Passive dosing device for generating organic pollutants with constant free state concentration as well as preparation method and application of passive dosing device

Abstract

The invention belongs to the technical field of biological experiment devices, and particularly relates to a passive drug delivery device for generating organic pollutants with constant free state concentration as well as a preparation method and application of the passive drug delivery device. According to the method, a PDMS coating coated at the bottom of a device bottle is modified through Span80, then in the step of pre-loading organic pollutants, ultrapure water is added for multiple times, the solubility of the organic pollutants in a methanol / water solution is reduced, the organic pollutants are pushed into the PDMS coating step by step, and therefore the passive drug delivery device is manufactured. According to the device, the microalgae exposure experiment is closer to a real water environment, and the microalgae can obtain a stable organic pollutant source in the long-time exposure experiment; moreover, through the design and optimization of the passive drug delivery device, the problem that the microalgae are easy to adhere to the wall (especially adhere to the bottom and adhere to the PDMS substrate) to grow in the pollutant exposure experiment is solved, so that the population exposure is more uniform, and the experimental result is more reliable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of biological experimental devices, and particularly relates to a passive dosing device for generating constant free concentration of organic pollutants and a preparation method and application thereof. BACKGROUND

[0002] In the experiment of exposing microalgae to organic pollutants, preparing the culture solution containing the target pollutant is a key step to ensure the reliability and reproducibility of the experiment. At present, for most organic pollutants (especially strong hydrophobic persistent organic pollutants such as polycyclic aromatic hydrocarbons PAHs, polychlorinated biphenyls PCBs, organochlorine pesticides, brominated flame retardants, etc.), there are the following three methods to prepare the microalgae culture solution: (1) Solvent dissolution method. This method is most commonly used. First, an organic solvent is used to prepare a high-concentration mother liquor containing the target pollutant, an appropriate amount is taken into the culture container, the solvent is volatilized, and then the culture medium is added. Ultrasonic stirring is used to promote the dissolution and dispersion of the organic pollutants remaining at the bottom of the bottle into the aqueous phase, and then the microalgae exposure experiment can be carried out.

[0003] (2) Carrier-assisted dispersion method. Dissolve the organic pollutant in a small amount of carrier (such as Tween 80, methanol, etc.) to temporarily increase its solubility, and then add the culture medium. This can significantly improve the apparent solubility and dispersion uniformity of the poorly soluble organic pollutant, obtain a uniform organic pollutant solution, and carry out the microalgae exposure experiment.

[0004] (3) Pre-equilibrium passive dosing method. This method has been applied to the culture of aquatic animals (such as Daphnia magna and fish), but there is no related report on microalgae. It is to use the high affinity of PDMS or other polymers for hydrophobic organic matter. First, the polymer is allowed to reach adsorption equilibrium (loading) in a high-concentration pollutant solution, and then the polymer loaded with the pollutant is placed in the culture solution to allow the pollutant to be released slowly.

[0005] However, the existing technology still has the following shortcomings: (1) For highly hydrophobic organic pollutants, the use of solvent dissolution method, even after ultrasonic treatment, the dissolved content is still much lower than the added amount, and most of it is adsorbed on the wall of the container; for volatile organic pollutants, ultrasonic treatment and the like will cause great loss.

[0006] (2) Using carrier-assisted dispersion method, the carrier itself can affect the physiological characteristics of algae (toxicity, membrane permeability change, etc.) or the bioavailability of pollutants (such as being wrapped by micelles); and the carrier solubilization changes the actual form of the pollutants; (3) Organic pollutants have two existing forms in water bodies, free state and bound state, and the free state organic pollutants are more bioavailable. The above two methods also have an important problem, that is, as the experiment proceeds, the free state organic pollutant concentration in the culture solution significantly decreases after the organic pollutants are absorbed by green algae (because the organic pollutants have high hydrophobicity, their equilibrium bioconcentration is much higher than the free state concentration in water bodies), so the observation of the physiological response and toxicity effect of microalgae and other behaviors is not accurate. This situation does not match the actual environment: in the actual water environment, because there are substrates such as organic matter and particulate matter that can adsorb organic pollutants, organic pollutants coexist in the form of bound state and free state, and when the free state organic pollutants are absorbed by microalgae, the bound state organic pollutants are released to supplement the free state concentration, so the free state organic pollutant concentration in the water body is basically constant.

