Ag / pd alloy hollow nanospheres, method for preparing the same and application thereof in preparing antibacterial composite materials

Abstract

This invention discloses an Ag / Pd alloy hollow nanosphere, its preparation method, and its application in the preparation of antibacterial composite materials. Ethylene glycol is used as the solvent. A vulcanizing agent, acid, polyvinylpyrrolidone, and AgNO3 are added to ethylene glycol to obtain a reaction solution. The reaction temperature is controlled at 130-150℃. During the reaction, when the solution turns grayish-yellow, it is rapidly cooled in an ice-water bath to prepare Ag hollow nanospheres. Then, Ag / Pd alloy hollow nanospheres are synthesized through a substitution reaction between Ag and Pd. These Ag / Pd hollow nanospheres exhibit excellent photothermal conversion properties. Using Ag / Pd alloy hollow nanospheres as an antibacterial agent, this invention prepares an antibacterial composite material by mixing them with a carrier material, reinforcing agent, plasticizer, etc., and then preparing the composite material through electrospinning. This material has excellent bactericidal ability. Under sunlight irradiation, its bactericidal speed is particularly significant, shortening the bactericidal time from 3 hours to 4 minutes.

Description

Technical Field

[0001] This invention belongs to the field of composite materials, specifically relating to an Ag / Pd hollow nanosphere, its preparation method, and its application in the preparation of antibacterial composite materials. Background Technology

[0002] Bacterial infections caused by pathogens can occur in the human respiratory tract, skin, and blood, seriously threatening human life and health. After the successful development of antibiotics, researchers used them to kill bacteria with good results. However, with the overuse of antibiotics, microbial resistance to antibiotics has gradually increased, and the bactericidal effect is no longer obvious. In addition, the abuse of antibiotics leaves residues in our living environment, further endangering human life and health. Current sterilization methods are still mostly traditional, including ultraviolet irradiation, chlorine, ozone, and other strong oxidants. These sterilization methods are not timely, take a long time, and are prone to causing secondary pollution to the environment. Therefore, there is an urgent need to develop a rapid, timely, and effective sterilization method.

[0003] The rapid development of nanotechnology has led to a qualitative leap in various fields and brought new research directions for antibacterial methods. Numerous scholars have demonstrated that many nanomaterials possess excellent antibacterial effects against bacteria. Within the nanostructure of materials, differences in shape, size, and specific surface area result in variations in chemical and physical properties. Therefore, utilizing nanomaterials as antibacterial agents is a highly effective method to address the shortage of antibacterial materials. Currently, nanomaterials used for antibacterial purposes include carbon-based materials, metal nanoparticles, metal oxides / sulfides, and functional polymers. Among numerous antibacterial nanomaterials, silver nanoparticles have seen significant development in the field of biology due to their excellent antibacterial ability and good biocompatibility. As an antibacterial agent, silver possesses broad-spectrum and strong antibacterial properties, making it a preferred choice for microbial antibacterial materials. Its large specific surface area provides more adsorption sites when in contact with bacteria. Furthermore, silver undergoes oxidation in oxygen-containing environments, releasing Ag. + Ag + It will damage the bacterial cell membrane, leading to the death of the bacteria.

[0004] Silver nanomaterials possess excellent interaction capabilities with microorganisms, making them a promising antibacterial agent. The generation of reactive oxygen species and the release of silver ions are two primary antibacterial mechanisms of silver nanoparticles. However, the high binding energy on the surface of pure silver nanomaterials and the tendency for nanostructures to aggregate limit their applications. Nanosilver is also expensive; using large quantities of metal elements as antibacterial materials would be costly, and excessive use of metals could negatively impact the human environment. It has been found that the antibacterial efficiency of single metal nanoparticles is insufficient for practical antibacterial requirements, thus the development of multifunctional antibacterial materials has attracted considerable attention. Summary of the Invention

