Air pathogen capture and detection filter membrane, integrated Janus composite membrane and preparation method and application thereof

Abstract

The invention discloses an air pathogen capture and detection filter membrane, an integrated Janus composite membrane and a preparation method and application thereof, and belongs to the technical field of filter membranes. According to the technical scheme, the filter membrane is a full-bio-based water-soluble air filter membrane, has a porous net-shaped structure, has high filter efficiency and low pressure drop, and is prepared by taking lignin and gelatin as raw materials through a phase separation process; the composite membrane is prepared by modifying a gemini type AIE surfactant G-MeOTTVP on the basis of the filtering membrane. The composite membrane disclosed by the invention realizes three-in-one function integration of capture, detection and inactivation, overcomes the key limitations of single function and step-by-step flow in a traditional biological aerosol treatment method, lays a foundation for developing an intelligent and multifunctional material system, and has a wide application prospect. The system has a wide application prospect in the field of active prevention and control of biological aerosol pollution in various scenes.

Description

Technical Field

[0001] This invention belongs to the field of filter membrane technology, specifically relating to an airborne pathogen capture and detection filter membrane, an integrated Janus composite membrane, its preparation method, and its application. Background Technology

[0002] Bioaerosols, acting as carriers of pathogens, viruses, and fungi, can remain suspended for extended periods and travel long distances, leading to the rapid and large-scale spread of infectious diseases. The ubiquity and long-distance transmission capabilities of airborne microorganisms make vigilant monitoring a fundamental element of hazard assessment, early warning, and risk mitigation. While traditional sampling methods (such as natural sedimentation on agar plates) are simple to operate, they are passive, time-consuming, and inefficient, and cannot capture representative airborne microbial communities, making it difficult to accurately characterize bioaerosol loads in real-world environments. These limitations highlight the urgent need for more advanced sampling strategies. Therefore, the prevention and control of airborne microbial contamination must be viewed as a dynamic and continuous process, requiring a complex and comprehensive offensive and defensive strategy, rather than a single passive response. Seamlessly combining efficient sampling, highly sensitive detection, and on-demand inactivation capabilities is crucial to effectively address the complexity, variability, and spatiotemporal diversity of airborne biological threats.

[0003] Air filtration is one of the most effective and widely used technologies for capturing bioaerosols. This method utilizes various physical mechanisms, including direct interception, inertial impaction, diffusion, and sieving in porous media, to trap particulate matter and capture airborne microorganisms. Compared to other active sampling methods (such as impactors, cyclones, and cyclones), filtration technology achieves high-efficiency collection across a wide particle size range (0.1–100 µm), making it a reliable solution for scenarios with low bioaerosol concentrations requiring efficient capture. Traditional air filtration primarily relies on non-degradable materials such as glass fibers and synthetic polymers. However, these traditional filter membranes have significant limitations in post-sampling analysis. Their insolubility and opacity make direct observation of colonies difficult, and the low elution efficiency of microorganisms from these solid matrices often results in substantial sample loss, affecting the accuracy of subsequent detection techniques such as polymerase chain reaction (PCR) and high-throughput sequencing. The development of water-soluble filter membranes has provided a key advance in addressing these challenges. Water-soluble filter membranes eliminate the complex elution step, which often leads to microbial loss and increases the risk of cross-contamination, enabling green capture of airborne microorganisms and maximizing sample retention for downstream analysis. After sampling, the entire filter membrane is directly dissolved in water, instantly releasing the captured microorganisms for efficient transfer to various downstream analytical platforms, including agar plate culture and molecular detection. Despite significant advancements in sampling and transfer technologies, key functional gaps remain. Current water-soluble filter membranes are primarily passive collection devices, adept at capture but inherently lacking integrated active functions, hindering efficient pathogen detection and controlled inactivation. They cannot provide real-time information on captured microorganisms or actively neutralize their potential biological threats. This functional limitation means that even with advanced water-soluble filter membranes, the complete process from capture and identification to eradication still relies on multiple independent steps and instruments. Therefore, there is a need to develop an integrated filter membrane material that not only captures pathogens but also facilitates their immediate identification and provides a controlled inactivation mechanism. Summary of the Invention

[0004] This invention provides an airborne pathogen capture and detection filter membrane, an integrated Janus composite membrane, its preparation method, and its application. The composite membrane achieves a three-in-one functional integration of "capture-detection-inactivation," overcoming the key limitations of traditional bioaerosol treatment methods, which are characterized by single function and step-by-step processes. This lays the foundation for the development of intelligent and multifunctional material systems. Such systems have broad application prospects in the field of active prevention and control of bioaerosol pollution in various scenarios.

[0005] The technical solution of this invention is as follows: In the first aspect, a filter membrane for capturing and detecting airborne pathogens is disclosed. The filter membrane is a fully bio-based water-soluble air filter membrane with a porous mesh structure, achieving a high particulate matter filtration efficiency of 99.4% and a low pressure drop of 40 mbar. It is prepared using lignin and gelatin as raw materials through a phase separation process.

[0006] Preferably, the method for preparing the filter membrane includes the following steps: 1) Preparation of membrane solution: Mix lignin and gelatin in water, heat and stir until completely dissolved, then add ethanol, continue stirring until the solution is clear, and then cool to room temperature to obtain the desired membrane solution; 2) Membrane shaping: Pour the membrane solution into a petri dish, then add a mixture of ethyl acetate and ethanol to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish; 3) Membrane formation: After adding ethanol, the particulate matter continues to precipitate until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Vacuum drying: The formed composite membrane is placed in a vacuum drying oven and dried to obtain the LGFM filter membrane.