[0007] (4) Compared with aquatic animals, microalgae are aquatic plants, and some species (such as needle-shaped algae, rhombic algae, and oblique grid algae) are easy to adsorb on solid surfaces. If the pre-equilibrium passive dosing method is used, the microalgae may be adsorbed on the bottle bottom or the PDMS membrane, which on the one hand leads to uneven exposure of the microalgae and makes it difficult to accurately measure the algae density; and on the other hand, it affects the diffusion of pollutants from the PDMS, affecting the free state concentration of pollutants in the culture solution. SUMMARY

[0008] The purpose of the present application is to overcome the shortcomings and deficiencies of the prior art and provide a passive dosing device for generating constant free state concentration of organic pollutants, so that the microalgae exposure experiment is closer to the real water environment, and the microalgae obtain a stable source of organic pollutants in a long-time exposure experiment; and through the design and optimization of the passive dosing device, the problem of microalgae growing on the wall (especially on the bottom and PDMS substrate) in the pollutant exposure experiment is solved, so that the population exposure is more uniform, and the experimental results are more reliable.

[0009] In order to achieve the above-mentioned purpose of the application, the technical scheme adopted by the present application is: In a first aspect, the present application provides a preparation method of a passive dosing device for generating constant free state concentration of organic pollutants, comprising the following steps: S1, mixing PDMS prepolymer and curing agent, removing bubbles, adding to the device bottle, rotating the device bottle under water bath conditions, so that the PDMS is coated and cured at the bottom of the device bottle, then adding methanol to immerse the PDMS coating in the device bottle, and ultrasonic treatment to remove the methanol; S2, dissolving the surfactant in the aqueous ethanol solution to obtain a surfactant solution, adding the surfactant solution into the device bottle to immerse the PDMS coating, soaking treatment, and then removing the solution; S3, dissolving the target organic pollutant in methanol to obtain an organic pollutant standard solution, adding the standard solution into the device bottle to immerse the PDMS coating, continuously shaking, adding water to the device bottle every other day, adding water for 4-6 days, continuing to shake for 8-20 days, removing the solution, adding methanol for rinsing, and then adding water for cleaning, to obtain the passive administration device.

[0010] Preferably, the surfactant comprises at least one of Span60, Span80 and Span85.

[0011] More preferably, the surfactant is Span80.

[0012] The present application modifies the PDMS coating coated on the bottom of the device bottle by using the preferred Span80 surfactant. The low-polarity physical adsorption surfactant has a two-hydrophilic molecular segment, the hydrophobic end of which is adsorbed on the PDMS surface, and the hydrophilic end of which extends outward to form a directional monolayer. Since the low-polarity segment is dominant, the adsorption layer has less hindrance to hydrophobic organic matter, and does not affect the diffusion of organic pollutants from PDMS to the water phase; at the same time, Span80 forms a low-surface-energy barrier on the surface of the PDMS coating, cutting off the hydrophobic interaction force between algae EPS and PDMS, reducing bio-adsorption, and thus solving the problem of wall adsorption in the process of microalgae cultivation.

[0013] In addition, in the step of preloading the organic pollutant, the solubility of the organic pollutant in methanol is reduced by adding ultrapure water multiple times, so that the organic pollutant is "pushed" into the PDMS coating, thereby providing a stable "source" of organic pollutants for a long time, so that the free organic pollutants in the microalgae experiment remain constant, which is consistent with the actual water environment, and the use of organic solvents is minimized, which is green and environmentally friendly.

[0014] Preferably, in step S1, the mass ratio of the PDMS prepolymer to the curing agent is (9-11):1, and the curing agent comprises Sylgard 184.

