Method for enhancing antibacterial performance of silver nanoparticles based on regulation and control of bacteria to tend to colloidal particle heteroaggregate

Abstract

The invention belongs to the field of biotechnology and nanometer materials, and relates to a method for enhancing the antibacterial performance of silver nanoparticles based on regulation and control of bacteria to tend to colloidal particle heteroaggregate. After the silver nanoparticles and the iron ore colloidal particles are subjected to heterogeneity agglomeration, the trend movement behavior of bacteria can be regulated and controlled. On one hand, after the silver nanoparticles and goethite particles are subjected to different agglomeration, the negative trend movement behaviors of escherichia coli and shewanella on the silver nanoparticles are weakened, and the weakening degrees are different due to different agglomeration states. And on the other hand, the silver nanoparticle-goethite heteroaggregate is easier to attract bacteria to approach compared with the silver nanoparticles. Test results show that in a disperse system and a non-disperse system, the silver nanoparticle-goethite heteroaggregate shows more excellent antibacterial performance compared with silver nanoparticles. The invention provides a new strategy method for improving the antibacterial performance of the silver nanoparticles in practical application, and the method can be used for regulating and controlling the amount of the silver nanoparticles in an antibacterial material and preparing a novel bacteriostatic agent.

Description

Technical Field

[0001] The invention belongs to the field of biotechnology and nanomaterials, and relates to a method for enhancing the antibacterial performance of silver nanoparticles based on regulating bacteria to tend toward colloidal particle heteroaggregates. Background Art

[0002] Silver nanoparticles (AgNPs) are one of the most widely used inorganic antimicrobial agents, which can kill bacteria, fungi and other microorganisms or inhibit their growth and reproduction within a certain period of time. Studies have shown that silver nanoparticles have toxic effects such as damaging bacterial DNA, destroying plasma membrane potential, changing cell membrane permeability, etc., which can cause cells to lose their replication ability or lead to cell death. They have significant antibacterial effects on a variety of common clinical Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, etc.) and Gram-negative bacteria (Escherichia coli, Vibrio cholerae, Pseudomonas aeruginosa and Shewanella, etc.).

[0003] Due to its long-lasting broad-spectrum antibacterial properties, silver nanoparticles have been widely used in various new antibacterial materials, such as food packaging paper (antibacterial packaging paper, silver-loaded nanocellulose composite cling film), oral implant tissue scaffolds (silver surface-coated dental implants, bone augmentation materials, bone regeneration barrier membranes), clothing fabrics (nanosilver-coated textile fabrics, silver fiber antibacterial non-woven fabrics), new pesticides (nano-herbicides, nano-pesticides) and new antibacterial agents (antibacterial sprays, antibacterial hand sanitizers, bactericidal gels), etc.

[0004] The key to antibacterial materials is that silver nanoparticles can effectively inhibit or kill bacteria. However, in the antibacterial process of silver nanoparticles, we should not only pay attention to the toxic effects of silver nanoparticles on bacterial cells, but also consider the migration and movement of bacteria themselves. Saeki EK et al. pointed out in Frontiers in Cellular and Infection Microbiology, Vol. 11, Article 656984, 2021 that biogenic silver nanoparticles can change the movement behavior of Pseudomonas aeruginosa and affect the formation of biofilms at sublethal concentrations; José-Julio et al. pointed out in Environmental Microbiology Reports, Vol. 3, No. 5, pp. 526-534, 2011 that Pseudomonas putida G7 will show negative tendency to move to lower but environmentally relevant sublethal concentrations of silver nanoparticles.

[0005] The tropism of microorganisms refers to the survival mechanism of motile bacteria in response to certain chemicals in the environment, thereby guiding them to move toward favorable substances or drive away harmful substances, which helps them to respond quickly to changes in the environment and move toward a more favorable environment. At present, negative tropism is generally believed to be the reverse axial movement of bacteria to chemical repellents, which is a basic physiological phenomenon of "avoiding harm". The negative tropism of bacteria to silver nanoparticles will reduce the exposure of microorganisms, keep bacteria away from silver nanoparticles, gather in areas without silver nanoparticles, and reduce the antibacterial effect of silver nanoparticles. Therefore, precise control of the tropism behavior of bacteria is very important for improving the antibacterial performance of silver nanoparticles.