[0007] Preferably, the mass ratio of lignin to gelatin is (0.4-0.6):10, the temperature is raised to 55-65℃ in step 1), the stirring time is 20-40 min, and the volume ratio of ethyl acetate to ethanol in step 2) is 1:1.

[0008] Secondly, an integrated Janus composite membrane prepared using the aforementioned filter membrane is disclosed. The composite membrane is based on the filter membrane modified with the gemini-type AIE surfactant G-MeOTTVP, and the structural formula of the AIE surfactant G-MeOTTVP is as follows: .

[0009] Thirdly, a method for preparing the integrated Janus composite membrane is disclosed, comprising the following steps: 1) Preparation of membrane solution: Mix lignin and gelatin in water, heat and stir until completely dissolved, then add ethanol, continue stirring until the solution is clear, and then cool to room temperature to obtain the desired membrane solution; 2) Membrane shaping: Pour the membrane solution into a petri dish, then add a mixture of ethyl acetate and ethanol to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish; 3) Membrane formation: After adding ethanol, the particulate matter continues to precipitate until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Asymmetric modification: Pour off the upper layer solution from step 3), add G-MeOTTVP solution dissolved in ethanol, soak, pour off the excess G-MeOTTVP solution and wash with ethanol; 5) Vacuum drying: Place the formed composite membrane in a vacuum drying oven and dry it to obtain the composite membrane AIE-LGFM.

[0010] Preferably, the mass ratio of lignin to gelatin is (0.4-0.6):10, the temperature is raised to 55-65℃ in step 1), the stirring time is 20-40 min, the volume ratio of ethyl acetate to ethanol in step 2) is 1:1, and the concentration of G-MeOTTVP solution in step 4) is 0.4-0.6 mmol / L.

[0011] Preferably, the preparation method of G-MeOTTVP includes the following steps: 1) After reacting 4-methylpyridine and 1,4-dibromobutane in acetonitrile overnight, the product was precipitated with diethyl ether, washed and centrifuged, and then mixed with N,N,N',N'-tetramethyl-1,6-hexanediamine in ethyl acetate and heated to reflux to obtain the first intermediate product; 2) Under nitrogen protection, 5-aldehyde-2-thiopheneboronic acid, 4-bromo-4',4'-dimethoxytriphenylamine, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride and potassium carbonate were mixed in a mixed solution of methanol and toluene, heated under reflux overnight, and separated by column chromatography to obtain the second intermediate product; 3) The first intermediate and the second intermediate were mixed in anhydrous ethanol, and piperidine was added as a catalyst. The mixture was heated under reflux overnight to generate the final product, which was then separated by column chromatography to obtain the gemini-type AIE surfactant G-MeOTTVP.

[0012] Preferably, in step 1), the molar ratio of 4-methylpyridine, 1,4-dibromobutane and N,N,N',N'-tetramethyl-1,6-hexanediamine is 2:2:1, and the heating temperature in step 1) is 80-90℃ and the heating time is 10-14h.

[0013] Preferably, the molar ratio of 5-aldehyde-2-thiopheneboronic acid, 4-bromo-4',4'-dimethoxytriphenylamine, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride and potassium carbonate is 20:25:(0.8-1.0):(8-12), and the volume ratio of methanol to toluene in the mixed solution of methanol and toluene is 1:1; the heating temperature in step 2) is 85-95℃; and the amount of piperidine added in step 3) is 1 / 10 of the mass of the first intermediate product.

[0014] Fourthly, the application of the integrated Janus composite membrane in the filtration, capture, detection, and inactivation of airborne pathogens is disclosed. The composite membrane achieves spatial separation of dual-sided functions: the unmodified back side can capture microorganisms with high fidelity for visual detection, while the active front side serves as a highly photoactivated bactericidal surface, enabling a complete "capture-detection-inactivation" process for airborne microorganisms. The specific synthetic route of the G-MeOTTVP molecule is as follows: .

[0015] The integrated Janus composite membrane AIE-LGFM described in this invention achieves a three-in-one functional integration of "capture-detection-inactivation," overcoming the key limitations of traditional bioaerosol control methods, which are characterized by single function and step-by-step processes. This lays the foundation for developing intelligent, multifunctional material systems and has broad application prospects in the field of proactive bioaerosol pollution control in various scenarios. The unmodified photosensitizer-treated back side of the AIE-LGFM composite membrane ensures high-fidelity capture of airborne microorganisms and efficient release of live bacteria for direct, label-free near-infrared fluorescence imaging (NIR FLI)-guided visualization detection. The active front side serves as a highly photoactivated bactericidal surface, enabling on-demand pathogen inactivation.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention prepares a fully biomass water-soluble air filter membrane (LGFM) using lignin and gelatin as raw materials. By adjusting the lignin concentration, the porous structure of GFM is controlled, giving it excellent particulate matter interception efficiency, low pressure drop, high biocompatibility and complete biodegradability, achieving a high particulate matter filtration efficiency of 99.4% and a low pressure drop of 40 mbar, making it a high-quality green alternative to traditional polymer-based filter membranes.

[0017] 2. This invention further synthesizes a multifunctional gemini-type AIE surfactant, G-MeOTTVP. This molecule not only possesses excellent water solubility and surface activity with a critical micelle concentration of only 11 µM, but also exhibits strong near-infrared fluorescence emission (λ). em With a wavelength of 750nm, high efficiency in generating reactive oxygen species, and excellent bacterial binding affinity, it can effectively transfect, image, and kill microorganisms.

