An Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity and its application

Abstract

The present invention belongs to the technical field of nanomaterials, and particularly relates to an Fe<subgt;3< / subgt;S<subgt;4< / subgt> / CDs nanomaterial with peroxidase-like catalytic activity and its application. The preparation method of the nanomaterial comprises the following steps: (1) using bayberry as a raw material to prepare carbon dots by a hydrothermal method; (2) using the prepared carbon dots as a solvent, adding ferric sulfate and L-cysteine, and synthesizing the Fe<subgt;3< / subgt;S<subgt;4< / subgt> / CDs nanomaterial by a one-step solvothermal synthesis method. The present invention synthesizes an Fe<subgt;3< / subgt;S<subgt;4< / subgt> / CDs nanomaterial with relatively high peroxidase-like catalytic activity by using carbon dots CDs prepared from bayberry fruits, which do not have peroxidase-like catalytic activity themselves. The material can oxidize TMB in the presence of hydrogen peroxide, and a sensing platform for sensitive detection of p-aminophenol p -Ap is constructed.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to an Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity and its application. Background Art

[0002] Natural enzymes with high substrate specificity and activity play an important role in various catalytic reactions and have been widely used in fields such as clinical medicine, bioengineering, agriculture, food industry, and environmental protection. However, the inherent disadvantages of natural enzymes severely limit their applications, such as high purification costs, environmental sensitivity, and low stability caused by denaturation. To overcome these disadvantages, more and more researchers have focused on the preparation and utilization of efficient enzyme mimics.

[0003] Nanozymes are nanomaterials with enzyme-like properties and are usually used to construct corresponding sensors. Compared with natural enzymes, nanozymes have the advantages of lower cost, high stability under harsh conditions (such as temperature, pH value, etc.), and larger surface area. In 2007, iron oxide (Fe3O4) was first found to have peroxidase-like activity, and in the presence of hydrogen peroxide, iron oxide catalyzes the chromogenic substrate TMB to produce a blue reaction with the maximum absorbance at 652 nm. Based on this principle, an H2O2 sensor was constructed. Currently, a large number of efficient and stable nanozyme materials have been developed, such as metal oxides, metal sulfides, carbon nanomaterials, metal-organic frameworks, and composites, which have broad application prospects in the fields of environmental chemistry, biotechnology, and medicine.

[0004] As a new type of carbon nanomaterial, carbon dots (CDs) have the advantages of low toxicity, low cost, high fluorescence intensity, and good biocompatibility. CDs have also been found to have peroxidase-like activity, and their application in glucose detection has been reported. In recent years, carbon-based hybrid nanomaterials have received great attention due to their simple preparation, storage, and separation, as well as their superior synergy compared with natural enzymes. Compared with individual CDs or metal compounds, metal nanocomposites based on CDs can improve their peroxidase-like activity. Among them, the carbon material should promote the generation of free radicals through synergistic catalysis, thereby improving the enzyme activity of the material. Therefore, the development and synthesis of carbon-based and iron-based composite nanomaterials with high peroxidase activity are beneficial to promoting the development of nanoscience and technology.

[0005] p-Aminophenol ( p -Ap) has broad industrial application prospects in the petroleum, rubber, dye, pharmaceutical, and photographic industries. At the same time, as the main degradation product of paracetamol, p-Ap has the dual toxicity of aniline and phenol. Therefore, from the aspects of environmental protection and occupational health, it is necessary to develop a simple, sensitive and convenient method to monitor p -Ap in environmental and biological samples. Most of the reported methods for determining p -Ap involve expensive, low-selectivity and complex sample processing procedures, which greatly limit their direct application in practice. However, the use of nanozymes to construct a colorimetric sensor for the determination of p -Ap has the advantages of convenience and sensitivity. Summary of the Invention

[0006] The object of the present invention is to overcome the disadvantages and deficiencies existing in the prior art, and to provide an Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity and its application.