[0006] Studies have shown that silver nanoparticles can heteroaggregate with colloidal particles such as iron oxides, clay minerals, and microbial colloids due to DLVO forces. Wang Rui et al. reported in Environmental Science: Nano, Vol. 6, No. 1, 195-206, 2019 that engineered silver nanoparticles can heteroaggregate with goethite and hematite under environmentally relevant conditions; Khanh AH et al. pointed out in Environmental Science and Technology, Vol. 1, 361-366, 2014 that heteroaggregation of silver nanoparticles and hematite can physically prevent silver nanoparticles from directly contacting Escherichia coli cells, and different aggregation states have different biological accessibility. At present, there is little research on how heteroaggregation of colloidal particles affects bacterial tropism behavior.

[0007] Based on the above analysis, a strategy is proposed to heteroaggregate silver nanoparticles with other colloidal particles to weaken the negative tropism of bacteria, thereby improving the antibacterial performance of silver nanoparticles. On the one hand, the heteroaggregation of colloid particles will weaken the negative tropism of bacteria by reducing the bioaccessibility of silver nanoparticles; on the other hand, if the other colloid particles that make up the heteroaggregate are metabolizable substrates that have an "attractive" effect on bacteria, they will induce bacteria to actively tend to the heteroaggregate, thereby promoting the silver nanoparticles to effectively kill bacteria. This strategy and method is simple to operate and provides a new idea for enhancing the antibacterial performance of silver nanoparticles and the preparation of silver nanoparticle antibacterial materials. Summary of the invention

[0008] The present invention provides a method for enhancing the antibacterial performance of silver nanoparticles based on regulating the tendency of bacteria to colloidal heteroaggregates, and the antibacterial performance of silver nanoparticles is improved by regulating the tendency movement behavior of bacteria to colloidal heteroaggregates in different aggregation states.

[0009] The technical solution adopted by the present invention is as follows:

[0010] A method for enhancing the antibacterial performance of silver nanoparticles based on regulating the tendency of bacteria to tend toward colloidal heteroaggregates. The bacteria are Gram-negative bacteria such as Escherichia coli and Shewanella. Gram-negative bacteria have the ability to metabolize iron and can reduce extracellular solid iron minerals.

[0011] The heteroaggregate is a heteroaggregate of silver nanoparticles and goethite colloid.

[0012] The silver nanoparticles are silver nanoparticles with a particle size of 15 nm, and the surface may be coated with a PVP (polyvinyl pyrrolidone) layer.

[0013] Goethite colloid is a common iron oxide mineral colloid. Under anaerobic conditions, goethite will "attract" Gram-negative bacteria to actively move toward its particles to complete the redox reaction.

[0014] The specific steps are as follows:

[0015] Step 1: Preparation of heteroaggregates of silver nanoparticles and heterogeneous colloid particles

[0016] First, the goethite colloid stock solution was ultrasonicated for 30 min and then diluted with ultrapure water for use. The pH of the ultrapure water was 6.0-7.0, preferably 6.5.

[0017] Then, a silver nanoparticle solution with a concentration of 0.02-0.4 mg / L is fully mixed with a goethite colloid solution, and the concentration ratio of the silver nanoparticles to the goethite colloid particles is 1:50-1500 to obtain a heteroagglomerate mixed solution.

[0018] Finally, the hydrodynamic diameter of the mixed solution of silver nanoparticles and goethite colloidal particles was determined using dynamic light scattering technology to evaluate the heteroaggregation behavior of the two colloidal particles.

[0019] Step 2: Colloidal heteroaggregates regulate bacterial tropism

[0020] The heteroaggregate mixed solution and the silver nanoparticle solution obtained in step 1 are mixed with Gram-negative bacteria solution respectively, and the negative tendency of Gram-negative bacteria to the heteroaggregates and the silver nanoparticles is evaluated by a modified inverted capillary test;

[0021] The solution in the capillary was collected and the number of cells that swam from the mixed bacterial solution into the capillary was counted using the plate colony counting method. The negative tropism index was defined as the ratio of the number of cells in the experimental group containing silver nanoparticles (N1) to the number of cells in the control group without silver nanoparticles (N0): I = N1 / N0. The regulation of heteroaggregates on bacterial tropism was evaluated by the change of the negative tropism index.

