Cysteine modified ZnFe2O4 nano material for identifying 3-chloropropanol as well as preparation method and application of cysteine modified ZnFe2O4 nano material

Abstract

The invention belongs to the technical field of preparation and detection of nano materials, and relates to a cysteine modified ZnFe2O4 nano material for identifying 3-chloropropanol as well as a preparation method and application of the cysteine modified ZnFe2O4 nano material. The method comprises the following steps: firstly, taking ferric chloride and zinc chloride as raw materials, adding sodium acetate trihydrate and polyethylene glycol into an ethylene glycol solvent, heating in a water bath and reacting in an autoclave, and washing and drying to obtain the ZnFe2O4 nanoparticles. And then, mixing the prepared ZnFe2O4 with cysteine according to a ratio, carrying out ultrasonic dispersion and mechanical stirring treatment, centrifuging and drying to obtain the cysteine-coated ZnFe2O4 nano material. The material is high in surface functionalization degree, and can generate specific action with 3-chloropropanol to generate obvious optical or color change, so that rapid, sensitive and visual detection of 3-chloropropanol is realized. The invention has the advantages of simple preparation process, high detection speed, high sensitivity and strong applicability, and is suitable for the fields of food safety, environmental monitoring and the like.

Description

Technical Field

[0001] This invention relates to a cysteine-modified ZnFe2O4 nanomaterial that recognizes 3-chloropropanol, its preparation method and application, belonging to the field of nanomaterials technology. Background Technology

[0002] Chloropropanols are a series of compounds formed by the substitution of one or more hydroxyl groups on glycerol with chloride ions, and are a common contaminant in food processing. Therefore, chloropropanol compounds can be detected in foods with high fat content and some heat-processed foods. Among these compounds, 3-chloro-1,2-propanediol (3-MCPD) is the most abundant MCPD, so using 3-MCPD as the primary detection indicator can reflect the contamination status of chloropropanols during food processing.

[0003] Currently, the internationally accepted standard method for detecting 3-chloropropanol is isotope dilution gas chromatography-mass spectrometry (ID-GC-MS). While this method offers advantages such as high sensitivity and specificity, its inherent limitations restrict its rapid on-site screening and widespread application. Therefore, there is an urgent need in the food safety field to establish rapid, sensitive, and visualized detection methods to monitor and control 3-MCPD residue levels and reduce its risks to public health.

[0004] In recent years, nanomaterials have shown great potential in the field of sensing and detection. Paramagnetic zinc ferrite spinel (ZnFe2O4) (hereinafter referred to as ZFO) is a nanoscale magnetic material with certain colorimetric effects. Studies have confirmed that modifying the surface of nanomaterials with amino acids can enhance the binding ability of target molecules, and cysteine ​​is a special amino acid. Its thiol group can form a strong covalent bond with metal nanoparticles, thus achieving a firm surface modification; secondly, after the thiol group forms a covalent bond with the metal nanoparticles, the remaining amino and carboxyl groups of cysteine ​​can be used for further functionalization or recognition reactions. Among other amino acids, most amino acids do not have a thiol group to anchor to metal nanoparticles, so their binding is unstable. Therefore, by modifying ZFO with cysteine, a firm surface modification is formed by the thiol group, and then a nucleophilic substitution reaction occurs between the amino group of cysteine ​​and the -Cl group in 3-MCPD under certain conditions, the detection of 3-MCPD is achieved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a cysteine-modified ZnFe2O4 nanomaterial for identifying 3-chloropropanol, its preparation method, and its applications. This method utilizes the adsorption effect of ZnFe2O4 nanomaterials and the fact that the -NH2 group of cysteine ​​can react with the -Cl group in 3-chloropropanol under alkaline conditions. Since the cysteine-modified ZnFe2O4 nanomaterials are themselves colorimetric labels, a color difference will be generated after reacting with 3-chloropropanol, thereby achieving rapid and visual detection of 3-chloropropanol.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol, characterized by comprising the following steps: (1) Preparation of ZFO Ferric chloride and zinc chloride are dissolved in ethylene glycol, stirred and mixed, and then sodium acetate trihydrate and polyethylene glycol are added. The mixture is then heated in a water bath to obtain solution A. Solution A is heated in a high-pressure reactor to obtain solution B; Solution B was washed successively with pure water and anhydrous ethanol, then centrifuged and dried to obtain ZFO; (2) Cysteine-modified ZFO ZFO and cysteine ​​were dissolved in the same volume of anhydrous ethanol, and then subjected to ultrasonic treatment to obtain ZFO ethanol solution and cysteine ​​ethanol solution respectively. After mixing ZFO ethanol solution and cysteine ​​ethanol solution, the mixture is first subjected to ultrasonic treatment, then mechanical stirring. The ultrasonic and stirring operations are repeated 2 to 3 times, followed by aging, centrifugation, and finally the supernatant is discarded and dried to obtain cysteine-modified ZFO nanomaterials (hereinafter referred to as L-ZFO).