[0018] 3. This invention prepares an integrated Janus composite membrane AIE-LGFM with a bifacial anisotropic structure by strategically modifying G-MeOTTVP on one side of the LGFM surface, achieving spatial decoupling of dual functions: its unmodified back side ensures high-fidelity capture of airborne microorganisms and efficient release of live bacteria for direct, label-free near-infrared fluorescence imaging-guided visualization detection, while the active front side serves as a powerful photoactivated bactericidal surface to achieve on-demand pathogen inactivation. Attached Figure Description

[0019] Figure 1 These are photographs of the front (+) and back (-) sides of the LGFM filter membrane prepared in Example 1 of this invention.

[0020] Figure 2 SEM images of the front (A), back (B), and cross-section (C) microstructure of the LGFM filter membrane prepared in Example 1 of this invention.

[0021] Figure 3 SEM images of the front (A), back (B), and cross-section (C) microstructure of the LGFM filter membrane prepared in Example 2 of this invention.

[0022] Figure 4 Images of different filter membranes prepared by varying the amount of lignin introduced in this invention.

[0023] Figure 5 SEM images of the front (A), back (B), and cross-section (C) microstructures of the LGFM-1 filter membrane prepared for Comparative Example 1.

[0024] Figure 6 SEM images of the front (A), back (B), and cross-section (C) microstructures of the LGFM-3 filter membrane prepared for Comparative Example 2.

[0025] Figure 7 SEM images of the front (A), back (B), and cross-section (C) microstructures of the LGFM-4 filter membrane prepared for Comparative Example 3.

[0026] Figure 8 SEM images of the front (A), back (B), and cross-section (C) microstructures of the LGFM-5 filter membrane prepared for Comparative Example 4.

[0027] Figure 9 The infrared spectrum (A) and pressure drop thickness comparison diagram (B) of different filter membranes prepared by changing the amount of lignin introduced in this invention are shown.

[0028] Figure 10 The above is the hydrogen nuclear magnetic resonance spectrum of G-MeOTTVP synthesized in Example 3 of this invention.

[0029] Figure 11 The image shows the carbon NMR spectrum of G-MeOTTVP synthesized in Example 3 of this invention.

[0030] Figure 12 This is a high-resolution mass spectrometer of G-MeOTTVP synthesized in Example 3 of the present invention.

[0031] Figure 13 The surface tension map (A), ultraviolet absorption spectrum (B), and fluorescence spectrum (C) of G-MeOTTVP synthesized in Example 3 of this invention are shown.

[0032] Figure 14 These are front (+) and back (-) photographs of the AIE-LGFM composite membrane prepared in Example 3 of this invention.

[0033] Figure 15 SEM images of the front (A), back (B), and cross-section (C) microstructure of the AIE-LGFM composite membrane prepared in Example 3 of this invention.

[0034] Figure 16 Photographs of the filter membranes prepared in Examples 2, 3, 5 and 6 of the present invention.

[0035] Figure 17 This is a SEM image of the microstructure collapse of the LGFM filter membrane prepared in Example 2 of the present invention after it comes into contact with water.

[0036] Figure 18 This is a comparison diagram of the LGFM filter membrane prepared in Example 2 of the present invention and the commercial MCE membrane in a soil burial experiment.

[0037] Figure 19 Near-infrared fluorescence imaging of E. coli and S. aureus using G-MeOTTVP synthesized in Example 3 of this invention.

[0038] Figure 20 The dark toxicity and phototoxicity (WL) of G-MeOTTVP synthesized in Example 3 of this invention to E. coli and S. aureus.

[0039] Figure 21 The colony culture results of the LGFM filter membrane prepared in Example 2 of this invention after sampling in both the positive (+) and negative (-) directions.

[0040] Figure 22 SEM images of the front (A), back (B), and back (C) sides of the LGFM filter membrane prepared in Example 2 of this invention after front sampling.

[0041] Figure 23Near-infrared fluorescence imaging of the AIE-LGFM filter membrane prepared in Example 3 of this invention after sampling and staining E. coli and S. aureus.

[0042] Figure 24 The dark toxicity and phototoxicity (WL) of the AIE-LGFM filter membrane prepared in Example 3 of this invention on the captured E. coli and S. aureus. Detailed Implementation

[0043] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions will be clearly and completely described below in conjunction with the embodiments of this invention.

[0044] Example 1 The method for preparing the airborne pathogen capture, detection, and inactivation filter membrane (LGFM) includes the following steps: 1) Preparation of membrane solution: Mix lignin (0.4g) and gelatin (10.0g) in deionized water (20.0mL), heat to 60℃ and stir continuously for 30min to completely dissolve it, then add ethanol solution (10mL), continue stirring until the solution is clear, and then cool to room temperature to obtain the required membrane solution; 2) Membrane shaping: Pour the membrane solution (3 mL) into a petri dish, and then add a mixture of ethyl acetate and ethanol (12 mL, with a volume ratio of ethyl acetate to ethanol of 1:1) to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish. 3) Membrane formation: After adding 2 mL of ethanol solution, continue to induce the precipitation of particulate matter for 4 hours until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Vacuum drying: The formed filter membrane is placed in a vacuum drying oven and dried at 30°C for 5 hours to obtain the filter membrane LGFM-2.

[0045] Figure 1 These are photos of the front and back sides of the LGFM-2 filter membrane after it has dried. Both sides are yellowish-brown, but the back side is slightly darker. Figure 2 A shows the microstructure of the front side of the filter membrane under a scanning electron microscope. Its structure is composed of countless small particles stacked together, filled with a pervasive, porous, cross-linked network, capable of filtering air and trapping microbial particles. (Example:) Figure 2 As shown in B and 2C, the porous network structure inside the LGFM-2 filter membrane can also be clearly observed from the microstructure of its back side and cross-section.

