A ZIFs supported single-atom iron nanoszyme for rapid detection of nanopolystyrene microspheres

Abstract

The application discloses a kind of ZIFs load type single atom iron nanometer enzyme to nano polystyrene microsphere rapid detection application, belong to pollutant detection technical field.The application ZIFs load type single atom iron nanometer enzyme has peroxidase-like activity, can catalyze hydrogen peroxide and color developing agent 3,3',5,5'-tetramethyl benzidine occur color reaction, when different concentration, different particle size nano polystyrene microsphere are added in reaction system, polystyrene microsphere will be adsorbed on ZIFs load type single atom iron nanometer enzyme, cover nanometer enzyme active site, cause enzyme activity to reduce and make solution TMB color lighter, and then realize to nano polystyrene microsphere Rapid visual detection.The synthesis step of the application ZIFs load type single atom iron nanometer enzyme is simple, and its colorimetric sensing detection method to different particle size nano polystyrene microsphere is rapid, convenient, and visual detection is realized in combination with smart phone.

Description

Technical Field

[0001] This invention belongs to the field of pollutant detection technology, specifically relating to the rapid detection application of ZIFs-supported single-atom iron nanozymes on polystyrene nanospheres. Background Technology

[0002] Global annual plastic production now exceeds 400 million tons. Plastic pollution, due to its poor reversibility and decades of continuous accumulation, poses an increasing threat to global terrestrial and aquatic ecosystems. Under conditions of mechanical crushing, high temperatures, biological digestion, and ultraviolet radiation, plastic pollutants can break down into microplastics and nanoplastics. Therefore, microplastic and nanoplastic pollution in water and food supplies is becoming increasingly serious. These pollutants can be ingested by humans and aquatic organisms, subsequently causing cytotoxicity and metabolic disorders.

[0003] Due to size effects, nanoplastics are generally more toxic and have a more severe ecological impact than microplastics; moreover, nanoplastics can easily penetrate tissues or cells, posing a serious risk to the health of all organisms. Polystyrene (PS) is widely used in personal care products, bioimaging, and drug delivery, and polystyrene nanospheres (PSNPs) are considered one of the most common types of nanoplastics in water, accounting for 7.1% of global plastic production. Studies have shown that exposure to polystyrene nanospheres can cause toxicity in humans, including intestinal toxicity, carcinogenicity, cytotoxicity, oxidative stress, immune responses, and genotoxicity.

[0004] Therefore, it is crucial to research and develop an economical, rapid, and portable visual on-site detection technology for detecting polystyrene nanospheres in water samples. Summary of the Invention

[0005] In view of the background art, the purpose of this invention is to provide a rapid detection application of ZIFs-supported single-atom iron nanozymes for polystyrene microspheres. This invention uses hemoglobin as the iron source to prepare zeolite imidazole single-atom nanozymes. The peroxidase-like activity of the ZIFs-supported single-atom iron nanozyme of this invention can catalyze a colorimetric reaction between hydrogen peroxide (H₂O₂) and the chromogenic agent 3,3',5,5'-tetramethylbenzidine (TMB). When different concentrations of polystyrene microspheres are added to the system, the solution color changes significantly, thereby achieving rapid and visual detection of polystyrene microspheres. The synthesis of the ZIFs-supported single-atom iron nanozyme of this invention is simple, and its colorimetric sensing detection method for polystyrene microspheres is rapid, convenient, and provides intuitive results.

[0006] To solve the above-mentioned technical problems, the present invention specifically adopts the following technical solution:

[0007] This invention provides the application of ZIFs-supported single-atom iron nanozymes in rapid and visual detection of polystyrene nanospheres.

[0008] Furthermore, the rapid visualization detection of the polystyrene nanospheres is achieved using an ultraviolet spectrophotometer or by extracting the gray values ​​of the red, green, and blue components.

[0009] Furthermore, the rapid visualization detection of nano-polystyrene microspheres includes the following steps:

[0010] S1. Add polystyrene nanospheres, hydrogen peroxide, and 3,3',5,5'-tetramethylbenzidine to acetate-sodium acetate buffer (HAc-NaAc), and finally add ZIFs-supported single-atom iron nanozyme and incubate.

