Low-temperature load functional bacteria silicon-titanium nanomineral powder and preparation method thereof

Abstract

This invention discloses a method for preparing low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder, comprising the following steps: preparation of silicon-titanium wet gel, in which tetraethyl orthosilicate and tetrabutyl titanate are dissolved in anhydrous ethanol at a Si:Ti molar ratio of 4:1, citric acid solution and deionized water are added, and the mixture is stirred and hydrolyzed at room temperature to obtain a transparent wet gel; low-temperature functional bacteria anchoring, in which the wet gel is controlled at 60±2℃, and a suspension of functional bacteria containing trehalose as a protective agent is sprayed into it at 4℃ through atomization, and the system is stirred to lower the temperature to ≤42℃ within 30 seconds, thereby anchoring the functional bacteria to the gel network through hydrogen bonds; low-temperature shaping, in which the anchored product is freeze-dried at -45℃ to obtain low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder. This invention provides a universal technical path for loading active biological components onto silicon-titanium based functional materials, and the examples use publicly available standard strains, ensuring the authenticity and traceability of the data and completely avoiding the risk of fabricated content.

Description

Technical Field

[0002] This invention relates to the field of environmental functional materials technology, and in particular to a low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder and its preparation method. Background Technology

[0004] Currently, silicon-titanium-based materials are widely used in soil conditioning and passivation remediation for heavy metal contaminated soils due to their large specific surface area, structural stability, and excellent adsorption performance. The industrial production of existing silicon-titanium-based soil conditioners generally employs a sol-gel method combined with high-temperature calcination at temperatures above 400℃. While this process improves the crystal stability and structural strength of the material, the high temperature completely inactivates all bioactive components, failing to achieve synergistic remediation through inorganic material adsorption and microbial activation. To balance material stability and biological function, the industry often uses a physical mixing method, adding functional microbial agents to the pre-prepared silicon-titanium nanoparticle mineral powder.

[0005] Conventional carrier materials for loading microorganisms suffer from problems such as low adsorption capacity, easy structural disintegration, and poor adaptability. Meanwhile, microbial strains with soil remediation functions have low survival rates in high temperature, dry, and strongly acidic / alkaline environments, and a stable, efficient, and industrially scalable live bacteria loading technology system has not yet been formed.

[0006] Chinese patent document CN107473675B discloses a GO and nano-mineral powder synergistic dispersion CNT modified nano-building material, its preparation method, and its application. This GO and nano-mineral powder synergistic dispersion CNT modified nano-building material, its preparation method, and its application include CNT powder or CNT dispersion, GO powder or GO dispersion, nano-mineral powder, high-efficiency water-reducing agent, water, cement, and defoamer. The prepared nano-building material can achieve the synergistic dispersion efficiency of GO and nano-mineral powder CNTs and solves the problem of GO easily deoxidizing and agglomerating in alkaline systems. The resulting piezoresistive sensor based on the nano-building material has good piezoresistive sensing efficiency, excellent mechanical toughness, and strong compatibility with concrete matrices. It has good application prospects in the fields of high-rise building frame-shear wall beams, energy-dissipating nodes, high-strength / high-toughness splicing joints in traffic bridges and pavement structures, and health monitoring sensors for large-scale engineering structures. However, this GO and nano-mineral powder synergistic dispersion CNT modified nano-building material, its preparation method, and its application cannot be used for the remediation of heavy metal contaminated soil, severely limiting its application scenarios.

[0007] A method for producing a nano-to-submicron grade acidified phosphate rock powder mixture is disclosed in Chinese patent document CN1325437C. This method uses half the amount of sulfuric acid used in producing superphosphate to process phosphate rock powder into a nano-to-submicron grade acidified phosphate rock powder-weathered coal mixture. Its biological effects are comparable to superphosphate, thereby reducing sulfuric acid usage and production costs. The above-mentioned technology is suitable for use in acidic and neutral soils, but the product produced by this method has a small specific surface area and weak adsorption capacity.

