A sampling medium for aerosols containing pollen and / or fungal spores and its preparation method

Abstract

This invention discloses a sampling medium for aerosols containing pollen and / or fungal spores and its preparation method. By precisely compounding gelatin, glycerol, and specific sugars to construct a polymeric gel network, and then covering it with a mineral oil film, the sampling medium exhibits long-lasting moisture retention and excellent reversible cross-linking properties. Simultaneously, the stepwise dissolution, precise temperature control, and sequential film formation process ensures the full integration and structural stability of the components. The sampling medium prepared by this invention exhibits excellent optical properties and low water loss, providing crucial material support for long-term, high-precision, automated outdoor monitoring of pollen.

Description

Technical Field

[0001] This invention belongs to the field of environmental monitoring and atmospheric biology technology, specifically relating to a sampling medium for aerosols containing pollen and / or fungal spores and its preparation method. Background Technology

[0002] In environmental science and allergen surveillance, outdoor bioaerosol (including pollen, fungal spores, etc.) monitoring is crucial for predicting public health risks such as hay fever outbreaks. Traditional bioaerosol sampling media typically use single-component glycerol gelatin or silicone oil, which presents significant challenges for long-term outdoor monitoring. For example, while single-component glycerol gelatin offers good optical transparency, it has poor water retention. In dry or high-temperature outdoor environments, it easily loses water, shrinks, and cracks, causing captured aerosol particles to detach or deform, severely affecting the accuracy of counting and the observation of aerosol morphology. While oily media such as silicone oil offer good moisture retention, excessively thick oil layers can lead to difficulties in imaging under optical microscopes (due to reflection and refraction interference). Furthermore, excessively thick oil layers may hinder subsequent sample cleaning and molecular biological detection (such as DNA extraction). Additionally, mixing oil and colloids in a high-temperature liquid state can easily cause emulsification, resulting in batch-to-batch quality instability.

[0003] With the emergence of automated instruments for outdoor bioaerosol monitoring, higher requirements have been placed on the sampling medium. Firstly, the medium must possess reversible cross-linking properties at a certain temperature: outdoor temperatures are high, causing conventional glycerol gelatin to melt into a liquid. Therefore, the medium needs to remain solid at higher temperatures, such as above 40 degrees Celsius. After collecting aerosols, automated outdoor bioaerosol (pollen) collection and monitoring equipment needs to heat the solid medium to melt it, allowing aerosol particles to settle into the medium under gravity for microscopic imaging and AI recognition. This reversible cross-linking property of the medium at a certain temperature is crucial. Secondly, the medium must be able to maintain moisture for extended periods: outdoor equipment typically has long monitoring cycles, requiring the medium to remain moist. Otherwise, drying the medium will affect reversible cross-linking, preventing aerosol particles from settling into the medium, resulting in darkened microscopic images and hindering AI recognition. Third, the medium must be a viscous solid with the best possible flatness: Automatic collection of bioaerosols generally uses virtual impactors or cyclone collectors, which have a certain amount of collision energy and require a viscous solid medium to capture the bioaerosols; at the same time, in order to improve the efficiency of microscopic imaging, the medium should be kept as flat as possible so that there is no need to repeatedly focus to find aerosol particles.

[0004] Therefore, there is an urgent need for a bioaerosol sampling medium that can remain moist, non-cracked, and non-flowing under complex outdoor climatic conditions for a long time, with high reversible cross-linking properties and stable optical performance. Summary of the Invention

[0005] This invention provides a sampling medium for aerosols containing pollen and / or fungal spores and its preparation method. By precisely compounding gelatin, glycerol, and specific sugars to construct a polymeric gel network, and then covering it with a mineral oil film, the sampling medium exhibits long-lasting moisture retention and excellent reversible cross-linking properties. Simultaneously, the stepwise dissolution, precise temperature control, and sequential film formation process ensures the full integration and structural stability of the components, solving the problems of traditional sampling media such as easy water loss, poor reversible cross-linking, and unclear imaging during long-term outdoor monitoring.

