A superhydrophilic coating for bioaerosol wet-wall cyclone sampling and its preparation method

Abstract

This invention proposes a superhydrophilic coating for wet-wall cyclone sampling of bioaerosols and its preparation method. By superhydrophilically modifying the inner wall of the sampling cup made of glass or plastic, the cyclone layer is less prone to breakage during sampling. As the liquid level decreases during sampling, the previously exposed portion above the cyclone layer is covered by a thin liquid film due to the superhydrophilic properties. This allows aerosol particles to be effectively captured upon impact with the liquid film, preventing them from bouncing off the exposed glass or plastic surface and escaping with the airflow. This method effectively solves the wall loss problem in low-flow-rate sampling and long-term sampling, thereby achieving efficient aerosol-water-solvent transfer of bioaerosol particles. It can significantly improve the sampling efficiency of wet-wall cyclone bioaerosol samplers and has broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of bioaerosol sampling and superwetting material preparation technology, specifically relating to a superhydrophilic coating for bioaerosol wet-wall cyclone sampling and its preparation method. Background Technology

[0002] Harmful bioaerosols pose a persistent threat to global public safety. Developing practical, real-time bioaerosol monitoring / detection methods remains a continuing challenge. Efficient and comprehensive sampling of microbial aerosols is fundamental and a prerequisite for their rapid detection. The sampling principles and methods for bioaerosols are essentially the same as for non-bioaerosols, namely, designing sampling methods based on the physical characteristics of the aerosols, such as size, weight, and charge. Commonly used sampling methods include solid impaction, liquid impaction, filtration, electrostatic sedimentation, and condensation sampling. Unlike non-bioaerosols, bioaerosol research focuses on microorganisms, generally evaluating sampling methods based on cell viability, culturability, and genetic material integrity, selecting appropriate methods according to the research content and objectives. Liquid-based sampling methods cause less biological damage and offer greater flexibility in sample processing and detection, allowing for the selection of different subsequent analytical methods as needed, such as microscopic (electron) microscopy, flow cytometry, ATP biofluorescence methods, real-time quantitative PCR, and enzyme-linked immunosorbent assays (ELISA).

[0003] The wet-wall cyclone method is a variation of the cyclone method and liquid impact sampling. Unlike common liquid impact aerosol samplers, wet-wall cyclone sampling does not require a high-power sampling pump to provide high sampling negative pressure. Instead, it uses a low-power, high-flow-rate fan to generate a high-speed cyclone in the cyclone chamber. The centrifugal force generated by the cyclone collects airborne biological samples onto a liquid film formed by the cyclone. This method can significantly increase the sampling flow rate of the sampler with less sampling liquid, achieving enrichment ratios that are difficult to achieve with traditional impact samplers. The collected samples are stored in the liquid and are suitable for various types of detection and analysis. During wet-wall cyclone sampling, the incoming swirling airflow forms a swirling layer on the inner wall of the cyclone sampler (usually made of glass or plastic) through centrifugal force and surface tension. Then, inertial impaction collects airborne particles into the liquid flow. However, two problems exist during the sampling process: First, the instability and non-uniformity of the vortex layer lead to frequent breakage, especially at low sampling flow rates, causing it to disintegrate into droplets. This results in some particles impacting the inner wall of the cup, rebounding, and being drawn away with the airflow. This situation improves with increasing the flow rate. Second, regardless of the sampling flow rate, as the sampling time increases (or in very dry conditions), the sampling liquid level gradually decreases, and the inner surface of the upper part of the cup that cannot be covered by the liquid vortex gradually increases. This causes impacting particles to rebound and be drawn away with the airflow, resulting in sampling loss. Currently, the method of replenishing liquid while sampling can solve this problem to some extent, but due to the influence of factors such as sampling speed and environmental humidity, it is difficult to accurately control the replenishment rate according to environmental changes. Therefore, a universal solution to reduce particle rebound loss during sampling is urgently needed.

[0004] In summary, given the need to develop efficient wet-wall cyclone sampling methods for bioaerosols, exploring how to reduce the rebound loss of aerosol particles during wet-wall cyclone sampling to achieve efficient aerosol-water transfer of bioaerosol particles remains an unresolved issue. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] This invention proposes a superhydrophilic coating for wet-wall cyclone sampling of bioaerosols and its preparation method. By superhydrophilic modification of the inner wall of the sampling cup made of glass or plastic, the cyclone layer is less prone to breakage during sampling. As the liquid level of the sample decreases during sampling, the part that was originally exposed above the cyclone layer is covered by a thin liquid film due to the superhydrophilic properties. This allows the particles to collide with the liquid film layer and avoid rebound and escape as much as possible, thus solving the wall loss during low-flow-rate sampling and long-term sampling, and realizing the technical problem of efficient aerosol-water-solvent transfer of bioaerosol particles.