[0005] To address the problems existing in the aforementioned technologies, this invention provides Ag / Pd hollow nanospheres, their preparation method, and their application in the preparation of antibacterial composite materials. This invention first prepares Ag hollow nanospheres, and then synthesizes Ag / Pd alloy hollow nanospheres with different molar ratios through a substitution reaction between Ag and Pd. The substitution reaction of Ag nanomaterials with Pd enhances the photocatalytic and photothermal properties of the Ag / Pd hollow nanospheres under visible light irradiation. It significantly improves oxidase-like performance under sunlight. 1 The O2 yield was increased by approximately 20%. The Ag / Pd-PAN nanocomposite material prepared in this invention has excellent bactericidal properties and can kill almost all bacteria within 3 hours without any auxiliary agents. If exposed to sunlight, it can kill all bacteria within 4 minutes, achieving rapid sterilization.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first objective of this invention is to provide a method for preparing Ag / Pd alloy hollow nanospheres, comprising the following steps:

[0008] Ethylene glycol is heated to 130-150°C, and then a vulcanizing agent, acid, polyvinylpyrrolidone, and AgNO3 solution are added to the ethylene glycol to obtain a reaction solution. The reaction is carried out under stirring until the reaction solution changes color to grayish-yellow. The resulting solution is then rapidly cooled in an ice-water bath to obtain a silver nanoparticle colloidal solution. The silver nanoparticle colloidal solution is centrifuged, and the obtained Ag hollow nanospheres are dispersed in water to obtain a silver nanoparticle aqueous dispersion. Preferably, the vulcanizing agent is sodium sulfide or sodium hydrosulfide; the acid is hydrochloric acid.

[0009] Silver nanoparticles were dispersed in ethylene glycol at 85-95℃, and palladium chloroplastate was added. After reacting for 3-8 minutes, the resulting solution was rapidly cooled in an ice-water bath. Following centrifugation and washing, Ag / Pd alloy hollow nanospheres were obtained. Preferably, the palladium chloroplastate is potassium palladium chloroplastate or sodium palladium chloroplastate. The molar ratio of Ag to Pd in ​​the Ag / Pd alloy hollow nanospheres was 1:(0.1-0.5).

[0010] The second objective of this invention is to provide an Ag / Pd alloy hollow nanosphere, which is prepared by the preparation method described in the first objective above.

[0011] A third object of the present invention is to provide the application of Ag / Pd alloy hollow nanospheres as described in the second object above in the preparation of antibacterial composite materials, wherein the antibacterial composite material comprises a carrier material, a reinforcing agent, a plasticizer, and Ag / Pd alloy hollow nanospheres. Preferably, the carrier material is polyacrylonitrile or polyvinylidene fluoride, the reinforcing agent is nanocellulose, and the plasticizer is polyethylene oxide.

[0012] A further embodiment of the method for preparing the antibacterial composite material is as follows: a carrier material, a reinforcing agent, a plasticizer, and Ag / Pd alloy hollow nanospheres are dispersed in a dispersant to obtain a mixture, and the mixture is electrospun to prepare a nanofiber membrane, which is the antibacterial composite material.

[0013] The beneficial effects of this invention are as follows:

[0014] This invention uses ethylene glycol as a solvent and controls the reaction temperature at 130-150℃. During the reaction, when the solution turns grayish-yellow, it is rapidly cooled in an ice-water bath to prepare Ag hollow nanospheres. Then, Ag / Pd alloy hollow nanospheres are synthesized through a substitution reaction between Ag and Pd. The Pd-substituted Ag nanospheres exhibit improved oxidase-like properties under light irradiation. 1 O2 production increased by approximately 20%. Simultaneously, the synthesized Ag / Pd hollow nanospheres exhibited excellent photothermal conversion performance (28.16%), and the temperature of the Ag / Pd-PAN film prepared thereby instantly increased to 58.5℃. The product prepared in this application has a hollow structure with a large specific surface area. Compared with traditional nanostructures, under the same material dosage, the hollow structure exhibits a corresponding photothermal effect that enhances and accelerates Ag production. + Effective release. This invention uses Ag / Pd alloy hollow nanospheres as an antibacterial agent, and prepares an antibacterial composite material by electrospinning after mixing them with carrier materials, reinforcing agents, plasticizers, etc. This material has excellent bactericidal ability. Under sunlight irradiation, its bactericidal speed is particularly obvious, shortening the bactericidal time from 3 hours to 4 minutes. The antibacterial mechanism shows that Ag... + The effective release of [resources], rapid ROS generation, and the dramatic increase in temperature under solar irradiation are the main reasons for its rapid sterilization. Furthermore, Ag / Pd alloy hollow nanospheres exhibit very low biotoxicity, and sterilization strategies based on this material show great promise for the timely sterilization of personal protective equipment such as masks. Attached Figure Description

[0015] Figure 1 This document describes the preparation and characterization of Ag / Pd hollow nanospheres. (A) Schematic diagram of the synthesis principle of Ag / Pd hollow nanospheres. (BG) Ag, AgPd 0.1 AgPd 0.2 AgPd 0.3 AgPd0.4 and AgPd 0.5 TEM image of hollow nanospheres. (HK)AgPd 0.4 EDS image of the hollow nanospheres.

