbance of sample solution at 516 nm.

[0063] Anti-skin adhesion performance: A mouse wound model was designed. Under general anesthesia, a full-thickness wound (d = 5 mm) was made on the lateral side of the spine of each mouse using a sterile scalpel. The negative pressure drainage sponge of the present invention was then applied to the wound surface (with the anti-adhesion layer directly contacting the wound surface). After 3 days, the presence of skin adhesion was observed. All animal experiments were approved by the Animal Care and Use Committee of Wuhan University of Technology, with the Animal Experiment Ethics Approval Number being WHUT (2022-042). The criterion for skin adhesion was whether granulation tissue grew between the dressing and the skin, forming an integrated structure.

[0064] Wound healing rate: A mouse wound model was designed. Under general anesthesia, a full-thickness wound (d = 10 mm) was insulated on the lateral side of the spinal column of each mouse using a sterile scalpel. The negative pressure drainage sponge of the present invention was then applied to the wound surface (with the anti-adhesive layer in direct contact with the wound surface). Healing was observed after 14 days. The healing criterion was as follows: a circular wound with a d = 10 mm wound was created on the first day. After 14 days, wound recovery was observed. If the wound area was neatly aligned and there was no redness, swelling, or exudate, it was considered healed.

[0065] The negative pressure drainage sponge samples prepared in each embodiment and comparative example were tested using the above method. The test results are shown in Table 1 below.

[0066] Table 1 Performance test results of various embodiments and comparative examples

[0067]

[0068] As can be seen from Table 1, except for Comparative Example 1, the water droplets dripped on the negative pressure drainage sponge samples obtained in other embodiments and comparative examples were quickly and completely absorbed into the sponge matrix, indicating good wettability, and therefore the water contact angles were all recorded as 0°. However, the water droplets on the sample of Comparative Example 1 could not be quickly adsorbed, and the actual contact angle measured was 116°, proving that the hydrophilic effect of the negative pressure drainage sponge obtained by adding sodium alginate in the present invention is good.

[0069] In Example 4, a slight adhesion occurred between the mouse back wound and the negative pressure drainage sponge, but the wound was able to heal within the same period of time; and compared with Example 1, the biggest difference in Example 4 was the removal of the anti-adhesion layer (the amount of silane coupling agent and stannous octoate used was very small, and its effect was negligible), and its antibacterial rate and free radical scavenging rate were also slightly reduced, indicating that the provision of an anti-adhesion layer is more beneficial to the antibacterial rate and the promotion of wound healing.

[0070] The content of low-valent copper was increased proportionally in Comparative Example 2-3 and Example 2-3. Among them, the wound on the back of the mouse in Comparative Example 2-3 had not healed, and a small number of colonies appeared in the antibacterial test, while the wound in Example 2-3 had healed. It can be concluded that the ultrasmall nano low-valent copper particles in the negative pressure drainage sponge of the present invention have an effect of promoting wound healing, and the concentration affects its promoting effect. It also has good antibacterial effect and free radical scavenging effect.

[0071] Therefore, the negative pressure drainage sponge prepared by the present invention effectively solves a series of problems, including storing wound tissue fluid, reducing reactive oxygen species concentration, preventing external bacterial infiltration, and preventing adhesion to the wound. Furthermore, the ultra-small nano-low-valent copper prepared from tea polyphenols or phenols in tea leaves and copper chloride can effectively remove reactive oxygen species and exert antibacterial effects even at extremely low concentrations. Furthermore, the tea polyphenols and tea phenol extracts acting as reducing agents are edible, thereby improving the clinical safety of the medical negative pressure drainage sponge. This invention can provide a new approach to the development of medical negative pressure drainage sponges.