[0007] The technical solution adopted by the present invention is as follows: an Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity, and its preparation method includes the following steps:

[0008] (1) Using bayberry as raw material, carbon dots are prepared by hydrothermal method;

[0009] (2) Using the prepared carbon dots as solvent, ferric sulfate and L-cysteine are added, and the Fe3S4 / CDs nanomaterial is synthesized by one-step solvothermal synthesis method.

[0010] Preferably, in step (1), the bayberry is crushed, mixed well with ultrapure water, sealed and heated at 180-200 °C for 8-14 h, cooled to room temperature, and the filtrate is taken by filtering with a 0.22 μm microporous membrane filter.

[0011] Preferably, in step (2), the molar ratio of ferric sulfate to L-cysteine is 1:1.

[0012] Preferably, in step (2), ferric sulfate and L-cysteine are added to the carbon dots and mixed well, sealed and heated at 180-200 °C for 8-16 h. After cooling to room temperature, the synthesized solid product is separated by magnetic adsorption, rinsed with distilled water and ethanol, and dried to obtain the Fe3S4 / CDs nanomaterial.

[0013] The application of the above-mentioned Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity in the preparation of products for detecting the content of p-aminophenol.

[0014] A method for detecting p-aminophenol, including the following steps:

[0015] 1. Mix a buffer solution with a pH of 2 - 5, TMB, H2O2, and the Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity as described above, and perform a shaking reaction at 25 - 55°C.

[0016] 2. Add the test solution to the system after the shaking reaction in step 1 and carry out the reaction.

[0017] Preferably, in step 1, the pH of the buffer solution is 3 - 4.

[0018] Preferably, in step 1, the pH of the buffer solution is 3.5.

[0019] Preferably, in step 1, the reaction temperature is 30 - 40°C.

[0020] Preferably, in step 1, the reaction temperature is 35°C.

[0021] Preferably, in step 2, after the reaction, it is measured by an ultraviolet - visible spectrophotometer, and in the range of 10 - 100 μmol / L, A 371 / A 652 shows a linear relationship.

[0022] The beneficial effects of the present invention are as follows: The present invention synthesizes an Fe3S4 / CDs nanomaterial with high peroxidase-like catalytic activity by using carbon dots CDS prepared from bayberry fruits, which do not have peroxidase-like catalytic activity themselves. This material can oxidize TMB in the presence of hydrogen peroxide, and a sensing platform for sensitive detection of p-aminophenol p -Ap is constructed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still belongs to the scope of the present invention.

[0024] Figure 1 Characterization of Fe3S4 / CDs: (a) XRD; (b) TEM;

[0025] Figure 2 Among them, (A) XPS spectrum of Fe3S4 / CDs; (B) High-resolution C 1s spectrum; (C) High-resolution N 1s spectrum; (D) High-resolution S 2p spectrum;

[0026] Figure 3Among them, (A) Comparison of UV-visible absorption spectra of the reaction system in the presence of different materials. The inset is a real photo; (B) Effect of pH value on the peroxidase-like activity; (C) Effect of temperature on the peroxidase-like activity; (D) Effect of the dosage of Fe3S4 / CDs on the peroxidase-like activity;

[0027] Figure 4 For the steady-state kinetic analysis of Fe3S4 / CDs: (A) Michaelis curve of H2O2; (B) Michaelis curve of TMB; (C) Double-reciprocal plot of H2O2; (D) Double-reciprocal plot of TMB;

[0028] Figure 5 UV-visible absorption spectra of the system in the presence of different radical scavengers (1: without quencher; 2: isopropanol; 3: ethylenediaminetetraacetic acid; 4: p-benzoquinone);

[0029] Figure 6 Among them, (A) Absorption spectra of the system when adding different concentrations of C p -Ap; (B) A 372 / A 652 And the linear relationship with C p -Ap in the system is: NaAc-Hac is 2610 μL (20 mM), TMB is 200 μL (6 mM), H2O2 is 40 μL (50 mM), Fe3S4 / CDs is 50 μg / mL, and pH is 3.5;

[0030] Figure 7 Among them, (A) p -Ap and the UV-visible spectra of the system in the presence of some common interfering substances; (B) Corresponding color changes. Specific implementation mode