[0046] Example 2 The method for preparing the airborne pathogen capture, detection, and inactivation filter membrane (LGFM) includes the following steps: 1) Preparation of membrane solution: Mix lignin (0.6g) and gelatin (10.0g) in deionized water (20.0mL), heat to 60℃ and stir continuously for 30min to completely dissolve it, then add ethanol solution (10mL), continue stirring until the solution is clear, and then cool to room temperature to obtain the required membrane solution; 2) Membrane shaping: Pour the membrane solution (3 mL) into a petri dish, and then add a mixture of ethyl acetate and ethanol (12 mL, with a volume ratio of ethyl acetate to ethanol of 1:1) to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish. 3) Membrane formation: After adding 2 mL of ethanol solution, continue to induce the precipitation of particulate matter for 4 hours until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Vacuum drying: The formed filter membrane is placed in a vacuum drying oven and dried at 30°C for 5 hours to obtain the filter membrane LGFM.

[0047] Figure 3 Images A, 3B, and 3C show the microstructure of the LGFM filter membrane under a scanning electron microscope, including its front, back, and cross-sections. The front side exhibits a spiderweb-like porous structure, and its internal structure is also composed of countless small particles, forming a pervasive porous network that filters air and traps microbial particles.

[0048] Comparative Example 1 Unlike Example 2, in this comparative example, less lignin (0.2 g) was used in step 1) to prepare the membrane solution. Under these circumstances, the prepared membrane material LGFM-1 was significantly lighter in color. Figure 4 SEM images of the front, back, and cross-section of the prepared membrane material LGFM-1 are shown below. Figure 5 As shown, the size of the internal particles is significantly reduced, resulting in a more compact structure.

[0049] Comparative Example 2 Unlike Example 2, in this comparative example, more lignin (1.0 g) was used in step 1) to prepare the membrane solution. In this case, the prepared membrane material was significantly darker in color. Figure 4 SEM images of the front, back, and cross-section of the prepared membrane material LGFM-3 are shown below. Figure 6 As shown, the surface particles begin to aggregate into sheets, and the size of the internal particles also begins to increase, resulting in a looser structure.

[0050] Comparative Example 3 Unlike Example 2, in this comparative example, more lignin (1.4 g) was used in step 1) to prepare the membrane solution, resulting in a further deepening of the color of the prepared membrane material. Figure 4SEM images of the front, back, and cross-section of the prepared membrane material LGFM-4 are shown below. Figure 7 As shown, the surface particles further aggregate, and the size of the internal particles further increases, resulting in a more porous structure.

[0051] Comparative Example 4 Unlike Example 2, in this comparative example, more lignin (2.0 g) was used in step 1) to prepare the membrane solution. In this case, the prepared membrane material turned dark brown. SEM images of the front, back, and cross-section of the prepared membrane material LGFM-5 are shown below. Figure 8 As shown, the size of the internal particles is at the micrometer level or above, and the structure is more porous.

[0052] To quantitatively verify the changes in filter membrane composition with increasing lignin introduction, Fourier transform infrared spectroscopy (FTIR) was used for analysis. Figure 9 As shown in Figure A, characteristic peaks at 1125 cm⁻¹ attributable to the in-plane bending vibrations of lignin aromatic CH groups can be observed in the spectra of LGFM-1 to LGFM-5. -1 The characteristic peak intensity gradually increased. This trend confirms the continuous increase in the relative lignin content in the membrane matrix. The concentration of lignin introduction also has a significant impact on key filtration parameters. With gelatin mass kept constant in all membrane samples, transmembrane pressure drop and membrane thickness gradually decreased with increasing lignin content. Figure 9 (B) This phenomenon is attributed to the coarsening of the microstructure caused by enhanced lignin adhesion. Stronger intermolecular forces promote the formation of larger aggregate structural units during phase separation, ultimately constructing a more porous structure with better permeability. The improved permeability observed in this series of membrane samples is consistent with the porosity change trend revealed by scanning electron microscopy images. However, although low pressure drop is beneficial for energy-saving filtration, excessively high lignin concentration can severely impair interception efficiency. The study determined that the optimal mass ratio of lignin to gelatin was 0.6:10 in Example 2. Under these conditions, the filter membrane simultaneously achieved low pressure drop (~40 mbar) and high interception efficiency (99.4%). A filter membrane structure that is too loose or too dense is not conducive to the efficient capture of airborne microorganisms.

[0053] Example 3 The preparation method of the G-MeOTTVP molecule includes the following steps: 1) After reacting 4-methylpyridine (20 mmol) and 1,4-dibromobutane (20 mmol) in acetonitrile (40 mL) overnight, the product was precipitated with diethyl ether, washed and centrifuged, and then mixed with N,N,N',N'-tetramethyl-1,6-hexanediamine (10 mmol) in ethyl acetate (40 mL). The mixture was heated to 85 °C and refluxed for 12 h to obtain the first intermediate product. 2) Under nitrogen protection, 5-aldehyde-2-thiopheneboronic acid (20 mmol), 4-bromo-4',4'-dimethoxytriphenylamine (25 mmol), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (1 mmol) and potassium carbonate (10 mmol) were mixed in a mixed solution of methanol (40 mL) and toluene (40 mL), heated to 90 °C and refluxed overnight. The second intermediate product was obtained by column chromatography. 3) The first and second intermediates were mixed in anhydrous ethanol (30 mL), and piperidine (1 / 10 of the mass of the first intermediate) was added as a catalyst. The mixture was heated to 90 °C and refluxed overnight to generate the final product. The Gemini AIE surfactant G-MeOTTVP was obtained by column chromatography.