[0015] More preferably, the mass ratio of the PDMS prepolymer to the curing agent is 10:1.

[0016] The mass ratio of the PDMS prepolymer and the curing agent has an important influence on regulating the cross-linking density of the PDMS, thereby balancing the physical stability and the controllability of the adsorption and release of pollutants. If the curing agent is relatively excessive, the long-chain siloxane of the prepolymer will be excessively cross-linked, resulting in an increase in the brittleness of the PDMS coating, a decrease in the elasticity, a decrease in the adhesion to the device bottle, and a hindering of the adsorption and diffusion of the organic pollutants, thereby failing to achieve the core requirement of "constant concentration". If the prepolymer is relatively excessive, the cross-linking reaction is insufficient, and the PDMS network structure is loose, which will result in poor structural stability of the coating, easy damage, and excessive adsorption of pollutants but uncontrollable release, thereby failing to maintain the goal of long-term constant release of pollutants. It is found through experimental exploration that the use of the above-mentioned preferred mass ratio of the PDMS prepolymer and the curing agent is one of the keys to ensuring that the passive drug delivery device prepared can achieve long-term generation of constant free-state concentration of organic pollutants, guaranteeing stable device performance and accurate and reliable experimental results.

[0017] Preferably, in step S1, the water bath conditions are 60-80°C for 2-10h.

[0018] The above-mentioned preferred water bath conditions can further ensure that the PDMS coating meets the performance requirements of physical stability and controllable porosity, thereby guaranteeing the ability of the device to subsequently adsorb target pollutants and maintain constant release.

[0019] Preferably, in step S2, the mass concentration of the surfactant is 0.1-1%.

[0020] More preferably, in step S2, the mass concentration of the surfactant is 0.5-1%.

[0021] It is found through experimental exploration that the use of the above-mentioned preferred surfactant concentration for modifying the coating in the device can effectively avoid the adhesion of algae on the coating while not affecting the core performance of the device to generate constant free-state pollutant concentration, thereby being applicable to long-term algae exposure tests.

[0022] Preferably, in step S2, the soaking treatment time is 2-6h.

[0023] The soaking time of the PDMS coating in the surfactant solution has an important influence on balancing the sufficiency and moderation of the modification of the PDMS. The above-mentioned preferred soaking time not only ensures that the surfactant uniformly and sufficiently modifies the PDMS, uniformly and stably loads the target pollutants, and reduces the adhesion of microalgae, but also avoids excessive modification resulting in a decrease in the loading amount, residual interference, and release fluctuations, thereby ultimately ensuring that the passive drug delivery device can continuously release constant concentration of free-state organic pollutants.

[0024] Preferably, in step S3, the volume-mass ratio of the standard solution and the PDMS prepolymer is (15-20) mL:1 g; and the concentration of the organic contaminant standard solution is 500-5000 ppm.

[0025] The passive dosing device of the present application can achieve pre-loading of high-concentration organic contaminants, thereby being repeatedly used without the need for frequent pre-loading steps.

[0026] Preferably, the organic contaminants include polychlorinated biphenyl compounds.

[0027] In a second aspect, the present application provides a passive dosing device for generating constant free-state concentration of organic contaminants, which is prepared by the preparation method.

[0028] In a fourth aspect, the present application provides use of the passive dosing device in microalgae exposure experiments.

[0029] Preferably, the microalgae include Microcystis aeruginosa and Nitzschia closterium.