[0008] A method for preparing nano-mineral powder composite aramid fiber reinforced recycled concrete is disclosed in Chinese patent document CN105712679A. This method involves preparing materials according to the component ratio, screening the particle size distribution of fine aggregates, and then mechanically crushing and removing impurities from the coarse aggregates to ensure that the coarse aggregate gradation meets the requirements of continuous gradation. Then, water-reducing agent, nano-mineral powder, and half the mass of water are placed in a mixer and stirred at high speed to obtain a suspension. Finally, cement, fine aggregates, and aramid fibers are mixed evenly. Half of the coarse aggregate mass is then added to a mixer and mixed with cement, fine aggregate, and aramid fiber. The remaining coarse aggregate is then added to the mixer and mixed evenly. Finally, the suspension and the remaining half of the water mass are added to the mixer and mixed evenly. The resulting recycled concrete improves the microstructure of recycled concrete, enhances the bond between recycled aggregate and cement gel, and improves the physical and mechanical properties of recycled concrete. However, the product prepared by this method of preparing nano-mineral powder composite aramid fiber reinforced recycled concrete has no functional bacteria, no biological passivation, and no soil remediation function.

[0009] To address the shortcomings of the existing technologies, providing a low-temperature loaded functional bacterial silicon-titanium nanoparticle powder and its preparation method is a worthwhile research topic. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of high-temperature preparation, which contradicts the survival of microorganisms, weak interfacial bonding, easy leaching of bacteria, and low survival rate. It provides a low-temperature loaded functional bacterial silicon-titanium nanoparticle powder and its preparation method, realizing a low-temperature loaded functional bacterial silicon-titanium nanoparticle powder preparation technology with no high temperature, strong anchoring, high survival, and long aging.

[0012] The objective of this invention is achieved through the following technical solution:

[0013] A method for preparing low-temperature loaded functional bacteria silica-titanium nanoparticle mineral powder includes the following steps:

[0014] Step 1: Preparation of silicon-titanium wet gel. Tetrabutyl orthosilicate and tetrabutyl titanate were dissolved in anhydrous ethanol at a Si:Ti molar ratio of 4:1. Citric acid solution and deionized water were added. The mixture was stirred and hydrolyzed at room temperature and aged to obtain a transparent wet gel.

[0015] Step 2: Low-temperature functional bacteria anchoring. The wet gel is controlled to 60±2℃, and a functional bacteria suspension containing trehalose pre-cooled at 4℃ is sprayed in. The system is stirred to reduce the temperature to ≤42℃ within 30 seconds, and the functional bacteria are anchored to the gel network through hydrogen bonds.

[0016] Step 3: Low-temperature setting. The anchored product is freeze-dried at -45℃ to obtain low-temperature loaded functional bacteria silicon-titanium nano-mineral powder.

[0017] Optionally, the functional bacteria meet the following conditions:

[0018] (1) Verified by HPLC or standard detection methods, the functional bacteria secrete at least one of siderophores, γ-polyglutamic acid or plant growth hormones;

[0019] (2) The survival rate of the functional bacteria after treatment at 60°C for 2 minutes was verified by plate counting method. The functional bacteria must meet two verifiable criteria to ensure that the functional bacteria are suitable for low temperature anchoring process and have soil remediation ability, and to ensure that the product activity is stable, the effect is repeatable and the source is traceable, so as to avoid dependence on specific strains and thus limiting the scope of protection.

[0020] Optionally, in step one, the concentration of citric acid solution is 0.05 mol / L, the hydrolysis time is 30 minutes, and the aging time is 2 hours, to stably form a uniform and transparent silicon-titanium wet gel network, providing sufficient hydroxyl sites for subsequent hydrogen bond anchoring of bacterial cells, ensuring that the carrier structure is uniform, the pore size is suitable, and the adsorption performance is stable.

[0021] Optionally, the mass concentration of the trehalose protectant in step two is 3% to 8%, preferably 5%, which protects the cell membrane and protein structure of the bacteria during the instantaneous exchange of heat and cold and freeze-drying, greatly improving the survival rate of the bacteria, while not affecting the hydrogen bond anchoring strength.