[0054] The molecular structure was fully verified using nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) (H1N, C1N, and HRMS spectra are shown below). Figure 10-12 (As shown), the NMR and mass spectrometry characterization data of the product are as follows: 1 H NMR (600 MHz, DMSO- d 6): δ 9.02-8.87 (m, 3H), 8.28-8.11 (m, 5H), 7.58-7.37 (m, 8H), 7.14-7.04 (m, 10H), 6.96 (ddd, J = 6.7, 5.8, 3.0 Hz, 10H), 6.77 (dd, J = 8.9, 2.3 Hz, 4H), 4.58 (dd, J = 20.5, 13.5 Hz, 4H), 3.76-3.69(m, 16H), 3.17-2.95 (m, 12H), 1.97 (d, J = 21.6 Hz, 4H), 1.74 (s, 8H), 1.37(dd, J = 23.9, 5.6 Hz, 4H), 1.28-1.20 (m, 4H). 13 C NMR (600 MHz, DMSO- d6):156.77, 153.29, 149.48, 148.55,144.42, 139.71, 138.50, 134.57, 130.12,127.81, 127.16, 124.39, 123.93, 123.65, 121.21, 118.89, 115.58, 63.61, 62.59,59.10, 55.77, 50.54, 27.46, 25.72, 22.07, 19.22. IR (cm -1 ): 3381 (s), 3033 (m), 2940 (m), 1596 (s), 1503 (vs), 1436 (s), 1237 (vs), 1170 (s), 1030 (s), 824 (s), 524 (m). ESI HRMS:C 80 H 92 Br4N6O4S2[M-2Br] 2+ The calculated value of / 2 is 712.2478, and the actual measured value is 712.2486; [M-3Br] 3+ The calculated value of / 3 is 448.5256, and the actual measured value is 448.5265; [M-4Br] 4+ The calculated value of / 4 is 316.1650, while the actual measured value is 316.1649. The molecular design of G-MeOTTVP integrates several key features to optimize its function. To enhance photosensitivity, a strongly electron-donating methoxy-modified triphenylamine (TPA) group is introduced into the conjugated backbone, constructing a stable intramolecular electron donor-acceptor (DA) system. Simultaneously, to improve water solubility and ensure efficient interaction with negatively charged bacterial cell membranes, symmetrically distributed positively charged pyridinium ions and long-chain hydrophilic quaternary ammonium salt groups are introduced. This unique twin structure is expected to endow the material with good water solubility and broad-spectrum targeting affinity for pathogenic bacteria. G-MeOTTVP exhibits amphiphilic characteristics, containing a hydrophobic tail (triphenylamine and conjugated chromophore) and a hydrophilic head group (pyridinium ion and quaternary ammonium salt group), thus exhibiting surfactant-like properties. Its surface activity was quantitatively analyzed by measuring the surface tension of aqueous solutions at different concentrations, and the critical micelle concentration (CMC) was determined. Figure 13 As shown in Figure A, its CMC value was measured to be 11 µM. This result indicates that the twin structure enhances molecular stacking ability and interfacial activity, thereby achieving a more efficient micellization process. Figure 13 As shown in B and 13C, the maximum ultraviolet absorption peak of the G-MeOTTVP molecule is 500 nm, and the maximum emission wavelength in the fluorescence emission spectrum is 750 nm.

[0055] The method for preparing the Janus composite membrane for capturing, detecting, and inactivating airborne pathogens includes the following steps: 1) Preparation of membrane solution: Mix lignin (0.6g) and gelatin (10.0g) in deionized water (20.0mL), heat to 60°C and stir continuously for 30min to completely dissolve it, then add ethanol solution (10mL), continue stirring until the solution is clear, and then cool to room temperature to obtain the required membrane solution; 2) Membrane shaping: Pour the membrane solution (3 mL) into a petri dish, and then add a mixture of ethyl acetate and ethanol (12 mL, with a volume ratio of ethyl acetate to ethanol of 1:1) to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish. 3) Membrane formation: After adding 2 mL of ethanol solution, continue to induce the precipitation of particulate matter for 4 hours until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Asymmetric modification: After removing the supernatant, add 0.3 mL of ethanol-dissolved G-MeOTTVP solution (0.4 mmol / L), soak for 20 min, remove excess G-MeOTTVP solution and wash with ethanol. 5) Vacuum drying: The formed filter membrane is placed in a vacuum drying oven and dried at 30°C for 5 hours to obtain the composite membrane AIE-LGFM.

[0056] Figure 14 This is a photo of the AIE-LGFM filter membrane after it has dried. Because AIE molecules are attached to its front side, the front side has turned dark red, while the back side remains yellowish-brown. Figure 15 The microstructure of the AIE-LGFM filter membrane is shown on its front, back, and side surfaces. Compared to the LGFM filter membrane before surface modification, its microstructure remains largely unchanged, retaining its spiderweb-like micro-nano porous structure. This non-destructive modification effectively ensures efficient interception and capture of microbial particles. Pressure drop and particulate matter interception efficiency tests revealed that the AIE-LGFM filter membrane achieves the same low pressure drop (~40 mbar) and high interception efficiency (99.4%) as LGFM alone. This retention of air filtration performance is primarily attributed to the excellent solubility of G-MeOTTVP, which allows it to disperse uniformly as a molecular coating without forming particle aggregates that clog the porous channels. Therefore, this unique one-sided modification strategy allows AIE-LGFM to perfectly retain the performance advantages of the original LGFM while endowing it with new specific surface functions.

[0057] Comparative Example 5 Unlike Example 3, in step 4) of this comparative example, the concentration of the G-MeOTTVP solution was adjusted to 0.2 mmol / L to prepare AIE-LGFM-1.

[0058] Comparative Example 6 Unlike Example 3, in step 4) of this comparative example, the concentration of the G-MeOTTVP solution was adjusted to 0.8 mmol / L to prepare AIE-LGFM-2.

