Janus air filtering membrane for capturing, detecting and sterilizing integration of biological aerosol and preparation method of Janus air filtering membrane

Abstract

The invention discloses a Janus air filtering membrane for capturing, detecting and sterilizing integrated biological aerosol and a preparation method of the Janus air filtering membrane, and belongs to the technical field of filtering membranes. According to the technical scheme, the air filtering membrane is provided with an asymmetric two-side structure and a soluble micro-nano porous network structure, the surface of the filtering membrane is asymmetrically modified through an amphiphilic AIE photosensitizer, the Janus structure is constructed on the basis that the overall structure of the filtering membrane is not damaged, aggregation of the AIE photosensitizer on the single side of the filtering membrane is achieved, and therefore the air filtering membrane is formed. The air filter membrane has green capture detection performance and AIE photodynamic disinfection performance. The preparation method comprises the steps of solution preparation, filter membrane forming, surface asymmetric modification and drying. According to the Janus air filtering membrane, efficient capture and enrichment of biological aerosol can be achieved, the Janus air filtering membrane is used for microbiological detection under the guidance of near-infrared fluorescence imaging after being colored, and effective inactivation of air pathogens can be achieved by means of white light irradiation.

Description

Technical Field

[0001] The invention belongs to the technical field of filter membranes, and in particular relates to a Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols and a preparation method thereof. Background Art

[0002] Bioaerosols contain a variety of microorganisms, such as bacteria, fungi, viruses, spores, and archaea. Due to their light weight and small particle size, they can not only stay suspended in the air for a long time, but also spread over long distances with airflow. Some pathogens generated from human and natural activities can also diffuse into the air, combine with bioaerosols and spread over a large range in a short period of time, thereby causing serious air microbial pollution events. Bioaerosol transmission has been proven to be one of the main routes of transmission of some infectious diseases. Exposure to and inhalation of infectious pathogens in bioaerosols can endanger human health and may even induce fatal diseases. In view of this, people have been committed to developing advanced bioaerosol capture and inactivation strategies to control air microbial pollution and improve air quality. However, blind disinfection cannot achieve the traceability and eradication of air microbial pollution, but will lead to serious waste of energy due to excessive disinfection. In order to gain a deeper understanding of the actual situation of bioaerosols and prevent environmental safety accidents caused by air microbial pollution, the collection and detection of air pathogens have been identified as a key prerequisite for real-time sensitive monitoring and targeted inactivation of bioaerosols. In addition, accurate bioaerosol detection technology can also provide timely warning, early prediction and risk estimation for the prevention and control of aerosol-borne diseases. In general, air microbial pollution prevention and control is a dynamic process. The complexity, variability and spatiotemporal diversity of airborne pathogens require us to fully understand their capture, detection and inactivation processes, and to achieve intelligent prevention and control by formulating both offensive and defensive strategies.

[0003] Air filtration is one of the most commonly used air purification methods and plays an important role in controlling the spread of bioaerosols and protecting human health. With the help of multiple forces such as diffusion, screening and interception, porous filter media can effectively intercept and capture microbial particles in the air. The filtration method has attracted much attention for its advantages such as convenient operation, good durability, high collection efficiency and low cost. By introducing bactericides or constructing destructive nanostructures in air filter materials, filtration-based disinfection can achieve effective interception and broad-spectrum antibacterial activity of airborne microorganisms, effectively control the spread of bioaerosols and reduce the risk of secondary pollution. Although this passive filtration capture, removal and disinfection mode can play a vital role in blocking the spread of pathogenic aerosols, this filtration sampling method is not friendly to the accurate detection of bioaerosols. The soluble filter membrane material prepared by dual green mode screening of raw materials and preparation processes can effectively overcome the above problems, not only ensuring the green capture and enrichment of airborne pathogens, but also easily achieving the maximum sample transfer after bioaerosol sampling by eliminating the extraction and elution steps, thereby realizing the rapid quantitative detection of air pathogens under filtration capture. Among them, efficient air microbial capture and non-invasive transfer methods provide a fast and accurate detection method for real-time monitoring of bioaerosols. However, due to the lack of necessary sterilization means, this method can only be applied to the capture and detection of bioaerosols, and cannot achieve the purpose of actively controlling microbial contamination. Faced with the complex problem of air microbial contamination, rapid detection and timely disinfection of bioaerosols are necessary means to combat airborne pathogens, and both are indispensable. However, the air filtration technology currently reported can usually only achieve a single detection or disinfection mode after bioaerosol sampling, which is far from achieving the purpose of intelligent prevention and control of bioaerosols. Therefore, we urgently need to develop an all-round filter material that can simultaneously capture, detect and disinfect bioaerosols to achieve intelligent prevention and control of air microbial contamination. Summary of the invention

[0004] The present invention provides a Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols and a preparation method thereof, aiming to overcome the limitations of the traditional single bioaerosol detection and disinfection mode and provide a new method for intelligent prevention and control of air microbial pollution. The Janus air filter membrane of the present invention can not only realize the efficient capture and enrichment of bioaerosols, but also be used for microbial detection under the guidance of near-infrared fluorescence imaging after coloring, and can also effectively inactivate air pathogens with the help of white light irradiation.