[0007] Preferably, in step (1), the molar ratio of ferric chloride to zinc chloride is controlled to be 2:1.

[0008] Preferably, in step (1), the stirring time is controlled to be 10 to 20 min, the water bath temperature is 45 to 55℃, and the time is 0.5 to 1.5 h.

[0009] Preferably, in step (1), the heating temperature of the high-pressure reactor is controlled at 180-220°C and the reaction time is 10-12 h.

[0010] Preferably, in step (2), the molar ratio of ZFO to cysteine ​​is controlled to be 1:4.

[0011] Preferably, in step (2), the time for each ultrasonic treatment is 15 to 30 minutes, and the time for each mechanical stirring is 0.5 to 1.5 hours.

[0012] Preferably, in step (2), the aging process parameters are: placed at room temperature for 12 h.

[0013] Preferably, in step (2), the centrifugation time is 10 min and the rotation speed is 400 rpm.

[0014] Secondly, the present invention provides a cysteine-modified ZnFe2O4 nanomaterial, characterized in that it is prepared by the above method.

[0015] Thirdly, the present invention provides the application of the above-mentioned cysteine-modified ZnFe2O4 nanomaterials in the detection of 3-chloropropanol.

[0016] Compared with the prior art, the present invention has the following advantages: ZFO is a colored label that can provide a significant colorimetric signal for qualitative detection; it has a special magnetic enrichment capability, which can easily separate the target from the food matrix in a magnetic field to reduce the matrix effect; after modifying ZFO with cysteine, the present invention further enhances its binding ability to 3-chloropropanol, enabling rapid and visual detection of 3-chloropropanol. Attached Figure Description

[0017] Figure 1 Scanning electron microscope image and elemental analysis diagram of ZFO prepared for this invention ( Figure 1 AB are scanning electron microscope images of ZFO. Figure 1 CD is a scanning electron microscope image of L-ZFO. Figure 1 EH is the elemental analysis diagram of ZFO. Figure 1 IL is the elemental analysis diagram of L-ZFO.

[0018] Figure 2 The particle size distribution diagram of ZFO prepared in this invention and the zeta potential diagram of whether or not it is modified with cysteine ​​are shown. Figure 2 A is the ZFO particle size distribution diagram. Figure 2 B represents the L-ZFO particle size. Figure 2 C represents the zeta potential diagram of ZFO and L-ZFO.

[0019] Figure 3 The magnetic performance test results of ZFO prepared in this invention are shown (the left side is a turbid ZFO solution, and the right side is a ZFO solution after being adsorbed by a magnet).

[0020] Figure 4 The ultraviolet absorption spectra of ZFO and L-ZFO prepared in this invention are shown.

[0021] Figure 5 The relationship curve between cysteine-modified ZFO prepared in this invention and 3-chloropropanol concentration ( Figure 5A is a graph showing the change of L-ZFO with 3-MCPD concentration. Figure 5 B is the concentration standard curve of L-ZFO and 3-MCPD.

[0022] Figure 6 The UV spectra of ZFO and 3-chloropropanol prepared for this invention with or without heating are shown.

[0023] Figure 7 A comparison of the fluorescence intensity of ZFO prepared in this invention, L-ZFO, and L-ZFO with added 3-MCPD. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0025] All raw materials involved in this invention can be purchased directly from the market. For process parameters not specifically specified, conventional techniques can be used as a reference.