[0016] Figure 2 The photothermal and enzyme-like properties of Ag / Pd hollow nanospheres. (A)AgPd 0.4 UV-vis-NIR absorption curves of the nano-hollow sphere solution. (B)AgPd 0.4 Heating curve of nano-hollow sphere solution (1W / cm) 2 (C) AgPd at a concentration of 1 mg / mL 0.4 Temperature changes in the solution after heating and natural cooling of the nano-hollow spheres. (D) Linear relationship between time and ln(θ). (E) Absorption curves of Ag / Pd nano-hollow sphere solutions with different molar ratios co-cultured with AA for 1, 2, and 3 h. (F) AgPd 0.4 The absorption of AA by co-culturing nano-hollow spheres with AA under Air, N2, and Ar conditions. (G) Different concentrations of AgPd 0.4 The absorption of DPBF by hollow nanospheres co-cultured with DPBF. (H) Under light-free conditions and a solar simulator 1 The amount of O2 generated.

[0017] Figure 3 This is a diagram illustrating the preparation method and antibacterial mechanism of Ag / Pd-PAN nanocomposite materials.

[0018] Figure 4 Characterization and photothermal properties of Ag / Pd-PAN nanocomposites. (A,D) SEM images of PAN and AgPd-PAN. (B,E) TEM images of PAN and AgPd-PAN. (C,F) Camera images and water contact angles of PAN and AgPd-PAN films. (G,H) Fiber diameters of PAN and AgPd-PAN. (I) Temperature rise and natural cooling curves of AgPd-PAN under a solar simulator (1W / cm²). 2 (J) Infrared camera images of AgPd-PAN heated and naturally cooled under a solar simulator (1W / cm²). 2 ).

[0019] Figure 5 This describes the antibacterial effect of PAN and Ag / Pd-PAN nanocomposites. (A,C) Digital images of Escherichia coli and Staphylococcus aureus colonies (under light). (B,D) Survival rates of Escherichia coli and Staphylococcus aureus (under light). (E,G) Digital images of Escherichia coli and Staphylococcus aureus colonies (under light). (F,H) Survival rates of Escherichia coli and Staphylococcus aureus (under light). Detailed Implementation

[0020] The present invention will be further described below with reference to embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0021] In addition, unless otherwise specified, the preparation processes in the following embodiments are all conventional methods in the prior art, and therefore will not be described in detail; the raw materials and reagents used in the following embodiments are all commercially available products.

[0022] Example 1

[0023] A method for preparing Ag / Pd alloy hollow nanospheres includes the following steps:

[0024] Take a 50 mL round-bottom flask and add 20 mL of ethylene glycol (EG) solution. Place the flask in a 150 °C oil bath and heat with stirring. When the EG solution in the flask reaches 150 °C, add 0.24 mL of EG solution in NaHS (3 mM) to the round-bottom flask and maintain the temperature at 150 °C for 10 min. Add 2 mL of HCl solution (3.5 mM) and 5 mL of PVP solution (20 mg / mL). Maintain the temperature and continue heating for 2 min. Add 1.5 mL of AgNO3 solution (48 mg / mL) to the flask, cover the flask, and continue heating at 150 °C. When the solution turns grayish-yellow, remove the heated flask and rapidly cool it in ice water. Take out the silver nanocolloid solution, place it in a centrifuge tube, wash it with acetone and deionized water respectively, and centrifuge three times. The centrifuged silver hollow nanospheres are separated and then dispersed in deionized water to form a silver nano aqueous dispersion for later use. It should be noted that in the above reaction, the temperature of the EG solution only needs to be controlled within the range of 130-150℃ to achieve the purpose of this invention.