[0007] (II) Technical Solution

[0008] To address the aforementioned technical problems, this invention proposes a method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling. This superhydrophilic coating preparation method includes:

[0009] S1. Fluoride modification of SiO2 nanoparticles and cellulose nanofibers respectively;

[0010] S2. Fluorinated SiO2 nanoparticles and cellulose nanofibers are mixed evenly in anhydrous ethanol to obtain a superhydrophilic coating liquid;

[0011] S3. By dip-lifting, a styrene-butadiene-styrene block copolymer primer and a superhydrophilic coating liquid are sequentially coated on the inner wall of the wet-wall cyclone sampling cup to prepare a superhydrophilic coating on the inner wall of the cup.

[0012] Further, step S1 includes the following steps:

[0013] (1) Dissolve FS-50 fluorocarbon surfactant in aqueous ethanol and stir at room temperature to obtain a uniform FS-50 ethanol solution, and divide the FS-50 ethanol solution into 2 portions;

[0014] (2) Take hydrophilic SiO2 nanoparticles and cellulose nanofibers CNFS, add them to 1 part of FS-50 ethanol solution, stir and react at room temperature, then centrifuge and separate them. Collect the centrifuged products and dry them in a vacuum drying oven to obtain FS-50 modified superhydrophilic SiO2 nanoparticles FS-50@SiO2NPs and FS-50 modified cellulose nanofibers FS-50@CNFS, respectively.

[0015] Furthermore, step S1 specifically includes the following steps:

[0016] (1) Dissolve 10g of FS-50 fluorocarbon surfactant in 100mL of anhydrous ethanol and stir for 40min at room temperature to obtain a uniform FS-50 ethanol solution. Divide the FS-50 ethanol solution into two portions.

[0017] (2) Take 2g of hydrophilic SiO2 nanoparticles with an average particle size of 100nm and 1g of cellulose nanofiber CNFS, respectively add them to 1 part of FS-50 ethanol solution, stir and react at room temperature for 30min, then centrifuge and separate them. Collect the centrifuged products and dry them in a vacuum drying oven to obtain FS-50 modified superhydrophilic SiO2 nanoparticles FS-50@SiO2 NPs and FS-50 modified cellulose nanofibers FS-50@CNFS.

[0018] Further, in step S1, the centrifuged product is dried in a vacuum drying oven at 120°C for 12 hours.

[0019] Further, step S2 includes the following steps:

[0020] (1) Take FS-50@SiO2 NPs and add them to anhydrous ethanol, then disperse them by ultrasonication to obtain a uniform FS-50@SiO2 NPs ethanol dispersion.

[0021] (2) Take rosin resin, add it to anhydrous ethanol, heat it to fully dissolve the rosin resin, and obtain an ethanol solution of rosin resin.

[0022] (3) Mix the ethanol dispersion of FS-50@SiO2 NPs with the ethanol solution of rosin resin, disperse by ultrasonication, add FS-50@CNFS, stir and mix, disperse by ultrasonication; then add bis(3-trimethoxysilylpropyl)amine, stir and react to prepare the superhydrophilic coating liquid.

[0023] Furthermore, step S2 specifically includes the following steps:

[0024] (1) Take 2g of FS-50@SiO2NPs, add it to 18mL of anhydrous ethanol, and ultrasonically disperse for 30min to obtain a uniform FS-50@SiO2NPs ethanol dispersion.

[0025] (2) Take 4.2g of rosin resin, add it to 5mL of anhydrous ethanol, heat to 90℃, and let the rosin resin dissolve completely to obtain an ethanol solution of rosin resin.

[0026] (3) Mix the ethanol dispersion of FS-50@SiO2 NPs with the ethanol solution of rosin resin, sonicate for 30 min, add 0.2 g of FS-50@CNFS, stir and mix for 10 min, sonicate for 30 min; then add 100 μL of bis(3-trimethoxysilylpropyl)amine, and stir and react at 45 °C for 2 h to prepare the superhydrophilic coating liquid.