[0022] I>1, indicating that the bacteria exhibit negative tropism toward silver nanoparticles;

[0023] I < 1 means that the bacteria do not show negative tropism behavior or lose motility due to death;

[0024] Step 3, test and comparison of the antibacterial performance of heteroaggregates in the dispersed system: The mixed solution of the colloidal heteroaggregates that can regulate the bacterial tendency movement detected in step 3 is mixed with the bacterial solution, and the number of live bacteria in the solution is counted by the plate colony counting method after contact culture for 4-6 hours. The antibacterial performance of the colloidal heteroaggregates in the dispersed system is evaluated.

[0025] Step 4, test and comparison of the antibacterial performance of heteroaggregates in non-dispersed systems: The colloid heteroaggregates detected in step 3 that can regulate bacterial movement are loaded on the surface of the non-woven fabric by dipping, and after drying, the bacterial solution is dripped on the surface and contact cultured for 4-6 hours. The number of live bacteria in the eluted solution is then counted using the plate colony counting method. The antibacterial performance of the colloid-loaded heteroaggregate non-woven fabric material is evaluated.

[0026] The beneficial effects of the present invention are:

[0027] The present invention significantly improves the antibacterial performance of silver nanoparticles against Gram-negative bacteria by heteroaggregating silver nanoparticles of different concentrations with common iron oxide colloidal particles to regulate the tropism movement behavior of bacteria. Specifically, the tropism movement behavior of bacteria can be regulated after the silver nanoparticles and iron ore colloidal particles are heteroaggregated. On the one hand, after the silver nanoparticles and goethite particles are heteroaggregated, the negative tropism movement behavior of Gram-negative bacteria towards the silver nanoparticles is weakened, and the degree of weakening varies depending on the aggregation state. On the other hand, the silver nanoparticle-goethite heteroaggregate is easier to "attract" bacteria to approach than the silver nanoparticles themselves. The test results show that in dispersed systems and non-dispersed systems, the silver nanoparticle-goethite heteroaggregate exhibits better antibacterial performance than silver nanoparticles. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is the hydrodynamic diameter D of the single phase and mixed system of silver nanoparticles AgNPs and goethite particles Gt at different concentrations under pH = 6.5 h Changes over time.

[0029] Figure 2 The number of cells of Shewanella and Escherichia coli swimming into the capillary under different culture backgrounds. The concentration of goethite Gt is 30 mg / L, and the concentration of silver nanoparticles AgNPs is 0.1 mg / L.

[0030] Figure 3 The number of cells of Shewanella and Escherichia coli swimming into the capillary under different culture backgrounds. The concentration of goethite Gt is 30 mg / L, and the concentration of silver nanoparticles AgNPs is 0.4 mg / L. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings and technical solutions.

[0032] Example 1: Heteroagglomeration of silver nanoparticles and goethite colloidal particles

[0033] In this example, goethite colloidal particles are taken as an example to evaluate the hetero-aggregation behavior and hetero-aggregation state of silver nanoparticles and hetero-species colloidal particles.

[0034] (1) Preparation of goethite colloidal solution

[0035] The colloidal solution of goethite Gt (FeOOH) was prepared by a hydrothermal method. 100 mL of 1 M Fe (NO3) 3·9H2O solution was placed on a magnetic stirrer (200 rpm, 30 ° C) and 180 mL of 5 M KOH solution was added dropwise, and a reddish brown precipitate was generated during the process. Subsequently, the suspension was diluted to 2 L with ultrapure water, sealed to prevent foreign objects from entering, and transferred to an electric blast drying oven. After heating at 70 ° C for 60 h, the loose reddish brown precipitate gradually turned into a brownish yellow precipitate. The precipitate was collected and washed 5 times with ultrapure water by centrifugation at 8000 rpm for 10 min. The washed precipitate was collected and fixed to volume, and stored after nitrogen aeration for 30 min.