[0025] Take a 50 mL round-bottom flask and add 20 mL of EG solution. Place it in a 90 °C oil bath and heat with stirring. Add the silver nanoparticle aqueous dispersion (1 mg / mL, 1 mL) to the flask. After heating continuously for 10 min, slowly add an EG solution of K2PdCl4 (0.5 mM) using a syringe pump. After reacting for 5 min, rapidly cool the flask in ice water. Wash repeatedly by centrifugation three times with acetone and deionized water. Remove the centrifuged AgPd hollow nanospheres to obtain Ag / Pd alloy hollow nanospheres. It should be noted that the EG temperature in the above reaction only needs to be controlled within the range of 85-95 °C to achieve the purpose of this invention.

[0026] Figure 1This paper describes the preparation and characterization of Ag / Pd alloy hollow nanospheres. First, we synthesized Ag hollow nanospheres. Based on TEM images of the Ag nanospheres, it was found that the Ag nanospheres have a uniform size, approximately 50 nm. Figure 1 B). Then, using the sacrificial template method, with Ag nanospheres as sacrificial templates, we synthesized Ag / Pd alloy hollow nanospheres through a substitution reaction of Pd replacing Ag. Different amounts of K₂PdCl₄ were added to a given palladium source (Ag to Pd molar ratios of 1:0.1, 1:0.2, 1:0.3, 1:0.4, and 1:0.5) to synthesize different Ag / Pd alloy hollow nanospheres. TEM images of the Ag / Pd alloy hollow nanospheres with different Ag and Pd molar ratios show that the Ag / Pd alloy nanospheres are uniform in size, spherical, with an outer Ag / Pd nanoalloy structure and an inner hollow structure, with a size of approximately 50 nm. Figure 1 CG). Meanwhile, AgPd 0.4 The elemental distribution map of the hollow nanospheres shows that Ag and Pd elements are uniformly distributed on the surface of the hollow nanospheres. Figure 1 HK).

[0027] Figure 2 It is AgPd 0.4 The photothermal and enzyme-like properties of hollow nanospheres. For example... Figure 2 As shown in A, AgPd 0.4 The nano-hollow sphere solution exhibits significant absorption characteristics in the 300-500 nm range, particularly a very strong absorption peak at 424 nm, which helps to enhance the absorption of AgPd. 0.4 The photocatalytic and photothermal properties of hollow nanospheres under visible light irradiation were investigated. Subsequently, we tested different concentrations of AgPd using a solar simulator. 0.4 Temperature variation characteristics of nano-hollow sphere solution Figure 2 B). Without adding AgPd 0.4 In aqueous solutions containing nano-hollow spheres, temperature changes are particularly insignificant, with a temperature rise of less than 25°C within 10 minutes. This is due to the presence of AgPd. 0.4 Hollow nanospheres possess excellent photothermal properties, AgPd 0.4 The concentration of the hollow nanospheres was only 0.1 mg / mL, and the temperature rose to 28.5℃ within 10 minutes. This temperature increase was related to AgPd. 0.4 The concentration of the hollow nanospheres is directly proportional to the concentration of AgPd. 0.4 When the concentration of hollow nanospheres reaches 4 mg / mL, the temperature can reach 49.5℃ within 10 minutes, indicating that AgPd... 0.4 Hollow nanospheres exhibit good photothermal effects. Then, the concentration of AgPd at 1 mg / mL was observed. 0.4 Heating and cooling process of nano-hollow spheres ( Figure 2C), and calculate the linear relationship between temperature change and corresponding time and lnθ during the cooling process ( Figure 2 D). AgPd 0.4 The photothermal conversion efficiency of the hollow nanospheres reached as high as 28.16%. This further demonstrates the effectiveness of AgPd. 0.4 Hollow nanospheres have good photothermal conversion efficiency.