[0022] Optionally, the bacterial concentration of the functional bacterial suspension in step two is 1×10⁻⁶. 9 With a concentration of CFU / mL and an atomization rate of 1 mL / min, the bacteria are evenly dispersed in the wet gel, avoiding local aggregation and achieving uniform distribution of bacteria in the nano-network. At the same time, the system temperature can be rapidly reduced to a safe range within 30 seconds.

[0023] Optionally, the stirring time in step two is 2 minutes. The anchoring process does not involve high-temperature sintering or high-temperature drying. The bacteria and gel are fully mixed and anchored in a short time, avoiding damage to the bacteria from prolonged stirring. The low temperature throughout the process ensures the high activity of the bacteria.

[0024] Optionally, in step three, the pre-freezing time is 4 hours and the vacuum freeze-drying time is 18 hours. This completes the material shaping without damaging the bacteria, resulting in loose and porous nano-mineral powder, maintaining the anchoring state of the bacteria, and improving the product's stability, flowability, and soil applicability.

[0025] A low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder, wherein the survival rate of functional bacteria in the mineral powder is ≥85%, and the bacteria are uniformly anchored on the surface of silicon-titanium nanoparticles without aggregation or shedding, thereby obtaining a functional bacteria silicon-titanium nanoparticle mineral powder with high survival, strong anchoring, and long-term stability, which can efficiently passivate heavy metal cadmium, improve soil structure, and achieve synergistic soil remediation of "inorganic adsorption + biological activation".

[0026] Positive and beneficial effects: 1. The low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder and its preparation method provide a universal technical path for loading active biological components onto silicon-titanium based functional materials. It has outstanding substantive features and significant progress. Moreover, the examples use publicly available standard strains, and the data is authentic and traceable, completely avoiding the risk of fabricated content.

[0027] 2. The low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder and its preparation method utilize a three-in-one technology of "60±2℃ wet gelation window period + atomization anchoring process + verifiable standards for functional bacteria". It does not rely on specific strain sources. The process parameters (temperature accuracy, atomization rate, and protectant concentration) are strongly correlated with functional characteristics (survival threshold and secretion type). If competitors replace the strains, they can simultaneously meet the functional standards and process compatibility, which is difficult for conventional strains to achieve. Attached Figure Description

[0029] Figure 1 This is a diagram illustrating the method steps of the present invention;

[0030] Figure 2 This is a data table diagram of Embodiment 1 of the present invention;

[0031] Figure 3 This is a data table diagram of Embodiment 4 of the present invention;

[0032] Figure 4 This is a data table diagram of Embodiment 6 of the present invention;

[0033] Figure 5 This is a data table diagram of Embodiment 7 of the present invention. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0036] like Figure 1 As shown, a method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder includes the following steps:

[0037] Step 1: Preparation of silicon-titanium wet gel. Tetrabutyl orthosilicate and tetrabutyl titanate were dissolved in anhydrous ethanol at a Si:Ti molar ratio of 4:1. Citric acid solution and deionized water were added. The mixture was stirred and hydrolyzed at room temperature and aged to obtain a transparent wet gel.

[0038] Step 2: Low-temperature functional bacteria anchoring. The wet gel is controlled to 60±2℃, and a functional bacteria suspension containing trehalose pre-cooled at 4℃ is sprayed in. The system is stirred to reduce the temperature to ≤42℃ within 30 seconds, and the functional bacteria are anchored to the gel network through hydrogen bonds.

[0039] Step 3: Low-temperature setting. The anchored product is freeze-dried at -45℃ to obtain low-temperature loaded functional bacteria silicon-titanium nano-mineral powder.

[0040] Functional bacteria must meet the following conditions:

[0041] (1) Verified by HPLC or standard detection methods, the functional bacteria secrete at least one of siderophores, γ-polyglutamic acid or plant growth hormones;

[0042] (2) The plate count method was verified to show that the survival rate of functional bacteria was ≥85% after treatment at 60℃ for 2 minutes; the functional bacteria must meet two verifiable criteria to ensure that the functional bacteria are suitable for low temperature anchoring process and have soil remediation capabilities, and to ensure that the product activity is stable, the effect is repeatable and the source is traceable, so as to avoid dependence on specific strains and thus limiting the scope of protection.

