Silver sulfide coated nano-silver composite material as well as preparation method and application thereof

Abstract

The invention provides a silver sulfide coated nano-silver composite material and a preparation method and application thereof, and belongs to the technical field of functional nano material preparation. The silver sulfide coated nano-silver composite material comprises an inner core and a shell, the inner core comprises a mixed phase mainly comprising nano-silver; and the shell comprises a mixed phase mainly comprising silver sulfide.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of functional nanomaterials, and particularly relates to a silver sulfide-coated silver nanocomposite material, a preparation method thereof, and an application thereof. Background Art

[0002] Silver nanoparticles have been widely used in many fields such as environmental protection, biomedicine, and food packaging due to their excellent antibacterial, conductive, and catalytic properties. However, the biological toxicity and environmental risks of silver nanoparticles restrict their wider and safer applications. According to existing research, when silver nanoparticles enter the environment or biological systems, they are likely to aggregate, dissolve, and transform into silver ions, thereby producing cytotoxic effects and causing harm to the ecological environment and human health.

[0003] Under the existing technical conditions, most of the studies on the toxic effects of silver nanoparticles are only simple simulations in the laboratory, and there is generally a lack of a general method to effectively reduce the cytotoxicity of silver nanoparticles. Therefore, it is of great practical significance to develop a material and method that are efficient, easy to operate, and reasonable in cost for reducing the toxicity of silver nanoparticles. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a silver sulfide-coated silver nanocomposite material, a preparation method thereof, and an application thereof, in order to at least partially solve the above technical problems. The specific technical solutions provided by the present invention are as follows.

[0005] As a first aspect of the present invention, there is provided a silver sulfide-coated silver nanocomposite material, comprising a core and a shell; the core comprises a mixed phase mainly composed of silver nanoparticles; the shell comprises a mixed phase mainly composed of silver sulfide.

[0006] As a second aspect of the present invention, there is provided a preparation method of a silver sulfide-coated silver nanocomposite material, comprising: mixing a silver nitrate solution and a sodium citrate solution to carry out a first redox reaction to obtain a seed solution; mixing the seed solution with a silver diamine solution and an ascorbic acid solution to carry out a second redox reaction to obtain silver nanoparticles; mixing the silver nanoparticles with a sulfiding agent solution to carry out a metathesis reaction to obtain a silver sulfide-coated silver nanocomposite material with silver nanoparticles as the core and silver sulfide as the shell.

[0007] As a third aspect of the present invention, there is provided an application of a silver sulfide-coated silver nanocomposite material, including at least one of the following: an application as a surface coating of a medical device in the biomedical field; an application as a catalyst in the sewage treatment field; an application as a packaging material in the food packaging field; an application as a photoelectric sensor in the electronic field; an application as a battery catalyst in the energy field.

[0008] Based on the above technical solution, the silver sulfide-coated nano-silver composite material and its preparation method and application provided by the present invention have at least one of the following beneficial effects.

[0009] In the embodiments of the present invention, the unique structure of the inner core being a nano-silver mixed phase and the outer shell being a silver sulfide mixed phase greatly slows down the dissolution rate of silver nanoparticles, significantly reduces the amount of silver ion release, and thus effectively reduces cytotoxicity, reduces potential harm to the ecological environment and human health, and broadens its application possibilities in fields with extremely high safety requirements such as biomedicine and food packaging. The silver sulfide shell enhances the overall stability of the material, prevents the inner core nano-silver from undergoing adverse changes such as agglomeration and oxidation due to interference from external factors in a complex environment, and ensures that the performance of the silver sulfide-coated nano-silver composite material (hereinafter referred to as the composite material) is long-term stable. The silver sulfide-coated nano-silver composite material provided by the present invention combines the excellent antibacterial, conductive, and catalytic properties of nano-silver with the special physical and chemical properties of silver sulfide, providing a material selection with better performance for applications in multiple fields.

[0010] In an embodiment of the present invention, a silver sulfide-coated nano-silver composite material can be accurately and controllably synthesized by sequentially performing a first redox reaction, a second redox reaction, and a double decomposition reaction. A seed solution is generated in the first redox reaction, laying the foundation for subsequent reactions, and the second redox reaction efficiently produces silver nanoparticles, ensuring the quality and performance of the core material. The key double decomposition reaction cleverly forms a silver sulfide shell on the surface of the silver nanoparticles. The process is gentle and easy to control, ensuring the uniformity and integrity of the coating structure.