[0028] We tested the enzymatic activity of Ag / Pd alloy hollow nanospheres. Ascorbic acid (AA) was used to detect ROS generation. Incubation of Ag / Pd hollow nanospheres with AA in PBS solution for different times and with different molar ratios of Ag / Pd hollow nanospheres resulted in varying degrees of reduction in AA absorption intensity. This indicates that Ag / Pd hollow nanospheres possess different efficiencies in ROS generation. Furthermore, the ROS generation efficiency of Ag / Pd hollow nanospheres did not increase with increasing Pd content. 0.1 The ROS generation efficiency is the lowest when reaching AgPd. 0.4 Previously, ROS generation efficiency tended to balance with the increase of Pd. Figure 2 E). In the preparation of Ag / Pd nanoalloys, during the process of Pd replacing Ag nanospheres, the lattice mismatch at the Ag / Pd hollow nanosphere interface affects the relationship between ROS generation and the lack of increase in Pd content. Therefore, Ag / Pd hollow nanospheres can spontaneously generate ROS without external stimulation. We found that with AgPd... 0.4 As a material, the efficiency of ROS cultivation in PBS solution is directly proportional to the cultivation time. After 1 hour of cultivation in PBS solution, the absorption intensity of AA decreased by approximately 16.17%, and after 3 hours of cultivation, the absorption intensity decreased by approximately 69.72%. Figure 2 E).

[0029] Most natural oxidases possess excellent catalytic properties, capable of decomposing O2 into oxygen atoms. To verify whether Ag / Pd hollow nanospheres exhibit this property, we used AgPd... 0.4 As a material, it was dissolved in PBS solution, and then air, N2, and Ar were injected into the solution. After incubation for 3 hours, the absorption intensity of AA was tested. Under Ar and N2 conditions, the absorption of AA decreased only slightly, which may be due to residual O2 in the solution. Figure 2 F). In an air environment, the solution contains a large amount of O2, and the absorbance of AA decreases significantly. Figure 2 F). Therefore, AgPd hollow nanospheres possess the basic conditions for oxidase.

[0030] We tested AgPd using DPBF. 0.4 Generation of nano-hollow spheres 1 The ability to detect O2. Using DPBF as the detection reagent, it was found that...1 O2 yield and AgPd 0.4 The concentration of the hollow nanospheres showed a positive correlation. In PBS solution, the concentration was positively correlated with that of AgPd. 0.4 After co-culturing (64ug / mL) hollow nanospheres for 3 hours, the DPBF absorbance decreased by approximately 35.45%. Figure 2 G). Subsequently, we studied AgPd. 0.4 Hollow nanospheres under light stimulation 1 O2 yield. When DPBF is compared with AgPd 0.4 When the nano-hollow sphere solution was mixed for 5 minutes, with the AgPd 0.4 The increase in the concentration of hollow nanospheres 1 The formation rate of O2 increased significantly. Figure 2 H). Without light stimulation, the concentration increased from 8 μg / mL to 128 μg / mL. 1 The O2 yield increased from 1.24% to 9.01%. This was achieved after introducing solar simulator irradiation. 1 The O2 formation rate increased significantly, with the yield increasing from 3.39% to 29.11%. More specifically, 1 The amount of O2 produced increased to 2.73, 2.66, 2.48, 3.10, and 3.23 times that of solar radiation.

[0031] Example 2

[0032] The preparation method of Ag / Pd-PAN antibacterial composite material includes the following steps:

[0033] Nanofiber films were prepared using polyacrylonitrile (PAN) as the main spinning component, cellulose nanofiber (CNF) as the reinforcing agent, and polyethylene oxide (PEO) as the plasticizer. First, 0.02 g of CNF was dissolved in DMF and stirred on a magnetic stirrer. After homogenization, 0.1 g of PEO was added and stirring continued. Simultaneously, 1.2 g of PAN powder and 1 mL of Ag / Pd hollow nanospheres prepared in Example 1 were dissolved in 10 mL of DMF solution and magnetically stirred. Then, the two solutions were mixed and stirred until homogenized. The resulting homogenous solution was injected into a 10 mL syringe for electrospinning. The spinning conditions were as follows: an 18-gauge stainless steel needle, a voltage of 20 kV, a delivery rate of 20 μL / min using an infusion tube, a distance of 15 cm between the collecting device and the spinneret, a rotating metal roller with a diameter of 10 cm and a length of 30 cm covered with tin foil, and a spinning speed of 100 rpm to collect the deposited nanofiber film, resulting in the Ag / Pd-PAN antibacterial composite material (referred to as AgPd-PAN).

[0034] For comparison, a PAN fiber membrane (hereinafter referred to as PAN) without Ag / Pd hollow nanospheres was prepared. The method was similar to that used to prepare Ag / Pd-PAN nanocomposite fabrics, but Ag / Pd hollow nanospheres were not added to the mixed solution.