[0026] The reagents used in this invention include: polyethylene glycol (PEG), manufactured by Shanghai Titan Technology Co., Ltd.; sodium acetate trihydrate, manufactured by Shanghai Titan Technology Co., Ltd.; ethylene glycol, manufactured by Sinopharm Chemical Reagent Co., Ltd.; ferric chloride hexahydrate, manufactured by Shanghai Titan Technology Co., Ltd.; zinc chloride, manufactured by Guangdong Guanghua Chemical Plant Co., Ltd.; DL-cysteine, manufactured by Shanghai Aladdin Biochemical Technology Co., Ltd.; and anhydrous ethanol, manufactured by Sinopharm Chemical Reagent Co., Ltd. Example 1

[0027] A method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol includes the following steps: (1) Preparation of ZFO Ferric chloride and zinc chloride are dissolved in ethylene glycol, stirred and mixed, and then sodium acetate trihydrate and polyethylene glycol are added. The mixture is then heated in a water bath to obtain solution A. Solution A is heated in a high-pressure reactor to obtain solution B; Solution B was washed successively with pure water and anhydrous ethanol, then centrifuged and dried to obtain ZFO; (2) Cysteine-modified ZFO ZFO and cysteine ​​were dissolved in the same volume of anhydrous ethanol, and then subjected to ultrasonic treatment to obtain ZFO ethanol solution and cysteine ​​ethanol solution respectively. After mixing ZFO ethanol solution and cysteine ​​ethanol solution, the mixture is first subjected to ultrasonic treatment, then mechanical stirring. The ultrasonic and stirring operations are repeated 2 to 3 times, followed by aging, centrifugation, and finally the supernatant is discarded and dried to obtain L-ZFO. Example 2

[0028] A method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol includes the following steps: (1) Preparation of ZFO According to the molar ratio of ferric chloride to zinc chloride of 2:1, 1.35 g of ferric chloride hexahydrate and 0.34 g of zinc chloride were weighed and dissolved in 40 mL of ethylene glycol. After stirring on a magnetic stirrer for 15 min to mix, a clear orange solution was obtained. Then, 3.6 g of sodium acetate trihydrate and 1 g of polyethylene glycol were added, and the mixture was placed in a 50℃ water bath and stirred for 1 h to obtain solution A. Solution A was placed in a high-pressure reactor and reacted at 200°C for 12 hours to obtain solution B. Wash solution B with pure water and anhydrous ethanol 2-3 times in sequence, then centrifuge and dry to obtain ZFO; store the obtained ZFO in a refrigerator at 4 ℃ for later use.

[0029] (2) Cysteine-modified ZFO According to the molar ratio of ZFO to cysteine ​​of 1:4, weigh 0.58 g of ZFO obtained in step (1) and weigh 0.121 g of cysteine, dissolve them in 10 mL of anhydrous ethanol respectively, and then perform ultrasonic treatment for 30 min to obtain ZFO ethanol solution and cysteine ​​ethanol solution. After mixing ZFO ethanol solution and cysteine ​​ethanol solution, the mixture is first subjected to ultrasonic treatment for 30 minutes, followed by mechanical stirring for 1 hour. The ultrasonic and stirring operations are repeated 2-3 times, then aged, centrifuged, and finally the supernatant is discarded and dried at 50°C to obtain L-ZFO. Example 3

[0030] Electron microscopy and elemental analysis of ZFO and L-ZFO.

[0031] The ZFO prepared in step (1) and the L-ZFO prepared in step (2) of Example 2 were subjected to electron microscopy and elemental analysis. The results are shown in the figure. Figure 1 .Depend on Figure 1 From A and B, we can see that ZFO itself is a hollow, unevenly shaped sphere, which facilitates surface modification with functional groups. As shown in the elemental analysis diagram, Figure 1 Elemental analysis of ZFO was performed at a magnification of 1 μm (E). Figure 1 From F, G, and H, we can see that the elemental distributions of Zn, Fe, and O are roughly as follows: Figure 1 As shown in E, the successful synthesis of ZFO can be inferred. Figure 1I confirmed the uniform distribution of N, S, and Fe, further suggesting the successful coating of L-Cys. Example 4

[0032] Particle size and zeta potential determination of ZFO and L-ZFO.