[0027] Further, step S3 includes the following steps:

[0028] (1) SBS primer coating: Add butyl acetate to SBS adhesive, stir and dilute thoroughly, and let stand to defoam to obtain SBS coating primer; punch holes in the bottom of the sampling cup and seal the outer wall with plastic wrap; immerse the cup in the SBS coating primer at a speed of 4500 μm / s and stay for 10s, then pull it up at a speed of 4500 μm / s and stay for 2min. After the butyl acetate evaporates, an SBS gel primer layer is obtained on the cup.

[0029] (2) Superhydrophilic coating: The cup coated with SBS gel primer layer is immersed in the superhydrophilic coating liquid at a speed of 5000μm / s and held for 1 minute by dip-lifting method. Then it is lifted at a speed of 5000μm / s and held for 1 minute. After cyclic immersion in the superhydrophilic coating liquid twice, it is ventilated and dried to obtain the superhydrophilic coating.

[0030] Furthermore, step S3 specifically includes the following steps:

[0031] (1) SBS primer coating: Add 5 mL of butyl acetate to 50 mL of SBS adhesive, stir and dilute for 20 min, and let stand for 2 h to defoam to obtain SBS coating primer; punch holes in the bottom of the sampling cup and seal the outer wall with plastic wrap; immerse the cup in the SBS coating primer at a speed of 4500 μm / s and hold for 10 s, then pull it up at a speed of 4500 μm / s and hold for 2 min. After the butyl acetate evaporates, an SBS gel primer layer is obtained on the cup.

[0032] (2) Superhydrophilic coating: The cup coated with SBS gel primer layer is immersed in the superhydrophilic coating liquid at a speed of 5000 μm / s and held for 1 min by dip-lifting method. Then it is lifted at a speed of 5000 μm / s and held for 1 min. After cyclic immersion in the superhydrophilic coating liquid twice, it is ventilated and dried for 12 h to obtain the superhydrophilic coating.

[0033] Furthermore, this invention also proposes a superhydrophilic coating for bioaerosol wet-wall cyclone sampling, which is prepared using the above-described method.

[0034] In addition, the present invention also proposes a wet-wall cyclone sampling cup with the inner wall modified by the above-mentioned superhydrophilic coating.

[0035] (III) Beneficial Effects

[0036] This invention proposes a superhydrophilic coating for wet-wall bioaerosol cyclone sampling and its preparation method. By superhydrophilically modifying the inner wall of a glass or plastic sampling cup, the cyclone layer is less prone to breakage during sampling. As the liquid level decreases during sampling, the previously exposed portion above the cyclone layer is covered by a thin liquid film due to the superhydrophilic properties. This allows aerosol particles to be effectively captured upon impact with the liquid film, preventing them from bouncing off the exposed glass or plastic surface and escaping with the airflow. This method effectively solves the wall loss problem during low-flow-rate sampling and long-term sampling, thereby achieving efficient aerosol-water-solvent transfer of bioaerosol particles. It can significantly improve the sampling efficiency of wet-wall cyclone bioaerosol samplers and has broad application prospects. Attached Figure Description

[0037] Figure 1This is a schematic diagram illustrating the principle of the superhydrophilic coating preparation method and application testing of the present invention;

[0038] Figure 2 FTIR and XPS characterization of the products FS-50@SiO2 NPs, FS-50@CNFS, and superhydrophilic coatings obtained in the embodiments of the present invention;

[0039] In the figure: a) FTIR spectra of SiO2 and FS-50@SiO2 NPs; b) FTIR spectra of CNFS and FS-50@CNFS; c) FTIR spectra of SC and SC-SBS surfaces; d) FTIR spectra of SC and SC-SBS surfaces from 1600 to 1350 cm⁻¹. -1 Enlarged view; e is the XPS scan full spectrum of the SC-SBS surface; f is the Si 2p spectrum; g is the C 1s spectrum; h is the F 1s spectrum; i is the Na 1s spectrum;

[0040] Figure 3 SEM and AFM characterization of the product SC-SBS obtained in the embodiments of the present invention;

[0041] In the figure: a is the SEM image of the SC-SBS surface at a 5μm scale; b is the SEM image of the SC-SBS surface at a 2μm scale; c is the SEM image of the SC-SBS surface at a 1μm scale; d is the elemental mapping of the main elements Si, C, O, F and Na on the SC-SBS surface; e is the AFM image of the SC-SBS surface.

[0042] Figure 4 The change in contact angle (CA) when SC-SBS comes into contact with water droplets (0-4s);

[0043] Figure 5 The change in CA (cathode) of the coating surface after 5 seconds of contact with water droplets during different peel tests of SC-SBS tape.