[0030] Compared with the prior art, the present application has the following beneficial effects: (1) Improved universality and convenience of the device: a conventional conical flask can be used as the device bottle for microalgae culture carrier, greatly improving the universality and convenience of the device; (2) Constant free-state contaminant concentration: the design of pre-loading of organic contaminants by the PDMS coating layer can construct a long-term stable organic contaminant "supply source", ensuring that the free-state organic contaminant concentration remains constant throughout the microalgae experiment, making the experimental environment consistent with the existence state of contaminants in the actual water environment, and significantly improving the authenticity and reliability of experimental data, providing more realistic experimental conditions for microalgae-related research; (3) Avoiding interference of microalgae adhesion with contaminant release: the PDMS coating layer is coated in a ring shape at the lower part of the bottle wall, which can effectively avoid the problem of microalgae aggregation and adhesion to the surface of the PDMS coating layer, prevent the blockage of coating pores or hinder the diffusion of contaminants due to the adhesion of microalgae, ensure the stability and sustainability of the organic contaminant release process, and avoid the influence of the growth state of microalgae on the release efficiency; (4) Solving the problem of microalgae adhesion: surface modification of the PDMS coating layer and the bottom of the container by Span80 can significantly reduce biological adsorption, fundamentally solving the problem of adhesion of microalgae during cultivation, ensuring uniform suspension growth of microalgae, avoiding abnormal growth state caused by adhesion of microalgae, and preventing interference of adhered microalgae on experimental results; (5) Achieving green and environmentally friendly preparation: In the organic pollutant preloading step, the solubility of pollutants in methanol / water solution is reduced by adding ultrapure water multiple times, and the pollutants are gradually "pushed" into the PDMS coating, thereby minimizing the amount of organic solvent used, reducing the impact of organic solvent on microalgae activity and environmental pollution, which is in line with the concept of green experiment and preparation. (6) Precise control of free concentration: based on the principle of distribution equilibrium of organic pollutants in the PDMS coating and aqueous phase (K=c PDMS / c water By simply controlling the concentration of pre-loaded pollutants in the PDMS coating, the target free state concentration of microalgae culture medium can be accurately obtained, solving the problem of the difficulty in accurately controlling the free state concentration in the existing technology, meeting the experimental needs of different concentration gradients, and improving the flexibility and accuracy of experiments. (7) It is economical to reuse: The high concentration and large loading of pollutants preloaded in the PDMS coating enable the device to be reused multiple times without the need for frequent preloading operations, which simplifies the experimental process and improves experimental efficiency. Attached Figure Description

[0031] Figure 1 Reference image for PDMS coating preparation ( Figure 1 A) and the theoretical reference diagram of the passive drug delivery device ( Figure 1 B); Figure 2 The graph shows the stability of PCB concentration in the passive drug delivery device prepared in Example 1 during prolonged exposure to green algae. Figure 3 A comparison of the stability of PCB concentration during green algae exposure for the passive drug delivery device containing different organic pollutants prepared in Example 1; Figure 4 This is a graph showing the concentration range of organic pollutants in the device after modification with different concentrations of surfactant Span80; Figure 5 This is a diagram showing the adhesion of microalgae in the device after modification with different concentrations of the surfactant Span80. Detailed Implementation

[0032] The following detailed embodiments illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments.

[0033] Unless otherwise specified, all reagents used in the examples are conventional reagents available in the art and can be purchased commercially. Experimental procedures not specifically described in the examples are conventional procedures in the art or can be understood or known by those skilled in the art based on their prior knowledge or common general knowledge.

[0034] Example 1 This example provides a method for producing a passive dosing device with constant free concentration of organic contaminant, comprising the following steps: (1) PDMS coating preparation Accurately weigh PDMS prepolymer 2.00 g and curing agent Sylgard 184 0.20 g, mix in a plastic cup; vacuumize (-0.1 MPa) in a vacuum drying oven until no bubbles (about 20 min); use a dropper to suck and add to the target area inside a clean and dry 150 mL conical flask placed horizontally, while rotating the conical flask to make the PDMS evenly coated (see Figure 1 A); rotate the horizontally placed conical flask in a water bath at 70°C for 3 h to make the PDMS coating solidify; after the preparation is completed, add 30 mL of methanol and ultrasonic for 30 min, replace the methanol and ultrasonic for another 30 min, a total of 2 times, to remove impurities during the preparation of the coating preparation, pour out the methanol and wait for use.