[0011] In the embodiments of the present invention, the silver sulfide-coated nanosilver composite material provided by the present invention shows excellent effects in many fields. In the field of biomedicine, as a surface coating of medical devices, it can effectively inhibit bacterial growth, reduce the risk of infection during the use of medical devices, and ensure patient safety by virtue of its low cytotoxicity and excellent antibacterial properties. At the same time, the stable structure ensures the long-term durability of the coating. When used as a catalyst for sewage treatment, its unique structure can accelerate the decomposition and transformation of pollutants, significantly improve the efficiency of sewage treatment, and has a significant effect on the removal of various organic pollutants and heavy metal ions. It has good self-stability and can be recycled many times to reduce the processing cost. In the field of food packaging, as a packaging material, it can inhibit the growth of microorganisms on the surface of food, extend the shelf life of food, maintain the freshness and quality of food, and at the same time, the material is highly safe and will not cause pollution to food. In the field of electronics, it is applied to photoelectric sensors, using the excellent conductivity of nanosilver and the special optical properties of silver sulfide to greatly improve the sensitivity and response speed of the sensor, and realize the accurate detection of weak light signals and electrical signals. In the field of energy, as a battery catalyst, it can accelerate the electrochemical reaction rate during the battery charging and discharging process, improve battery performance, including improving charging and discharging efficiency, increasing battery capacity, and extending battery cycle life. Description of the Drawings

[0012] Figure 1 It is a flowchart of the preparation method of the silver sulfide-coated silver nanocomposite in the embodiment of the present invention;

[0013] Figure 2 It is a transmission electron microscope (TEM) image of silver nanoparticles in Example 1 of the present invention;

[0014] Figure 3 It is an ultraviolet absorption spectrum of silver nanoparticles in Example 1 of the present invention;

[0015] Figure 4 It is a transmission electron microscope (TEM) image of the silver sulfide-coated silver nanocomposite in Example 1 of the present invention;

[0016] Figure 5 It is an ultraviolet absorption spectrum of the silver sulfide-coated silver nanocomposite in Example 1 of the present invention;

[0017] Figure 6 It is a transmission electron microscope (TEM) image of the silver sulfide-coated silver nanocomposite in Example 2 of the present invention;

[0018] Figure 7 It is an ultraviolet absorption spectrum of the silver sulfide-coated silver nanocomposite in Example 2 of the present invention;

[0019] Figure 8 It is a transmission electron microscope (TEM) image of the silver sulfide-coated silver nanocomposite in Example 3 of the present invention;

[0020] Figure 9 It is an ultraviolet absorption spectrum of the silver sulfide-coated silver nanocomposite in Example 3 of the present invention;

[0021] Figure 10 It is a transmission electron microscope (TEM) image of silver nanoparticles in Example 4 of the present invention;

[0022] Figure 11 It is an ultraviolet absorption spectrum of silver nanoparticles in Example 4 of the present invention;

[0023] Figure 12 It is a transmission electron microscope (TEM) image of the silver sulfide-coated silver nanocomposite in Example 4 of the present invention;

[0024] Figure 13 It is an ultraviolet absorption spectrum of the silver sulfide-coated silver nanocomposite in Example 4 of the present invention;

[0025] Figure 14 It is a transmission electron microscope (TEM) image of silver nanoparticles in Example 5 of the present invention;

[0026] Figure 15 It is the ultraviolet absorption spectrum diagram of silver nanoparticles in Example 5 of the present invention;

[0027] Figure 16 It is the transmission electron microscope (TEM) diagram of silver sulfide-coated silver nanocomposites in Example 5 of the present invention;

[0028] Figure 17 It is the ultraviolet absorption spectrum diagram of silver sulfide-coated silver nanocomposites in Example 5 of the present invention;

[0029] Figure 18 It is the diagram of the cytotoxicity test results of different silver sulfide-coated 30 nm silver nanocomposites in the examples of the present invention;

[0030] Figure 19 It is the diagram of the dark field imaging results of composite materials with different particle sizes in different media in the examples of the present invention. Detailed implementation manners

[0031] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further elaborates on the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0032] In order to effectively reduce the dissolution rate of silver nanoparticles and the release amount of silver ions, thereby reducing the cytotoxicity of silver nanoparticles, the present invention provides a silver sulfide-coated silver nanocomposite. By constructing a silver sulfide shell structure on the surface of silver nanoparticles, this composite material can significantly slow down the dissolution rate of silver nanoparticles, greatly reduce the release amount of silver ions, and ultimately achieve the purpose of reducing the cytotoxicity of silver nanoparticles.

[0033] As the first aspect of the present invention, a silver sulfide-coated silver nanocomposite is provided, which includes a core and a shell; the core includes a mixed phase mainly composed of silver nanoparticles; the shell includes a mixed phase mainly composed of silver sulfide.

[0034] In the embodiments of the present invention, with the unique structure of a core of silver nanoparticle mixed phase and a shell of silver sulfide mixed phase, the dissolution rate of silver nanoparticles is greatly slowed down, the release amount of silver ions is significantly reduced, thereby effectively reducing cytotoxicity and reducing potential hazards to the ecological environment and human health, and broadening its application possibilities in fields with extremely high safety requirements such as biomedicine and food packaging. The silver sulfide shell enhances the overall stability of the material, preventing the core silver nanoparticles from undergoing adverse changes such as aggregation and oxidation due to external factor interference in a complex environment, and ensuring the long-term stability of the composite material performance. The silver sulfide-coated silver nanocomposite provided by the present invention combines the excellent antibacterial, conductive, and catalytic properties of silver nanoparticles with the special physical and chemical properties of silver sulfide, providing a material with better performance for multi-field applications.