[0031] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Example 1:

[0033] (1) Synthesis of carbon dots (MN-CDs)

[0034] Carbon dots (MN-CDs) were prepared by a hydrothermal method. First, bayberry (5 g) was crushed and transferred to the inner liner of a 100 mL reaction kettle, and then ultrapure water (25 mL) was added and mixed thoroughly. The autoclave was placed in a forced-air drying oven and heated at 190 °C for 11 h. After the autoclave was cooled to room temperature, the above solution was filtered through a 0.22 μm microporous membrane filter. And the prepared carbon dot solution was stored in a refrigerator at 4 °C for later use.

[0035] (2) Synthesis of Fe3S4 / CDs

[0036] Using the prepared carbon dots as the solvent, Fe3S4 / CDs nanomaterials were synthesized by a one-step solvothermal method. 0.834 g of FeSO4•7H2O (0.003 mol) and 0.363 g of L-cysteine (0.003 mol) were respectively dissolved in 30 mL of the carbon dot solution, and magnetically stirred for 20 min at room temperature to form a mixture. Subsequently, it was transferred to a polytetrafluoroethylene autoclave and heated at 190 °C for 12 h. After cooling to room temperature, the synthesized solid product was separated by magnetic adsorption, rinsed three times with distilled water and ethanol in sequence, and finally dried in a vacuum drying oven at 60 °C for 6 h until the material was completely dry. After grinding and weighing, it was reserved for use.

[0037] First, we analyzed the synthesized Fe3S4 / CDs by X-ray diffractometer (XRD). As Figure 1 shown in Figure 1 Figure

[0038] A, the specific diffraction peaks at five positions of 25.4°, 30.0°, 36.3°, 47.8° and 52.4° correspond to the (220), (311), (400), (511) and (440) crystal planes of Fe3S4. The results show that the peaks of the sample match the standard XRD pattern of Fe3S4. The XRD pattern of Fe3S4 / CDs has a new small peak at the position of 20°, which may be caused by amorphous carbon. The morphology of the material was studied by scanning electron microscope (TEM). The nanomaterials exhibit a hollow flower-like structure ( Figure 2 Figure 2p B), and the material has a larger contact area compared with pure Fe3S4. 2s As shown in the XPS spectrum of 1s Figure 1s A, the binding energies of 1s S, 2p S, Figure 2 C, 2p N, Figure 2 O and 2p1 / 2 Fe are 164 eV, 228 eV, 286 eV, 415 eV, 530 eV and 711 eV respectively, indicating that all elements are present in the material. In the C1s spectrum ( 2p3 / 2 Figure 3+ B), there are two peaks at 286.5 eV and 284.8 eV, corresponding to C-N bonds and C-C bonds respectively. In the high-resolution spectrum of Figure 2It can be seen that the binding energies at 163.7 eV and 164.5 eV correspond to S 2p3 / 2 and S 2p1 / 2 , respectively, and the 167.8 eV corresponds to the satellite peak.

[0039] Example 2: Peroxidase-like catalytic activity of Fe3S4 / CDs nanomaterials.

[0040] Add 2610 μL of NaAc-Hac, 200 μL of TMB, 40 μL of H2O2, and 50 μL of Fe3S4 / CDs into a 4 mL centrifuge tube, and shake the resulting mixture at 30 °C for 20 min.

[0041] As Figure 3 shown in the inset of Figure 3 A, TMB is oxidized to oxTMB under the action of peroxidase, forming a bright blue suspension. In the buffer solution, only TMB / H2O2 is added as a blank control, and CDs, Fe3S4, and Fe3S4 / CDs are added respectively to observe the ultraviolet-visible absorption spectra (

[0042] A) of each system. It can be found that the absorbance (0.615 a.u.) after adding Fe3S4 / CDs is higher than that after adding Fe3S4 and CDs (0.423 a.u. and 0.050 a.u.), which confirms the improved peroxidase-like activity of Fe3S4 / CDs.