[0059] The composite membranes prepared in Examples 2, 3, 5, and 6 are as follows: Figure 16 As shown in the figure, by changing the amount of AIE molecules modified on the surface of the filter membrane, it can be seen from the figure that when the concentration of G-MeOTTVP solution is increased, the color of the front side of the modified filter membrane will gradually deepen, which means that more AIE molecules are introduced into the filter membrane.

[0060] The water solubility and biodegradability of the LGFM filter membrane prepared in Example 2 were verified as follows: LGFM filter membranes are assembled entirely through physical non-covalent interactions without chemical cross-linking, thus retaining the inherent water solubility of their components. Therefore, upon contact with water, the complex porous three-dimensional structure immediately disintegrates and collapses. Figure 17 The membrane rapidly disperses, returning to its original colloidal solution state. This characteristic offers significant advantages in post-treatment stages of air filtration applications, particularly for the remediation of bioaerosol pollution. Airborne pathogens captured by LGFM can be efficiently converted into a conventional microbial suspension after membrane dissolution. This water-induced conversion process facilitates a series of downstream microbial analyses or treatments, thereby improving the practicality and safety of hazardous biological particulate matter treatment. For example, after bioaerosol sampling, LGFM can be aseptically transferred directly to LB agar plates. Upon contact with the agar surface, the membrane rapidly and spontaneously disintegrates, releasing the captured microorganisms. Immediate and uniform inoculation of microorganisms can be achieved simply by spreading with a sterile inoculation swab, eliminating the extraction step and minimizing potential analyte loss.

[0061] A comparative soil burial test was conducted between LGFM and commercially available mixed cellulose ester (MCE) membranes. Figure 18 Upon spraying with water, LGFM immediately dissolved into a colloidal solution and seeped into the soil, while the MCE membrane remained intact. Due to the inherent biodegradability of both lignin and gelatin, the LGFM residue completely degraded within 48 hours, leaving no visible trace on the soil. In contrast, the intact white MCE membrane remained on the soil surface. These results demonstrate that LGFM is a truly sustainable material that can be disposed of through soil burial after use, thus avoiding the "white pollution" problem associated with traditional polymer membranes.

[0062] The evaluation of the ability of G-MeOTTVP prepared in Example 3 to transfect and kill microorganisms is as follows: E. coli ( E. coli ) and Staphylococcus aureus ( S.aureus The samples were mixed separately with G-MeOTTVP aqueous solution (2µM), thoroughly dispersed, and incubated in the dark for different times under shaking conditions at 37°C and 200 rpm. The transfected samples were then centrifuged, washed with PBS, and 2µL of the sample was dropped onto a glass slide for observation using a confocal microscope. Figure 19 As shown, it only takes 10 minutes of incubation to... E. coli and S.aureus A red fluorescent signal was observed in the bacterial suspension, and a high signal-to-noise ratio was observed after 30 minutes of incubation, demonstrating that G-MeOTTVP molecules can effectively transfect bacteria. E. coli and S.aureus These two types of bacteria.

[0063] The antibacterial effect of G-MeOTTVP against bacterial strains was evaluated using a traditional surface coating method. The specific steps are as follows: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] E. coli and S. aureus Bacterial suspension (100µL, concentration 5×10⁻⁶) 7 CFU / mL was added to solutions containing different concentrations of G-MeOTTVP, and incubated for 30 minutes at 37°C and 200 rpm with shaking. Then, a pre-defined sample group was selected and tested under white light (24 mW / cm²). 2 Irradiate for 10 minutes, then collect all treated bacterial cells, wash with phosphate-buffered saline (PBS) and perform serial dilutions; take approximately 5 × 10⁻⁶ cells. 3 A diluted suspension of CFU / mL (100 µL) was spread onto LB agar plates and incubated at 37°C for 48 hours. The plates were then photographed, and the number of colony-forming units (CFU) on each plate was counted. Figure 20 As shown, G-MeOTTVP molecules pair E. coli and S. aureus Both bacteria exhibit concentration-dependent dark toxicity, particularly to... S. aureus With the aid of light, bacteria can be effectively inactivated.