[0044] Figure 6 The cross-cut method is used to characterize the adhesion of coatings;

[0045] In the figure: a is a diagram of the cross-cut test classification of GB / T9286-2021 standard, from top to bottom representing levels 0, 1, 2, 3, and 4; b is the cross-cut test result of the SC layer alone; c is the cross-cut test result of SC-SBS.

[0046] Figure 7 Fluorescence measurements were performed on fluorescent particle aerosols of different particle sizes after sampling with and without an ultra-clear water coating.

[0047] In the figure: a) is the measurement result after sampling 0.51μm fluorescent particle aerosol; b) is the measurement result after sampling 1.1μm fluorescent particle aerosol; c) is the measurement result after sampling 2.9μm fluorescent particle aerosol.

[0048] Figure 8 The culture and counting results of Bacillus subtilis spore aerosols after sampling with or without ultra-clear water coating;

[0049] In the figure: a shows the improvement in sampling enrichment effect of the superhydrophilic coating compared to the uncoated coating at different flow rates; b shows the sampling and culture counting statistics with and without the superhydrophilic coating; c shows the sampling and culture results with and without the superhydrophilic coating.

[0050] Figure 9 The ATP fluorescence of the sample solution was measured after sampling air with or without an ultra-clear water coating at a sampling flow rate of 100 L / min. Detailed Implementation

[0051] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0052] This embodiment proposes a method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling. The method specifically includes the following steps:

[0053] S1. Fluorination modification of SiO2 nanoparticles and cellulose nanofibers respectively.

[0054] (1) Dissolve 10g of FS-50 fluorocarbon surfactant in 100mL of anhydrous ethanol and stir for 40min at room temperature to obtain a uniform FS-50 ethanol solution. Divide the FS-50 ethanol solution into two portions.

[0055] (2) Take 2g of hydrophilic SiO2 nanoparticles with an average particle size of 100nm and 1g of cellulose nanofibers CNFS, respectively, and add them to 1 part of FS-50 ethanol solution. Stir and react at room temperature for 30min, then centrifuge and separate. Collect the centrifuged products and dry them in a vacuum drying oven at 120℃ for 12h to obtain FS-50 modified superhydrophilic SiO2 nanoparticles FS-50@SiO2 NPs and FS-50 modified cellulose nanofibers FS-50@CNFS.

[0056] S2. Fluorinated SiO2 nanoparticles and cellulose nanofibers are mixed evenly in anhydrous ethanol to obtain a superhydrophilic coating liquid.

[0057] (1) Take 2g of FS-50@SiO2NPs, add it to 18mL of anhydrous ethanol, and ultrasonically disperse for 30min to obtain a uniform FS-50@SiO2NPs ethanol dispersion.

[0058] (2) Take 4.2g of rosin resin, add it to 5mL of anhydrous ethanol, heat to 90℃, and let the rosin resin dissolve completely to obtain an ethanol solution of rosin resin.

[0059] (3) Mix the ethanol dispersion of FS-50@SiO2 NPs with the ethanol solution of rosin resin, sonicate for 30 min, add 0.2 g of FS-50@CNFS, stir and mix for 10 min, sonicate for 30 min; then add 100 μL of bis(3-trimethoxysilylpropyl)amine, and stir and react at 45 °C for 2 h to prepare the superhydrophilic coating liquid.

[0060] S3. Using an dip-lift method, a styrene-butadiene-styrene block copolymer (SBS) primer and a superhydrophilic coating liquid are sequentially coated onto the inner wall of the wet-wall cyclone sampling cup to prepare a superhydrophilic coating on the inner wall of the cup.

[0061] (1) SBS primer coating: Add 5 mL of butyl acetate to 50 mL of SBS adhesive, stir and dilute for 20 min, and let stand for 2 h to defoam to obtain SBS coating primer; punch holes in the bottom of the sampling cup and seal the outer wall with plastic wrap; immerse the cup in the SBS coating primer at a speed of 4500 μm / s and hold for 10 s, then pull it up at a speed of 4500 μm / s and hold for 2 min. After the butyl acetate evaporates, an SBS gel primer layer is obtained on the cup.

[0062] (2) Superhydrophilic coating: The cup coated with SBS gel primer layer is immersed in the superhydrophilic coating liquid at a speed of 5000 μm / s and held for 1 min by dip-lifting method. After being lifted at a speed of 5000 μm / s and held for 1 min, the cup is circulated and dipped in the superhydrophilic coating liquid twice. After being ventilated and dried for 12 h, a superhydrophilic coating (SC-SBS) is obtained. The outer wall plastic wrap layer is removed to obtain a sampling cup with the inner wall modified by superhydrophilic coating. The bottom hole is sealed for later use.

