Rapid detection application of ZIFs supported monatomic iron nano-enzyme to nano polystyrene microspheres

Abstract

The invention discloses rapid detection application of ZIFs (Zinc Ion Factor) supported monatomic iron nano-enzyme to nano polystyrene microspheres, and belongs to the technical field of pollutant detection. The ZIFs supported monatomic iron nano-enzyme has peroxidase-like activity and can catalyze hydrogen peroxide and a color developing agent 3, 3 ', 5, 5'-tetramethyl benzidine to generate a color developing reaction, after nano polystyrene microspheres with different concentrations and different particle sizes are added into a reaction system, the polystyrene microspheres can be adsorbed on the ZIFs supported monatomic iron nano-enzyme, and the ZIFs supported monatomic iron nano-enzyme can be used as a color developing agent. The active sites of the nano enzyme are covered, so that the enzyme activity is reduced, and the color of the TMB in the solution becomes light, so that the rapid visual detection of the nano polystyrene microspheres is realized. The ZIFs supported monatomic iron nano-enzyme is simple in synthesis step, the colorimetric sensing detection method of the ZIFs supported monatomic iron nano-enzyme on nano polystyrene microspheres with different particle sizes is rapid and convenient, and visual detection is realized by combining with a smart phone.

Description

Technical Field

[0001] The invention belongs to the technical field of pollutant detection, and specifically relates to a rapid detection application of a ZIFs-loaded single-atom iron nanoenzyme to nano-polystyrene microspheres. Background Art

[0002] Today, the global annual production of plastics has exceeded 400 million tons. Plastic pollution poses an increasing threat to global terrestrial and aquatic ecosystems due to its poor reversibility and continued accumulation over the past few decades. Under the conditions of mechanical crushing, high temperature, biological digestion and ultraviolet radiation, plastic pollutants can be broken into microplastics and nanoplastics. As a result, microplastic and nanoplastic pollution in water and food supplies has become increasingly serious. These pollutants can be ingested by humans and aquatic organisms, and then cause cytotoxicity and metabolic disorders.

[0003] Due to the size effect, nanoplastics are generally more toxic and have more serious ecological impacts than microplastics; at the same time, nanoplastics can easily penetrate tissues or cells, posing serious risks to the health of all organisms. Polystyrene (PS) has been widely used in personal care products, bioimaging and drug delivery, and nano-polystyrene microspheres (PSNPs) are considered to be one of the most common types of nanoplastics in water, accounting for 7.1% of the total global plastic production. Studies have shown that exposure to nano-polystyrene microspheres can cause toxicity to the human body, such as enterotoxicity, carcinogenicity, cytotoxicity, oxidative stress, immune response and genotoxicity.

[0004] In view of this, it is crucial to develop an economical, rapid, and portable visual on-site detection technology to detect nano-polystyrene microspheres in water samples. Summary of the invention

[0005] In view of the content of the background technology, the purpose of the present invention is to provide a ZIFs-loaded single-atom iron nanozyme for rapid detection of nano-polystyrene microspheres. The present invention uses hemoglobin as an iron source to prepare a zeolite imidazole single-atom nanozyme. The peroxidase-like activity of the ZIFs-loaded single-atom iron nanozyme of the present invention can catalyze a color reaction between hydrogen peroxide (H2O2) and the color developer 3,3',5,5'-tetramethylbenzidine (TMB). When different concentrations of nano-polystyrene microspheres are added to the system, the color of the solution changes significantly, thereby realizing a visual rapid detection of nano-polystyrene microspheres. The ZIFs-loaded single-atom iron nanozyme of the present invention is simple to synthesize, and its colorimetric sensing detection method for nano-polystyrene microspheres is fast and convenient, and the results are intuitive.

[0006] In order to solve the above technical problems, the present invention specifically adopts the following technical solutions: The present invention provides application of ZIFs-loaded single-atom iron nanozyme in rapid visual detection of nano polystyrene microspheres.

[0007] Furthermore, the rapid visual detection of nano-polystyrene microspheres is performed by ultraviolet spectrophotometer detection or gray value extraction detection of red, green and blue components.