[0035] According to an embodiment of the present invention, the diameter of the core is 30 - 100 nm, and the size of the shell is 1 - 3 nm.

[0036] In an embodiment of the present invention, when the core diameter is in the range of 30 - 100 nm, the silver nanocore can fully exert its quantum size effect and high specific surface area characteristics. On the one hand, the quantum size effect endows silver nanoparticles with unique physical and chemical activities, laying the foundation for the overall performance of the material. For example, in catalytic reactions, it can effectively reduce the reaction activation energy and significantly improve the catalytic efficiency. On the other hand, the high specific surface area can increase the contact area with external substances. In antibacterial applications, it can more efficiently contact microorganisms such as bacteria and destroy their cell membrane structures, demonstrating strong antibacterial capabilities. When the shell size is in the range of 1 - 3 nm, the silver sulfide shell can closely and uniformly coat the core without overly hindering the interaction between the core and the external environment. As an effective physical barrier, it can not only significantly reduce the dissolution rate of silver nanoparticles and the release amount of silver ions, thereby reducing cytotoxicity, but also regulate the optical, electrical and other properties of the material to a certain extent. For example, in optoelectronic sensor applications, it can optimize the response characteristics to external signals, enabling the composite material to exhibit excellent comprehensive performance in various field applications.

[0037] Figure 1 It is a flow chart of the preparation method of the silver sulfide-coated silver nanocomposite material in the embodiment of the present invention.

[0038] As the second aspect of the present invention, a preparation method of a silver sulfide-coated silver nanocomposite material is provided, as Figure 1 shown, including step S1 - step S3.

[0039] S1: Mix the silver nitrate solution and the sodium citrate solution, and carry out the first redox reaction to obtain a seed solution.

[0040] S2: Mix the seed solution with the diamminesilver solution and the ascorbic acid solution, and carry out the second redox reaction to obtain silver nanoparticles.

[0041] S3: Mix the silver nanoparticles with the sulfiding agent solution, and carry out a metathesis reaction to obtain a silver sulfide-coated silver nanocomposite material with a silver nanocore as the core and a silver sulfide as the shell.

[0042] In an embodiment of the present invention, through the sequentially performed first redox reaction, second redox reaction, and metathesis reaction, a silver sulfide-coated silver nanocomposite can be precisely and controllably synthesized. A seed solution is generated in the first redox reaction, laying the foundation for subsequent reactions. The second redox reaction efficiently produces silver nanoparticles, ensuring the quality and performance of the core material. The crucial metathesis reaction cleverly forms a silver sulfide shell on the surface of the silver nanoparticles. The process is mild and easy to control, ensuring the uniformity and integrity of the coating structure.

[0043] According to an embodiment of the present invention, the concentration of the silver nitrate solution is 10 - 30 mg / mL; the concentration of the sodium citrate solution is 20 - 40 mg / mL; the molar ratio of silver nitrate to sodium citrate is 1:1 - 3.

[0044] In an embodiment of the present invention, when the concentration of the silver nitrate solution is in the range of 10 - 30 mg / mL, it can ensure the reaction activity while avoiding the reaction being too violent and difficult to control due to too high a concentration, or the reaction being slow and the product yield being low due to too low a concentration. When the concentration of the sodium citrate solution is maintained at 20 - 40 mg / mL, it can effectively play its role as a reducing agent. When the molar ratio of silver nitrate to sodium citrate is 1:1 - 3, this ratio range helps to generate a uniform, stable, and size - controllable seed solution in the first redox reaction. A reasonable ratio can ensure the full progress of the reaction, resulting in a moderate number of generated seeds and a narrow particle size distribution, laying a solid foundation for the subsequent synthesis of high - quality silver nanoparticles. This not only helps to improve the purity and crystallinity of the silver nanoparticles but also ensures the uniform coating of the subsequent silver sulfide shell, ultimately obtaining a silver sulfide - coated silver nanocomposite with excellent performance and stable quality, meeting the stringent requirements for material performance in various fields.

[0045] According to an embodiment of the present invention, the temperature of the first redox reaction is 90 - 100 °C, and the time of the first redox reaction is 0.5 - 1.5 h.

[0046] In an embodiment of the present invention, within this temperature range, the redox reaction between silver nitrate and sodium citrate can proceed at an appropriate rate. The lower temperature limit of 90 °C can ensure that the reaction has sufficient activation energy to initiate and proceed smoothly, without the reaction stagnating or being too slow due to too low a temperature, which would affect production efficiency. The upper temperature limit of 100 °C avoids the reaction being too violent and prevents side reactions caused by local overheating, ensuring the controllability and safety of the reaction. The reaction time is maintained at 0.5 - 1.5 h, which can enable the reaction to be fully completed and ensure the quality of the resulting seed solution. The shorter 0.5 h can meet the initial nucleation requirements of the reaction and avoid agglomeration caused by too long a reaction time; the 1.5 h duration can ensure that all substances in the reaction system react fully, resulting in a sufficient number of seeds with uniform particle sizes, providing a stable and high-quality basis for the subsequent synthesis of silver nanoparticles, and ultimately obtaining a silver sulfide-coated silver nanocomposite with uniform performance and stable structure, meeting the strict requirements for material performance in multiple fields.