[0063] Characterization and testing of FS-50@SiO2 nps, FS-50@CNFS, and superhydrophilic coatings:

[0064] The obtained products FS-50@SiO2 NPs, FS-50@CNFS and the superhydrophilic coating were characterized by FTIR, XPS, SEM, wettability, stability and mechanical properties.

[0065] (1) FTIR characterization

[0066] The chemical composition of the coating surface was investigated using FTIR. Figure 2 In the middle, a and b are at 711 and 1305 cm respectively. -1 709cm -1 and 1322cm -1 The absorption peak at 1637 cm⁻¹ confirms the presence of -CF₂- and -CF₃- groups on FS-50@SiO₂NPs and FS-50@CNFS, while the peak at 1637 cm⁻¹... -1 and 1635cm -1 The absorption peaks may originate from the carboxyl groups (-COO) of the carboxylates in the functionalized groups on FS-50@SiO2NPs and FS-50@CNFS. - The asymmetric stretching vibrations of ) are observed. These results indicate that SiO2 nanoparticles and cellulose nanofibers have been successfully modified. Furthermore, the polar component of the functionalized part may be ~COO - ~Na + This gives the surface a strong affinity for polar water molecules, thus exhibiting superhydrophilicity. Simultaneously, the infrared spectra of SBS-free superhydrophilic coatings (SC) and SC-SBS surfaces... Figure 2 c) and 1600~1350cm -1 A magnified view reveals that SC and SC-SBS are located at 1070 cm⁻¹. -1 The peak at 1457 cm⁻¹ corresponds to the asymmetric vibrational absorption peak of Si-O. -1 and 1386cm -1 The absorption peak at 2825 cm⁻¹ is attributed to the bending vibration of -CF₃ / -CF₂-, indicating that the functionalized nanoparticles are dispersed on the coating surface, providing hydrophilic polar groups for the coating. -1 and 2871cm -1 The absorption peak at 1694 cm⁻¹ likely originates from the vibrations of the -CH₂- and -CH₃- groups in the rosin resin on the coating surface. -1 The peak at 966 cm⁻¹ was assigned to the stretching vibration of C=O, possibly originating from both rosin resin and the functionalizing agent FS-50. The peak at 966 cm⁻¹... -1 The absorption peak at 1560 cm⁻¹ only appears in the FTIR spectrum of SC-SBS and is considered a characteristic peak of SBS adhesive. It may originate from the bending vibration of the CH bond in C=CH. Additionally, the absorption peak at 1560 cm⁻¹ is also present. -1 1540cm -1 1520cm -1 1507cm -1 and 1488cm -1The absorption peak may originate from the benzene ring skeleton in the SBS adhesive. Therefore, it can be demonstrated that, in addition to serving as an intermediate layer for the coating and bonding the coating and substrate, some of the incompletely cured SBS adhesive diffuses to the coating surface, forming a continuous phase of the coating together with the rosin resin.

[0067] (2) XPS characterization

[0068] The chemical composition of the coating surface was studied in depth using XPS. Figure 2 The image shown in EI is an XPS image of the SC-SBS surface. Figure 2 The image shows a full scan of the coating surface, revealing photoelectron peaks for Na 1s, F 1s, F KL1, C 1s, O 1s, and Si 2p, indicating the formation of a composite coating. Notably, the C 1s region contains photoelectron peaks for -CF2- and -CF3- groups. Figure 2 The presence of photoelectron peaks of -CF2- / -CF3- was also observed in F 1s (g), Figure 2 In the middle (h), Na 1s represents Na + ( Figure 1 The term "i" represents the presence of polar components. Simultaneously, the photoelectron peak of SiO2 exists in Si 2p. Figure 2 The presence of -CO- and -C=O- in C1s indicates that the polar component originates from functionalized nanoparticles FS-50@SiO2, which is the source of the coating's superhydrophilicity. The presence of -CO- and -C=O- in C1s may be attributed to the presence of rosin resin. Figure 2 (g), thus ensuring the strong adhesion performance of SC-SBS.

