A magnetic fluorescent nanosensor with a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate, its preparation method and application.

Abstract

The present application relates to a kind of 3-mercapto-1-propane sulfonic acid sodium modified Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor, specifically, the magnetic fluorescent nanosensor of the present application can be used to measure, detect, screen or separate silver ion.The present application synthesizes magnetic fluorescent nanosensor, simple operation, short synthesis time, rapid detection, and magnetic fluorescent nanosensor can be separated out by magnetic separation method, solve the enrichment, detection, separation of silver ion, realize the complete purification of silver ion and the problem of secondary pollution to environment.

Description

Technical Field

[0001] This invention belongs to the field of fluorescent nanosensors, specifically relating to a magnetic fluorescent nanosensor with a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate and its application in measuring, detecting, screening or separating silver ions, as well as in magnetic resonance imaging or fluorescence imaging; this invention also provides a method for preparing the magnetic fluorescent nanosensor. Background Technology

[0002] Silver has long attracted attention due to its unique chemical properties, including strong corrosion resistance and high antioxidant capacity. Because of its rarity and excellent luster, it is widely used in the manufacture of everyday items. However, this widespread use can easily impact the environment. Excessive human contact with silver can lead to silver poisoning and growth retardation, while excessive ingestion may damage the skin and eyes. Therefore, appropriate testing methods are needed to analyze its properties.

[0003] In recent years, magnetic nanomaterials have attracted great attention in the fields of analytical chemistry and biosensors due to their excellent stability, high biocompatibility, low toxicity, and strong magnetic responsiveness. Among them, superparamagnetic iron oxide (Fe3O4) has unique high coercivity and excellent controllable magnetic responsiveness. It can be manipulated by external magnetic fields, and its controllable size and surface can be easily functionalized. This has enabled researchers in various fields such as chemistry, biology, medicine, and materials science to use MNPs to construct multifunctional nanoprobes for many studies in wastewater treatment, bioimaging, and drug delivery.

[0004] However, due to the strong magnetic dipole attraction between particles, Fe3O4 nanoparticles tend to aggregate. Therefore, to improve stability, their surfaces are often modified with stabilizers such as organic compounds and oxides containing specific functional groups. Functionalizing and modifying the surface of Fe3O4 nanoparticles using various biocompatible polymers to impart new functions is currently a hot research topic. Introducing fluorescent materials while maintaining stability can enable magnetic resonance imaging and fluorescence imaging, leading to better magnetic separation and targeted movement.

[0005] Silver detection employs various instrumental techniques, including flame atomic absorption spectrometry, inductively coupled plasma atomic emission spectrometry, and electrochemical detection. In addition to these techniques, extraction methods utilizing molecular acceptors or chelating ligands have also been used to detect Ag(I). However, compared to traditional analysis, fluorescence detection offers significant advantages: rapid reaction, simple operation, low cost, and high sensitivity. Furthermore, it allows for deeper penetration and selection in higher three-dimensional space, enabling the observation of silver ion distribution during cell processing. Therefore, developing a highly stable, selective, sensitive, and rapid magnetic fluorescent nanosensor for the measurement, detection, screening, and separation of silver ions is of paramount importance. Summary of the Invention

[0006] In view of this, the present invention provides a Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate. It is simple to synthesize, has rapid detection and good selectivity, and can separate the magnetic fluorescent nanosensor by magnetic separation, thus solving the problems of silver ion enrichment, detection and separation, achieving complete purification of silver ions and avoiding secondary pollution to the environment.

[0007] Specifically, the present invention provides a magnetic fluorescent nanosensor (Ⅰ) with Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate. Sodium 3-mercapto-1-propanesulfonate is modified on the surface of Fe3O4@ZnS core-shell structure microspheres, the core of Fe3O4@ZnS core-shell structure microspheres is Fe3O4, wherein ZnS quantum dots are wrapped on the surface of Fe3O4.

[0008] In some specific embodiments of the present invention, the preparation of the Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate includes the following steps:

[0009] ①Preparation of Fe3O4 magnetic microspheres

[0010] FeCl3·6H2O was placed in a container, ethylene glycol was added, and the mixture was heated and stirred until it was fully dissolved to obtain a clear black solution. Then, sodium acetate and surfactant were added to the solution, and after stirring for a certain period of time, a reddish-brown viscous solution was obtained. The solution was then transferred to a polytetrafluoroethylene reactor, which was placed in a stainless steel jacket and sealed. The reactor was then placed in a forced-air drying oven for hydrothermal reaction for a certain period of time, and then removed and allowed to cool naturally for a certain period of time. After opening the reactor lid, the supernatant was removed, and the black precipitate at the bottom was collected. The precipitate was then washed with deionized water to obtain Fe3O4 nanomagnetic microspheres. Water was then added to prepare a dispersion for the next step of magnetic microsphere surface modification.