[0036] (2) Determination of hydrodynamic diameter

[0037] Dynamic light scattering (DLS) was used to measure the hydrodynamic diameter D of single-phase solutions and mixed solutions during self-aggregation or heteroaggregation. h Before the measurement, the goethite colloid stock solution was ultrasonicated for 30 minutes and then diluted with ultrapure water for use. The pH of the ultrapure water used was about 6.5. For the mixed system, different concentrations of silver nanoparticle solutions (0.02-0.4 mg / L) and 30 mg / L goethite particle solution were mixed, and the pH of the mixed solution was kept at about 6.5. After mixing, it was immediately shaken with a vortex oscillator for 5 seconds, and the hydrodynamic diameter D was measured using a nanoparticle size analyzer. h During the measurement, the temperature in the instrument was set to 25°C, the scattering angle was set to 90°, and manual measurements were taken at regular intervals to record the D h Changes over time.

[0038] As attached Figure 1 As shown, goethite colloidal solution D h Stable around 230nm, silver nanoparticles D h Stable at around 330nm, the D h Greater than two single-phase solutions D h , indicating that heteroaggregation occurs between colloidal particles. When the concentration of silver nanoparticles is 0.02-0.1 mg / L, heteroaggregates D hAs the amount of silver nanoparticles increases, all silver nanoparticles aggregate with goethite particles, and the aggregates further form larger clusters; when the concentration of silver nanoparticles exceeds 0.1 mg / L, the heteroaggregate D h Gradually decreases, and when the concentration reaches 0.4 mg / L, the D h Reduced to slightly greater than the D when goethite exists in a single phase h , indicating that the surface charge of goethite is reversed at this time, and the silver nanoparticle-goethite aggregates no longer aggregate to form larger clusters.

[0039] Example 2: Colloidal particle heteroaggregation regulates the tropism behavior of Shewanella

[0040] In this example, the negative tropism behavior of Shewanella to silver nanoparticles and the change of bacterial tropism after heteroaggregation of silver nanoparticles were evaluated by a modified inverted capillary test, and the change of negative tropism index I was used to evaluate the degree of weakening of negative tropism after heteroaggregation of colloid particles.

[0041] (1) Bacterial culture

[0042] Cultivation of Shewanella: Take 0.1mL of thawed Shewanella oneidensis MR-1 and inoculate it into 30mL of 3% tryptic soytone liquid medium, place it in a constant temperature shaker (30°C, 150rev / min) and culture it for 12h; then take 1mL of the bacterial solution and transfer it to 100mL of 3% tryptic soytone liquid medium, place it in a constant temperature shaker and culture it for 12h again to obtain the Shewanella culture solution in the logarithmic growth phase. Take 20mL of the culture solution and centrifuge it (6000rpm, 3min), collect the precipitated cells and wash them 3 times by centrifugation with 30mM HEPES buffer (pH=7.0-7.2), resuspend it to 100μL as Shewanella suspension for later use.

[0043] (2) Improved inverted capillary experiment

[0044] Prepare modified Lactate-Medium (LM) culture medium: 0.1 g / L tryptone, 0.2 g / L yeast extract powder, 5 mM sodium lactate, 10 mM HEPES, adjust pH to 7.0-7.2, and sterilize by high pressure steam at 121°C for 20 min. Add LM culture medium solution and bacterial suspension (cell concentration is about 5 × 10 7cells / mL) and mixed solutions of silver nanoparticles or silver nanoparticles-goethite particles of different concentrations were fully mixed and sealed with polybutylene rubber plugs. 0.4 mL of LM culture medium solution was drawn with a 1 mL syringe with a 22G needle and inserted into a serum bottle. A blank control without silver nanoparticles was set. After 6 hours of culture, the solution in the syringe was collected, and the cell concentration entering the syringe was counted by the plate colony counting method. In order to prevent Shewanella from tending to dissolved oxygen and causing errors, the experiment was carried out in an anaerobic glove box.

[0045] (3) Plate colony counting method

[0046] Prepare LB medium containing 2.0% agar, sterilize with high pressure steam at 121℃ for 20min, pour into a sterile culture dish, and cool to solidify. Dilute the bacterial solution to be tested to 10 3 ~10 4 cells / mL, take 20 μL of the diluted bacterial solution and drop it onto the solidified LB solid medium surface, and evenly spread it with glass beads. Then, place the culture dish upside down in a biochemical incubator, and count the number of colonies generated after 24 hours of incubation.