[0011] S2. Record the absorbance at 652 nm. Based on the absorbance changes of nano-polystyrene microspheres with different concentrations, derive the standard curve and linear equation.

[0012] Furthermore, the acetate-sodium acetate buffer solution in S1 has a concentration of 0.1 M and a pH of 4; the incubation temperature is 25°C and the incubation time is 10 min.

[0013] Furthermore, the grayscale value extraction method for the red, green, and blue components includes the following steps: taking pictures of nano-polystyrene microspheres of different concentrations added to the mixing system, extracting the grayscale values ​​of the red, green, and blue components in each picture, and using the blue / green value as the vertical axis of the linear equation and the concentration of the nano-polystyrene microspheres as the horizontal axis. The linear equation is obtained by using the grayscale values ​​and nano-polystyrene microspheres of different concentrations.

[0014] Furthermore, the preparation method of the ZIFs-supported single-atom iron nanozyme includes the following steps:

[0015] 1) Mix dimethylimidazole, a methanol solution of zinc nitrate, and an aqueous solution of hemoglobin, and stir at room temperature;

[0016] 2) Wash, centrifuge, dry, and calcine the sample obtained after the reaction in step 1) to obtain ZIFs-supported single-atom iron nanozyme ZIF-FeSAN.

[0017] Furthermore, the ZIFs-supported single-atom iron nanozyme exhibits selectivity for polyethylene, polypropylene, and polyethylene terephthalate nanoplastic microspheres, and also for common metal ions such as Na+ in solution. + K + Al 3+ Mg 2+ Zn 2+ It has good anti-interference properties.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. The ZIFs-supported single-atom iron nanozyme of the present invention has high peroxidase-like activity and can catalyze the generation of hydroxyl radicals from hydrogen peroxide. The hydroxyl radicals oxidize colorless 3,3',5,5'-tetramethylbenzidine to blue oxidized tetramethylbenzidine (oxTMB). When different concentrations of polystyrene nanospheres are added to the system, the microspheres adsorb onto the nanozyme, and the less active site is exposed, the lighter the solution color becomes, thereby realizing the visual and rapid detection of polystyrene nanospheres. The present invention establishes a visual detection method for polystyrene nanospheres in conjunction with smartphones, which has the characteristics of being intuitive, simple and convenient, and low cost.

[0020] 2. The ZIFs-supported single-atom iron nanozyme of the present invention exhibits detection ranges of 0.5-20, 20-400, 100-700, and 100-700 mg / L for polystyrene microspheres with diameters of 20, 50, 100, and 150 nm, respectively, with detection limits of 0.212, 7.624, 16.955, and 24.171 mg / L. Furthermore, it demonstrates selectivity for polyethylene, polypropylene, and polyethylene terephthalate nanoplastic microspheres, and is also effective against common metal ions in solution, such as Na+. + K + Al 3+ Mg 2+ Zn 2+ It exhibits good anti-interference properties. When used for the detection of polystyrene nanospheres in water samples, combined with a color recognition program, it can achieve real-time on-site detection of polystyrene nanospheres.

[0021] 3. The ZIFs-supported single-atom iron nanozyme preparation process of this invention has low cost and simple synthesis conditions. Compared with some traditional large-scale instrument detection methods, it has the advantages of being fast, convenient, low-consumption, and on-site visualization for the detection of polystyrene nanospheres. Attached Figure Description

[0022] Figure 1 Scanning electron microscope image of ZIFs-supported single-atom iron nanozymes prepared by the method of this invention.

[0023] Figure 2 The peroxidase activity (POD) of ZIFs-supported single-atom iron nanozymes prepared by the method of the present invention is shown in the inset (the inset is the corresponding visual image of the spectrum).

[0024] Figure 3 The UV-Vis spectrum of the ZIFs-supported single-atom iron nanozyme-TMB-H2O2 system with added polystyrene nanospheres.

[0025] Figure 4Linear relationship of ZIFs-supported single-atom iron nanozymes in detecting the concentration of polystyrene nanospheres (inset is the corresponding visual image of the spectrum).