[0043] As Figure 3 shown in

[0044] B, observe the change of enzyme activity of the material in the pH range of 2.0 - 8.0. By measuring the absorbance of the test system at 652 nm, it is found that as the pH value of the solution increases from 2.0 to 3.5, the absorbance rapidly increases to (0.506 a.u.). However, as the pH value further increases to 8.0, the absorbance rapidly decreases (0.01 a.u.). Therefore, the peroxidase activity of the material is the highest at pH 3.5. Figure 3 C, when the temperature increases from 10 °C to 35 °C, the absorbance of the solution at 652 nm gradually increases from (0.395 a.u.) to (0.549 a.u.); but when the temperature continues to rise from 35 °C to 55 °C, the absorbance of the solution slowly decreases to (0.19 a.u.). From the above experiments, it can be concluded that Fe3S4 / CDs has the maximum peroxidase-like activity at 35 °C.

[0045] The amount of Fe3S4 / CDs during the experiment also has a direct impact on enzyme activity. When the amount of Fe3S4 / CDs material in the system gradually increases to 50 μg / mL, the absorbance of the solution at 652 nm slowly increases to (0.615 a.u.), and it can be found that after further increasing the amount, the absorbance does not change significantly ( Figure 3 D). From the aspect of saving material usage and achieving the best catalytic effect, 50 μg / mL is confirmed as the optimal amount.

[0046] In summary, the optimal catalytic conditions are: solution pH is 3.5, reaction temperature is 35 °C, and material usage is 50 μg / mL. Under the optimized optimal experimental conditions, the steady-state kinetics of the colorimetric sensor based on this nanomaterial was studied using the Michaelis-Menten equation. As Figure 4 shown, in the experiments, TMB and hydrogen peroxide were used as substrates respectively. Each time an experiment was carried out, the substrate concentration was changed once, and the experiments at each concentration were repeated three times. The lower the Km value, the higher the affinity between the nanozyme and the substrate. As shown in the data in Table 1, the Km values obtained for this nanomaterial with different concentrations of TMB and hydrogen peroxide added were 0.186 and 0.366 respectively. Therefore, compared with the natural enzyme HRP, the affinity of the nanomaterial increased. These data indicate that Fe3S4 / CDs greatly improves the peroxidase activity.

[0047] Table 1 Comparison of catalytic kinetic parameters of Fe3S4 / CDs and horseradish peroxidase

[0048] .

[0049] The enzyme-catalyzed colorimetric sensing system generally generates three active substances, namely h + , O 2− and ·OH, which can be scavenged by scavengers PBQ, EDTA, and IPA respectively. If these three active substances are generated during the catalytic reaction, then with the addition of the scavengers, the absorbance of the catalytic system will decrease. As Figure 5 shown, after adding PBQ, the absorbance of the system decreased more, indicating that h + plays a major role during the catalysis. After adding the other two radical scavengers, the absorbance of the system also decreased slightly, indicating that the other two radicals are also involved in the catalytic process. The above data show that this catalyst can greatly promote the decomposition of hydrogen peroxide, release free radicals, and thus improve the catalytic activity.

[0050] Example 3:

[0051] 2610 μL of NaAc-Hac (concentration 20 mM, pH 3.5), 200 μL of TMB, 40 μL of H2O2, and 50 μL of Fe3S4 / CDs were added to a 4 mL centrifuge tube. After the resulting mixture was shaken and reacted at 30 °C for 20 min, 100 μL of p -Ap with different concentrations was added, and the spectrum of the system was measured using a UV-visible spectrophotometer.

[0052] Figure 6 It was shown that as p -Ap increased continuously, the peaks at 371 nm and 652 nm in the spectrum decreased continuously. In the range of 10 - 100 μmol / L, A 371 / A 652 showed a good linear relationship: Y = 0.01 + 0.0052X (R 2 = 0.994).