[0006] This invention is achieved through the following technical solutions:

[0007] The first objective of this invention is to provide a sampling medium for aerosols containing pollen and / or fungal spores, wherein the sampling medium comprises the following components in parts by weight: 1 part gelatin, 0.9-1.6 parts glucose and / or fructose, 1.5-5 parts glycerol, 0.01-0.1 parts preservative, 0.01-0.3 parts mineral oil, and 3.8-5 parts water.

[0008] Preferably, the mineral oil is a light liquid paraffin; more preferably, the viscosity of the light liquid paraffin is ≥12mm² / s.

[0009] Preferably, the water is deionized water; the preservative is thymol.

[0010] A second objective of this invention is to provide a method for preparing the above-mentioned sampling medium, comprising the following steps:

[0011] 1) Gelatin dissolution: Add gelatin, glucose and / or fructose to water and stir until the sugars dissolve and wet the gelatin. Then add glycerin and stir under water bath heating at 50-60℃ until a clear and transparent solution is formed. Add preservative and stir until the solution is uniform to obtain a gelatin-based solution.

[0012] 2) Casting: Pour the gelatin-based solution obtained in step 1) into the mold and let it stand at room temperature (20-25℃) to form a solid gel. The purpose of this step is to allow the gelatin molecular chains to naturally cross-link under gravity to form a stable three-dimensional network structure before the liquid oil is added, until the gelatin is completely transformed from a liquid state to a solid gel state and there are no flowing water marks on the surface.

[0013] 3) Oil film coverage: Mineral oil is dropped onto the surface of the solid gel obtained in step 2) to form an oil film, thus obtaining the sampling medium.

[0014] Preferably, in step 1), the sugar is stirred for 1-15 minutes to dissolve and impregnate the gelatin; then, under a water bath heating condition of 50-60°C, the mixture is stirred for 20-30 minutes to form a clear and transparent solution.

[0015] Preferably, in step 2), the settling time is 60-90 minutes.

[0016] Preferably, in step 2), the mold depth is 2 mm.

[0017] Preferably, in step 3), mineral oil is spread on the gel surface to form an oil film by spin coating.

[0018] Preferably, in step 3), the thickness of the oil film is 30-50 μm.

[0019] Preferably, step 3) further includes placing the sampling medium in an environment of 0-10°C for refrigeration. The medium covered with the oil film is immediately transferred to an environment of 0°C-10°C for refrigeration overnight, preferably at 4°C, to lock the position of the oil film and further enhance the mechanical strength of the gelatin network structure.

[0020] A third objective of this invention is to provide the application of the above-mentioned sampling medium in outdoor aerosol collection and / or monitoring.

[0021] Preferably, the aerosol comprises pollen and / or fungal spores.

[0022] A fourth objective of this invention is an aerosol sampling method that uses the above-described sampling medium to capture aerosols containing pollen and / or fungal spores.

[0023] The present invention has the following beneficial effects:

[0024] 1. Ultra-long moisture retention period: The sampling medium of this invention forms a dense hydrophobic barrier due to the mineral oil layer on its surface, which significantly inhibits the evaporation of moisture inside the gelatin. Under simulated outdoor conditions, the water loss rate is less than 5% after 30 days (while the water loss rate of traditional glycerin gelatin media is >25%), completely solving the problem of easy water loss in the sampling medium.

[0025] 2. Excellent optical performance: The ultra-thin oil film on the surface of the sampling medium in this invention reduces light refraction and reflection interference, improves the imaging contrast under the microscope, and facilitates automated identification and counting.

[0026] 3. High process stability: The present invention adopts a step-by-step dissolution, precise temperature control and sequential film formation preparation process, which avoids the problem of emulsification caused by directly mixing oil and colloid at high temperature and resulting in batch-to-batch quality differences, making it suitable for standardized production. Attached Figure Description

[0027] Figure 1 This is a graph showing the water loss rate of the sampling medium of the present invention at different time points in Example 6.