[0047] Calculate the negative tropism index: I = N1 / N0. Where N1 is the number of cells in the capillary tube containing the experimental group, and N0 is the number of cells in the capillary tube of the blank control group. I>1 means that Shewanella exhibits negative tropism behavior towards silver nanoparticles, and I<1 means that Shewanella does not exhibit negative tropism behavior or loses its motility due to death.

[0048] As attached Figure 2 and attached Figure 3 As shown in the figure, Shewanella exhibited negative tropism behavior towards 0.1mg / L and 0.4mg / L silver nanoparticles, and their negative tropism indexes were 3.9 and 2.7, respectively. In contrast, the negative tropism index of the experimental group containing silver nanoparticles-goethite particles heteroaggregates decreased by 68.3% and 44.0%, respectively, compared with the experimental group containing only silver nanoparticles. The results show that the heteroaggregates of silver nanoparticles and goethite particles weakened the negative tropism of Shewanella towards silver nanoparticles, and the degree of weakening of negative tropism varied with the heteroaggregate state.

[0049] From the implementation case 1, it can be seen that when the Gt / AgNPs concentration ratio is 30 / 0.1, the particle size is the largest, the silver nanoparticles are coated between the goethite particles, the bioaccessibility is reduced, and the negative taxis movement is weakened; when the Gt / AgNPs concentration ratio is 30 / 0.4, the charge is reversed, and the silver nanoparticles agglomerated on the surface of the goethite are saturated, so the silver nanoparticles are easier to contact with cells, causing the cells to repel or avoid behavior. In addition, the negative taxis movement index of the experimental group containing only goethite is less than 1, because goethite can be used as a metabolic substrate for Shewanella, and under anaerobic conditions Shewanella will actively move toward goethite to complete the redox reaction. Therefore, compared with silver nanoparticles, heteroaggregates are more likely to attract Shewanella to positive chemotaxis.

[0050] Example 3: Colloidal particle heteroaggregation regulates the tropism behavior of Escherichia coli

[0051] In this example, the negative tropism behavior of Escherichia coli towards silver nanoparticles and the change in bacterial tropism after heteroaggregation of silver nanoparticles were evaluated by a modified inverted capillary test, and the change in the negative tropism index I was used to evaluate the degree of weakening of the negative tropism after heteroaggregation of the colloid particles.

[0052] (1) Bacterial culture

[0053] Cultivation of Escherichia coli: Take 0.1mL of melted Escherichia coli K12 and inoculate it into 30mL of 3% tryptic soytone liquid medium, place it in a constant temperature shaker (37°C, 150rev / min) and culture it for 18h; then take 1mL of the bacterial solution and transfer it to 100mL of 3% tryptic soytone liquid medium, place it in a constant temperature shaker and culture it for 18h again to obtain the Escherichia coli culture solution in the logarithmic growth phase. Take 20mL of the culture solution and centrifuge it (6000rpm, 3min), collect the precipitated cells and wash them 3 times by centrifugation with 30mM HEPES buffer (pH=7.0-7.2), resuspend it to 100μL as Escherichia coli suspension for use.

[0054] (2) Improved inverted capillary experiment

[0055] Prepare modified Lactate-Medium (LM) culture medium: 0.1 g / L tryptone, 0.2 g / L yeast extract powder, 5 mM sodium lactate, 10 mM HEPES, adjust pH to 7.0-7.2, and sterilize by high pressure steam at 121°C for 20 min. Add LM culture medium solution and bacterial suspension (cell concentration is about 5 × 10 7cells / mL) and mixed solutions of silver nanoparticles or silver nanoparticles-goethite particles of different concentrations were fully mixed and sealed with polybutylene rubber plugs. 0.4 mL of LM culture medium solution was drawn with a 1 mL syringe with a 22G needle and inserted into a serum bottle. A blank control without silver nanoparticles was set. After 6 hours of culture, the solution in the syringe was collected, and the cell concentration entering the syringe was counted by the plate colony counting method. In order to prevent errors caused by Escherichia coli tending to dissolved oxygen, the experiment was carried out in an anaerobic glove box.