[0035] Figure 3 This is a diagram illustrating the preparation method and antibacterial mechanism of Ag / Pd-PAN antibacterial composite material. Figure 3 As can be seen, our preparation of Ag / Pd-PAN nanocomposites mainly uses polyacrylonitrile (PAN) as the main spinning component, nanocellulose (CNF) as the reinforcing agent, polyethylene oxide (PEO) as the plasticizer, Ag / Pd hollow nanospheres as the antibacterial material, and N,N-dimethylformamide as the solvent, and then utilizes electrospinning technology to synthesize Ag / Pd-PAN nanocomposites. The synthesized Ag / Pd-PAN nanocomposites can rapidly increase in temperature under light conditions, with the highest temperature reaching 58.5℃ (solar simulator 1W / cm²). 2 Furthermore, the synthesized Ag / Pd-PAN nanocomposite material can be used as a material for face masks, and it can produce… 1 O2 and Ag + Therefore, the prepared composite material can achieve ROS and Ag... + It has photothermal antibacterial properties and also has extremely low biotoxicity.

[0036] Figure 4 This section describes the characterization and photothermal properties of Ag / Pd-PAN films. From... Figure 4 It can be seen that the PAN fiber membrane spun from PAN blends is white and composed of many smooth, overlapping filaments. The spun fibers have a uniform diameter distribution, with an average diameter of approximately 232 nm. Figure 4 A,G). The Ag / Pd-PAN fiber membrane is gray. Due to the addition of Ag / Pd hollow nanospheres, the surface of the spun fibers in the film exhibits unevenness, with nanoparticles embedded on the fiber surface. Figure 4 D). TEM images further clearly revealed small particles embedded in the spun fibers. These small particles are Ag / Pd hollow nanospheres added to the spinning solution. Figure 4 E). Adding Ag / Pd hollow nanospheres to the spinning solution increases the diameter of the spun nanofibers to 254 nm. Figure 4 H). The main component of the nanofiber film spinning solution is polyacrylonitrile (PAN), which has strong hydrophilicity. Based on the measurement of the water contact angle, which is 0°, the PAN fiber membrane was found to have excellent hydrophilicity. Figure 4 C). In the water contact angle measurement of Ag / Pd-PAN fiber membrane, it was found that the addition of a small amount of Ag / Pd hollow nanospheres did not change the hydrophilicity of the film, and the water contact angle was 0°, indicating that the film still has excellent hydrophilicity. Figure 4F). The film's excellent hydrophilicity allows it to adsorb droplets from the air and adhere to substances containing moisture. Furthermore, the gaps between the fibers mean the film also possesses good air permeability. Subsequently, we tested it on a solar simulator (1W / cm²). 2 The photothermal properties of Ag / Pd-PAN fiber membranes were investigated under solar simulator irradiation. The temperature of the Ag / Pd-PAN fiber membrane reached 58.5℃ within 1 minute, demonstrating excellent photothermal performance. Figure 4 I). Meanwhile, the infrared camera clearly recorded the temperature change, finding it to be the same as the former (…). Figure 4 J). It can be seen that the excellent photothermal heating properties of Ag / Pd-PAN fiber membrane provide a basis for its photothermal sterilization.

[0037] Figure 5 The antibacterial effects of PAN and AgPd-PAN membranes were investigated. The plate count method was used to study the antibacterial effects of PAN and AgPd-PAN membranes. Figure 5 It can be seen that after co-culturing with PAN for 3 hours, the number of colonies in the agar culture dish did not decrease significantly, and the survival rates of Escherichia coli and Staphylococcus aureus were 97.12% and 98.33%, respectively. Figure 5 B, D). However, the number of colonies significantly decreased when co-cultured with AgPd-PAN (B, D). Figure 5 (A, C) The survival rates of Escherichia coli and Staphylococcus aureus were only 0.05% and 0.03%, respectively, indicating that almost all bacteria were killed. Figure 5 (B,D). Therefore, the AgPd-PAN film itself has excellent antibacterial properties. It can be used as a bactericidal layer in masks, killing bacteria without external influence and ensuring the wearer's safety.