[0005] The technical solution of the present invention is: On the first aspect, a Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols is disclosed. The air filter membrane has an asymmetric two-sided structure and a soluble porous network structure. The surface of the filter membrane is asymmetrically modified by an amphiphilic AIE photosensitizer. The Janus structure is constructed without destroying the overall structure of the filter membrane to achieve the aggregation of the AIE photosensitizer on a single side of the filter membrane. The air filter membrane has green capture, detection and photodynamic disinfection properties. It can not only effectively overcome the aggregation-induced quenching (ACQ) effect and generate strong fluorescence emission for microbial imaging, but also has a high reactive oxygen production capacity for efficient sterilization under light control.

[0006] Preferably, the AIE photosensitizer introduced into the air filtration membrane has a broad-spectrum microbial transfection ability, can effectively stain both Gram-positive bacteria and Gram-negative bacteria, and can achieve visual detection of captured microorganisms under the guidance of near-infrared fluorescence imaging.

[0007] Preferably, the asymmetric two-sided structure includes a capture surface and an AIE photosensitive surface, and the capture, detection and disinfection of microbial aerosols are achieved by selecting the capture surface and the AIE photosensitive surface.

[0008] Preferably, the AIE photosensitizer is an amphiphilic molecule that is soluble in organic solvents for asymmetric modification of the filter membrane surface and is also soluble in water. There should be a strong interaction force between the porous network structure of the filter membrane and the AIE photosensitizer to ensure that the photosensitizer can be firmly modified on the surface of the filter membrane.

[0009] Preferably, the structural formula of the AIE photosensitizer is: .

[0010] In a second aspect, a method for preparing the Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols is disclosed, comprising the following steps: 1) Dissolve the biomass material in water, heat and stir, add solvent until it is completely dissolved, and obtain a stable membrane solution; 2) Introduce the membrane solution into a plate and construct a porous network structure through poor solvent-induced phase separation technology until the filter membrane is fully formed; 3) The remaining poor solvent in step 2) is discarded, the filter membrane is retained, and the AIE photosensitizer solution is added to the surface of the filter membrane, and the filter membrane is washed after loading to achieve single-sided modification of the filter membrane; when the filter membrane surface is asymmetric modified, the filter membrane is kept on the base plate, and the openness of the front side of the filter membrane is used to achieve its single-sided modification; AIE photosensitizer molecules have good solubility in both water and ethanol, and have a high positive potential (24.9mV), which can generate a strong electrostatic force with the negative potential filter membrane (-8.5mV).

[0011] 4) The modified filter membrane is vacuum dried to obtain the Janus air filter membrane.

[0012] Preferably, the biomass material in step 1) is one or two of sodium hyaluronate, soybean polysaccharide, starch, cellulose and gelatin.

[0013] Preferably, the solvent in step 1) is one of anhydrous ethanol, methanol and acetone, and the volume ratio of water to solvent is 1:(0.4-0.9); the poor solvent in step 2) is one or more of methanol, ethanol, glycerol, acetone, dimethyl sulfoxide, dimethylformamide, ethyl acetate, methyl acetate, cyclohexane, dichloromethane and petroleum ether.

[0014] Preferably, the concentration of the AIE photosensitizer solution in step 3) is 0.3-0.5 mmol / L.

[0015] The third aspect discloses the application of the Janus air filter membrane for integrated capture, detection and sterilization of bioaerosols in filtration, capture, detection and sterilization of bioaerosols. The air filter membrane can select different surfaces for use according to needs. For sampling for detection purposes, the capture surface is used, and the sampled air filter membrane is directly placed in a culture dish for colony counting detection after cultivation, or directly dissolved in water, and rapid quantitative detection is performed using the ATP bioluminescence method, or visual detection of air microorganisms is performed using fluorescence imaging after incubation. For sampling for sterilization purposes, the AIE photosensitive surface must be used to achieve effective removal and inactivation of bioaerosols in the environment through air filtration and photodynamic effect under illumination.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention prepares an air filtration membrane material with a Janus structure by phase separation and asymmetric modification. The preparation method is simple and effective. By controlling the single-sided introduction of the amphiphilic AIE photosensitizer, while maintaining its original green capture performance, the performance advantages of the near-infrared AIE photosensitizer are further introduced, thereby realizing the integrated integration of bioaerosol filtration capture, detection and disinfection performance.