[0047] According to an embodiment of the present invention, when synthesizing the seed solution, a glycerol aqueous solution can be added to provide a uniform reaction medium for the first redox reaction of silver nitrate and sodium citrate. Glycerol has a high boiling point and viscosity, which can slow down the movement speed of reactant molecules during the reaction, thereby controlling the redox reaction rate between silver nitrate and sodium citrate. Avoiding the reaction being too violent is beneficial for the formation of silver nanoparticles with uniform sizes. At the same time, glycerol can adsorb on the surface of silver nanoparticle seeds to form a protective film, preventing the mutual collision and agglomeration of silver nanoparticle seeds, thereby improving the stability of silver nanoparticle seeds in the solution and keeping the resulting seed solution clear and uniform. In some specific embodiments, the mass fraction of the glycerol aqueous solution is 40%. The mass ratio of glycerol to silver nitrate is 15 - 25:1.

[0048] According to an embodiment of the present invention, the concentration of the diamminesilver solution is 10 - 20 mg / mL; the concentration of the ascorbic acid solution is 0.1 - 1 mg / mL; the volume ratio of the seed solution to the diamminesilver solution is 1 - 15:1; the volume ratio of the seed solution to the ascorbic acid solution is 1:5 - 50.

[0049] In an embodiment of the present invention, the concentration of the silver diamine solution is maintained at 10-20 mg / mL, which can provide an appropriate source of silver ions. If the concentration is too low, it cannot meet the reaction requirements, and if it is too high, it may cause the silver nanoparticles to grow too fast and the size to be difficult to control. The concentration of the ascorbic acid solution is in the range of 0.1-1 mg / mL, which can not only efficiently exert its strong reducibility but also avoid the reaction rate from getting out of control due to improper concentration. The volume ratio of the seed solution to the silver diamine solution is 1-15:1, which can ensure the uniform deposition of silver ions around the seeds. When the ratio is appropriate, the size uniformity of the generated silver nanoparticles is better. The volume ratio of the seed solution to the ascorbic acid solution is 1:5-50, which can ensure that the ascorbic acid fully reduces the silver ions provided by the silver diamine, while maintaining the stability of the reaction system and avoiding side reactions caused by excessive or insufficient ascorbic acid.

[0050] According to an embodiment of the present invention, the temperature of the second redox reaction is 15-35 °C, and the time of the second redox reaction is 2-4 h.

[0051] In an embodiment of the present invention, the temperature of the second redox reaction is 15-35 °C, which can provide a suitable environment for the reduction of silver ions and the growth of silver nanoparticles, ensuring that the reaction between the silver diamine solution and the ascorbic acid solution proceeds at a stable and controllable rate. If the temperature is too high, the reaction is too intense, and the silver nanoparticles will nucleate and grow rapidly, resulting in uneven particle size distribution and increased aggregation; if the temperature is too low, the reaction is sluggish and may not be fully completed, affecting the yield and quality of the silver nanoparticles. By controlling the reaction time within 2-4 h, the reaction can be ensured to proceed fully. The lower limit time of 2 h allows sufficient time for the reaction to complete the basic reduction process, effectively converting silver ions into silver nanoparticles; the upper limit time of 4 h avoids the overgrowth or structural changes of silver nanoparticles caused by too long reaction time. Through this precise time control, silver nanoparticles with uniform particle size and good crystallinity can be obtained, creating favorable conditions for the uniform coating of silver sulfide subsequently, and finally preparing a silver sulfide-coated silver nanocomposite with stable performance and meeting the stringent application requirements in multiple fields.

[0052] According to an embodiment of the present invention, the silver diamine solution can be prepared by mixing silver nitrate solution and ammonia water. To ensure the full contact and reaction of each substance, a glycerol aqueous solution is added to provide a homogeneous liquid phase environment for the second redox reaction. Further, to improve the stability of silver nanoparticles in the reaction solution, polyvinylpyrrolidone (PVP) is added to the reaction solution to adsorb on the surface of silver nanoparticles, forming a protective film to prevent the aggregation of silver nanoparticles. At the same time, PVP can interact with silver ions, affect the growth process of silver nanoparticles, and play a certain role in regulating the morphology and size of the particles.

[0053] According to an embodiment of the present invention, the vulcanizing agent includes any one of metal hydrosulfides and metal sulfides; the molar ratio of silver nanoparticles to the vulcanizing agent is 1:5 - 100.