[0069] (3) SEM characterization

[0070] SEM images show numerous micron-sized irregular protrusions and pores. Figure 3 (a) Magnified SEM image display ( Figure 3 In sections b and c), these protrusions and pores are formed by many nanoscale particles bonded together, resembling the structure of a coral reef with distinct protrusions and depressions. Figure 3 In the image, d represents the elemental distribution of the coating mapping. The image shows that Si, C, O, F, and Na elements are uniformly distributed on the SC-SBS surface. The F and Na elements are presumed to originate from functionalized reagents, further confirming that the polar components are likely ~COO-~Na+, and that the coating is introduced into the coating by a uniformly dispersed phase composed of functionalized FS-50@SiO2NPs and FS-50@CNFS. Furthermore, the AFM image reveals a rugged, mountain-like structure with irregular surface features. Figure 3(e). The arithmetic mean roughness (Ra) calculated from AFM data is 297 nm. Overall, this roughness variation facilitates the rapid penetration of water droplets into pores and voids, allowing them to spread quickly across the coating surface.

[0071] (4) Characterization of wettability

[0072] For superhydrophilic coatings, the dynamic change in the water contact angle (CA) of the coating surface most directly reflects its extreme wetting performance. The contact angle change of the SC-SBS surface was measured using a dynamic contact angle meter. The results are as follows: Figure 4 As shown, when a water droplet first contacts the coating surface (0s), the CA is 10.27°, at 1s the CA is 6.86°, at 2s the CA is 5.23°, and at 4s the CA is 4.97°. Therefore, SC-SBS has excellent superhydrophilicity.

[0073] (5) Stability and mechanical performance testing

[0074] The mechanical stability of the coating is crucial to its wettability and practical application. The mechanical strength of the coating was tested using a tape application-peeling machine. Figure 5 The change in coating adhesion (CA) after 5 seconds of contact with a water droplet was demonstrated under different tape peel cycles. Even after 40 tape peel cycles, the coating surface maintained excellent superhydrophilicity, with CA remaining below 10° (CA = 6.54°). After 40 tape peel cycles, the CA of the coating increased slightly (from 4.72° to 6.54°), but the coating effectively maintained adhesion to the substrate during tape peeling without significant damage. The cross-cut test according to GB / T9286-2021 standard was used. Figure 6 (a) characterizes the coating's resistance to detachment from the substrate, compared to simple SC ( Figure 6 Compared to (b), the scratches on SC-SBS are clearly visible at the edges and intersections, with only a very small amount of coating peeling off, affecting less than 5% of the area. Figure 6 (c) Therefore, the detachment resistance level of SC-SBS from the substrate reaches 1 to 0. These results indicate that SC-SBS possesses mechanical durability and excellent adhesion, enabling it to withstand repeated tape peeling and the challenges associated with strong adhesion requirements, and resisting the shear forces of water flow during wet-wall cyclone sampling.

[0075] Furthermore, to characterize the resistance of SC-SBS to the impact and shearing effects of high-speed rotating water flow during sampling, 1, 10, 20, and 30 sampling cycles were conducted at a sampling flow rate of 300 L / min and a sampling time of 10 min. Then, 5 μL of methylene blue aqueous solution was dropped onto the inner surface of each sample, and the water droplet morphology was observed to verify the coating's resistance to water impact and shearing. For the sampling cup without the superhydrophilic coating, due to the poor wettability of the polycarbonate material itself, the water droplets formed a hemispherical shape on the inner surface, wetting only a small portion of the inner surface. However, after introducing the SC-SBS superhydrophilic coating, after one sampling cycle, the water droplets spread out on the inner surface of the sampler, with the largest spreading area. After 10 (100 min), 20 (200 min), and 30 (300 min) sampling cycles, water droplets spread out on the inner surface of the sampler. The spreading area decreased slightly with increasing sampling cycles, likely due to the prolonged underwater impact and shearing, which slightly reduced the superhydrophilicity provided by the inner surface coating. However, the wetting range was still significantly greater than that of the uncoated sampling cup. These results indicate that the inner surface of the sampling cup with the SC-SBS coating can withstand prolonged water flow shearing and impact, meeting the requirements for longer sampling times and possessing practical application value.