[0017] 2. The Janus air filter membrane prepared by the present invention is suitable for a variety of microbial detection methods. After bioaerosol sampling, it can transfer samples to the maximum extent, which is conducive to the accurate monitoring of air microorganisms. The air filter membrane after sampling can be directly placed in a culture dish for colony counting after cultivation, or it can be directly integrated into water to extract the captured microorganisms, and rapid quantitative detection can be achieved by ATP bioluminescence method. Importantly, the AIE photosensitizer loaded thereon can effectively transfect various types of microorganisms, and the captured microorganisms can be stained after incubation for visual detection under near-infrared fluorescence imaging.

[0018] 3. The Janus structure described in the present invention allows the AIE photosensitizer to be concentrated in large quantities on the front side of the filter membrane, so that it can fully receive light, avoid dispersion and weakening after the generation of active oxygen, and effectively exert photodynamic sterilization effects, thereby achieving efficient inactivation of captured microorganisms. This surface-dependent disinfection function under light is conducive to the timely control and on-demand disinfection of air microbial pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A photograph of the Janus air filter membrane prepared in Example 1 of the present invention; Figure 2 The front side (A) of the Janus air filtration membrane prepared in Example 1 of the present invention and the front side (B) of the membrane material prepared in Comparative Example 1 without surface modification are compared in SEM images at the same magnification; Figure 3 The SEM images of the front side (A) and the back side (B) of the membrane material prepared in Comparative Example 1; Figure 4 Comparison of images of HAFM, AIE-HAFM-1, AIE-HAFM-2 and AIE-HAFM filter membranes prepared in Comparative Examples 1-3 and Example 2; Figure 5 It is a comparison diagram of the ultraviolet absorption spectra of the membrane solutions obtained after the membrane materials prepared in Example 2, Comparative Examples 2 and 3 are dissolved in water; Figure 6 This is a picture of a filter membrane prepared in Comparative Example 4 that does not have a Janus structure but is also surface-modified; Figure 7 This is a graph showing the changes of the Janus air filter membrane prepared in Example 2 of the present invention before and after being immersed in water; Figure 8 The microstructure SEM images of the membrane material (A) prepared in comparative example 1 and the Janus air filtration membrane (B) prepared in example 2 of the present invention after contacting water; Fig. 9 The membrane solution (0-20 mg / mL) prepared by the Janus air filtration membrane prepared in Example 2 of the present invention was effective against Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) Effects on cell viability; Fig.10 The AIE photosensitizer and the Janus air filter membrane prepared in Example 2 of the present invention were used to detect Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus ) near-infrared fluorescence imaging; Fig.11The filter membranes prepared with different AIE photosensitizer introduction amounts (HAFM, AIE-HAFM-1, AIE-HAFM and AIE-HAFM-2 correspond to the filter membranes prepared in Comparative Example 1, Comparative Example 2, Example 2 and Comparative Example 3, respectively) under light or not have any effect on the activity of Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus )’s killing effect, WL represents white light irradiation; Fig.12 SEM images of the microstructure of the front and back surfaces of the Janus air filter membrane prepared in Example 2 of the present invention after bioaerosol sampling; Fig.13 This is a picture of the changes that occur when the Janus air filter membrane prepared in Example 2 of the present invention is placed directly in a culture dish after bioaerosol sampling; Fig.14 A comparison chart of the RLU values ​​of the Janus air filtration membrane prepared in Example 2 of the present invention and the membrane material prepared in Comparative Example 1 after sampling under the same bioaerosol environment and performing ATP bioluminescence detection; Fig.15 The Janus air filtration membrane prepared in Example 2 of the present invention, after capturing bioaerosols, was incubated and colored to detect Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus )’s near-infrared fluorescence imaging; Fig.16 The photodynamic killing effect of the Janus air filter membrane prepared in Example 2 of the present invention under different bioaerosol environments by selecting different surfaces for capture under illumination or not, AIE-HAFM (+) and AIE-HAFM (-) represent the front and back sampling of the Janus air filter membrane, respectively, and WL represents white light irradiation; Fig.17 The Janus air filtration membrane prepared in Example 2 of the present invention has a significant effect on the bioaerosol concentration of Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus )’s killing effect. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0021] The preparation method of the AIE photosensitizer is as follows: 1) (3-bromopropyl)trimethylammonium bromide (2.0 g, 7.66 mmol) and 4-methylpyridine (0.734 g, 7.88 mmol) are mixed, and the mixture is refluxed in a DMF solution under nitrogen protection overnight. After the reaction, the compound 1 is separated and purified; 2) 4-bromo-4',4'-dimethoxytriphenylamine (0.192 g, 0.5 mmol), 5-formyl-2-thiopheneboronic acid (0.0936 g, 0.6 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (0.0183 g, 0.025mmol) and potassium carbonate (0.345g) were mixed, and 10mL of a 1:1 mixed solvent of toluene and methanol was added under nitrogen protection. The mixture was refluxed overnight to react and separated by column chromatography to obtain compound 2; 3) Compound 1 (70.8mg, 0.20mmol) and compound 2 (87.2mg, 0.21mmol) were dissolved in anhydrous ethanol (10mL), and then 100 microliters of piperidine was added as a catalyst. The mixture was stirred and refluxed overnight. After the reaction was complete, the mixture was cooled and concentrated under reduced pressure to obtain a crude product. The crude product was purified by neutral alumina column chromatography using dichloromethane / methanol (50:1) as an eluent to obtain a black-red solid product, i.e., an AIE photosensitizer.