[0035] (2) Surface modification Prepare a Span 80 ethanol / water = 1:1 solution, put the container coated with the PDMS film into 30 mL of 0.5% mass concentration of Span 80 surfactant solution, soak for 4 h and pour out the Span 80 solution, gently rinse with water to remove the molecules that are not firmly adsorbed, dry at room temperature and wait for use.

[0036] (3) Loading of organic contaminant Take PCB 9, 11, 77 as representatives of organic contaminants, prepare a 500 ppm standard solution, the solvent is methanol, add 30 mL to the above conical flask to just cover the PDMS coating, shake at 200 rpm at room temperature, add appropriate amount of ultrapure water at the following times and continue to shake: 1 d add 10 mL, 2 d add 10 mL, 3 d add 15 mL, 4 d add 15 mL, 5 d add 20 mL, to a total solution volume of 100 mL, continue to shake until 10 d; pour out all the solution, rinse the PDMS coating with about 10 mL of methanol quickly (15 s) for 3 times, then wash the coating with 30 mL of ultrapure water for 3 times, each time for 15 min; pour out all the solution, cover with a sterile dustproof film, and the passive dosing device is obtained.

[0037] Example 2 This example provides a method for producing a passive dosing device with constant free concentration of organic contaminant, comprising the following steps: (1) PDMS coating preparation Accurately weigh 1.80 g of PDMS prepolymer and 0.20 g of curing agent Sylgard 184 into a plastic cup; vacuumize (-0.1 MPa) in a vacuum drying oven until no bubbles (about 20 min); use a dropper to draw and add into the target area inside a clean and dry 150 mL conical flask laid horizontally, while rotating the conical flask to make the PDMS evenly coated; rotate the conical flask laid horizontally in a water bath at 80°C for 2 h to make the PDMS coating solidify; after the preparation is completed, add 30 mL of methanol and ultrasonic for 30 min, and ultrasonic again after replacing the methanol for 30 min, a total of 2 times, to remove the impurities in the preparation process of the prepared coating, pour out the methanol, and wait for use.

[0038] (2) Surface modification Prepare a Span 60 ethanol / water = 1:1 solution, put the PDMS film coated container into 27 mL of 0.5% mass concentration Span 60 surfactant solution, soak for 2 h, pour out the Span 60 solution, gently rinse with water to remove the molecules that are not firmly adsorbed, dry at room temperature, and wait for use.

[0039] (3) Loading organic pollutants Take PCB 9, 11, 18 as representatives of organic pollutants, prepare a 500 ppm standard solution, the solvent is methanol, add 30 mL to the above conical flask to just cover the PDMS coating, shake at 200 rpm at room temperature, add an appropriate amount of ultrapure water at the following times and continue to shake: 1 d add 10 mL, 2 d add 10 mL, 3 d add 15 mL, 4 d add 15 mL, 5 d add 20 mL, to a total solution volume of 100 mL, continue to shake until 10 d; pour out all the solution, quickly (15 s) rinse the PDMS coating with about 10 mL of methanol for 3 times, and then wash the coating with 30 mL of ultrapure water for 3 times, each time for 15 min; pour out all the solution, cover with a sterile dustproof film, and the passive drug delivery device is obtained.

[0040] Example 3 The present embodiment provides a method for preparing a passive drug delivery device generating constant free-state concentration of organic pollutants, comprising the following steps: (1) PDMS coating preparation Accurately weigh 2.20 g of PDMS prepolymer and 0.20 g of curing agent Sylgard 184 into a plastic cup; vacuumize (-0.1 MPa) in a vacuum drying oven until no air bubbles (about 20 min); use a dropper to draw and add into the target area inside a clean and dry 150 mL conical flask laid horizontally, while rotating the conical flask to make the PDMS evenly coated; rotate the conical flask laid horizontally in a water bath at 60 °C for 5 h to make the PDMS coating solidified; after the preparation is completed, add 30 mL of methanol and ultrasonic for 30 min, replace the methanol and ultrasonic for another 30 min, a total of 2 times, to remove the impurities in the preparation of the coating preparation process, pour out the methanol and wait for use.