[0033] The particle size of ZFO prepared in step (1) of Example 2 was measured, and the results are shown in the figure. Figure 2 A. The ZFO prepared in step (1) and the L-ZFO prepared in step (2) of Example 2 were subjected to potential measurement, and the results are shown in [the table below]. Figure 2 B.

[0034] Depend on Figure 2 As can be seen from A, the particle size of the synthesized ZFO particles is around 300 nm, and after coating with cysteine, Figure 2 The particle size of B increased to 432 nm, further confirming the successful modification with L-Cys. Figure 2 The change in potential from positive to negative in C provides strong evidence for the modification of cysteine. Example 5

[0035] Performance testing of ZFO and L-ZFO.

[0036] (1) Weigh 1.0 mg of ZFO obtained in step (1) of Example 2 and dissolve it in 1 mL of pure water to obtain a 1 mg / mL ZFO solution. Then, disperse it by ultrasonication until the solution becomes turbid. Place a magnet next to the turbid solution and record the time required for the solution to become basically clear from a turbid state. Figure 3 As shown in the figure. Take 600 μL of 1 mg / mL ZFO solution and add 400 μL of pure water to obtain a 0.6 mg / mL ZFO solution. Set the wavelength range of the UV spectrophotometer to 200 nm~800 nm and record the test results as shown in the figure. Figure 4 As shown. By Figure 4 It can be seen that the peak position of ZFO measured by the ultraviolet spectrophotometer is around 425nm.

[0037] (2) Weigh 1.0 mg of L-ZFO obtained in step (2) of Example 2 and dissolve it in 1 mL of pure water to obtain a 1.0 mg / mL L-ZFO solution. Take 400 μL of the mother solution and add 600 μL of pure water to obtain 1 mL of a 0.4 mg / mL L-ZFO sub-solution. Measure the solution using a UV spectrophotometer. Set the wavelength range of the UV spectrophotometer to 200 nm to 800 nm and record the test results. The results are as follows: Figure 4 As shown.

[0038] Depend on Figure 4It can be seen that the L-ZFO UV absorption peak has an additional shoulder peak at around 250nm compared to ZFO, which may be due to the modification of cysteine. Example 6

[0039] Reaction effect test of L-ZFO with 3-chloropropanol.

[0040] (1) The reaction effect of L-ZFO with different concentrations of 3-chloropropanol Weigh 1.0 mg of L-ZFO obtained in step (2) of Example 2 and dissolve it in 1 mL of pure water to obtain a 1.0 mg / mL L-ZFO solution. Take 600 μL of the mother solution and add 400 μL of pure water to obtain 1 mL of a 0.6 mg / mL L-ZFO sub-solution. Add 10, 20, 30, 40, and 50 μL of 3-chloropropanol to the sub-solution to obtain different concentration gradients. Set the wavelength range of the UV spectrophotometer to 200 nm to 800 nm for testing. Compare with Example 5. The results are shown in the figure. Figure 5 A.

[0041] Depend on Figure 5 As shown in AB, the absorbance of the solution decreases with increasing 3-MCPD concentration. Plot a standard curve comparing 3-MCPD concentration with L-ZFO.

[0042] (2) Reaction effect of L-ZFO with 3-chloropropanol under heating conditions: 1.0 mg of L-ZFO obtained in step (2) of Example 2 was weighed and dissolved in 1 mL of pure water to obtain a 1.0 mg / mL L-ZFO solution. 600 μL of the mother liquor was taken and 400 μL of pure water was added to obtain 1 mL of L-ZFO sub-liquid with a concentration of 0.46 mg / mL. 50 μL of 3-chloropropanol was added to the sub-liquid, and the solution was heated in a water bath at 25℃ and 100℃ respectively. Then, the wavelength range of the ultraviolet spectrophotometer was set to 200 nm~800 nm for testing, and the results were compared with the blank group without the addition of 3-chloropropanol. The data were recorded as follows. Figure 6 As shown.