[0076] Evaluation of wet-wall cyclone aerosol sampling performance:

[0077] (1) Fluorescent particle aerosol sampling

[0078] Stable fluorescent particle aerosols were generated, and sampling and enrichment were carried out simultaneously in coated and uncoated sampling cups at different flow rates. The fluorescence of the sampled liquid was measured after sampling to determine the sampling effect. Results are as follows: Figure 7As shown in Figure 1, for fluorescent particle aerosols of different particle sizes, the fluorescence intensity of the sampling solution with SC-SBS introduced was significantly higher than that without the coating. At the characteristic wavelength of the fluorescent particles used, 484 nm, for aerosols generated from 0.51 μm fluorescent particles, at sampling flow rates of 100 L / min, 200 L / min, and 300 L / min, the fluorescence values ​​after introducing SC-SBS were 6.02, 3.91, and 1.65 times that without SC-SBS, respectively; for 1.1 μm fluorescent particles, they were 6.66, 3.37, and 1.60 times; and for 2.9 μm fluorescent particles, they were 17.24, 5.47, and 6.25 times. This is likely because a larger sampling flow rate provides stronger centrifugal force, allowing the liquid film in the cyclone zone to cover a larger area, thus reducing the area of ​​the gas-liquid cyclone layer and the cyclone layer itself. However, the liquid film formed on the inner surface of the sampler with the SC-SBS coating can essentially cover the entire sampler even at lower flow rates, resulting in a significant improvement in enrichment at low flow rates and a good improvement even at high flow rates. These results indicate that introducing the SC-SBS coating can significantly improve the enrichment effect of wet-wall cyclone samplers for fluorescent particle aerosols, with the most significant improvement at low flow rates.

[0079] (2) Artificial bioaerosol sampling

[0080] Sampling was performed after stable Bacillus subtilis spore aerosol formation. Colony counts were then performed after sampling to determine the sampling effectiveness. Results are as follows: Figure 8 As shown, when sampling simultaneously at different flow rates, the enrichment effect of introducing the SC-SBS coating is significantly improved compared to the uncoated sample. Specifically, under a low flow rate of 100 L / min, the enrichment improvement rate reaches 143.3%, and even under a high flow rate of 300 L / min, the improvement rate reaches 78.5%. Furthermore, the enrichment improvement rate generally decreases with increasing sampling flow rate.

[0081] The above results indicate that the introduction of the SC-SBS coating can significantly improve the sampling and enrichment capacity of the wet-wall cyclone sampler for bioaerosol particles, and the improvement is most significant at lower flow rates.

[0082] (3) Air sampling

[0083] To further verify the actual enrichment effect of the SC-SBS sampler on atmospheric bioaerosol particles, simultaneous air sampling was conducted in the laboratory under low flow rate conditions (100 L / min), and ATP fluorescence was used to qualitatively illustrate the sampling effect. Figure 9As shown, when sampling for 5 min, 10 min, 15 min, and 20 min simultaneously, the ATP fluorescence value of the sample solution after introducing SC-SBS sampling was significantly higher than that of the sample solution without the coating, indicating that the former sampled more airborne microorganisms in the sample solution.

[0084] The above results indicate that the introduction of the SC-SBS coating can significantly improve the enrichment effect of the wet-wall cyclone sampler on airborne bioaerosol particles.

[0085] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling, characterized in that, The method for preparing the superhydrophilic coating includes: S1. Fluoride modification of SiO2 nanoparticles and cellulose nanofibers respectively; specifically including the following steps: (1) Dissolve FS-50 fluorocarbon surfactant in anhydrous ethanol and stir at room temperature to obtain a uniform FS-50 ethanol solution, and divide the FS-50 ethanol solution into 2 portions; (2) Take hydrophilic SiO2 nanoparticles and cellulose nanofibers CNFS, add them to 1 part of FS-50 ethanol solution respectively, stir and react at room temperature, centrifuge and separate, collect the centrifuged products and dry them in a vacuum drying oven to obtain FS-50 modified superhydrophilic SiO2 nanoparticles FS-50@SiO2 NPs and FS-50 modified cellulose nanofibers FS-50@CNFS respectively; S2. Fluorinated SiO2 nanoparticles and cellulose nanofibers are mixed evenly in anhydrous ethanol to obtain a superhydrophilic coating liquid; S3. By dip-lifting, a styrene-butadiene-styrene block copolymer primer and a superhydrophilic coating liquid are sequentially coated on the inner wall of the wet-wall cyclone sampling cup to prepare a superhydrophilic coating on the inner wall of the cup.

2. The method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling as described in claim 1, characterized in that, Step S1 specifically includes the following steps: (1) Dissolve 10g of FS-50 fluorocarbon surfactant in 100mL of anhydrous ethanol and stir for 40min at room temperature to obtain a uniform FS-50 ethanol solution. Divide the FS-50 ethanol solution into two portions. (2) Take 2g of hydrophilic SiO2 nanoparticles with an average particle size of 100nm and 1g of cellulose nanofiber CNFS, respectively add them to 1 part of FS-50 ethanol solution, stir and react at room temperature for 30min, then centrifuge and separate them. Collect the centrifuged products and dry them in a vacuum drying oven to obtain FS-50 modified superhydrophilic SiO2 nanoparticles FS-50@SiO2 NPs and FS-50 modified cellulose nanofibers FS-50@CNFS.