[0064] The bioaerosol capture performance of the LGFM prepared in Example 2, the AIE-LGFM filter membrane prepared in Example 3, the AIE-LGFM-1 prepared in Comparative Example 5, the AIE-LGFM-2 prepared in Comparative Example 6, and the commercial MCE filter membrane was investigated and tested as follows: Simulated bioaerosols used to evaluate filter membrane performance were generated within a customized nebulization chamber (dimensions: 800 mm × 600 mm × 800 mm). Diverse bioaerosol environments were constructed by loading different bacterial suspensions into the nebulizer (nebulization flow rate: 10 L / min, nebulization duration: 2 minutes). To facilitate quantification of the bioaerosol load within the sealed chamber, sampling conditions were defined based on the concentration of the bacterial suspension used in the nebulizer, with 20 mL of a specific concentration (n × 10⁻⁶) being used. 5 Bacterial suspensions (CFU / mL, where n=1, 5, 10) were added to the nebulizer reservoir, and the bioaerosol generation rate (10 L / min) and generation time (2 minutes) were fixed. To clarify the characteristics of the simulated bioaerosols, the bioaerosol concentration in the sealed chamber was labeled as the concentration of the corresponding bacterial suspension; after nebulization, the aerodynamic diameter of the simulated bioaerosols generated by these suspensions was mainly distributed in the range of 1-5 μm. Throughout the experiment, the ambient temperature inside the chamber was maintained at 20-30℃, and the relative humidity was controlled at 30-70%. All filter membranes (LGFM, AIE-LGFM, AIE-LGFM-1, AIE-LGFM-2, and MCE) were cut to a uniform diameter (25 mm) and securely installed on the air sampler (Sartorius MD8, Germany) for bioaerosol collection. After the nebulization cycle was completed, the air sampler was immediately started to capture the atomized microbial particles (sampling flow rate: 10 L / min, sampling time: 10 minutes). To minimize the impact of natural bioaerosol deposition, the MD8 air sampler is placed horizontally during operation. Furthermore, although the front (+) and back (-) sides of the LGFM exhibit morphological differences, both demonstrate comparable microbial capture capabilities, with no statistically significant difference in CFU counts obtained under the same conditions (Figure 21). This indicates that particle interception primarily occurs within the internal porous network of the filter membrane, rather than being limited to its surface. As shown in Figure 22A, significant particle accumulation was observed within the pores while the original filter membrane skeleton remained clearly visible. Simultaneously, after bioaerosol sampling with the front side as the inlet, the back side remained unchanged, showing no structural deformation or blockage, confirming the structural stability and continuous operation capability of the LGFM (Figure 22B). When the back side was used as the inlet, it exhibited similar particle loading characteristics, and the other side surface remained intact. Figure 22 C). For AIE-LGFM, AIE-LGFM-1, and AIE-LGFM-2 filter membranes, due to the molecular-level modification of G-MeOTTVP on their surface, the modified filter membranes can achieve the same level of pressure drop and particulate matter interception efficiency as LGFM alone. The testing procedure for the bioaerosol capture performance of these filter membranes is consistent with that of LGFM. The evaluation of the microbial transfection and killing ability of AIE-LGFM is as follows: To achieve fluorescence visualization analysis of captured bioaerosols, the composite membrane AIE-LGFM prepared in Example 3 was sampled and aseptically transferred to a centrifuge tube, dissolved in 1 mL of buffer. The resulting suspension was vigorously vortexed to ensure homogeneity, and then incubated in the dark at 37°C and 200 rpm for 30 minutes. The stained bacteria were recovered by centrifugation at 6000 rpm for 3 minutes and resuspended in PBS. 2 µL of the stained bacterial suspension was added to a glass slide, covered with a coverslip, and observed using a confocal microscope. As shown in Figure 23, after 30 minutes of incubation, a clear red fluorescence signal with a high signal-to-noise ratio was observed. E. coli and S. aureus The cell membranes were effectively illuminated, confirming that the components after membrane dissolution did not interfere with the binding of G-MeOTTVP to microorganisms. This characteristic allows for direct visualization of captured pathogens after sampling, without the need for additional staining steps. Ideally, the AIE photosensitizer immobilized on the membrane surface is in a "closed" state during air filtration and capture, but is rapidly activated after membrane dissolution, enabling microbial staining and fluorescence detection.

[0065] The antibacterial properties of LGFM prepared in Example 2, AIE-LGFM prepared in Example 3, AIE-LGFM-1 prepared in Comparative Example 6, and AIE-LGFM-2 prepared in Comparative Example 6 were tested under conditions with and without white light irradiation. The different filter membranes were installed on samplers, and the same volume of air was sampled under the same bioaerosol environment. After sampling, the filter membranes were subjected to light-shielded conditions (10 min) and light irradiation (10 min, 24 mW / cm²), respectively. 2The treated filter membranes were then dispersed in petri dishes for colony culture. The photodynamic antibacterial performance was evaluated by comparing the number of colony-forming units (CFUs) recovered from AIE-LGFM and the original LGFM under white light (WL) irradiation conditions after bioaerosol sampling. As shown in Figure 24, since LGFM does not contain photosensitizers, there was no significant difference in bacterial survival rate regardless of light irradiation. In stark contrast, AIE-LGFM achieved near-complete eradication of captured bacteria after white light irradiation, while significant bacterial survival was recorded under dark conditions. To investigate the dose-dependent effect, two additional twin membranes (AIE-LGFM-1 and AIE-LGFM-2) were prepared, corresponding to lower and higher G-MeOTTVP coating concentrations, respectively. Quantitative analysis of drug loading using absorption spectroscopy of the residual modified solution revealed drug loadings of 2.81, 5.73, and 9.37 mg / g for AIE-LGFM-1, AIE-LGFM, and AIE-LGFM-2, respectively. The reduced photosensitizer loading in AIE-LGFM-1 led to decreased photodynamic efficacy, with survival rates of 25.1% for E. coli and 19.9% ​​for Staphylococcus aureus after irradiation. AIE-LGFM-2 achieved 100% inactivation under light irradiation but exhibited significantly higher dark toxicity, particularly against Staphylococcus aureus (survival rate of 35.5% under dark conditions), attributed to the inherent bactericidal activity of the excess quaternary ammonium compound. These results indicate that by adjusting the G-MeOTTVP loading, the photodynamic bactericidal ability and dark toxicity of the composite membrane can be controllably regulated, achieving an optimal balance between the two.

[0066] This invention, through rational design and preparation, develops a novel bifacial anisotropic Janus-structured AIE active air filter membrane that integrates a complete "capture-detection-inactivation" workflow. The specific strategy is as follows: First, a fully bio-based water-soluble lignin-gelatin filter membrane (LGFM) is prepared using a green phase separation process, serving as a sustainable and efficient microbial capture substrate. By adjusting the lignin concentration, the internal porous structure of LGFM is precisely controlled, resulting in excellent filtration efficiency, low airflow resistance, and complete environmental biodegradability. Subsequently, an amphiphilic gemini-type AIE surfactant, G-MeOTTVP, is synthesized, possessing strong near-infrared fluorescence, high reactive oxygen species yield, and excellent bacterial membrane targeting ability. This G-MeOTTVP is asymmetrically coated onto a single surface of LGFM, constructing the bifacial anisotropic structure AIE-LGFM. This asymmetric configuration achieves spatial decoupling of functions: the unmodified back side ensures non-destructive bioaerosol sampling and allows for direct microbial staining for fluorescent detection; while the active front side serves as a highly photoactivated bactericidal surface. The results show that AIE-LGFM exhibits superior performance in precise bioaerosol monitoring and active pathogen inactivation. This invention establishes a sustainable and multifunctional material platform that overcomes the inherent limitations of traditional single-function filter membranes, opening up new pathways for the intelligent and comprehensive prevention and control of airborne biological threats.