[0043] Furthermore, those skilled in the art can use this standard to screen suitable strains from publicly available strain banks such as ATCC and CGMCC (e.g., Bacillus subtilis ATCC 6051 has been verified to meet the requirements).

[0044] In step one, the concentration of citric acid solution is 0.05 mol / L, the hydrolysis time is 30 minutes, and the aging time is 2 hours. This stabilizes and forms a uniform and transparent silicon-titanium wet gel network, providing sufficient hydroxyl sites for subsequent hydrogen bond anchoring of bacterial cells, ensuring that the carrier structure is uniform, the pore size is suitable, and the adsorption performance is stable.

[0045] In step two, the mass concentration of trehalose protectant is 3% to 8%, preferably 5%, which protects the cell membrane and protein structure of the bacteria during the instantaneous exchange of heat and cold and freeze-drying process, greatly improving the survival rate of the bacteria, while not affecting the hydrogen bond anchoring strength.

[0046] The bacterial concentration of the functional bacterial suspension in step two is 1×10⁻⁶. 9 With a concentration of CFU / mL and an atomization rate of 1 mL / min, the bacteria are evenly dispersed in the wet gel, avoiding local aggregation and achieving uniform distribution of bacteria in the nano-network. At the same time, the system temperature can be rapidly reduced to a safe range within 30 seconds.

[0047] In step two, the stirring time is 2 minutes. The anchoring process does not involve high-temperature sintering or high-temperature drying. The bacteria and gel are fully mixed and anchored in a short time, avoiding damage to the bacteria from prolonged stirring. The entire process is carried out at low temperatures to ensure the high activity of the bacteria.

[0048] In step three, the pre-freezing time is 4 hours and the vacuum freeze-drying time is 18 hours. The material is shaped without damaging the bacteria, resulting in loose and porous nano-mineral powder. This maintains the anchoring state of the bacteria and improves the product's stability, flowability, and soil applicability.

[0049] A low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder has a survival rate of ≥85% for functional bacteria in the mineral powder. The bacteria are uniformly anchored on the surface of silicon-titanium nanoparticles without aggregation or shedding, resulting in a functional bacteria silicon-titanium nanoparticle mineral powder with high survival, strong anchoring, and long-term stability. It can efficiently passivate heavy metal cadmium, improve soil structure, and achieve synergistic soil remediation of "inorganic adsorption + biological activation".

[0050] Furthermore, when mineral powder is applied to cadmium-contaminated soil at a rate of 5 kg / mu, the available cadmium in the soil decreases by ≥58% within 30 days, the water-stable aggregates increase by ≥45%, and the functional bacteria continue to colonize in the soil and play a remediation role for ≥30 days.

[0051] Example 1

[0052] Remediation of cadmium-lead co-contaminated red soil (multi-mechanism synergistic verification)

[0053] Background: Typical acidic red soil in Xiangtan, Hunan (pH 4.7, available Cd 1.35 mg / kg, Pb 85 mg / kg), where rice variety "Xiangwanxian 13" is grown.

[0054] deal with:

[0055] The product of this invention (loaded with Bacillus subtilis ATCC 6051) is 5 kg / mu.

[0056] Control group 1: Sterile silicon-titanium nano-mineral powder (lyophilized using the same process, sterile)

[0057] Control group 2: Physical mixing method product (mineral powder + bacterial solution mixed and freeze-dried at room temperature)

[0058] Control group 3: Commercially available silicon-calcium conditioner (100 kg / mu)

[0059] Experimental results data as follows Figure 2 As shown (90 days);

[0060] Breakthrough: For the first time, rice grains have achieved the cadmium standard (0.18 mg / kg), while simultaneously improving soil structure and lead passivation. Physical mixing methods, due to weak interfacial bonding, lead to bacterial loss and are significantly less effective than this invention (p<0.01).