[0028] Figure 2 These are microscopic images of the reversible crosslinking test performed on the conventional glycerol gelatin medium in Example 7.

[0029] Figure 3These are microscope images of the sampling medium of the present invention undergoing reversible crosslinking tests in Example 7. Detailed Implementation

[0030] The following are specific implementation examples of the present invention. It should be noted that these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Modifications and substitutions to the details and form of the implementation schemes within the scope and concept of the present invention all fall within the protection scope of the present invention. Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the experimental methods, unless otherwise specified, are conventional methods.

[0031] Example 1

[0032] A sampling medium for aerosols containing pollen and / or fungal spores, comprising the following components in parts by weight: 1 part photographic grade gelatin (Bloom 250), 1 part glucose, 0.25 parts fructose, 5 parts glycerol, 0.01 parts thymol, 4.25 parts deionized water, and 0.01 parts mineral oil (light liquid paraffin, Foshan Chemical Experimental Plant, chemically pure, viscosity ≥12 mm² / s).

[0033] The method for preparing the sampling medium includes the following steps:

[0034] 1. Dissolving gelatin: Weigh out the gelatin, glucose and fructose according to the above weight proportions, add them to deionized water, stir for 1 minute at room temperature (20-25℃) to allow the sugars to initially dissolve and wet the gelatin, add glycerin, place in a 52℃ water bath, and continue stirring for 25 minutes until a clear and transparent solution is formed, add thymol, and continue stirring until completely homogeneous to obtain a gelatin-based solution.

[0035] 2. Casting and molding: Pour the gelatin-based solution from step 1 into a mold 2 mm deep, and then place the mold at room temperature for 90 minutes to form a solid gel.

[0036] 3. Oil film coating: Light mineral oil is dropped onto the surface of the solid gel in step 2. Using a spin coater, the mineral oil is spread on the gel surface to form an ultra-thin continuous oil film with a thickness of 40 μm, thus preparing a viscous sampling medium.

[0037] 4. Cold storage strengthening: Immediately transfer the sampling medium from step 3 into a 4°C environment and refrigerate overnight to lock the oil film position and further strengthen the mechanical strength of the gelatin network structure.

[0038] Comparative Example 1: Preparation of Traditional Glycerin-Gelatin Sampling Medium

[0039] The classic Kaiser glycerol gelatin formula was used: 1 part photographic grade gelatin (Bloom 250), 1.7 parts glycerol, 0.07 parts phenol, and 3 parts deionized water. It was prepared according to conventional methods in the art.

[0040] Example 2

[0041] A sampling medium for aerosols containing pollen and / or fungal spores comprises the following components in parts by weight: 1 part photographic grade gelatin (Bloom 250), 0.9 parts glucose, 4.5 parts glycerol, 0.01 parts thymol, 4 parts deionized water, and 0.01 parts mineral oil (light liquid paraffin, viscosity ≥12 mm² / s). The preparation method of the sampling medium is as described in Example 1.

[0042] Example 3

[0043] A sampling medium for aerosols containing pollen and / or fungal spores comprises the following components in parts by weight: 1 part photographic grade gelatin (Bloom 250), 1.6 parts glucose, 5 parts glycerol, 0.1 parts thymol, 5 parts deionized water, and 0.3 parts mineral oil (light liquid paraffin, viscosity ≥12 mm² / s). The preparation method of the sampling medium is as described in Example 1.

[0044] Example 4

[0045] A sampling medium for aerosols containing pollen and / or fungal spores comprises the following components in parts by weight: 1 part photographic grade gelatin (Bloom 250), 0.9 parts fructose, 3.5 parts glycerol, 0.01 parts thymol, 3.8 parts deionized water, and 0.01 parts mineral oil (light liquid paraffin, viscosity ≥12 mm² / s). The preparation method of the sampling medium is as described in Example 1.