[0056] (3) Plate colony counting method

[0057] Prepare LB medium containing 2.0% agar, sterilize with high pressure steam at 121℃ for 20min, pour into a sterile culture dish, and cool to solidify. Dilute the bacterial solution to be tested to 10 3 ~10 4 cells / mL, take 20 μL of the diluted bacterial solution and drop it onto the solidified LB solid medium surface, and evenly spread it with glass beads. Then, place the culture dish upside down in a biochemical incubator, and count the number of colonies generated after 24 hours of incubation.

[0058] Calculate the negative tropism index: I = N1 / N0. Where N1 is the number of cells in the capillary containing the experimental group, and N0 is the number of cells in the capillary of the blank control group. I>1 means that E. coli exhibits negative tropism behavior towards silver nanoparticles, and I<1 means that E. coli does not exhibit negative tropism behavior or loses its motility due to death.

[0059] By the attached Figure 2 and attached Figure 3 It can be seen that the negative tropism index of Escherichia coli to 0.1 mg / L and 0.4 mg / L silver nanoparticles was 3.4 and 4.6, respectively, while in the experimental group containing silver nanoparticle-goethite particle heteroaggregates, its negative tropism index decreased by 52.3% and 11.0%, respectively, compared with the experimental group containing only silver nanoparticles. The results show that the heteroaggregates of silver nanoparticles and goethite particles weakened the negative tropism of Escherichia coli to silver nanoparticles, and the degree of weakening of negative tropism varied with the heteroaggregate state. Similarly, the negative tropism index of the experimental group containing only goethite was less than 1, because goethite can be used as a metabolic substrate for Escherichia coli, and under anaerobic conditions, Escherichia coli will actively tend to goethite to complete the redox reaction. Therefore, compared with silver nanoparticles, heteroaggregates are more likely to attract Escherichia coli to positive chemotaxis.

[0060] Implementation Case 4: Testing and comparison of antibacterial properties of heteroaggregate particles

[0061] This implementation case takes Shewanella as an example to evaluate the antibacterial performance of silver nanoparticle-goethite particle heteroaggregate particles in a dispersed system.

[0062] In an anaerobic glove box, 10 mL of 0.4 mg / L silver nanoparticle solution, 10 mL of a mixed solution of 0.4 mg / L silver nanoparticles and 30 mg / L goethite particles, and 10 mL of ultrapure water (control group) were added to three serum bottles, respectively. After shaking, the Shewanella suspension cultured to the logarithmic growth phase in Example 2 was added to make the cell concentration in the solution about 5 × 10 7 After 4 h of contact culture, the cell concentration in the solution was counted using the plate colony counting method.

[0063] Calculate the antibacterial rate: R = (AB) / A × 100%. Where A is the number of colonies in the blank control group with an antibacterial concentration of 0; B is the number of colonies in the experimental group. The antibacterial performance results are shown in Table 1.

[0064] Table 1 Antibacterial effect of heteroaggregates in dispersed systems

[0065]

[0066] From the experimental results in Table 1, it can be seen that the antibacterial rate of the silver nanoparticle-goethite particle heteroaggregate is 92.8%, which is better than the antibacterial performance of the silver nanoparticles alone (65.6%).

[0067] Implementation case 5: Testing and comparison of antibacterial properties of nonwoven fabrics loaded with heteroaggregates

[0068] In this embodiment, the colloidal heteroagglomerates are loaded into a non-woven fabric material to evaluate the antibacterial properties of the silver nanoparticle-goethite particle heteroagglomerate particles in a non-dispersed system.

[0069] Add 10 mL of 0.4 mg / L silver nanoparticle solution, 10 mL of 0.4 mg / L silver nanoparticle and 30 mg / L goethite particle mixed solution and 10 mL of ultrapure water (control group) to three serum bottles respectively. After shaking, add 6 cm × 6 cm medical sterile non-woven fabric, immerse for 2 hours, take out and dry.

[0070] In the anaerobic glove box, spread the dried nonwoven fabric on a sterile culture dish and take 1 mL of Shewanella suspension in the logarithmic growth phase (cell concentration is about 5×10 7 cells / mL) was dripped onto the surface of the non-woven fabric to make the bacterial solution evenly contact the sample. The culture dish was covered and contact culture was carried out for 4 hours.