[0041] (2) Surface modification Prepare a Span 85 ethanol / water = 1:1 solution, put the PDMS film coated container into 44 mL of 0.5% mass concentration of Span 85 surfactant solution, soak for 6 h and pour out the Span 85 solution, gently rinse with water to remove the molecules that are not firmly adsorbed, dry at room temperature and wait for use.

[0042] (3) Load organic pollutants Take PCB1, 9, 11, 18, 77 as representatives of organic pollutants, prepare a 500 ppm standard solution, the solvent is methanol, add 30 mL to the above conical flask to just cover the PDMS coating, shake at 200 rpm at room temperature, add an appropriate amount of ultrapure water at the following times and continue to shake: 1 d add 10 mL, 2 d add 10 mL, 3 d add 15 mL, 4 d add 15 mL, 5 d add 20 mL, to a total solution volume of 100 mL, continue to shake until 10 d; pour out all the solution, quickly (15 s) rinse the PDMS coating with about 10 mL of methanol 3 times, then wash the coating with 30 mL of ultrapure water 3 times, each time for 15 min; pour out all the solution, cover with a sterile dustproof film, and the passive drug delivery device is obtained.

[0043] Example 4 The present example provides a method for preparing a passive drug delivery device that generates a constant free state concentration of organic pollutants, which is only different from Example 1 in that: In the surface modification process, the mass concentration of the Span 80 surfactant solution is 0.1%.

[0044] Example 5 The present example provides a method for preparing a passive drug delivery device that generates a constant free state concentration of organic pollutants, which is only different from Example 1 in that: In the surface modification process, the mass concentration of the Span 80 surfactant solution is 1%.

[0045] Comparative Example 1 This comparative example provides a method for preparing a passive dosing device, which is only different from Example 1 in that no Span 80 surface modification process is performed.

[0046] Comparative Example 2 This comparative example provides a method for preparing a passive dosing device, which is only different from Example 1 in that in the preparation of the PDMS coating, the amount of curing agent Sylgard 184 added is 0.1 g. Comparative Example 3 This comparative example provides a method for preparing a passive dosing device, which is only different from Example 1 in that in the preparation of the PDMS coating, the amount of curing agent Sylgard 184 added is 0.4 g.

[0047] Effect Example 1 This effect example uses the passive dosing device prepared in Example 1 to conduct a microalgae exposure experiment to detect the constant concentration release stability of the device, and the specific experimental method is as follows: Take Microcystis aeruginosa as a representative of microalgae, prepare BG-11 liquid medium, and after sterilization and cooling, add 60 mL to the passive dosing device, and inoculate Microcystis aeruginosa. Place in a 25°C incubator, and the light condition is light:dark = 12h:12h. Every 7 days, monitor the PCB concentration in the culture solution, and the specific operation is as follows: shake the microalgae culture solution, remove 5 mL into a centrifuge tube, centrifuge at 4500 rpm for 15 min, take 3 mL of supernatant into a glass sample bottle, add 1 mL of n-hexane extraction liquid (containing 50 μg / L of PCB 77-D6 internal standard), extract for 24 h under the condition of 200 rpm, and then transfer the organic phase into a 2 mL chromatographic sample bottle for gas chromatography-mass spectrometry analysis to determine the content of PCB. Monitor the PCB concentration of each device for 1, 2, 3, and 4 weeks to monitor the stability of the PCB concentration of the device during long-term green algae exposure (see Figure 2 ); At the same time, 3 devices containing different organic pollutants (PCB 9, 11, 77) are made and compared horizontally to monitor the repeatability between devices (see Figure 3 ). Each test is done in triplicate.

[0048] The results show that the concentration deviations of different organic pollutants PCB 9, 11, 77 in the device within 28 days are 7.2%, 12.0%, and 14.8%, respectively, and there is no significant difference in the concentrations of all organic pollutants between the 3 bottles (p>0.05). This indicates that when using the device for microalgae exposure experiments, the concentration of organic pollutants is relatively stable in the time scale; the concentration of the prepared device is comparable, and the device is reproducible and can be mass produced / prepared to serve batch experiments.