[0038] Because Ag / Pd-PAN film has significant photo-enhanced ROS, photothermal effect and Ag + We further investigated the bactericidal ability of the Ag / Pd-PAN membrane against *Escherichia coli* and *Staphylococcus aureus* under solar simulator irradiation. When using the PAN membrane as the experimental material, the activity of *E. coli* and *Staphylococcus aureus* remained unaffected. However, when using the Ag / Pd-PAN membrane, we found that the bactericidal effect of the Ag / Pd-PAN membrane against *E. coli* and *Staphylococcus aureus* was directly proportional to the time required to isolate colonies from the solid culture dish. When the time reached 4 minutes, almost no colonies remained in the solid culture dish. Figure 5 E, G). The bacterial survival rate histogram further showed that, under visible light conditions, the Ag / Pd-PAN membrane achieved a bactericidal efficiency of 99.9% against Escherichia coli and Staphylococcus aureus. Figure 5F,H). Specifically, the bactericidal mechanism of Ag / Pd-PAN membrane is described as follows: (1) Ag / Pd hollow nanospheres have the ability to generate ROS. They can induce the peroxidation of unsaturated fatty acids on bacterial cell membranes, thereby destroying the bacterial structure and causing bacterial death. (2) The photothermal effect of Ag / Pd hollow nanospheres promotes the generation of ROS, and the high temperature generated by the photothermal effect also promotes the increase of oxidative stress, leading to severe DNA damage and bacterial death. (3) Ag is an effective bactericide that can destroy the bacterial cell membrane, leading to bacterial death. In summary, this material has excellent photothermal conversion performance and significant antibacterial ability, and has great application prospects in the field of bactericidal masks.

[0039] The above description is merely an implementation example and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing Ag / Pd alloy hollow nanospheres, characterized in that: Includes the following steps: Ethylene glycol is heated to 130-150℃, and then a vulcanizing agent, acid, polyvinylpyrrolidone and AgNO3 solution are added to the ethylene glycol to obtain a reaction solution. The reaction is carried out under stirring until the reaction solution changes color to grayish-yellow. Then the obtained solution is placed in an ice-water bath for rapid cooling to obtain a silver nanoparticle colloidal solution. The silver nanocolloid solution was centrifuged, and the resulting Ag hollow nanospheres were dispersed in water to obtain a silver nano aqueous dispersion. Silver nanoparticles were dispersed in ethylene glycol at a temperature of 85-95℃, and palladium chloride was added. After reacting for 3-8 minutes, the resulting solution was rapidly cooled in an ice-water bath. After centrifugation and washing, Ag / Pd alloy hollow nanospheres were obtained.

2. The method for preparing Ag / Pd alloy hollow nanospheres according to claim 1, characterized in that: The sulfiding agent is sodium sulfide or sodium hydrosulfide.

3. The method for preparing Ag / Pd alloy hollow nanospheres according to claim 1, characterized in that: The acid solution is hydrochloric acid.

4. The method for preparing Ag / Pd alloy hollow nanospheres according to claim 1, characterized in that: The chloropalladium salt is potassium chloropalladium or sodium chloropalladium.

5. The method for preparing Ag / Pd alloy hollow nanospheres according to any one of claims 1 to 4, characterized in that: The molar ratio of Ag to Pd in ​​the Ag / Pd alloy hollow nanospheres is 1:(0.1-0.5).

6. An Ag / Pd alloy hollow nanosphere, characterized in that: It is prepared by the preparation method as described in any one of claims 1 to 4.

7. The application of the Ag / Pd alloy hollow nanospheres as described in claim 6 in the preparation of antibacterial composite materials, characterized in that: The antibacterial composite material includes a carrier material, a reinforcing agent, a plasticizer, and Ag / Pd alloy hollow nanospheres as described in claim 6.

8. The application of the Ag / Pd alloy hollow nanospheres according to claim 7 in the preparation of antibacterial composite materials, characterized in that: The carrier material is polyacrylonitrile or polyvinylidene fluoride.

9. The application of Ag / Pd alloy hollow nanospheres according to claim 7 or 8 in the preparation of antibacterial composite materials, characterized in that: The preparation method of the antibacterial composite material is as follows: a carrier material, reinforcing agent, plasticizer and Ag / Pd alloy hollow nanospheres are dispersed in a dispersant to obtain a mixture, and the mixture is electrospinned to prepare a nanofiber membrane, which is the antibacterial composite material.

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