[0008] Furthermore, the rapid visual detection of nano-polystyrene microspheres comprises the following steps: S1, adding nano-polystyrene microspheres, hydrogen peroxide, and 3,3',5,5'-tetramethylbenzidine to acetic acid-sodium acetate buffer (HAc-NaAc), and finally adding ZIFs-loaded single-atom iron nanozymes for incubation; S2. Record the absorbance at 652 nm and obtain the standard curve and linear equation based on the absorbance changes of nano-polystyrene microspheres with different concentrations.

[0009] Furthermore, the concentration of the acetic acid-sodium acetate buffer in S1 is 0.1 M, pH=4; the incubation temperature is 25°C, and the incubation time is 10 min.

[0010] Furthermore, the grayscale value extraction method of the red, green and blue components includes the following steps: taking pictures of nano-polystyrene microspheres of different concentrations added to the mixed system, extracting the grayscale values ​​of the red, green and blue components in each picture, the ordinate of the linear equation is the blue / green value, and the abscissa is the concentration of the nano-polystyrene microspheres. The linear equation is obtained through the grayscale value and different concentrations of nano-polystyrene microspheres.

[0011] Furthermore, the preparation method of the ZIFs-loaded single-atom iron nanozyme comprises the following steps: 1) Mix dimethylimidazole, zinc nitrate methanol solution and hemoglobin aqueous solution and stir at room temperature; 2) The sample obtained after the reaction in step 1) is washed, centrifuged, dried, and calcined to obtain ZIFs-loaded single-atom iron nanozyme ZIF-FeSAN.

[0012] Furthermore, the ZIFs-loaded single-atom iron nanozyme is selective for polyethylene, polypropylene and polyethylene terephthalate nanoplastic microspheres, and is selective for common metal ions Na + , K + 、Al 3+ Mg 2+ 、Zn 2+ Has good anti-interference performance.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The ZIFs-loaded single-atom iron nanozyme of the present invention has high peroxidase-like activity and can catalyze hydrogen peroxide to produce hydroxyl radicals, which will oxidize colorless 3,3',5,5'-tetramethylbenzidine to blue oxidized tetramethylbenzidine (oxTMB). When different concentrations of nano-polystyrene microspheres are added to the system, the microspheres will be adsorbed on the nano-zyme, and the active sites will be less exposed, making the solution color lighter, thereby realizing the visual rapid detection of nano-polystyrene microspheres. The present invention combines smart phones and the like to establish a visual detection method for nano-polystyrene microspheres, which is intuitive, simple, convenient and low-cost.

[0014] 2. The detection ranges of the ZIFs-loaded single-atom iron nanozyme for polystyrene microspheres with diameters of 20, 50, 100, and 150 nm are 0.5-20, 20-400, 100-700, and 100-700 mg / L, respectively, and the detection limits are 0.212, 7.624, 16.955, and 24.171 mg / L, respectively. It is also selective for polyethylene, polypropylene, and polyethylene terephthalate nanoplastic microspheres, and is sensitive to common metal ions Na in the solution. + , K + 、Al 3+ Mg 2+ 、Zn 2+ It has good anti-interference properties. It can be used to detect nano-polystyrene microspheres in water samples, and combined with the color recognition program, it can realize on-site instant detection of nano-polystyrene microspheres.

[0015] 3. The preparation process of the ZIFs-loaded single-atom iron nanozyme of the present invention has low cost and simple synthesis conditions. Compared with some traditional large-scale instrument detection methods, the detection of nano-polystyrene microspheres has the advantages of being fast, convenient, low-consumption, and having on-site visualization. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of the ZIFs-loaded single-atom iron nanozyme prepared by the method of the present invention.

[0017] Figure 2 This is a graph of the peroxidase activity (POD) of the ZIFs-loaded single-atom iron nanozyme prepared by the method of the present invention (the inset is the corresponding naked eye image of the spectrum).

