Method for quantitatively detecting thiocyanate ions through PCN-224-Fe complex reaction

Abstract

The invention discloses a method for quantitatively detecting thiocyanate ions through PCN-224-Fe complexation reaction, and belongs to the technical field of nano sensing, the method for quantitatively detecting thiocyanate ions through PCN-224-Fe complexation reaction can be used for detecting the concentration of thiocyanate ions in food or human body fluid, and the method is high in detection sensitivity, rapid, accurate and low in cost. The method has practical application in practical sample analysis.

Description

Technical Field

[0001] The invention belongs to the technical field of nanosensors, and more specifically, relates to a method for quantitatively detecting thiocyanate ions through a PCN-224-Fe complex reaction. Background Art

[0002] Thiocyanate ions are widely present in nature. For example, foods such as milk may contain a certain amount of thiocyanate ions. In addition, some industrial processes and chemicals may also be sources of thiocyanate ions. The human body can be exposed to thiocyanate ions through food intake, skin contact or inhalation. Thiocyanate ions have potential acute and chronic toxic effects on the human body. Therefore, the detection of thiocyanate ions (SCN) in food and body fluids is very important. - ) content is of great significance.

[0003] With the development of the times, detection of SCN - Recently, the detection of SCN - There are many methods for SCN detection, such as fluorescence, ion chromatography, gas chromatography, electrochemistry, etc. However, these methods are often accompanied by disadvantages such as low sensitivity, expensive and complex instruments, and the need for professional personnel. Therefore, it is necessary to develop a method with high sensitivity, rapid and accurate detection of SCN at low cost. - The method is crucial.

[0004] Porphyrin, as a macromolecular heterocyclic compound, exists in nature in coordination with metal ions, such as chlorophyll (magnesium porphyrin), heme (iron porphyrin), ceruloplasmin (copper porphyrin), etc., and has good enzymatic activity. As an important branch of MOFs, the PCN series of materials is a channel-type framework structure material with a large specific surface area, among which PCN-224 is a prominent representative. PCN-224 has a porphyrin cavity, and its structure is similar to heme. When metals are doped into the cavity, a structure similar to heme (iron porphyrin) is formed, and materials with enzyme-like properties can be obtained. Therefore, doping metals into the porphyrin cavity of PCN-224 provides a good platform for the design and performance development of nanozymes. Summary of the invention

[0005] An object of the present invention is to address at least the above-mentioned disadvantages and to provide at least the advantages which will be described hereinafter.

[0006] The present invention provides a method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction, which realizes the quantitative detection of SCN by simple complex reaction. - Using metal-doped PCN-224 as a nanosensor, based on Fe and SCN - The precipitation reaction occurred, achieving SCN - Quantitative detection.

[0007] The invention provides a method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction, which is used for detecting the concentration of thiocyanate ions in food or human body fluids.

[0008] Preferably, the method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction is used for detecting the thiocyanate ion content in milk or human urine samples.

[0009] Preferably, the method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction comprises adding PCN-224-Fe, H2O2 and TMB to the analyte, and adding NaAc-HAc buffer solution to make the solution pH = 4, mixing to obtain a mixture solution, recording the ultraviolet absorbance at 652 nm after 10 minutes, and calculating the content of thiocyanate ions; wherein the concentration of PCN-224-Fe in the mixture solution is 9 μg / mL, the concentration of TMB is 0.5 mM, and the concentration of H2O2 is 10 mM.

[0010] Preferably, the synthesis method of the above PCN-224-Fe comprises: Step 1, dissolving TCPP, ZrOCl2·8H2O and benzoic acid in DMF, and then placing in a 90 °C oil bath for reaction for 6 h to obtain a purple mixture; purifying the obtained mixture by centrifugation, washing the precipitate with DMF until the supernatant is clear, and freeze-drying to obtain PCN-224; wherein the weight ratio of TCPP: ZrOCl2·8H2O: benzoic acid is 0.05: 0.15: 1.4; Step 2: Disperse PCN-224 and FeCl3·6H2O in DMF, and then place it in an oil bath at 120 °C for 12 hours to obtain a reddish-brown mixture; purify it by centrifugation, wash the precipitate with DMF until the supernatant is clear, and freeze-dry to obtain PCN-224-Fe; wherein the weight ratio of PCN-224:FeCl3·6H2O is 50:150.