[0011] ②Preparation of Fe3O4@ZnS magnetic fluorescent nanoparticles

[0012] Take the Fe3O4 nanomagnetic microsphere dispersion obtained in step ①, add deionized water, add a small amount of ammonia to maintain pH stability, and stir for a certain time under constant temperature heating water bath; dissolve Zn(Ac)2·2H2O in deionized water and transfer it to Fe3O4 solution, slowly add Na2S·9H2O solution to Fe3O4 mixed solution, when the Na2S·9H2O solution is completely added, ZnS quantum dots will form on the surface of Fe3O4, stir for a certain time under constant temperature heating water bath, and wash with magnetic water until the aqueous solution is clear to prepare Fe3O4@ZnS magnetic fluorescent nanoparticles;

[0013] ③ Fabrication of Fe3O4@ZnS core-shell magnetic fluorescent nanosensors modified with sodium 3-mercapto-1-propanesulfonate

[0014] Fe3O4@ZnS magnetic fluorescent nanoparticles were dispersed in water, and then a sodium 3-mercapto-1-propanesulfonate acetic acid solution was added. The mixture was heated in a water bath and stirred in the dark for a certain period of time. Then, water was magnetically absorbed until the aqueous solution was clear, thus preparing a Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor (II) modified with sodium 3-mercapto-1-propanesulfonate.

[0015] This invention also provides a method for preparing a Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate, comprising the following steps:

[0016] ①Preparation of Fe3O4 magnetic microspheres

[0017] FeCl3·6H2O was placed in a container, ethylene glycol was added, and the mixture was heated and stirred at T1℃ to fully dissolve it, resulting in a clear black solution. Then, sodium acetate and a surfactant were added to the solution, and after stirring for t1 hours, a reddish-brown viscous solution was obtained. The solution was then transferred to a polytetrafluoroethylene reactor, which was placed in a stainless steel jacket and sealed. The reactor was then placed in a forced-air drying oven for hydrothermal reaction at T2℃ for t2 hours. After removal and natural cooling for t3 hours, the reactor lid was opened, the supernatant was removed, and the black precipitate at the bottom was collected. The precipitate was then washed with deionized water to obtain Fe3O4 magnetic nanospheres. Water was then added to prepare a dispersion for the next step of preparing Fe3O4@ZnS magnetic fluorescent nanoparticles.

[0018] ②Preparation of Fe3O4@ZnS magnetic fluorescent nanoparticles

[0019] Take the Fe3O4 nanomagnetic microsphere dispersion obtained in step ①, add deionized water, add a small amount of ammonia to maintain pH stability, and stir in a constant temperature water bath at T3℃ for t4 hours; dissolve Zn(Ac)2·2H2O in deionized water and transfer it to the Fe3O4 solution, and slowly add Na2S·9H2O solution to the Fe3O4 mixed solution. When the Na2S·9H2O solution is completely added, ZnS quantum dots will form on the surface of Fe3O4. Stir in a constant temperature water bath at T4℃ for t5 hours, and wash with magnetic water until the aqueous solution is clear to prepare Fe3O4@ZnS magnetic fluorescent nanoparticles;

[0020] ③ Fabrication of Fe3O4@ZnS core-shell magnetic fluorescent nanosensors modified with sodium 3-mercapto-1-propanesulfonate

[0021] Fe3O4@ZnS magnetic fluorescent nanoparticles were dispersed in water, and then a sodium 3-mercapto-1-propanesulfonate acetic acid solution was added. The mixture was stirred in a water bath at 5°C in the dark for 6 hours, and then the solution was magnetically absorbed until it became clear, thus preparing a core-shell structured magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate.

[0022] In some specific embodiments of the present invention, T1 = 80-90; t1 = 0.5-1; T2 = 160-200; t2 = 10-12; t3 = 12-13; T3 = 80; t4 = 0.5-1; T4 = 70-80; t5 = 6-7; T5 = 40; t6 = 4.

[0023] In some specific embodiments of the present invention, T1 = 85; t1 = 0.5; T2 = 200; t2 = 12; t3 = 12; T3 = 80; t4 = 0.5; T4 = 80; t5 = 6; T5 = 40; t6 = 4.