[0054] In the embodiments of the present invention, different types of vulcanizing agents, such as sodium sulfide, sodium hydrosulfide, copper sulfide, zinc sulfide, etc., can effectively provide a sulfur source during the reaction according to their own characteristics, promoting the formation of a silver sulfide shell. The appropriate molar ratio range ensures that the reaction can proceed fully, and the quality of the composite material will not be affected by too much or too little vulcanizing agent. When the molar ratio is 1:100, it can ensure that there are enough silver nanoparticles to react with the vulcanizing agent to form a complete and tight silver sulfide coating layer, avoiding incomplete coating due to insufficient vulcanizing agent, thus unable to effectively reduce the dissolution rate of silver nanoparticles and the release amount of silver ions. When the molar ratio is 1:5, the excessive silver nanoparticles can prevent side reactions caused by excessive vulcanizing agent, ensuring the stability of the composite material performance. Within this ratio range, a uniform and stable silver sulfide shell can be formed, effectively improving the stability of the composite material, reducing its cytotoxicity, and at the same time optimizing the application performance of the material in antibacterial, catalytic and other fields, meeting the diverse requirements of different application scenarios for the material.

[0055] According to an embodiment of the present invention, the temperature of the metathesis reaction is 15 - 35 °C, and the time of the metathesis reaction is 2 - 4 h.

[0056] In the embodiments of the present invention, the suitable reaction temperature of 15 - 35 °C can provide ideal kinetic conditions for the metathesis reaction between silver nanoparticles and the vulcanizing agent, which can not only promote the molecules in the reaction system to have appropriate activity, ensuring that the metathesis reaction can be efficiently initiated, but also avoid local over-reaction caused by too high temperature, resulting in uneven growth of the silver sulfide shell, or slow or difficult reaction due to too low temperature. The reaction duration is within the range of 2 - 4 h. 2 h is sufficient for the metathesis reaction to initially complete the nucleation and initial growth of silver sulfide on the surface of silver nanoparticles, ensuring the start of the formation of the coating layer. As the time extends to 4 h, the reaction can proceed fully, enabling silver sulfide to continuously deposit and thicken evenly on the surface of silver nanoparticles, finally forming a complete, dense and appropriately thick silver sulfide shell. Such precisely controlled metathesis reaction conditions can effectively ensure the stability and uniformity of the silver sulfide coating structure in the composite material, greatly improving the performance of the composite material, effectively reducing the dissolution rate of silver nanoparticles and the release amount of silver ions, and meeting the strict requirements for material safety and functionality in many fields such as biomedicine and environmental governance.

[0057] In some specific embodiments, a method for preparing a silver sulfide-coated silver nanocomposite is provided, including: adding a silver nitrate solution and a sodium citrate solution to an aqueous glycerol solution and mixing them evenly to carry out a first redox reaction to obtain a seed solution; adding the seed solution, a diamminesilver solution, and an ascorbic acid solution to a mixed solution of an aqueous glycerol solution and polyvinylpyrrolidone and mixing them evenly to carry out a second redox reaction to obtain silver nanoparticles; mixing the silver nanoparticles with a sulfiding agent solution to carry out a metathesis reaction to obtain a silver sulfide-coated silver nanocomposite with a silver nanocore and a silver sulfide shell.

[0058] As a third aspect of the present invention, an application of a silver sulfide-coated silver nanocomposite is provided, including at least one of the following: an application as a surface coating for medical devices in the biomedical field; an application as a catalyst in the sewage treatment field; an application as a packaging material in the food packaging field; an application as a photoelectric sensor in the electronic field; an application as a battery catalyst in the energy field.

[0059] In the embodiments of the present invention, the silver sulfide-coated silver nanocomposite provided by the present invention shows excellent effects in multiple fields. As a surface coating for medical devices in the biomedical field, with its low cytotoxicity and excellent antibacterial properties, it can effectively inhibit the growth of bacteria, reduce the infection risk during the use of medical devices, ensure patient safety, and at the same time, its stable structure ensures the long-term durability of the coating. When used as a catalyst in sewage treatment, its unique structure can accelerate the decomposition and transformation of pollutants, significantly improve the sewage treatment efficiency, has a significant removal effect on various organic pollutants and heavy metal ions, and has good self-stability and can be recycled multiple times, reducing the treatment cost. In the food packaging field, as a packaging material, it can inhibit the growth of microorganisms on the surface of food, extend the shelf life of food, maintain the freshness and quality of food, and at the same time, the material has high safety and will not cause pollution to food. In the electronic field, when applied to a photoelectric sensor, using the excellent conductivity of silver nanoparticles and the special optical properties of silver sulfide, it can greatly improve the sensitivity and response speed of the sensor, and achieve precise detection of weak optical signals and electrical signals. In the energy field, as a battery catalyst, it can accelerate the electrochemical reaction rate during the charge and discharge process of the battery, improve the battery performance, including increasing the charge and discharge efficiency, increasing the battery capacity, and extending the battery cycle life.