[0011] Preferably, the centrifugal speed for purification by centrifugation in step 1 and step 2 is 10000 rpm and the centrifugation time is 30 min.

[0012] The sensor detects SCN - The linear range is 0.1 μM-20 μM, and the detection limit is 44 nM (0.1-1 μM) and 0.41 μM (1-20 μM). This detection method can be applied to SCN in milk. - Content detection, due to SCN in milk -The content is low, and the recovery rate through spike addition is 97.33%-100.78%, indicating that the detection method is highly sensitive, rapid, accurate and low-cost, and can be used for actual sample detection.

[0013] The present invention has at least the following beneficial effects: The present invention utilizes PCN-224-Fe to monitor the thiocyanate ion (SCN - ) levels are of great significance to food safety and human health.

[0014] The present invention develops a SCN based on an iron-modified porphyrin metal organic framework (PCN-224-Fe). - Detection method. 3+ The modification in PCN-224 resulted in the formation of Fe-N4 structure and endowed the nanoprobe with peroxidase-like activity, whereby the colorless TMB was oxidized to blue oxTMB in the presence of H2O2. 3- The formation of SCN - The active Fe-N4 site can be destroyed, thereby inhibiting the peroxidase-like activity of PCN-224-Fe and the oxidation of TMB. - The colorimetric linear concentration responses were 0.1-1μM and 1-20μM, respectively, and the detection limits were 44 nM and 0.41μM, respectively. The method showed its sensing accuracy for SCN- in milk and human urine samples, with recoveries ranging from 97.33% to 100.78%, proving that the detection method of the present invention is highly sensitive, rapid, accurate, and low-cost, and has practical applications in actual sample analysis.

[0015] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the XPS comparison chart of PCN-224 and PCN-224-Fe; Figure 2 for Figure 1 High-resolution spectrum peak fitting diagram of Fe2p; Figure 3 This is a comparison of fluorescence spectra of PCN-224 and PCN-224-Fe; Figure 4 This is a comparison chart of the UV spectra of PCN-224 and PCN-224-Fe; Figure 5 TEM image of PCN-224-Fe; Figure 6This is a curve diagram for verifying the activity of PCN-224-Fe peroxidase; Figure 7 This is a graph showing the stability of PCN-224-Fe peroxidase activity; Figure 8 Detection of SCN for PCN-224-Fe - Standard curve graph. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0018] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0019] The invention provides a method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction, which is used for detecting the concentration of thiocyanate ions in food or human body fluids.

[0020] Furthermore, the method of quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction is used to detect the thiocyanate ion content in milk or human urine samples.

[0021] Furthermore, a method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction is provided, specifically, PCN-224-Fe, H2O2 and TMB are added to the milk sample to be tested, and NaAc-HAc buffer solution pH=4 is added, mixed to obtain a mixture solution, and the absorbance at 652 nm is recorded after 10 minutes, and the content of thiocyanate ions is calculated; wherein, the concentration of PCN-224-Fe in the mixture solution is 9 μg / mL, the concentration of TMB is 0.5 mM, and the concentration of H2O2 is 10 mM.

[0022] During the calculation process, a standard linear equation was first established, and the absorbance value of the PCN-224-Fe-H2O2-TMB reaction system was related to the SCN - The concentrations show a good bilinear relationship ( Figure 8 ). At 0.1-1 μM, the linear equation is Y=-0.498X+1.809(R 2 =0.989), the detection limit was 44nM; at 1-20 μM, the linear equation was Y=-0.053X+1.295(R 2 =0.990) with a detection limit of 0.41 μM.