[0022] Example 1 This embodiment provides a method for preparing a Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols, comprising the following steps: 1) Solution preparation: First, sodium hyaluronate (0.4 g) and gelatin (0.8 g) were dissolved in deionized water (20.0 mL), placed in a 60°C water bath and stirred for 30 min to fully mix, then anhydrous ethanol (10 mL) was added and stirred for another 30 min to obtain the desired membrane solution; 2) Filter membrane formation: Pour 3 mL of membrane solution into a 6 cm diameter dish, add anhydrous ethanol (6 mL) and ethyl acetate mixture (6 mL) to induce phase separation, respectively, until the filter membrane is completely formed; 3) Surface asymmetric modification: After removing the remaining poor solvent that induced phase separation, AIE photosensitizer (0.5 mL, 0.4 mmol / L) dissolved in ethanol was directly added without moving the filter membrane. After soaking for 15 min, the remaining photosensitizer solution was removed and washed with ethanol. 4) Drying: The surface-modified filter membrane is subjected to vacuum freeze drying for 5 hours to obtain the Janus air filter membrane.

[0023] Figure 1This is a photo of the Janus air filter membrane after drying. It can be seen that its AIE photosensitive surface (hereinafter referred to as the front side) turns red due to the presence of the AIE photosensitizer, and the capture surface (hereinafter referred to as the back side) remains white. These two colors can be seen on its side. Figure 2 (A) shows the microstructural changes of the front side of the filter membrane before and after modification with the AIE photosensitizer, compared with the filter membrane prepared in Comparative Example 1 without surface modification. Figure 2 (B) Compared with the Janus air filter membrane, a layer of attachment can be clearly observed on its surface, but its surface still maintains a heterogeneous micro-nano porous structure, ensuring efficient retention and collection of microbial particles during the sampling process.

[0024] Example 2 1) Solution preparation: First, sodium hyaluronate (0.4 g) and gelatin (0.8 g) were dissolved in deionized water (20.0 mL), placed in a 60°C water bath and stirred for 30 min to fully mix, then anhydrous ethanol (10 mL) was added and stirred for another 30 min to obtain the desired membrane solution; 2) Filter membrane formation: Pour 3 mL of membrane solution into a 6 cm diameter dish, add anhydrous ethanol (6 mL) and ethyl acetate mixture (6 mL) to induce phase separation, respectively, until the filter membrane is completely formed; 3) Surface modification: After removing the remaining poor solvent that induced phase separation, AIE photosensitizer (0.5 mL, 0.4 mmol / L) dissolved in ethanol was directly added without moving the filter membrane. After soaking for 15 min, the remaining solution was removed and washed with anhydrous ethanol. 4) Drying: The surface-modified filter membrane was vacuum freeze-dried for 5 h to obtain the Janus air filter membrane (AIE-HAFM for short). After the filter membrane was dissolved in water to prepare a solution, the intensity change of the characteristic absorption peak of the AIE photosensitizer can be clearly observed in the ultraviolet absorption spectrum, such as Figure 5 shown.

[0025] Comparative Example 1 Different from Example 2, this comparative example does not include step 3) surface modification by AIE photosensitizer solution. In this case, the prepared membrane material is white and named HAFM. Its SEM image is as follows: Figure 3 As shown, the actual photos are as Figure 4 shown.

[0026] Comparative Example 2 Different from Example 2, the concentration of the AIE photosensitizer solution in step 3) of this comparative example is adjusted to 0.2 mmol / L, and the other conditions are the same as those of Example 2, thereby preparing Janus air filter membranes with different AIE photosensitizer concentrations on the surface. The prepared Janus filter membrane is named AIE-HAFM-1. Due to the low concentration of AIE photosensitizer on its surface, the front side is pink, such as Figure 4 After the filter membrane is dissolved in water to prepare a solution, the intensity change of the characteristic absorption peak of the AIE photosensitizer can be clearly observed in the ultraviolet absorption spectrum, as shown in FIG. Figure 5 shown.