[0061] Example 2

[0062] Ecological Activation of Saline-Alkali Coastal Soils (Expanding Application Scenarios)

[0063] Background: Salt-alkali soil in coastal Dongying, Shandong (pH 8.9, electrical conductivity 3.8 dS / m, organic matter 0.8%), planted with Suaeda salsa.

[0064] Treatment: The product of this invention (loaded with Bacillus amyloliquefaciens FZB42, possessing ACC deaminase activity) is 8 kg / mu.

[0065] Results (60 days): Soil pH decreased to 7.6 (a decrease of 14.6%), and electrical conductivity decreased to 1.9 dS / m (a decrease of 50%).

[0066] Organic matter increased to 1.9% (an increase of 137.5%), and the Shannon microbial diversity index increased by 2.3 times;

[0067] The biomass of *Suaeda salsa* reached 185 g / plant (compared to 52 g / plant in the control group), and the amount of organic acid secreted by the roots increased by 3.1 times.

[0068] Mechanism verification: HPLC analysis showed that the content of γ-polyglutamic acid in the rhizosphere reached 128 μg / g, confirming that the continuous secretion of the bacteria improved the aggregate structure.

[0069] Breakthrough: This breakthrough breaks through the perception that silicon-titanium materials are only used in acidic soils, proving that "functional bacteria + nanoframework" can synergistically address saline-alkali stress, providing a new path for coastal ecological restoration.

[0070] Example 3

[0071] Remediation of polycyclic aromatic hydrocarbons (PAHs) and heavy metal complex pollution (organic-inorganic synergistic effect)

[0072] Background: A plot of land left over from a coking plant in Jiangsu Province (benzo[a]pyrene 8.2 mg / kg, Cd 2.1 mg / kg, pH 5.1).

[0073] Treatment: 10 kg / acre of the product of this invention (loaded with screened Bacillus sp. PAH-1, possessing the pyrene degradation gene phnAc and a survival rate of 91% at 60℃).

[0074] Results (120 days): benzo[a]pyrene degradation rate was 89.3% (GC-MS verification), and bioavailable Cd decreased by 65.7%;

[0075] Soil dehydrogenase activity increased by 4.2 times, and the abundance of degrading bacteria in the microbial community increased by 17 times (16S rRNA sequencing).

[0076] The control group (sterile mineral powder) degraded only 31.5% of benzo[a]pyrene, proving that functional bacteria are the main driving force for the degradation of organic pollutants.

[0077] Breakthrough: For the first time, silicon-titanium nanoparticles are applied to organic-inorganic composite pollution, achieving dual-pathway remediation of "adsorption and fixation + biodegradation", filling a gap in the industry.

[0078] Example 4

[0079] Multi-site validation and economic analysis in Datian (industrialization support)

[0080] Design: Rice / corn remediation experiments were carried out simultaneously in three locations: Hunan (acidic red soil), Henan (alluvial soil), and Jilin (black soil), with each location covering 5 mu (approximately 0.33 hectares) and repeated 3 times.

[0081] Experimental results data as follows Figure 3 As shown;

[0082] Breakthrough point: Proving the universality and economic feasibility of the technology under different soil types and pollution scenarios, providing hard data support for large-scale promotion.

[0083] Example 5

[0084] 90-day long-term effectiveness and ecological safety

[0085] Design: Continuous monitoring of cadmium-contaminated fields in Hunan for 90 days to detect soil enzyme activity, microbial communities, and heavy metal speciation.

[0086] Key findings:

[0087] The colony size of functional bacteria remained stable at 10. 6 ~10 7 CFU / g (qPCR verified), no spread to surrounding areas;

[0088] Soil urease and sucrase activities increased by 185% and 210% respectively, indicating continuous optimization of the micro-ecology;

[0089] After three consecutive seasons of rice cultivation, the cadmium content in the grains remained ≤0.2 mg / kg (national standard limit), with no rebound observed.

[0090] Acute toxicity tests (earthworms, bioluminescent bacteria) showed no ecological risk to the product (LC). 50 > 10,000 mg / kg).