3. The method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling as described in claim 1 or 2, characterized in that, In step S1, the centrifuged product is dried in a vacuum drying oven at 120°C for 12 hours.

4. The method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling as described in claim 1, characterized in that, Step S2 includes the following steps: (1) Take FS-50@SiO2 NPs and add them to anhydrous ethanol, then disperse them by ultrasonication to obtain a uniform FS-50@SiO2 NPs ethanol dispersion; (2) Take rosin resin, add it to anhydrous ethanol, heat it to fully dissolve the rosin resin, and obtain an ethanol solution of rosin resin; (3) Mix the ethanol dispersion of FS-50@SiO2 NPs with the ethanol solution of rosin resin, disperse by ultrasonication, add FS-50@CNFS, stir and mix, disperse by ultrasonication; then add bis(3-trimethoxysilylpropyl)amine, stir and react to prepare the superhydrophilic coating liquid.

5. The method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling as described in claim 4, characterized in that, Step S2 specifically includes the following steps: (1) Take 2g of FS-50@SiO2 NPs, add it to 18mL of anhydrous ethanol, and ultrasonically disperse for 30min to obtain a uniform FS-50@SiO2 NPs ethanol dispersion. (2) Take 4.2g of rosin resin, add it to 5mL of anhydrous ethanol, heat to 90℃, and let the rosin resin dissolve completely to obtain an ethanol solution of rosin resin; (3) Mix the ethanol dispersion of FS-50@SiO2 NPs with the ethanol solution of rosin resin, sonicate for 30 min, add 0.2 g of FS-50@CNFS, stir and mix for 10 min, sonicate for 30 min; then add 100 μL of bis(3-trimethoxysilylpropyl)amine, and stir and react at 45 °C for 2 h to prepare the superhydrophilic coating liquid.

6. The method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling as described in claim 1, characterized in that, Step S3 includes the following steps: (1) SBS primer coating: Add butyl acetate to SBS adhesive, stir and dilute thoroughly, and let stand to defoam to obtain SBS coating primer; punch holes in the bottom of the sampling cup and seal the outer wall with plastic wrap; immerse the cup in the SBS coating primer at a speed of 4500 μm / s and stay for 10s, then pull it up at a speed of 4500 μm / s and stay for 2min. After the butyl acetate evaporates, an SBS gel primer layer is obtained on the cup. (2) Superhydrophilic coating: The cup coated with SBS gel primer layer is immersed in the superhydrophilic coating liquid at a speed of 5000 μm / s and held for 1 min by dip-lifting method. Then it is lifted at a speed of 5000 μm / s and held for 1 min. After cyclic immersion in the superhydrophilic coating liquid twice, it is ventilated and dried to obtain the superhydrophilic coating.

7. The method for preparing a superhydrophilic coating for bioaerosol wet-wall cyclone sampling as described in claim 6, characterized in that, Step S3 specifically includes the following steps: (1) SBS primer coating: Add 5 mL of butyl acetate to 50 mL of SBS adhesive, stir and dilute for 20 min, and let stand for 2 h to defoam to obtain SBS coating primer; punch holes in the bottom of the sampling cup and seal the outer wall with plastic wrap; immerse the cup in the SBS coating primer at a speed of 4500 μm / s and hold for 10 s, then pull it up at a speed of 4500 μm / s and hold for 2 min. After the butyl acetate evaporates, an SBS gel primer layer is obtained on the cup. (2) Superhydrophilic coating: The cup coated with SBS gel primer layer is immersed in the superhydrophilic coating liquid at a speed of 5000 μm / s and held for 1 min by dip-lifting method. Then it is lifted at a speed of 5000 μm / s and held for 1 min. After cyclic immersion in the superhydrophilic coating liquid twice, it is ventilated and dried for 12 h to obtain the superhydrophilic coating.

8. A superhydrophilic coating for bioaerosol wet-wall cyclone sampling, characterized in that, The superhydrophilic coating is prepared by the method described in any one of claims 1 to 7.

9. A wet-wall cyclone sampling cup with an inner wall modified by the superhydrophilic coating as described in claim 8.

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