[0027] Comparative Example 3 Different from Example 2, in this comparative example, the concentration of the AIE photosensitizer solution in step 3) is 0.8 mmol / L, and the other conditions are the same as those in Example 2, thereby preparing Janus air filter membranes with different AIE photosensitizer concentrations on the surface. The prepared Janus filter membrane is named AIE-HAFM-2. Due to the high concentration of AIE photosensitizer on its surface, the front side is dark red. Figure 4 As shown by Figure 4 It can be seen that as the concentration of the AIE photosensitizer solution increases, the color of the front surface gradually deepens. After the filter membrane prepared in this comparative example is dissolved in water to make a solution, the intensity change of the characteristic absorption peak of the AIE photosensitizer can be clearly observed in its ultraviolet absorption spectrum, such as Figure 5 shown.

[0028] Comparative Example 4 Unlike Example 2, in step 1) of this comparative example, the ethanol-dissolved AIE photosensitizer (0.5 mL, 0.4 mmol / L) is directly mixed into the membrane solution for dissolution, and the surface modification of step 3) is not included, and the rest is the same as Example 2. At this time, the membrane solution directly changes from colorless to red, and a pink membrane can be directly obtained after the subsequent filter membrane is formed and dried. Although this method can also introduce the AIE photosensitizer into the filter membrane, the filter membrane does not have an asymmetric Janus structure, which will lose the original green capture performance. The dispersed photosensitizer can easily cause damage to the captured microorganisms, thereby affecting the accurate assessment of the bioaerosol. In addition, this dispersed doping method will also greatly reduce the photosensitizer concentration within the front range of the membrane, affecting the photodynamic sterilization effect.

[0029] Comparative Example 5 Different from Example 2, in step 3) of this comparative example, the formed membrane is first removed from the substrate, and then the AIE photosensitizer solution is added for surface modification, and the rest is the same as Example 2. Due to the strong electrostatic interaction between the AIE photosensitizer and the filter membrane, the AIE photosensitizer molecules will wrap the entire outer surface of the filter membrane for adsorption modification, and finally only a pink filter membrane without a Janus structure can be obtained, and its structure is as follows Figure 6 shown.

[0030] Comparative Example 6 The difference from Example 2 is that the amount of AIE photosensitizer solution added in step 3) is 0.1 mL, and the concentration is 2 mmol / L, and the rest is the same as Example 2. Although the total amount of AIE photosensitizer added at this time is consistent with that in Example 2, due to the reduction in the total volume of the photosensitizer solution, accompanied by the volatilization of the solvent, it is difficult to fully cover the entire filter membrane surface during the surface modification process, and the distribution of the photosensitizer will become very uneven, and the filter membrane surface cannot be fully modified.

[0031] Comparative Example 7 The difference from Example 2 is that the amount of AIE photosensitizer solution added in step 3) is 1 mL, and the concentration is 0.2 mmol / L, and the rest is the same as Example 2. Although the total amount of AIE photosensitizer added at this time is consistent with that in Example 2, due to the decrease in the concentration of the photosensitizer solution, the modification effect can only reach the effect of Comparative Example 2 in the same time, and the surface modification cannot be completed efficiently.

[0032] Example 3: Verification of water solubility of Janus air filtration membrane When the Janus air filter membrane prepared in Example 2 is directly immersed in water, it can be found that its structure disintegrates instantly, as shown in FIG. Figure 7 shown. Figure 8 This is a microscopic structure diagram of the filter membrane after contact with water. It can be seen that its 3D structure completely disappears after collapsing in water. Its good water solubility is mainly because the main body of the air filter membrane is a water-soluble filter membrane, which is self-assembled by biological macromolecule chains. Once it comes into contact with water, its internal porous network structure will automatically disintegrate. In addition, since the AIE photosensitizer modified on its surface also has excellent water solubility, the final Janus air filter membrane also has good water solubility. This characteristic of disintegration in water makes it more convenient to handle after sampling, which can effectively avoid sample elution and loss in extraction, and is suitable for a variety of post-processing detection methods.

[0033] Example 4: Biocompatibility verification of Janus air filtration membrane Escherichia coli ( E. coli ) and Staphylococcus aureus ( S. aureus) were used as representative bacteria of Gram-negative bacteria and Gram-positive bacteria in air microorganisms, respectively. The biocompatibility of the Janus air filter membrane was evaluated by mixing membrane solutions of different concentrations with bacterial suspensions of microorganisms and then co-culturing. To avoid the influence of photodynamic effect, this part of the operation was carried out under light-proof conditions. First, the Janus air filter membrane prepared in Example 2 was dissolved in LB culture medium to prepare a concentrated solution (40 mg / mL), and then diluted in a proportional gradient to dilute solutions of different concentrations (0-20 mg / mL). Equal amounts of E. coli and S. aureus The membrane solutions of different concentrations were mixed evenly to prepare bacterial suspensions at different membrane solution concentrations. Finally, the mixed solution was inoculated onto LB agar medium, and colonies were counted after incubation at 37°C for 48 hours to calculate the survival rate of the microorganisms. Fig. 9 The results show that the concentration of membrane solution is different E. coli and S. aureus By comparing the microbial activities, both bacteria can maintain high biological activities within the membrane solution concentration range of 0-20 mg / mL, which proves that the porous filtration membrane prepared in the dark has good biocompatibility.