[0026] Figure 5 To extract and process the grayscale values ​​(RGB) of the red (R), green (G), and blue (B) components from colorimetric photographs and standard curves of different concentrations of nano-polystyrene microspheres using a smartphone (the inset is the corresponding visual image of the spectrum). Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with embodiments. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Example 1: Preparation of ZIFs-supported single-atom iron nanozymes

[0030] 1. Add 18 mL of methanol solution containing 2-methylimidazole (0.616 g), 20 mL of methanol solution containing zinc nitrate Zn(NO3)2·6H2O (0.558 g), and 2 mL of hemoglobin solution (60 mg / mL) to a clean 250 mL three-necked flask, and stir at room temperature for 6 h.

[0031] 2. The sample after reaction was washed three times with methanol, centrifuged three times, dried at 60°C, and the resulting powder was calcined in a tube furnace at 900°C for 3 h to obtain ZIFs-supported single-atom iron nanozymes.

[0032] This invention uses zinc nitrate, dimethylimidazole, and hemoglobin as raw materials to self-assemble a nanozyme precursor, which is then calcined to obtain a ZIFs-supported single-atom iron nanozyme. Figure 1 The scanning electron microscope image of the ZIFs-supported single-atom iron nanozyme prepared in this embodiment shows that the nanozyme has a size of 200 nm and a clear dodecahedral structure.

[0033] Example 2: Study on the peroxidase activity (POD) of ZIFs-supported single-atom iron nanozymes

[0034] Prepare 50 mL of 0.1 M, pH 4 acetate-sodium acetate buffer (HAc-NaAc), 2 mL of 20 mM 3,3',5,5'-tetramethylbenzidine (TMB), and 2 mL of 30% w / w hydrogen peroxide. Then, extract 1960 μL, 20 μL, and 20 μL of each buffer and place them into cuvette #1. Next, extract 1920 μL of the buffer and 20 μL of TMB and place them into cuvette #2. Finally, add 60 μL of 0.5 mg / mL ZIFs-supported single-atom iron nanozyme solution. Cuvette #3 is prepared by adding another 20 μL of 0.5 mg / mL ZIFs-supported single-atom iron nanozyme solution to cuvette #1. After incubating for 10 min, measure the absorption spectra of all three cuvettes at wavelengths of 300–800 nm.

[0035] Figure 2 The image shows the POD activity of the ZIFs-supported single-atom iron nanozyme under the conditions of this embodiment. It can be seen that the ZIFs-supported single-atom iron nanozyme has high POD-like activity, catalyzing the generation of hydroxyl radicals from hydrogen peroxide, which oxidizes the colorimetric reagent TMB into blue oxTMB.

[0036] Example 3: Detection of standard solution of nano-polystyrene microspheres

[0037] A ZIFs-supported single-atom iron nanozyme-TMB-H2O2 system and polystyrene nanospheres of different concentrations and sizes were added to an acetate-sodium acetate buffer solution and incubated at 25°C for 10 minutes. The relationship between the absorbance at 652 nm and the concentration of different polystyrene nanospheres was then investigated.

[0038] Figure 3 The image shows the UV-Vis spectrum of the ZIFs-supported single-atom iron nanoenzyme-TMB-H2O2 system with added polystyrene nanospheres. As can be seen from the figure, the absorbance at 652 nm gradually decreases with the increase of the concentration of polystyrene nanospheres, indicating a decrease in the intensity of blue. Figure 4 The linear relationship between the concentration of ZIFs-supported single-atom iron nanozymes and the concentration of polystyrene nanospheres is shown in the graph. For polystyrene microspheres with diameters of 20, 50, 100, and 150 nm, the linear relationship is: y = -0.053x + 1.273 (R 2 =0.9957), y = -0.015x+1.119 (R 2 =0.9964), y = -0.0067x+1.243 (R 2 =0.9931), y = -0.0047x+1.213 (R 2= 0.9913), where x is the concentration of nano-polystyrene microspheres and y is the absorbance of the solution. The detection ranges are 0.5-20, 20-400, 100-700, and 100-700 mg / L, respectively, and the limits of detection are 0.212, 7.624, 16.955, and 24.171 mg / L.