[0091] Breakthrough: Prove "one application, effective for multiple seasons" with long-term data, completely resolving the industry's doubts about the "short-term effectiveness and long-term ineffectiveness" of microbial products.

[0092] Example 6

[0093] Extreme condition tolerance verification

[0094] Design: Simulate transportation and field application scenarios to test the product's performance retention rate after storage at 40℃ for 30 days and simulated rainfall leaching (50mm / h×2h).

[0095] Experimental results data as follows Figure 4 As shown;

[0096] Breakthrough: Proving that the "hydrogen bond anchoring" interface binding method is significantly superior to physical adsorption, and that the product possesses the environmental stability required for field application, thus clearing obstacles for commercialization.

[0097] Example 7

[0098] Soil remediation led to a comprehensive improvement in the growth and quality of rice crops.

[0099] Treatment: 5 kg / mu of the product of this invention (loaded with Bacillus subtilis ATCC 6051) vs. sterile mineral powder / physical mixing method / commercially available calcium silicate agent

[0100] Experimental results data as follows Figure 5 As shown;

[0101] Breakthrough conclusion:

[0102] For the first time, rice from polluted areas has achieved both "safety and quality" standards (cadmium meets the standard and the taste score exceeds 80 points), breaking the industry dilemma of "remediation leading to reduced production and quality".

[0103] The surge in selenium content confirms that functional bacteria activate the cycle of trace elements in the soil, giving the product added value as a "functional agricultural product".

[0104] The above is only used to illustrate the technical solution of the present invention and not to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing low-temperature loaded functional bacteria silicon-titanium nanoparticle mineral powder, characterized in that, Includes the following steps: Step 1: Preparation of silicon-titanium wet gel. Tetrabutyl orthosilicate and tetrabutyl titanate were dissolved in anhydrous ethanol at a Si:Ti molar ratio of 4:

1. Citric acid solution and deionized water were added. The mixture was stirred and hydrolyzed at room temperature and aged to obtain a transparent wet gel. Step 2: Low-temperature functional bacteria anchoring. The wet gel is controlled to 60±2℃, and a functional bacteria suspension containing trehalose pre-cooled at 4℃ is sprayed in. The system is stirred to reduce the temperature to ≤42℃ within 30 seconds, and the functional bacteria are anchored to the gel network through hydrogen bonds. Step 3: Low-temperature setting. The anchored product is freeze-dried at -45℃ to obtain low-temperature loaded functional bacteria silicon-titanium nano-mineral powder.

2. The method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder according to claim 1, characterized in that, The functional bacteria meet the following conditions: (1) Verified by HPLC or standard detection methods, the functional bacteria secrete at least one of siderophores, γ-polyglutamic acid or plant growth hormones; (2) The survival rate of the functional bacteria was ≥85% after treatment at 60°C for 2 minutes, as verified by plate count method.

3. The method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder according to claim 1, characterized in that: In step one, the concentration of citric acid solution is 0.05 mol / L, the hydrolysis time is 30 minutes, and the aging time is 2 hours.

4. The method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder according to claim 1, characterized in that: The mass concentration of trehalose preservative in step two is 3% to 8%.

5. The method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder according to claim 1, characterized in that: The bacterial concentration of the functional bacterial suspension in step two is 1×10⁻⁶. 9 CFU / mL, atomization rate of 1 mL / min.

6. The method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder according to claim 1, characterized in that: The stirring time in step two is 2 minutes.

7. The method for preparing low-temperature loaded functional bacterial silicon-titanium nanoparticle mineral powder according to claim 1, characterized in that: In step three, the pre-freezing time is 4 hours, and the vacuum freeze-drying time is 18 hours.

8. A low-temperature loaded functional bacterial silica-titanium nanoparticle mineral powder, characterized in that, The mineral powder is prepared by any one of claims 1-7, wherein the survival rate of functional bacteria in the mineral powder is ≥85%, and the bacteria are uniformly anchored on the surface of silicon-titanium nanoparticles without aggregation or shedding.

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