[0034] Example 5: Evaluation of the transfection ability of AIE photosensitizer and Janus air filtration membrane on microorganisms The cultured E. coli and S. aureus (10 8 CFU / mL) were mixed with an aqueous solution of an AIE photosensitizer (3 µM) and an aqueous solution of the Janus air filter membrane prepared in Example 2 (20 mg / mL). After being fully dispersed by vortexing, the mixture was incubated at 37°C in the dark for 30 min. The transfected bacterial samples were collected by centrifugation, washed with PBS, and the samples (2 µL) were dropped on a glass slide and observed with a confocal microscope. Fig.10 Showing that AIE photosensitizer molecules can be well transfected E. coli and S. aureus Bright red fluorescence signals can be observed in both bacteria in the samples. Similar situations can also be observed in the two bacteria transfected with Janus air filter membrane solution, which shows that the AIE photosensitizer molecules loaded into the air filter membrane still have a broad spectrum of transfection ability and can effectively stain and analyze microorganisms.

[0035] Example 6: Evaluation of the photodynamic bactericidal performance of Janus air filtration membrane Due to the strong electron donor-acceptor interaction in the conjugated structure of AIE photosensitizers, a variety of reactive oxygen species can be efficiently generated under white light irradiation, including singlet oxygen ( 1 O 2) and hydroxyl radicals (·OH), all of which have good bactericidal effects. By dripping bacterial solution on the surface of the filter membrane and irradiating with light, the photodynamic bactericidal effect of the AIE photosensitizer modified on the front of the Janus air filter membrane on pathogenic bacteria was directly evaluated. First, the air filter membranes prepared in Example 2 and Comparative Examples 1-3 were cut into circles of the same size, and then directly placed on the agar plate. After the filter membrane was completely wetted, a concentration of 10 4 CFU / mL bacterial suspension (20 μL, E. coli and S. aureus ) were dropped at the center of the filter membrane and then irradiated under white light (24 mW / cm 2 , 10min), and finally the dissolved filter membrane was evenly applied on the surface of the culture dish, and the colonies were counted after incubation at 37°C for 48h. Among them, the control group was operated in the dark under the same conditions without white light irradiation. In addition, the HAFM filter membrane prepared in Comparative Example 1 of the same size was taken as the blank group. Fig.11 As shown in the figure, compared with the control group without white light irradiation, the Janus air filter membrane after illumination had a strong killing effect on microorganisms. E. coli and S. aureus The survival rates dropped to 3.2% and 2.0%, respectively. In contrast, due to the absence of photosensitizer, the bacterial colonies and survival rates in the HAFM filter membrane hardly changed before and after illumination. In addition, by reducing the amount of AIE photosensitizer introduced on the surface of the filter membrane, the survival rate of bacteria in the AIE-HAFM-1 filter membrane prepared in Comparative Example 2 after illumination can still reach 40.2%. This is mainly because the reduction of surface photosensitizers leads to a decrease in the photodynamic killing effect. Similarly, when the amount of AIE photosensitizer introduced on the surface of the filter membrane is increased, the mortality rate of bacteria in the AIE-HAFM-2 filter membrane prepared in Comparative Example 3 after illumination is close to 100%, but the introduction of excessively high concentrations of AIE photosensitizers will also increase the dark toxicity of the filter membrane. Even in the absence of light, the survival rate of microorganisms will still drop a lot. These results show that the AIE photosensitizer molecules asymmetrically modified on the surface of the filter membrane have dose-dependent dark toxicity and photodynamic killing effects on pathogens, especially for S. aureus This type of Gram-positive bacteria has a greater killing effect. By changing the amount of AIE photosensitizer introduced on the filter membrane surface, a balance between dark toxicity and photodynamic inactivation effects can be achieved in the Janus air filter membrane, which helps to build a multifunctional integrated air filter membrane material.