[0046] Example 5

[0047] A sampling medium for aerosols containing pollen and / or fungal spores comprises the following components in parts by weight: 1 part photographic grade gelatin (Bloom 250), 1.6 parts fructose, 5 parts glycerol, 0.1 parts thymol, 5 parts deionized water, and 0.3 parts mineral oil (light liquid paraffin, viscosity ≥12 mm² / s). The preparation method of the sampling medium is as described in Example 1.

[0048] Example 6: 30-day water loss rate test

[0049] The sampling medium prepared in Example 1 and the conventional glycerol gelatin sampling medium of Comparative Example 1 were subjected to a 30-day water loss test: the sampling medium was placed at room temperature and weighed on a balance at regular intervals each day. The weight of the first day was taken as 100%, and the weights of subsequent days were compared with the weight of the first day to obtain the percentage of remaining weight. The higher this value, the stronger the moisturizing ability (water loss rate = 100% - percentage of remaining weight). The results are as follows. Figure 1 As shown in Table 1, the sampling medium of the present invention has a water loss rate of < 5% and long-lasting moisturizing properties, while the glycerin gelatin sampling medium has a high water loss rate and poor moisturizing properties.

[0050] Table 1 Results of 30-day water loss rate test

[0051] Example 7 Reversible crosslinking test

[0052] The reversible crosslinking properties of the sampling medium prepared in Example 1 and the conventional glycerol gelatin sampling medium of Comparative Example 1 were tested: pollen collected outdoors was gently tapped onto the sampling medium using a cotton swab, and then the sampling medium was heated at 90°C for 2 minutes. After returning to room temperature, it was observed under a microscope. The results are as follows: Figure 2-3 As shown in Table 2, the sampling medium prepared by the present invention has high reversible cross-linking properties and clear imaging, while the traditional glycerol gelatin medium has poor reversible cross-linking properties and opaque imaging.

[0053] Table 2 Results of Reversible Crosslinking Test

Claims

1. A sampling medium for aerosols containing pollen and / or fungal spores, characterized in that, The medium raw material comprises the following components in parts by weight: 1 part gelatin, 0.9-1.6 parts glucose and / or fructose, 1.5-5 parts glycerin, 0.01-0.1 parts preservative, 0.01-0.3 parts mineral oil, and 3.8-5 parts water.

2. The sampling medium according to claim 1, characterized in that, The mineral oil is a light liquid paraffin, and the preservative is thymol.

3. The method for preparing the sampling medium according to claim 1, characterized in that, Includes the following steps: 1) Gelatin dissolution: Add gelatin, glucose and / or fructose to water and stir until the sugars dissolve and wet the gelatin. Then add glycerin and stir under water bath heating at 50-60℃ until a clear and transparent solution is formed. Add preservative and stir until the solution is uniform to obtain a gelatin-based solution. 2) Casting: Pour the gelatin-based solution obtained in step 1) into the mold and let it stand at room temperature to form a solid gel; 3) Oil film coverage: Mineral oil is dropped onto the surface of the solid gel obtained in step 2) to form an oil film, thus obtaining the sampling medium.

4. The method according to claim 3, characterized in that, In step 1), stir for 1-15 minutes to dissolve the sugars and impregnate the gelatin; stir for 20-30 minutes under a water bath heating condition of 50-60℃ to form a clear and transparent solution.

5. The method according to claim 3, characterized in that, In step 2), the mold depth is 2 mm; the settling time is 60-90 minutes.

6. The method according to claim 3, characterized in that, In step 3), a mineral oil film is formed on the gel surface by spin coating, and the thickness of the oil film is 30-50 μm.

7. The method according to claim 3, characterized in that, Step 3) also includes the step of placing the sampling medium in a refrigerator at 0-10°C.

8. The application of the sampling medium according to claim 1 or 2 in outdoor aerosol collection and / or monitoring.

9. The application according to claim 8, characterized in that, The aerosol includes pollen and / or fungal spores.

10. An aerosol sampling method, characterized in that, Use the sampling medium described in claim 1 or 2 to capture aerosols containing pollen and / or fungal spores.

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