[0053] Example 4:

[0054] 2610 μL of NaAc-Hac (concentration 20 mM, pH 3.5), 200 μL of TMB, 40 μL of H2O2, and 50 μL of Fe3S4 / CDs were added to a 4 mL centrifuge tube, and the solution concentration was 200 μM. After the resulting mixture was shaken and reacted at 30 °C for 20 min, a series of interfering substances were added to the system, including Ca 2+ , K + , Mg 2+ , NO 3- , SO4 2- , CO3 2- , Glu, Thr, and p-Np, and no obvious color change occurred, indicating that the selectivity of this detection system is very good.

[0055] Example 5:

[0056] (1) River water, tap water, and drinking water were respectively taken from the river, water pipe, and water dispenser of Wenzhou Medical University. The standard addition method was used to detect the three water samples. The water samples were filtered through a syringe filter (0.45 μm) and reserved for use.

[0057] (2) 2610 μL of NaAc-Hac, 200 μL of TMB, 40 μL of H2O2, and 50 μL of Fe3S4 / CDs were added to a 4 mL centrifuge tube. After the resulting mixture was shaken and reacted at 30 °C for 20 min, 100 μL of the water sample to be measured was added, and the spectrum of the system was measured using a UV-visible spectrophotometer.

[0058] (3) Add 2610 μL of NaAc-Hac, 200 μL of TMB, 40 μL of H2O2, and 50 μL of Fe3S4 / CDs into a 4 mL centrifuge tube. After reacting the resulting mixture with shaking at 30 °C for 20 min, add 100 μL of the p water sample to be tested containing 60 μM

[0059] As shown in Table 3, p-aminophenol was not detected in the tap water, drinking water, and river water taken, indicating that the content of p-aminophenol in these samples was very low. At the same time, we used the standard addition method and added 60 μM p -Ap to the three water samples. The recovery rate was between 99.21 - 102.42%, and the relative standard deviation was less than 3.94%. These test results prove that this colorimetric detection platform can be used for the sensitive detection of p -Ap in different water samples.

[0060] Table 2 Colorimetric detection of p -Ap in different water samples

[0061] .

[0062] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of the rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. An Fe3S4 / CDs nanomaterial with peroxidase-like catalytic activity, characterized in that The preparation method comprises the following steps: (1) Using bayberry as raw material, carbon dots are prepared by hydrothermal method; (2) Using the prepared carbon dots as solvent, ferric sulfate and L-cysteine are added, and Fe3S4 / CDs nanomaterials are synthesized by one-step solvothermal synthesis method; In step (1), the bayberry is crushed, mixed well with ultrapure water, heated at 190 °C for 11 h after sealing, cooled to room temperature, and the filtrate is taken by filtering with a 0.22 μm microporous membrane filter; In step (2), the molar ratio of ferric sulfate to L-cysteine is 1:1; In step (2), ferric sulfate and L-cysteine are added to the carbon dots and mixed well, heated at 190 °C for 12 h after sealing, the synthesized solid product is separated by magnetic adsorption after cooling to room temperature, and then rinsed with distilled water and ethanol, and the Fe3S4 / CDs nanomaterials are obtained after drying.

2. Application of the Fe3S4 / CDs nanomaterials with peroxidase-like catalytic activity as described in claim 1 in the preparation of products for detecting the content of p-aminophenol.

3. A method for detecting p-aminophenol, characterized in that Comprises the following steps: First, a buffer solution with a pH of 2-5, TMB, H2O2, and the Fe3S4 / CDs nanomaterials with peroxidase-like catalytic activity as described in claim 1 are mixed and subjected to a shaking reaction at 25-55 °C; Second, a test solution is added to the system after the shaking reaction in the first step for reaction.

4. The method for detecting p-aminophenol according to claim 3, characterized in that: In the first step, the pH of the buffer solution is 3-4.

5. The method for detecting p-aminophenol according to claim 4, characterized in that: In the first step, the pH of the buffer solution is 3.

5.

6. The method for detecting p-aminophenol according to claim 3, characterized in that: In the first step, the reaction temperature is 30-40 °C.

7. The method for detecting p-aminophenol according to claim 3, wherein: Step 2, after the reaction, measure by ultraviolet-visible spectrophotometer. In the range of 10 - 100 μmol / L, A 371 / A 652 shows a linear relationship.

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