[0036] Example 7: Testing of the Bioaerosol Capture Performance of the Janus Air Filter Membrane Various bioaerosol environment simulations and filter membrane sampling studies were conducted in a closed atomization chamber to test and evaluate the bioaerosol capture performance of the Janus air filter membrane prepared in Example 2 of the present invention. First, a microbial suspension ( E. coli and S. aureus ) for atomization, the concentration range of bacterial suspension is 10 4 -10 6 CFU / mL, the atomization time is 2min, and the atomization flow rate is 10L / min. The air filter membranes prepared in Example 2 and Comparative Examples 1-3 were uniformly cut into circles with a diameter of 25mm, placed on an MD8 filter sampler for sampling, with a sampling speed of 10L / min and a collection time of 5min. The particle concentration, particle size distribution, temperature, humidity and pressure in the atomization bin were recorded in real time by a particle size analyzer. By testing the change in particle concentration before and after the gas in the bin passes through the filter membrane, it can be determined that the Janus air filter membrane has a retention rate of 99.4% for aerosol particles, which is consistent with the simple HAFM filter membrane, and the pressure drop is not much different between the two. This is mainly due to the amphiphilicity of the AIE photosensitizer molecules, which can still be well dissolved in ethanol, so that uniform coating can be achieved when the asymmetric surface of the filter membrane is modified, and the filtration channel will not be blocked like particulate matter, maintaining the original retention and capture performance of the filter membrane. Fig.12 The SEM image of the Janus air filter membrane prepared in Example 2 of the present invention after bioaerosol sampling shows that a large amount of accumulated particles can be found on its surface, and the back structure does not show any deformation or cracks after continuous operation for 2 hours. All these prove that the Janus air filter membrane has good air filtration performance, high structural stability, can effectively intercept air microbial particles, and achieve effective capture of bioaerosols.

[0037] Example 8: Feasibility analysis of combining Janus air filtration membrane sampling with colony culture method and ATP bioluminescence method The Janus air filter membrane has excellent water solubility. The air filter membrane prepared in Example 2 is sampled in a bioaerosol simulation environment using the method of Example 7. After the sampling is completed, it is placed in a culture dish and automatically absorbs water and disintegrates. After being evenly smeared on the surface of the culture dish, the captured microorganisms can be successfully inoculated. After incubation at 37°C for 48 hours, the colony count is performed to achieve the culture method detection of the captured microorganisms. Fig.13The series of changes of the Janus air filter membrane after being placed in a culture dish are shown, and its characteristics of rapid water absorption and automatic disintegration can be clearly observed. In order to achieve rapid quantitative detection of microorganisms captured by the filter membrane, the sampled filter membrane can be directly dissolved in water, and the captured air microorganisms can be collected after centrifugation. After the microorganisms are lysed, luciferin / luciferase solution (100µL, enhanced ATP detection kit) is added. According to the linear relationship between the ATP bioluminescence intensity (RLU) value and the colony count (CFU), the corresponding microorganism capture number can be estimated by testing the RLU value. Fig.14 The relationship between the RLU values ​​obtained by the ATP bioluminescence method after sampling the Janus air filter membrane prepared in Example 2 and the HAFM filter membrane prepared in Comparative Example 1 under the same bioaerosol environment is shown. It can be found that the values ​​of the two are consistent, which indicates that the microorganisms captured and collected by the Janus air filter membrane can also be well combined with the ATP bioluminescence method for rapid quantitative detection of air pathogens.

[0038] Example 9: Visual detection and evaluation of bioaerosols by the Janus air filter membrane The Janus air filter membrane prepared according to Example 2 of the present invention is collected respectively from E. coli and S. aureus Bioaerosol obtained by atomization of bacterial suspension. After collection, the air filter membrane was directly transferred to a centrifuge tube and dissolved in PBS. After being fully dispersed by vortex, it was incubated at 37°C in the dark for 30 minutes. The transfected sample was collected by centrifugation, washed with PBS, and the sample (2µL) was dropped on a slide and observed with a confocal microscope. Fig.15 It was shown that the Janus air filtration membrane can effectively capture and transfect the two bacteria, and bright red fluorescence signals can be observed in the samples. This broad-spectrum visual detection method has important application potential in tracking and exploring unknown bioaerosols.

[0039] Example 10: Evaluation of the performance of the Janus air filter membrane in disinfecting bioaerosols Since the AIE photosensitizer is concentrated on the front of the air filter membrane, the photodynamic bactericidal performance of the Janus air filter membrane has obvious surface dependence. In order to further study the photodynamic bactericidal effect of the Janus air filter membrane under light induction, three different microorganisms ( E.coli, S. aureus The killing of microorganisms by the air filtration membrane prepared in Example 2 was analyzed by the colony counting method in a bioaerosol simulated environment under the condition of 1% parasitic bacteria and mixed bacteria. Fig.16It shows the disinfecting of captured microorganisms by different sides of the Janus air filter membrane with or without illumination after sampling in different bioaerosol environments. Since there is no photosensitizer on the back of the Janus air filter membrane, the number of bacterial colonies captured is not much different regardless of whether it is illuminated or not. In contrast, the microorganisms collected on the front of the Janus air filter membrane are almost all killed after being exposed to white light, while the bacteria that are not exposed to white light grow well. In addition, the Janus air filter membrane has a significant disinfecting effect on bioaerosols at different concentrations ( Fig.17 ), when the aerosol concentration is 10 6 CFU / mL, E. coli and S. aureus The killing rates of 100 and 100 μg / cm2 can reach 99.4% and 99.7% respectively. These results show that the photodynamic sterilization effect of the Janus air filter membrane has significant surface dependence and light controllability, and the on-demand sterilization of bioaerosols can be achieved by selecting the capture surface of the filter membrane and controlling the light.