[0060] The present invention will be further illustrated by the following examples and related test experiments. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present invention. However, obviously, one or more embodiments can also be implemented without these specific details. Moreover, without conflict, the details in the following embodiments can be arbitrarily combined into other feasible embodiments. All instruments, consumables, reagents, etc. in the following examples can be obtained from commercial channels without special instructions.

[0061] Example 1

[0062] In this Example 1, 30-nm silver nanoparticles and silver sulfide-coated silver nanocomposites were prepared by the following method.

[0063] 50 mL of 40% glycerol aqueous solution was heated to 95 °C in a 100 mL flask and stirred at a speed of 1200 rpm for 1 min. Subsequently, 0.45 mL of 20 mg / mL silver nitrate solution was added to this solution, and 1 mL of 3.0 wt% sodium citrate solution was added. Stirring was continued at 95 °C for 1 h until a clear and uniform 30 nm silver nanoparticle (Ag NPs) solution was obtained. After the synthesis was completed, the product was collected by centrifugation (8000 rpm, 15 min), washed three times with deionized water to remove unreacted solutes and by-products. Finally, the washed Ag NPs were resuspended in deionized water and stored at 4 °C for later use.

[0064] The silver nanoparticle solution was mixed with 10 mg / mL sodium sulfide solution (Na2S) such that the molar ratio of silver to sulfur was 1:100. Under stirring conditions of 400 rpm, the reaction was carried out at 25 °C for 3 h to ensure the formation of a silver sulfide shell layer on the surface of the silver nanoparticles. After the reaction was completed, the silver sulfide-coated silver nanocomposites were collected by centrifugation (8000 rpm, 15 min), washed three times to remove the unreacted sodium sulfide solution, and the final silver sulfide-coated silver nanocomposites (denoted as S-Ag NPs-L) were obtained.

[0065] Example 2

[0066] In this Example 2, silver sulfide-coated silver nanocomposites with different degrees of sulfidation were prepared using the 30-nm silver nanoparticles in Example 1.

[0067] The silver nanoparticle solution in Example 1 was mixed with 10 mg / mL sodium sulfide solution (Na2S) such that the molar ratio of silver to sulfur was 1:50. Under stirring conditions of 400 rpm, the reaction was carried out at 25 °C for 3 h to ensure the formation of a silver sulfide shell layer on the surface of the silver nanoparticles. After the reaction was completed, the silver sulfide-coated silver nanocomposites were collected by centrifugation (8000 rpm, 15 min), washed three times to remove the unreacted sodium sulfide solution, and the final silver sulfide-coated silver nanocomposites (denoted as S-Ag NPs-1) were obtained.

[0068] Example 3

[0069] In this Example 3, silver sulfide-coated silver nanocomposites with different degrees of sulfidation were prepared using the 30-nm silver nanoparticles in Example 1.

[0070] The silver nanoparticle solution in Example 1 was mixed with a 50 mg / mL sodium sulfide solution (Na2S) such that the molar ratio of silver to sulfur was 1:5. Under stirring conditions of 400 rpm, the reaction was carried out at 25 °C for 3 h to ensure the formation of a silver sulfide shell layer on the surface of the silver nanoparticles. After the reaction, the silver sulfide-coated silver nanocomposite was collected by centrifugation (8000 rpm, 15 min), washed three times to remove the unreacted sodium sulfide solution, and the final silver sulfide-coated silver nanocomposite (denoted as S-Ag NPs-H) was obtained.

[0071] Example 4

[0072] In this Example 4, 70 nm silver nanoparticles and silver sulfide-coated silver nanocomposites were prepared by the following method.

[0073] 50 mL of a 40% aqueous glycerol solution was heated to 95 °C in a 100 mL flask and stirred at a speed of 1200 rpm for 1 min. Subsequently, 0.45 mL of a 20 mg / mL silver nitrate solution was added to the solution, and 1 mL of a 3.0 wt% sodium citrate solution was added, and the stirring was continued at 95 °C for 1 h until a clear and uniform seed solution was obtained.

[0074] 290 mg of PVP and 11.5 mL of glycerol were added to 69 mL of deionized water and stirred in a 250 mL flask at a speed of 700 rpm. 5.75 mL of the pre-prepared seed solution was added, and 575 μL of a diamminesilver solution (prepared by mixing 1 mL of a 20 mg / mL silver nitrate solution with 270 μL of 30% ammonia water) was added after 20 s. After another 20 s, 46 mL of a 0.4 mg / mL ascorbic acid (AA) solution was added, and the stirring was carried out at 700 rpm for 3 h to promote the uniform growth of silver nanoparticles. After the synthesis, the product was collected by centrifugation (8000 rpm, 15 min), washed 3 times with deionized water to remove the unreacted solutes and by-products. Finally, the washed AgNPs were resuspended in deionized water and stored at 4 °C for later use.