[0043] Depend on Figure 6 It can be seen that as the temperature increases, the L-ZFO solution with added 3-MCPD becomes significantly clearer, indicating that temperature has a significant impact on the reaction between -Cl in 3-MCPD and -NH2 in L-ZFO. Example 7

[0044] Fluorescence performance testing of L-ZFO.

[0045] 1. Sample preparation Weigh 1.0 mg of ZFO obtained in step (1) of Example 2 and dissolve it in 1 mL of pure water to obtain a ZFO solution of 1.0 mg / mL. Take 400 μL of the mother liquor and add 600 μL of pure water to obtain 1 mL of ZFO sub-liquid of 0.4 mg / mL. Weigh 1.0 mg of L-ZFO obtained in step (2) of Example 2 and dissolve it in 1 mL of pure water to obtain an L-ZFO solution with a concentration of 1.0 mg / mL. Take 400 μL of the mother liquor and add 600 μL of pure water to obtain 1 mL of L-ZFO sub-liquid with a concentration of 0.4 mg / mL. Weigh 1.0 mg of L-ZFO obtained in step (2) of Example 2 and dissolve it in 1 mL of pure water to obtain an L-ZFO solution with a concentration of 1.0 mg / mL. Take 400 μL of the mother liquor and add 600 μL of pure water to obtain 1 mL of L-ZFO sub-liquid with a concentration of 0.4 mg / mL. Add 50 μL of 3-chloropropanol to the sub-liquid to obtain the ZFO sub-liquid with added 3-chloropropanol. Fluorescence signals were measured for ZFO sub-solutions (ZFO group), L-ZFO sub-solution (L-ZFO group), and ZFO sub-solution with added 3-chloropropanol (+3-MCPD group), all with a concentration of 0.4 mg / mL. The results are as follows: Figure 7 As shown.

[0046] Depend on Figure 7 It can be seen that ZFO fluorescence is stronger than L-ZFO. After modification with cysteine, its fluorescence intensity is further reduced. On the other hand, after adding 3-MCPD, the fluorescence intensity of L-ZFO is also further reduced.

Claims

1. A method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol, characterized in that, Includes the following steps: (1) Preparation of ZFO Ferric chloride and zinc chloride are dissolved in ethylene glycol, stirred and mixed, and then sodium acetate trihydrate and polyethylene glycol are added. The mixture is then heated in a water bath to obtain solution A. Solution A is heated in a high-pressure reactor to obtain solution B; Solution B was washed successively with pure water and anhydrous ethanol, then centrifuged and dried to obtain ZFO; (2) Cysteine-modified ZFO ZFO and cysteine ​​were dissolved in the same volume of anhydrous ethanol, and then subjected to ultrasonic treatment to obtain ZFO ethanol solution and cysteine ​​ethanol solution respectively. After mixing ZFO ethanol solution and cysteine ​​ethanol solution, the mixture is first subjected to ultrasonic treatment, then mechanical stirring. The ultrasonic and stirring operations are repeated 2-3 times, followed by aging, centrifugation, and finally the supernatant is discarded and dried to obtain cysteine-modified ZFO nanomaterials.

2. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (1), the molar ratio of ferric chloride to zinc chloride is controlled to be 2:

1.

3. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (1), the stirring time is controlled to be 10-20 min, the water bath temperature is 45-55℃, and the time is 0.5-1.5 h.

4. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (1), the heating temperature of the high-pressure reactor is controlled at 180-220℃ and the reaction time is 10-12h.

5. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (2), the molar ratio of ZFO to cysteine ​​is controlled to be 1:

4.

6. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (2), the time for each ultrasonic treatment is 15 to 30 minutes, and the time for each mechanical stirring is 0.5 to 1.5 hours.

7. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (2), the aging process parameters are: placed at room temperature for 12 h.

8. The method for preparing cysteine-modified ZnFe2O4 nanomaterials that recognize 3-chloropropanol as described in claim 1, characterized in that, In step (2), the centrifugation time is 10 min and the rotation speed is 4000 rpm.

9. A cysteine-modified ZnFe2O4 nanomaterial, characterized in that, It is prepared by the method described in any one of claims 1 to 8.

10. The application of the cysteine-modified ZnFe2O4 nanomaterial as described in claim 9 in the detection of 3-chloropropanol.

Images