[0040] The present invention prepares a Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols based on an asymmetric self-assembly strategy. Compared with ordinary filter membranes, the Janus air filter membrane prepared by the present invention has a soluble micro-nano porous network structure for efficiently capturing bioaerosol particles, and has multiple advantages such as high interception efficiency, low pressure drop, large sample load, large sample transfer volume, and flexible post-sampling processing methods. Importantly, its unique Janus structure allows the introduced AIE photosensitizer to be asymmetrically aggregated on the front of the filter membrane without affecting the overall properties of the filter membrane. While maintaining the original green capture properties, it has strong near-infrared fluorescence emission and high reactive oxygen production capacity. The Janus air filter membrane prepared by the present invention can not only achieve efficient capture and enrichment of bioaerosols for rapid quantitative detection or visual detection of microorganisms under the guidance of near-infrared fluorescence, but also can achieve effective photodynamic inactivation of airborne pathogens with the help of light. This multifunctional integrated system can effectively overcome the limitations of traditional single detection and sterilization modes, and can simultaneously meet the requirements of effective capture, dynamic detection and on-demand disinfection of bioaerosols, providing new ideas for the intelligent prevention and control of air microbial pollution.

Claims

1. Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols, characterized by: The air filtration membrane has an asymmetric two-sided structure and a soluble porous network structure. It is formed by asymmetric modification of the filter membrane surface by an amphiphilic AIE photosensitizer. The Janus structure is constructed without destroying the overall structure of the filter membrane to achieve the aggregation of the AIE photosensitizer on a single side of the filter membrane. The air filtration membrane has green capture, detection performance and photodynamic disinfection performance.

2. The Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 1, characterized in that: The AIE photosensitizer introduced into the air filtration membrane has a broad-spectrum microbial transfection ability, can effectively stain both Gram-positive bacteria and Gram-negative bacteria, and can achieve visual detection of captured microorganisms under the guidance of near-infrared fluorescence imaging.

3. The Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 1, characterized in that: The asymmetric two-sided structure includes a capture surface and an AIE photosensitive surface. The capture, detection and disinfection of microbial aerosols are achieved by selecting the capture surface and the AIE photosensitive surface.

4. The Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 1, characterized in that: AIE photosensitizers are amphiphilic molecules that are soluble in organic solvents for asymmetric modification of the filter membrane surface and are also soluble in water.

5. The Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols as claimed in claim 4, characterized in that: The structural formula of AIE photosensitizer is: 。 6. The method for preparing the Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 1, characterized in that: The following steps are involved: 1) Dissolve the biomass material in water, heat and stir, add solvent until it is completely dissolved, and obtain a stable membrane solution; 2) Introduce the membrane solution into a plate and construct a porous network structure through poor solvent-induced phase separation technology until the filter membrane is fully formed; 3) discarding the remaining poor solvent in step 2), retaining the filter membrane, adding the AIE photosensitizer solution on the surface of the filter membrane, and washing after loading to achieve single-sided modification of the filter membrane; 4) The modified filter membrane is vacuum dried to obtain the air filter membrane.

7. The method for preparing the Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 6, characterized in that: In step 1), the biomass material is one or two of sodium hyaluronate, soybean polysaccharide, starch, cellulose and gelatin.

8. The method for preparing the Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 6, characterized in that: In step 1), the solvent is one of anhydrous ethanol, methanol and acetone, and the volume ratio of water to the solvent is 1:(0.4-0.9); in step 2), the poor solvent is one or more of methanol, ethanol, glycerol, acetone, dimethyl sulfoxide, dimethylformamide, ethyl acetate, methyl acetate, cyclohexane, dichloromethane and petroleum ether.

9. The method for preparing the Janus air filter membrane for integrated capture, detection and disinfection of bioaerosols according to claim 6, characterized in that: In step 3), the concentration of the AIE photosensitizer solution is 0.3-0.5 mmol / L.

10. The use of the Janus air filter membrane for integrated capture, detection and sterilization of bioaerosols as claimed in any one of claims 1 to 5 in the filtration, capture, detection and sterilization of bioaerosols, characterized in that: The air filter membrane can be used on different surfaces according to needs; for sampling for detection purposes, the capture surface is used, and the air filter membrane after sampling is directly placed in a culture dish for colony counting detection after cultivation, or directly dissolved in water, and rapid quantitative detection is performed using ATP bioluminescence, or visual detection of air microorganisms is performed using fluorescence imaging after incubation; for sampling for the purpose of sterilization, the AIE photosensitive surface needs to be used, and the effective removal and inactivation of bioaerosols in the environment can be achieved through air filtration and photodynamic effect under illumination.

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