[0075] The silver nanoparticle solution was mixed with a 10 mg / mL sodium sulfide solution (Na2S) such that the molar ratio of silver to sulfur was 1:50. Under stirring conditions of 400 rpm, the reaction was carried out at 25 °C for 3 h to ensure the formation of a silver sulfide shell layer on the surface of the silver nanoparticles. After the reaction, the silver sulfide-coated silver nanocomposite was collected by centrifugation (8000 rpm, 15 min), washed three times to remove the unreacted sodium sulfide solution, and the final silver sulfide-coated silver nanocomposite (denoted as S-Ag NPs-2) was obtained.

[0076] Example 5

[0077] In this Example 5, 100-nm silver nanoparticles and silver sulfide-coated silver nanocomposites were prepared by the following method.

[0078] 50 mL of a 40% glycerol aqueous solution was heated to 95 °C in a 100-mL flask and stirred at a speed of 1200 rpm for 1 min. Subsequently, 0.45 mL of a 20 mg / mL silver nitrate solution was added to the solution, and 1 mL of a 3.0 wt% sodium citrate solution was added. Stirring was continued at 95 °C for 1 h until a clear and uniform seed solution was obtained.

[0079] 290 mg of PVP and 11.5 mL of glycerol were added to 69 mL of deionized water and stirred in a 250-mL flask at a speed of 700 rpm. 1.3 mL of the pre-prepared seed solution was added. After 20 s, 575 μL of a diamminesilver solution (prepared by mixing 1 mL of a 20 mg / mL silver nitrate solution with 270 μL of 30% ammonia water) was added. After another 20 s, 46 mL of a 0.4 mg / mL ascorbic acid (AA) solution was added, and stirring was carried out at 700 rpm for 3 h to promote the uniform growth of silver nanoparticles. After the synthesis was completed, the product was collected by centrifugation (8000 rpm, 15 min), washed three times with deionized water to remove unreacted solutes and by-products. Finally, the washed AgNPs were resuspended in deionized water and stored at 4 °C for standby.

[0080] The silver nanoparticle solution was mixed with a 10 mg / mL sodium sulfide solution (Na2S) such that the molar ratio of silver to sulfur was 1:50. Under stirring conditions of 400 rpm, the reaction was carried out at 25 °C for 3 h to ensure the formation of a silver sulfide shell layer on the surface of the silver nanoparticles. After the reaction was completed, the silver sulfide-coated silver nanocomposites were collected by centrifugation (8000 rpm, 15 min), washed three times to remove the unreacted sodium sulfide solution, and the final silver sulfide-coated silver nanocomposites (denoted as S-Ag NPs-3) were obtained.

[0081] Furthermore, the silver nanoparticles and silver sulfide-coated silver nanocomposites obtained in the above examples were structurally characterized.

[0082] The absorbance of the silver nanoparticles and silver sulfide-coated silver nanocomposites was measured using a UV-Vis spectrophotometer to ensure the morphology and stability of the silver nanoparticles and silver sulfide-coated silver nanocomposites.

[0083] The morphology of the silver nanoparticles and the silver sulfide core-shell structure were observed using a transmission electron microscope (TEM).

[0084] Figure 2 This is the transmission electron microscope (TEM) image of the silver nanoparticles in Example 1 of the present invention; Figure 3UV absorption spectrum of silver nanoparticles in Example 1 of the present invention; Figure 4 Transmission electron microscope (TEM) image of silver sulfide-coated silver nanocomposite in Example 1 of the present invention; Figure 5 UV absorption spectrum of silver sulfide-coated silver nanocomposite in Example 1 of the present invention; Figure 6 Transmission electron microscope (TEM) image of silver sulfide-coated silver nanocomposite in Example 2 of the present invention; Figure 7 UV absorption spectrum of silver sulfide-coated silver nanocomposite in Example 2 of the present invention; Figure 8 Transmission electron microscope (TEM) image of silver sulfide-coated silver nanocomposite in Example 3 of the present invention; Figure 9 UV absorption spectrum of silver sulfide-coated silver nanocomposite in Example 3 of the present invention; Figure 10 Transmission electron microscope (TEM) image of silver nanoparticles in Example 4 of the present invention; Figure 11 UV absorption spectrum of silver nanoparticles in Example 4 of the present invention; Figure 12 Transmission electron microscope (TEM) image of silver sulfide-coated silver nanocomposite in Example 4 of the present invention; Figure 13 UV absorption spectrum of silver sulfide-coated silver nanocomposite in Example 4 of the present invention; Figure 14 Transmission electron microscope (TEM) image of silver nanoparticles in Example 5 of the present invention; Figure 15 UV absorption spectrum of silver nanoparticles in Example 5 of the present invention; Figure 16 Transmission electron microscope (TEM) image of silver sulfide-coated silver nanocomposite in Example 5 of the present invention; Figure 17 UV absorption spectrum of silver sulfide-coated silver nanocomposite in Example 5 of the present invention.

[0085] It can be seen from Figure 2 - Figure 17 that the size of the silver sulfide-coated silver nanocomposite is relatively uniform, the morphology is single, and it has good dispersibility. The sulfidation treatment does not significantly affect the particle size of the composite material.