[0024] In some specific embodiments of the present invention, in the preparation steps ①-③ of the method for preparing the Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate, the molar ratio of the components is: FeCl3·6H2O: sodium acetate = 1:0.3-1:0.8; Zn(Ac)2·2H2O: Na2S·9H2O = 1:0.5-1:2; Fe3O4@ZnS: sodium 3-mercapto-1-propanesulfonate = 1:1-1.5:1. The amount of Fe3O4@ZnS is based on the amount of zinc sulfide. The concentration of zinc sulfide can be adjusted according to the synthesized microspheres of different diameters to select the optimal fluorescence intensity. The molar ratio of sodium 3-mercapto-1-propanesulfonate to zinc sulfide can be adjusted according to the optimal fluorescence intensity.

[0025] In some specific embodiments of the present invention, the surfactant is polyethylene glycol.

[0026] This invention also provides a method for preparing a magnetic fluorescent nanosensor with a core-shell structure of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate. The magnetic fluorescent nanosensor with a core-shell structure of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate can be used for measuring, detecting, screening, separating silver ions, and for magnetic resonance imaging or fluorescence imaging.

[0027] The present invention also provides a magnetic fluorescent nanosensor composition for measuring, detecting, screening or separating silver ions, comprising a magnetic fluorescent nanosensor (I) or (II) with a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate.

[0028] In some specific embodiments of the present invention, the magnetic fluorescent nanosensor composition further comprises a solvent, an acid, a base, a buffer solution, or a combination thereof.

[0029] The present invention also provides a method for detecting the presence of silver ions in a sample or determining the silver ion content in a sample, comprising:

[0030] a) A product that produces a fluorescence change when a Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor (Ⅰ) or (Ⅱ) modified with sodium 3-mercapto-1-propanesulfonate is brought into contact with a sample.

[0031] b) Determine the fluorescence properties of the product.

[0032] In some specific embodiments of the present invention, the sample is a water sample, a chemical sample, or a biological sample.

[0033] The present invention also provides a method for separating silver ions from a sample, comprising:

[0034] a) Contact the Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor (Ⅰ) or (Ⅱ) modified with sodium 3-mercapto-1-propanesulfonate with the sample;

[0035] b) Separation of the sample from the Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate was achieved under an external magnetic field.

[0036] In some specific embodiments of the present invention, the sample is a water sample, a chemical sample, or a biological sample.

[0037] The present invention also provides a kit for detecting the presence of silver ions in a sample, determining the content of silver ions in a sample, or separating silver ions from a sample, comprising a magnetic fluorescent nanosensor (I) or (II) of a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate.

[0038] The present invention has the following significant advantages and effects compared with the prior art: the Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate of the present invention is used for the simultaneous ultrasensitive detection and removal of Ag in aqueous solution. + It exhibits significant fluorescence quenching and resistance to Ag. + It exhibits high selectivity. Furthermore, this magnetic fluorescent nanosensor is simple to synthesize, has a short synthesis time, and enables rapid detection, solving the problems of silver ion enrichment, detection, and separation, thus achieving complete purification of silver ions and reducing secondary pollution to the environment. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This describes the preparation of a magnetic fluorescent nanosensor with a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate.

[0041] Figure 2 These are SEM and TEM images of Fe3O4 magnetic microspheres (a,c) and Fe3O4@ZnS-MPS (b,d);

[0042] Figure 3 These are the XRD spectra of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic nanoparticles, and Fe3O4@ZnS-MPS.

[0043] Figure 4 These are the infrared spectra of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic nanoparticles, Fe3O4@ZnS-MPS, and sodium 3-mercapto-1-propanesulfonate.

[0044] Figure 5 The images show the XPS full spectrum analysis of Fe3O4@ZnS-MPS (a), and the high-resolution XPS spectra of Fe2p (b), Zn2p (c), and S2p (d) of Fe3O4@ZnS-MPS.

[0045] Figure 6 The graphs show the hysteresis loops of Fe3O4 magnetic microspheres and Fe3O4@ZnS-MPS.

[0046] Figure 7 Thermogravimetric curves of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic nanoparticles, and Fe3O4@ZnS-MPS are shown.

[0047] Figure 8 Does Fe3O4@ZnS-MPS contain Ag at different pH values? + Fluorescence intensity when present;

[0048] Figure 9 It is Ag + Comparison of fluorescence spectra of Fe3O4@ZnS-MPS before and after addition, with the inset showing Ag. + TEM images of Fe3O4@ZnS-MPS before and after addition;

[0049] Figure 10Fe3O4@ZnS-MPS with different concentrations of Ag + The fluorescence spectrum after (0-100 μM) is shown in the inset, where the fluorescence intensity and Ag are at 425 nm. + Linear relationship graph (0-100μM);