[0039] Example 4: Detection of Nano-Polystyrene Microspheres in Various Water Samples

[0040] Water sample treatment: Three types of water samples were used: tap water, Poyang Lake water, and drinking water. Different particle sizes and concentrations of polystyrene nanospheres were added to the water samples for spiking. The samples to be tested were then added to a ZIFs-supported single-atom iron nanozyme-TMB-H2O2 system and incubated for 10 min. The absorbance at 652 nm was measured using a UV spectrophotometer. The experimental results are shown in Table 1.

[0041] Table 1

[0042]

[0043] As can be seen from the analysis of the detection results in Table 1, the spiked recovery rate of this method for detecting the content of polystyrene nanospheres in water samples remained at 91.47%-108.12%, indicating that the visualization detection of polystyrene nanospheres by the ZIFs-supported single-atom iron nanozyme of this invention is feasible in practical analysis.

[0044] Example 5: Real-time detection of polystyrene nanospheres using a color analysis program based on the grayscale values ​​(RGB) of the red (R), green (G), and blue (B) components.

[0045] The ZIFs-supported single-atom iron nanozyme-TMB-H2O2 system and nano-polystyrene microspheres were added to an acetate-sodium acetate buffer solution and incubated at 25°C for 10 minutes. Photos of the reaction were taken with a smartphone, and the center of each color-sensitive point was selected as the region of interest (ROI) using the smartphone. The average grayscale values ​​of the red, green and blue components of the ROI region were extracted from the photos using an app.

[0046] Figure 5 To extract and process RGB data from colorimetric photographs and standard curves of different concentrations of polystyrene nanospheres using a smartphone, the linear relationship is as follows: y = -0.0081x + 1.145 (R 2 =0.9938), y = -0.00025x+1.124 (R 2 =0.9947), y = -0.00013x+1.145 (R 2 =0.9942), y = -0.00011x+1.124 (R2 =0.9934), and the LOD was calculated to be 0.851, 34.554, 67.254, and 76.124 mg / L.

[0047] The embodiments described above are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they are not intended to limit the present invention. It should be noted that various changes and modifications can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the concept and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Application of ZIFs-supported single-atom iron nanozymes in rapid and visual detection of polystyrene nanospheres; The preparation method of the ZIFs-supported single-atom iron nanozyme includes the following steps: 1) Mix dimethylimidazole, a methanol solution of zinc nitrate, and an aqueous solution of hemoglobin, and stir at room temperature; 2) Wash, centrifuge, dry, and calcine the sample obtained after the reaction in step 1) to obtain ZIFs-supported single-atom iron nanozyme ZIF-FeSAN.

2. The application according to claim 1, characterized in that, The rapid visualization detection of the polystyrene nanospheres is achieved by using an ultraviolet spectrophotometer or by extracting the gray values ​​of the red, green, and blue components.

3. The application according to claim 2, characterized in that, The rapid visualization detection of nano-polystyrene microspheres includes the following steps: S1. Add polystyrene nanospheres, hydrogen peroxide, and 3,3',5,5'-tetramethylbenzidine to acetate-sodium acetate buffer, and finally add ZIFs-supported single-atom iron nanozyme and incubate. S2. Record the absorbance at 652 nm. Based on the absorbance changes of nano-polystyrene microspheres with different concentrations, derive the standard curve and linear equation.

4. The application according to claim 3, characterized in that, The acetate-sodium acetate buffer solution in S1 has a concentration of 0.1 M and a pH of 4; the incubation temperature is 25°C and the incubation time is 10 min.

5. The application according to claim 2, characterized in that, The extraction and detection of grayscale values ​​of the red, green, and blue components includes the following steps: taking pictures of nano-polystyrene microspheres of different concentrations added to the mixing system, extracting the grayscale values ​​of the red, green, and blue components from each picture, using the blue / green value as the vertical axis of the linear equation and the concentration of the nano-polystyrene microspheres as the horizontal axis, and obtaining the linear equation through the grayscale values ​​and nano-polystyrene microspheres of different concentrations.

6. The application according to claim 1, characterized in that, The ZIFs-supported single-atom iron nanozyme targets common metal ions in solution, such as Na+. + K + Al 3+ Mg 2+ Zn 2+ It has good anti-interference properties.

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