[0086] Furthermore, cytotoxicity tests were conducted on the silver sulfide-coated silver nanocomposites obtained in the above examples.

[0087] The specific test method is as follows: The human colon adenocarcinoma cell line (Caco-2) is used as a cell model to evaluate the cytotoxicity of different silver sulfide-coated silver nanocomposites. The cells are cultured in Dulbecco's Modified Eagle Medium (DMEM) containing 20% fetal bovine serum and 1% penicillin-streptomycin, and cultured in a constant temperature incubator at 37°C and 5% CO2. The cell status is observed morphologically through an inverted microscope to ensure good cell adhesion and logarithmic growth phase. In the experiment, Caco-2 cells are inoculated into 96-well plates at a density of 1.0×10 4 cells / well, and after incubation for 24 h, different silver sulfide-coated silver nanocomposite treatment groups are added respectively, and incubation is continued for 24 h. Subsequently, the culture medium is discarded, and the cells are washed twice with phosphate buffer (PBS). Prepare alamarblue working solution (diluted at a ratio of 1:9 using a 10-fold stock solution), add 100 μL of the working solution to each well, and incubate at 37°C for 3 h in the dark. A multifunctional microplate reader is used to measure the fluorescence intensity (excitation wavelength 530 nm, emission wavelength 590 nm) to reflect the cell activity level. Each group of experiments is performed at least three independent experiments to ensure the repeatability and reliability of the data.

[0088] Figure 18 This is the cytotoxicity test result diagram of different silver sulfide-coated 30 nm silver nanocomposites in the embodiments of the present invention.

[0089] From Figure 18 it can be seen that as the concentration of sodium sulfide increases, the cytotoxicity of the silver sulfide-coated silver nanocomposites gradually decreases, and the cell survival rate of the high sulfurization treatment group is the highest, showing good biocompatibility.

[0090] Figure 19 This is the dark field imaging result diagram of different particle size composites in different media in the embodiments of the present invention.

[0091] From Figure 19 it can be seen that the composites show high stability in inorganic buffer (PBS) and simulated body fluid (ALF), have good environmental adaptability and potential controllable dissolution characteristics, providing a basis for their promotion in green antibacterial materials and biomedical materials.

[0092] The above specific embodiments further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A silver sulfide-coated silver nanocomposite material, characterized in that, The silver sulfide-coated silver nanocomposite includes a core and a shell; The core includes a mixed phase mainly composed of silver nanoparticles; The shell includes a mixed phase mainly composed of silver sulfide.

2. The silver sulfide-coated silver nanocomposite material according to claim 1, wherein The diameter of the core is 30 - 100 nm, and the size of the shell is 1 - 3 nm.

3. A method for preparing a silver sulfide-coated silver nanocomposite material as described in any one of claims 1-2, characterized in that, It includes: Mix a silver nitrate solution and a sodium citrate solution, and conduct a first redox reaction to obtain a seed solution; Mix the seed solution with a silver diamine solution and an ascorbic acid solution, and conduct a second redox reaction to obtain silver nanoparticles; Mix the silver nanoparticles with a sulfiding agent solution, and conduct a metathesis reaction to obtain a silver sulfide-coated silver nanocomposite with a silver nanoparticle core and a silver sulfide shell.

4. The preparation method according to claim 3, characterized in that, The concentration of the silver nitrate solution is 10 - 30 mg / mL; The concentration of the sodium citrate solution is 20 - 40 mg / mL; The molar ratio of the silver nitrate to the sodium citrate is 1:1 - 3.

5. The preparation method according to claim 4, characterized in that, The temperature of the first redox reaction is 90 - 100 °C, and the time of the first redox reaction is 0.5 - 1.5 h.

6. The preparation method according to claim 3, characterized in that, The concentration of the silver diamine solution is 10 - 20 mg / mL; The concentration of the ascorbic acid solution is 0.1 - 1 mg / mL; The volume ratio of the seed solution to the silver diamine solution is 1 - 15:1; The volume ratio of the seed solution to the ascorbic acid solution is 1:5 - 50.

7. The preparation method according to claim 6, wherein The temperature of the second redox reaction is 15 - 35 °C, and the time of the second redox reaction is 2 - 4 h.

8. The preparation method according to claim 3, characterized in that, The sulfiding agent includes any one of metal hydrosulfides and metal sulfides; The molar ratio of the silver nanoparticles to the sulfiding agent is 1:5 - 100.

9. The preparation method according to claim 8, wherein The temperature of the metathesis reaction is 15 - 35 °C, and the time of the metathesis reaction is 2 - 4 h.

10. Use of the silver sulfide-coated silver nanocomposite material according to any one of claims 1-2, characterized in that, The applications include at least one of the following: Application as a surface coating for medical devices in the biomedical field; Application as a catalyst in the sewage treatment field; Application as a packaging material in the food packaging field; Application as a photoelectric sensor in the electronics field; Application as a battery catalyst in the energy field.

Images