[0071] After 4 hours of culture, the sample was transferred into a sterile container, 10 mL of 30 mM HEPES buffer was added, and the mixture was shaken and eluted, and the elution was repeated 3 times. The number of cells in the eluted solution was counted using the plate colony counting method.

[0072] Calculate the antibacterial rate: R = (AB) / A × 100%. Where A is the number of colonies in the blank control group with an antibacterial concentration of 0; B is the number of colonies in the experimental group. The antibacterial performance results are shown in Table 2.

[0073] Table 2 Antibacterial effect of heteroaggregates in non-dispersed systems

[0074]

[0075] From the experimental results in Table 2, it can be seen that the antibacterial rate of the non-woven fabric loaded with silver nanoparticles-goethite particle heteroagglomerates is 84.7%, which is better than the antibacterial performance of the non-woven fabric loaded with silver nanoparticles (56.7%).

Claims

1. A method for enhancing the antibacterial properties of silver nanoparticles based on regulating the tendency of bacteria to colloid heteroaggregates, characterized in that: Step 1: Preparation of heteroaggregates of silver nanoparticles and heterogeneous colloid particles First, the goethite colloid stock solution was ultrasonicated for 30 minutes and then diluted with ultrapure water for later use, and the pH of the ultrapure water was 6.0-7.0; Then, a silver nanoparticle solution with a concentration of 0.02-0.4 mg / L is fully mixed with a goethite colloidal solution, wherein the concentration ratio of the silver nanoparticles to the goethite colloidal particles is 1:50-1500, to obtain a heteroagglomerate mixed solution; Finally, the hydrodynamic diameter of the mixed solution of silver nanoparticles and goethite colloidal particles was measured using dynamic light scattering technology to evaluate the heteroaggregation behavior of the two colloidal particles; Step 2: Colloidal heteroaggregates regulate bacterial tropism The heteroaggregate mixed solution and the silver nanoparticle solution obtained in step 1 are mixed with Gram-negative bacteria solution respectively, and the negative tendency of Gram-negative bacteria to the heteroaggregates and the silver nanoparticles is evaluated by a modified inverted capillary test; The solution in the capillary was collected and the number of cells that swam from the mixed bacterial solution into the capillary was counted using the plate colony counting method. The negative tropism index was defined as the ratio of the number of cells in the experimental group containing silver nanoparticles (N1) to the number of cells in the control group without silver nanoparticles (N0): I = N1 / N0. The regulation of heteroaggregates on bacterial tropism was evaluated by the change of the negative tropism index. I>1, indicating that the bacteria exhibit negative tropism toward silver nanoparticles; I < 1 means that the bacteria do not show negative tropism behavior or lose motility due to death; Step 3, testing and comparing the antibacterial performance of heteroaggregates in the dispersed system: the mixed solution of the colloidal heteroaggregates that can regulate the bacterial tendency movement detected in step 3 is mixed with the bacterial solution, and the number of live bacteria in the solution is counted by the plate colony counting method after contact culture for 4-6 hours; the antibacterial performance of the colloidal heteroaggregates in the dispersed system is evaluated; Step 4. Testing and comparison of the antibacterial properties of heteroaggregates in non-dispersed systems: The colloid heteroaggregates detected in step 3 that can regulate the bacterial movement are loaded on the surface of the non-woven fabric by immersion, and after drying, bacterial solution is dripped on the surface and cultured for 4-6 hours; then the plate colony counting method is used to count the number of live bacteria in the elution solution; and the antibacterial properties of the non-woven fabric material of the colloid-loaded heteroaggregates are evaluated.

2. The method of enhancing the antibacterial performance of silver nanoparticles based on regulating the tendency of bacteria to colloidal heteroaggregates according to claim 1, characterized in that: The pH of the ultrapure water is 6.

5.

3. The method of claim 1, wherein the method comprises: The Gram-negative bacteria is at least one of Escherichia coli and Shewanella.

4. The method of claim 1, wherein the method comprises: The silver nanoparticles are silver nanoparticles with a particle size of 15 nm.

5. The method of enhancing the antibacterial performance of silver nanoparticles based on regulating the tendency of bacteria to colloidal heteroaggregates according to claim 4, characterized in that: The surface of the silver nanoparticles is coated with a PVP (polyvinyl pyrrolidone) layer.

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