[0023] Example 1 Step 1: TCPP (0.05 g), ZrOCl2·8H2O (0.15 g) and benzoic acid (1.4 g) were dissolved in 50 mL DMF, and then the solution was transferred to a round-bottom flask and reacted in a 90 °C oil bath for 6 h to obtain a purple mixture. The obtained mixture was purified by centrifugation, that is, the mixture was centrifuged at a centrifugal speed of 10,000 rpm for 30 min, the precipitate was dispersed and washed with DMF, and then centrifuged for multiple times until the supernatant was clear, and the precipitate was freeze-dried to obtain PCN-224.

[0024] Step 2: PCN-224 (50 mg) and FeCl3·6H2O (150 mg) prepared in step 1 were dispersed in 20 mL of DMF, and then the solution was transferred to a round-bottom flask and reacted in an oil bath at 120 °C for 12 h to obtain a reddish-brown mixture. Purification was performed by centrifugation, that is, the mixture was centrifuged at a centrifugal speed of 10,000 rpm for 30 min, the precipitate was dispersed and washed with DMF, and then centrifuged again, and this was repeated several times until the supernatant was clear, and the precipitate was freeze-dried to obtain PCN-224-Fe.

[0025] Step 3. Add the PCN-224-Fe synthesized in step 2, as well as H2O2 and TMB to the milk sample to be tested, and add NaAc-HAc buffer solution to make the solution pH = 4. The total volume of the mixture solution is prepared to 2 mL. After 10 min, the ultraviolet absorbance at 652 nm is recorded. The content of thiocyanate ion in the milk sample to be tested can be calculated using a linear equation; wherein the concentration of PCN-224-Fe in the mixture solution is 9 μg / mL, the concentration of TMB is 0.5 mM, and the concentration of H2O2 is 10 mM.

[0026] Experiment 1: Analysis of the physical and chemical properties of PCN-224-Fe The PCN-224 of Example 1 and PCN-224-Fe were compared by X-ray photoelectron spectroscopy. Figure 1 As shown, XPS, as a surface analysis technique, can understand the elemental composition and chemical state of materials, and thus understand the properties of materials. The full XPS spectrum of PCN-224 and PCN-224-Fe shows that the peak of Fe2p appears in PCN-224-Fe, and the peak of Fe2p is located at 711.08 eV.

[0027] Figure 2 The high-resolution spectrum of Fe2p is shown to be fitted, and 711.08 eV and 724.88 eV belong to the peaks of Fe(III). The synthesis of PCN-224-Fe was analyzed by UV-vis. Figure 3The fluorescence spectra of PCN-224 and PCN-224-Fe are compared. Figure 4 The figure shows a comparison of the UV spectra of PCN-224 and PCN-224-Fe. When Fe is doped into the porphyrin cavity of PCN-224, the fluorescence of PCN-224 at 650 nm is quenched, and the four absorption peaks of the Q band of PCN-224 at 500-700 nm are reduced to two, indicating that Fe is successfully doped into the porphyrin cavity of PCN-224.

[0028] Figure 5 The TEM image of PCN-224-Fe shows that when Fe 3+ After doping into the PCN-224 cavity, the edges become blurred.

[0029] Figure 6 The peroxidase activity of PCN-224-Fe was verified by catalytic oxidation of TMB in the presence of H2O2. In the TMB+H2O2+PCN-224-Fe group, an obvious absorption peak appeared at 652 nm, indicating that PCN-224-Fe has peroxidase activity.

[0030] Figure 7 The stability of the peroxidase activity of PCN-224-Fe is shown. The enzyme activity of PCN-224-Fe was measured for 30 consecutive days, in which PCN-224-Fe (9 μg / mL), TMB (0.5 mM), and H2O2 (10 mM) were present in the solution. Within 30 days, the catalytic activity of PCN-224-Fe remained basically unchanged, indicating that PCN-224-Fe has good catalytic stability.