[0018] Figure 3 UV-visible spectrum of the ZIFs-loaded single-atom iron nanozyme-TMB-H2O2 system with added nano-polystyrene microspheres.

[0019] Figure 4Linear relationship diagram of the concentration of nanopolystyrene microspheres detected by ZIFs-loaded single-atom iron nanozymes (the inset is the corresponding naked eye image of the spectrum).

[0020] Figure 5 Grayscale value (RGB) extraction and data processing of red (R), green (G), and blue (B) components of colorimetric photographs of different nano-PS microsphere concentrations and standard curves were performed using a smartphone (the inset is the corresponding naked eye image of the spectrum). DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0023] Example 1: Preparation of ZIFs-loaded single-atom iron nanozymes 1. Add 18 mL of 2-methylimidazole (0.616 g) in methanol, 20 mL of zinc nitrate Zn(NO3)2·6H2O (0.558 g) in methanol, and 2 mL of hemoglobin solution (60 mg / mL) into a clean 250 mL three-necked flask and stir at room temperature for 6 h.

[0024] 2. The sample after the reaction was washed with methanol three times, centrifuged three times, and dried at 60°C. The obtained powder was calcined at 900°C for 3 h in a tube furnace to obtain ZIFs-loaded single-atom iron nanozyme.

[0025] The present invention uses zinc nitrate, dimethylimidazole and hemoglobin as raw materials, self-assembles to form a nanozyme precursor, and then calcines to obtain the ZIFs-loaded single-atom iron nanozyme. Figure 1 The scanning electron micrograph of the ZIFs-loaded single-atom iron nanozyme prepared in this example shows that the size of the nanozyme is 200 nm and the regular dodecahedron structure can be clearly seen.

[0026] Example 2: Study on the peroxidase activity (POD) of ZIFs-loaded single-atom iron nanozymes Prepare 50 mL of acetic acid-sodium acetate buffer (HAc-NaAc) with an ion concentration of 0.1 M and pH = 4, 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 from each and put them into cuvette No. 1. Then extract 1920 μL of buffer and 20 μL of TMB into cuvette No. 2, and finally add 60 μL of 0.5 mg / mL ZIFs-loaded single-atom iron nanozyme solution. Cuvette No. 3 is based on cuvette No. 1 and adds 20 μL of 0.5 mg / mL ZIFs-loaded single-atom iron nanozyme solution. After incubation for 10 min, the absorption spectra of the three cuvettes at wavelengths of 300-800 nm were measured.

[0027] Figure 2 This is a diagram of the POD-like activity of ZIFs-loaded single-atom iron nanozyme under the conditions of this example. It can be seen that the ZIFs-loaded single-atom iron nanozyme has high POD-like activity, catalyzing hydrogen peroxide to produce hydroxyl radicals, and oxidizing the color developer TMB into blue oxTMB.

[0028] Example 3: Detection of Nano-polystyrene Microsphere Standard Solution The ZIFs-loaded single-atom iron nanozyme-TMB-H2O2 system and nano-polystyrene microspheres of different concentrations and particle sizes were added to acetic acid-sodium acetate buffer and incubated at 25°C for 10 minutes. Then, the relationship between its absorbance at 652 nm and the concentration of different nano-polystyrene microspheres was studied.

[0029] Figure 3 This is the UV-visible spectrum of the ZIFs-loaded single-atom iron nanozyme-TMB-H2O2 system with the addition of nano-polystyrene microspheres. It can be seen from the figure that with the increase in the concentration of nano-polystyrene microspheres, the absorbance at a wavelength of 652 nm gradually decreases, showing a decrease in the degree of blue. Figure 4 This is the linear relationship diagram of the concentration of nano-polystyrene microspheres detected by ZIFs-loaded single-atom iron nanozymes. For polystyrene microspheres with diameters of 20, 50, 100, and 150 nm, a linear relationship can be obtained: 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, y is the absorbance of the solution, the detection ranges are 0.5-20, 20-400, 100-700, 100-700 mg / L, and the minimum detection limits are 0.212, 7.624, 16.955, and 24.171 mg / L.