[0049] Effect Example 2 The passive drug delivery device prepared by Example 1, 4-5 and Comparative Example 1-3 was used to determine the release of organic pollutants, to explore the effect of surface modification on the constant concentration release stability of the device. 60 mL of sterilized and cooled pure water was added to the device containing PCB1 organic pollutants, and the device was placed at 25℃, and the PCB concentration in the water was monitored regularly (for specific operation, refer to Effect Example 1).

[0050] In addition, the passive drug delivery device prepared by Example 1, 4-5 and Comparative Example 1 was used for microalgae exposure experiment to explore the stability of the device and the adhesion of microalgae. Taking Microcystis aeruginosa and Nitzschia closterium as representatives, after 15 days of inoculation according to the inoculation method of Effect Example 1, the algal density adhering to the surface of the coating of the device was tested. The lower the algal density, the better the anti-adhesion effect.

[0051] Figure 4 The figure shows that different concentrations of Span80 modification (Example 1, 4-5 and Comparative Example 1) have no significant effect on the concentration of organic pollutants produced by the device (p>0.05), which indicates that surface modification does not affect the stability of the device and can be applied to long-term algae exposure experiments. In Comparative Example 3, due to the relatively high curing agent Sylgard184, the PDMS coating of the device fell off after 9 days of placement; in Comparative Example 2, due to the relatively low curing agent Sylgard184, the release of organic pollutants in the device was out of control, and it was basically released completely on the 12th day, which could not achieve long-term constant release of pollutants.

[0052] Figure 5 The figure shows that surface modification with Span80 can effectively prevent algae from adhering to the coating, especially when the concentration of Span80 is 0.5-1%.

[0053] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and do not limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a passive drug delivery device that generates a constant free concentration of organic pollutants, characterized in that, Includes the following steps: S1. Mix the PDMS prepolymer and curing agent, remove air bubbles, add to the device bottle, rotate the device bottle under water bath conditions to coat and cure the PDMS at the bottom of the device bottle, then add methanol to the device bottle to immerse the PDMS coating, and sonicate to remove the methanol. S2. Dissolve the surfactant in an aqueous ethanol solution to prepare a surfactant solution. Add the surfactant solution to the device bottle to immerse the PDMS coating, perform immersion treatment, and then remove the solution. S3. Dissolve the target organic pollutant in methanol to prepare a standard solution of organic pollutant. Add the standard solution to the device bottle to immerse the PDMS coating, shake continuously, and add water to the device bottle every other day for 4-6 days. Continue shaking for 8-20 days, remove the solution, add methanol to rinse, and then add water to clean, thus obtaining the passive drug delivery device.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the PDMS prepolymer to the curing agent is (9-11):1, and the curing agent includes Sylgard 184.

3. The preparation method according to claim 1, characterized in that, In step S1, the water bath conditions are: water bath at 60-80℃ for 2-10 hours.

4. The preparation method according to claim 1, characterized in that, In step S2, the mass concentration of the surfactant is 0.1-1%, and the surfactant includes at least one of Span60, Span80, and Span85.

5. The preparation method according to claim 4, characterized in that, In step S2, the mass concentration of the surfactant is 0.5-1%.

6. The preparation method according to claim 1, characterized in that, In step S2, the soaking time is 2-6 hours.

7. The preparation method according to claim 1, characterized in that, In step S3, the volume-to-mass ratio of the standard solution to the PDMS prepolymer is (15-20) mL: 1 g; the concentration of the organic pollutant standard solution is 500-5000 ppm.

8. The preparation method according to claim 1, characterized in that, The organic pollutants include polychlorinated biphenyls (PCBs).

9. A passive drug delivery device for generating a constant free concentration of organic pollutants, prepared by the method according to any one of claims 1-8.

10. The application of the passive drug delivery device as described in claim 9 in microalgae exposure experiments.

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