[0067] Although the present invention has been described in detail by way of preferred embodiments, the invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An airborne pathogen capture and detection filter membrane, characterized in that, The filter membrane is a fully bio-based water-soluble air filter membrane with a porous mesh structure, prepared from lignin and gelatin through a phase separation process.

2. The airborne pathogen capture and detection filter membrane as described in claim 1, characterized in that, The preparation method includes the following steps: 1) Preparation of membrane solution: Mix lignin and gelatin in water, heat and stir until completely dissolved, then add ethanol, continue stirring until the solution is clear, and then cool to room temperature to obtain the desired membrane solution; 2) Membrane shaping: Pour the membrane solution into a petri dish, then add a mixture of ethyl acetate and ethanol to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish; 3) Membrane formation: Add ethanol to continue inducing particulate matter precipitation until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Vacuum drying: The formed composite membrane is placed in a vacuum drying oven and dried to obtain the filter membrane.

3. The airborne pathogen capture and detection filter membrane as described in claim 2, characterized in that, The mass ratio of lignin to gelatin is (0.4-0.6):

10. In step 1), the temperature is raised to 55-65℃ and the stirring time is 20-40 min. In step 2), the volume ratio of ethyl acetate to ethanol is 1:

1.

4. An integrated Janus composite membrane prepared using the filter membrane according to any one of claims 1-3, characterized in that, The composite membrane is a filter membrane modified with the gemini-type AIE surfactant G-MeOTTVP, and the structural formula of the AIE surfactant G-MeOTTVP is as follows: 。 5. The method for preparing the integrated Janus composite membrane as described in claim 4, characterized in that, Includes the following steps: 1) Preparation of membrane solution: Mix lignin and gelatin in water, heat and stir until completely dissolved, then add ethanol, continue stirring until the solution is clear, and then cool to room temperature to obtain the desired membrane solution; 2) Membrane shaping: Pour the membrane solution into a petri dish, then add a mixture of ethyl acetate and ethanol to force the particulate matter to precipitate out, thereby shaping the porous structure at the bottom of the petri dish; 3) Membrane formation: After adding ethanol, the particulate matter continues to precipitate until the membrane solution is completely transformed into a solid membrane, thus achieving membrane formation; 4) Asymmetric modification: Pour off the upper layer solution from step 3), add G-MeOTTVP solution dissolved in ethanol, soak, pour off the excess G-MeOTTVP solution and wash with ethanol; 5) Vacuum drying: Place the formed composite film in a vacuum drying oven and dry it to obtain the composite film.

6. The method for preparing the integrated Janus composite membrane as described in claim 5, characterized in that, The mass ratio of lignin to gelatin is (0.4-0.6):

10. In step 1), the temperature is raised to 55-65℃ and the stirring time is 20-40 min. In step 2), the volume ratio of ethyl acetate to ethanol is 1:

1. In step 4), the concentration of G-MeOTTVP solution is 0.4-0.6 mmol / L.

7. The method for preparing the integrated Janus composite membrane as described in claim 5, characterized in that, The preparation method of G-MeOTTVP includes the following steps: 1) After reacting 4-methylpyridine and 1,4-dibromobutane in acetonitrile overnight, the product was precipitated with diethyl ether, washed and centrifuged, and then mixed with N,N,N',N'-tetramethyl-1,6-hexanediamine in ethyl acetate and heated to reflux to obtain the first intermediate product; 2) Under nitrogen protection, 5-aldehyde-2-thiopheneboronic acid, 4-bromo-4',4'-dimethoxytriphenylamine, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride and potassium carbonate were mixed in a mixed solution of methanol and toluene, heated under reflux overnight, and separated by column chromatography to obtain the second intermediate product; 3) The first intermediate and the second intermediate were mixed in ethanol, and piperidine was added as a catalyst. The mixture was heated under reflux overnight to generate the final product, which was then separated by column chromatography to obtain the gemini-type AIE surfactant G-MeOTTVP.

8. The method for preparing the integrated Janus composite membrane as described in claim 5, characterized in that, In step 1), the molar ratio of 4-methylpyridine, 1,4-dibromobutane, and N,N,N',N'-tetramethyl-1,6-hexanediamine is 2:2:1, and the heating temperature in step 1) is 80-90℃, and the heating time is 10-14h.

9. The method for preparing the integrated Janus composite membrane as described in claim 5, characterized in that, The molar ratio of 5-aldehyde-2-thiopheneboronic acid, 4-bromo-4',4'-dimethoxytriphenylamine, [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride and potassium carbonate is 20:25:(0.8-1.0):(8-12); the volume ratio of methanol to toluene in the mixed solution of methanol and toluene is 1:1; the heating temperature in step 2) is 85-95℃; the amount of piperidine added in step 3) is 1 / 10 of the mass of the first intermediate product.

10. The application of the integrated Janus composite membrane as described in claim 4 in the filtration, capture, detection, and inactivation of airborne pathogens, characterized in that, The composite membrane achieves spatial separation of dual-sided functions: the unmodified back side can capture microorganisms with high fidelity for visual detection, while the active front side serves as a powerful photoactivated bactericidal surface, enabling a complete process of "capture-detection-inactivation" for airborne microorganisms.

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