[0072] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. An ultra-small nano low-cost copper negative pressure drainage sponge, characterized in that: It includes a sponge base and, optionally, a release layer provided on the sponge base; The raw materials of the sponge matrix include, by weight: 8 to 12 parts of polyester polyol, 0.1 to 0.2 parts of ultra-small nano low-cost copper particles, 0.2 to 0.4 parts of foaming agent, 0.2 to 0.3 parts of silicon surfactant, 0.3 to 0.4 parts of catalyst, 1.5 to 2.5 parts of sodium alginate and 12 to 18 parts of hexamethylene diisocyanate; The ultra-small nanometer low-valent copper particles are prepared by using copper salt and phenol reducing agent as raw materials, and contain Cu2O and CuO in a molar ratio of 1: (6-8).

2. The ultra-small nano low-cost copper negative pressure drainage sponge according to claim 1, characterized in that: The mass ratio of the polyester polyol to the ultra-small nano low-valent copper particles is 10: (0.1-0.2); The molar ratio of the total hydroxyl value of the polyester polyol to the total isocyanate value of the hexamethylene diisocyanate is 1:(1.1-1.2).

3. The ultra-small nano low-cost copper negative pressure drainage sponge according to claim 1, characterized in that: The foaming agent includes deionized water; The silicon surfactant includes a silane coupling agent; The catalyst includes stannous octoate.

4. The ultra-small nano low-cost copper negative pressure drainage sponge according to claim 1, characterized in that: The raw material of the anti-sticking layer includes polydimethylsiloxane; The thickness of the negative pressure drainage sponge is 24 to 32 mm, and the thickness of the anti-sticking layer is 1.5 to 6.5 mm.

5. The method for preparing the ultra-small nano-low-cost copper negative pressure drainage sponge according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, preparing ultrasmall nano-sized low-valent copper particles using copper salt and phenolic reducing agent as raw materials; S2, uniformly mixing polyester polyol, ultra-small nano-low-cost copper particles, foaming agent, silicon surfactant, catalyst, sodium alginate and hexamethylene diisocyanate to obtain a mixture; foaming and curing the mixture to obtain a sponge matrix; optionally, S3, coating an anti-sticking layer on the sponge matrix to obtain an ultra-small nano-low-cost copper negative pressure drainage sponge.

6. The method for preparing the ultra-small nano low-cost copper negative pressure drainage sponge according to claim 5, characterized in that: In step S1, the preparation of ultrasmall nano low-valent copper particles specifically includes: adding copper salt and phenolic reducing agent to deionized water, reacting at 75-95°C for 12-18 hours, cooling to room temperature after the reaction is completed and standing to separate layers, taking the supernatant and centrifuging, dialyzing and drying to obtain ultrasmall nano low-valent copper particles.

7. The method for preparing the ultra-small nano low-cost copper negative pressure drainage sponge according to claim 6, characterized in that: The copper salt includes copper chloride, and the phenolic reducing agent includes tea polyphenols; the mass ratio of the copper salt to the phenolic reducing agent is 1: (2.4-2.6); the mass ratio of the copper salt to deionized water is (4-6): 100; The centrifugal conditions include: a rotation speed of 3000 to 5000 r / min and a time of 20 to 30 min; The dialysis uses a dialysis bag with a molecular weight cut-off of 8000 to 10000 Da.

8. The method for preparing the ultra-small nano-low-cost copper negative pressure drainage sponge according to claim 5, characterized in that: In step S2, the polyester polyol is first mixed evenly with the ultra-small nano low-valent copper particles, and then a foaming agent, a silicon surfactant, a catalyst and sodium alginate are added, and the mixture is stirred at a speed of 800 to 1200 r / min for 10 to 20 seconds. Finally, hexamethylene diisocyanate is added, and the mixture is stirred at a speed of 1000 to 1500 r / min for 15 to 25 seconds to obtain a mixture.

9. The method for preparing the ultra-small nano-low-cost copper negative pressure drainage sponge according to claim 5, characterized in that: In step S2, the foaming conditions are: stirring at a rotation speed of 600 to 1200 r / min for 20 to 30 seconds; the curing temperature is 55 to 65° C., and the curing time is 18 to 24 hours.

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