[0031] Test 2 Take the PCN-224-Fe synthesized in step 2, as well as H2O2 and TMB, add NaAc-HAc buffer solution to make the solution pH = 4, add different concentration gradients of SCN-, and the volume of the mixture solution is 2 mL; wherein, the concentration of PCN-224-Fe in the mixture solution is 9 μg / mL, the concentration of TMB is 0.5 mM, and the concentration of H2O2 is 10 mM; measure its ultraviolet absorbance at 652 nm, and obtain the absorbance value of the PCN-224-Fe-H2O2-TMB reaction system and SCN - The concentrations show a good bilinear relationship ( Figure 8 ). At 0.1-1 μM, the linear equation is Y=-0.498X+1.809(R 2=0.989), the detection limit was 44nM; at 1-20 μM, the linear equation was Y=-0.053X+1.295(R 2 =0.990) with a detection limit of 0.41 μM.

[0032] Test 3 PCN-224-Fe (18 μg), H2O2 (20 μL, 1 M) and TMB (200 μL, 5 mM) were added to the spiked milk samples, and NaAc-HAc buffer solution was added to make the solution pH = 4 to determine the SCN in the milk samples. - The total volume of the mixture solution was 2 mL. After 10 min, the absorbance at 652 nm was recorded and the SCN was calculated. - The standard addition method was used to verify the detection of SCN in milk by PCN-224-Fe. - To ensure accuracy, record the absorbance at 652 nm and calculate SCN - The calculated concentration is then divided by the known SCN added - The concentration of the known SCN added to the qualified milk sample is - The concentrations were 0.1, 1, 3, and 5 μM, and the recovery rates verified by the above-mentioned spike addition were 97.33%-100.78%, indicating that the detection method of the present invention is highly sensitive, rapid, accurate, and low-cost, and can be applied to actual sample detection.

[0033] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and the embodiments. They can be applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily realized.

Claims

1. A method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction, characterized in that: Used to detect the concentration of thiocyanate ions in food or human fluids.

2. The method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction according to claim 1, characterized in that: Used to detect the content of thiocyanate ions in milk or human urine samples.

3. The method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction according to any one of claims 1 or 2, characterized in that: PCN-224-Fe, H2O2 and TMB were added to the test object, and NaAc-HAc buffer solution was added to make the solution pH = 4, and mixed to obtain a mixture solution. After 10 min, the ultraviolet absorbance at 652 nm was recorded, and the content of thiocyanate ion was calculated; wherein, the concentration of PCN-224-Fe in the mixture solution was 9 μg / mL, the concentration of TMB was 0.5 mM, and the concentration of H2O2 was 10 mM.

4. The method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction as claimed in claim 3, characterized in that: The synthesis method of the PCN-224-Fe comprises: Step 1, dissolving TCPP, ZrOCl2·8H2O and benzoic acid in DMF, and then placing in a 90 °C oil bath for reaction for 6 hours to obtain a purple mixture; purifying the obtained mixture by centrifugation, washing the precipitate with DMF until the supernatant is clear, and freeze-drying to obtain PCN-224; wherein the weight ratio of TCPP: ZrOCl2·8H2O: benzoic acid is 0.05: 0.15: 1.4; Step 2: Disperse PCN-224 and FeCl3·6H2O in DMF, and then place it in an oil bath at 120 °C for 12 h to obtain a reddish-brown mixture; purify it by centrifugation, wash the precipitate with DMF until the supernatant is clear, and freeze-dry to obtain PCN-224-Fe; wherein the weight ratio of PCN-224:FeCl3·6H2O is 50:

150.

5. The method for quantitatively detecting thiocyanate ions by PCN-224-Fe complex reaction according to claim 4, characterized in that: The centrifugal speed for purification by centrifugation method in step 1 and step 2 is 10000 rpm, and the centrifugation time is 30 min.

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