[0030] Example 4: Detection of Nano-polystyrene Microspheres in Various Water Samples Water sample treatment: Three water samples, namely tap water, Poyang Lake water, and drinking water, were spiked with nano-polystyrene microspheres of different particle sizes and concentrations, and then the samples to be tested were added to the ZIFs-loaded single-atom iron nanozyme-TMB-H2O2 system. After incubation for 10 min, the absorbance at 652 nm was measured using a UV spectrophotometer. The experimental results are shown in Table 1.

[0031] Table 1

[0032] From the analysis of the test results in Table 1, it can be seen that the spiked recovery rate of the method for detecting the content of nano-polystyrene microspheres in water samples is maintained at 91.47%-108.12%, indicating that the visual detection of nano-polystyrene microspheres by the ZIFs-loaded single-atom iron nanozyme of the present invention is feasible in actual analysis.

[0033] Example 5: Real-time detection of nano-polystyrene microspheres using grayscale (RGB) color analysis program of red (R), green (G) and blue (B) components The ZIFs-loaded single-atom iron nanozyme-TMB-H2O2 system and nano-polystyrene microspheres were added to an acetic acid-sodium acetate buffer solution and incubated at 25°C for 10 minutes. Photos after the reaction were taken with a smartphone. The center of each color-sensitive point was then used as the region of interest (ROI) using the smartphone, and the grayscale averages of the red, green, and blue components of the ROI area were extracted from the photo using an App.

[0034] Figure 5 To extract RGB and process data of colorimetric photos and standard curves of different nano-PS microsphere concentrations 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 (R 2=0.9934), and the LOD was calculated to be 0.851, 34.554, 67.254, and 76.124 mg / L.

[0035] The embodiments described above only express several preferred embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but are not intended to limit the present invention. It should be noted that for those skilled in the art, the present invention may also have various changes and modifications, and any modifications, equivalent substitutions, improvements, etc. made within the concept and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Application of ZIFs-loaded single-atom iron nanozymes in rapid visual detection of nanopolystyrene microspheres.

2. The application according to claim 1, characterized in that: The rapid visual detection of nano polystyrene microspheres adopts ultraviolet spectrophotometer detection or gray value extraction detection of red, green and blue components.

3. The application according to claim 2, characterized in that: The rapid visual detection of nano polystyrene microspheres comprises the following steps: S1, adding nano-polystyrene microspheres, hydrogen peroxide, and 3,3',5,5'-tetramethylbenzidine to acetic acid-sodium acetate buffer, and finally adding ZIFs-loaded single-atom iron nanozymes for incubation; S2. Record the absorbance at 652 nm and obtain the standard curve and linear equation based on the absorbance changes of nano-polystyrene microspheres with different concentrations.

4. The use according to claim 3, characterized in that: The concentration of the acetic acid-sodium acetate buffer in S1 is 0.1 M, pH=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 grayscale value extraction method of the red, green and blue components includes the following steps: taking pictures of nano-polystyrene microspheres of different concentrations added to a mixed system, extracting the grayscale values ​​of the red, green and blue components in each picture, the ordinate of the linear equation is the blue / green value, and the abscissa is the concentration of the nano-polystyrene microspheres, and the linear equation is obtained through the grayscale value and different concentrations of nano-polystyrene microspheres.

6. The use according to claim 1, characterized in that: The preparation method of the ZIFs-loaded single-atom iron nanozyme comprises the following steps: 1) Mix dimethylimidazole, zinc nitrate methanol solution and hemoglobin aqueous solution and stir at room temperature; 2) The sample obtained after the reaction in step 1) is washed, centrifuged, dried, and calcined to obtain ZIFs-loaded single-atom iron nanozyme ZIF-FeSAN.

7. The use according to claim 6, characterized in that: The ZIFs-loaded single-atom iron nanozyme is selective for polyethylene, polypropylene, and polyethylene terephthalate nanoplastic microspheres, and is sensitive to common metal ions Na + , K + 、Al 3+ Mg 2+ 、Zn 2+ Has good anti-interference performance.

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