[0050] Figure 11 This section describes the effects of silver ions and other different ion analytes on the fluorescence intensity of Fe3O4@ZnS-MPS, as well as the fluorescence intensity of Fe3O4@ZnS-MPS after recognizing silver ions in the presence of different ion analytes. (a) The bar chart represents the fluorescence intensity of different metal ions (1, Co...). 2+ ;2,Pb 2+ ;3,Ni 2+ ; 4,Hg 2+ ;5,Al 3+ ;6,Cu 2+ 7, Zn 2+ ;8,Cd 2+ ;9,Fe 3+ ;10,Fe 2+ ;11,K + ;12,Ca 2+ ;13,Na + ;14,Ag + (b) The bar chart shows the proportion of MFNS fluorescence quenching when 1 equal amount of Ag+ is added to a solution containing 1 equal amount of other metal ions (1, Co). 2+ ;2,Pb 2+ ;3,Ni 2+ ; 4,Hg 2+ ;5,Al 3+ ;6,Cu 2+ 7, Zn 2+ ;8,Cd 2+ ;9,Fe 3+ ;10,Fe 2+ ;11,K + ;12,Ca 2+ ;13,Na + ;14, Blank);

[0051] Figure 12 It is Ag + Effect of initial concentration on adsorption capacity and removal rate of Fe3O4@ZnS-MPS. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention and should not be used to limit the scope of protection of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1: Fabrication of a Fe3O4@ZnS core-shell magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate

[0054] The following steps were taken to prepare a Fe3O4@ZnS core-shell magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate:

[0055] ①Preparation of Fe3O4 magnetic microspheres

[0056] Magnetic Fe3O4 nanoparticles were synthesized using a solvothermal method. The preparation process is as follows: 2.7 g of FeCl3·6H2O was placed in a 100 mL beaker, and 60 mL of ethylene glycol was added. The beaker was then placed in an 85 °C water bath and magnetically stirred until fully dissolved, resulting in a clear black solution. Next, 7.2 g of sodium acetate trihydrate and 0.5 g of surfactant were added to the solution, and the mixture was magnetically stirred for 30 min to obtain a reddish-brown viscous solution. The solution was then transferred to a 100 mL polytetrafluoroethylene (PTFE) reactor, which was placed in a stainless steel jacket and sealed tightly. The reactor was then placed in a forced-air drying oven and subjected to a hydrothermal reaction at 200 °C for 12 h. After removal and natural cooling for 12 h, the reactor lid was opened, the supernatant was removed, and the black precipitate at the bottom was collected. The precipitate was then washed 3–4 times with deionized water. The prepared Fe3O4 nanoparticles were then dispersed in water for further surface modification of magnetic microspheres.

[0057] ②Preparation of Fe3O4@ZnS magnetic fluorescent nanoparticles

[0058] Take 10 mL of the Fe3O4 dispersion prepared above, and dilute to 100 mL with deionized water. Add a small amount of ammonia to maintain pH stability, and stir in an 80℃ water bath for half an hour. Dissolve 2.5 mmol of Zn(Ac)2·2H2O in 50 mL of deionized water and transfer it to the Fe3O4 solution. Slowly add 50 mL of Na2S·9H2O (2.5 mmol) solution to the above mixed solution. After the Na2S·9H2O solution is completely added, ZnS quantum dots will form on the surface of Fe3O4. Stir in an 80℃ water bath for 6 hours, and magnetically wash with water until the aqueous solution is clear. The prepared Fe3O4@ZnS microspheres are then dispersed in water for the next step of magnetic microsphere surface modification.

[0059] ③ Fabrication of Fe3O4@ZnS core-shell magnetic fluorescent nanosensors modified with sodium 3-mercapto-1-propanesulfonate (MPS)

[0060] 5 mL of Fe3O4@ZnS ethanol solution was placed in a round-bottom flask, followed by 5 mL of sodium 3-mercapto-1-propanesulfonate (MPS) (89.105 mg, 0.1 mmol / L) aqueous solution. The mixture was stirred in a 40°C water bath in the dark for 4 h. The solution was then magnetically washed with water until clear, thus preparing a Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate.

[0061] Example 2: SEM and TEM tests of Fe3O4 and Fe3O4@ZnS-MPS

[0062] SEM testing conditions: At room temperature, take an appropriate amount of sample, disperse it with ethanol, and after drying, drop it onto the sample stage with conductive adhesive.

[0063] TEM testing conditions: At room temperature, take an appropriate amount of sample, disperse it with ethanol, take one drop, let it dry, and then test it.

[0064] The morphology and particle size of Fe3O4 magnetic microspheres and Fe3O4@ZnS-MPS core-shell nanocomposites were measured using SEM and TEM. Figures a and c show SEM and TEM images of the Fe3O4 magnetic microspheres, revealing that the Fe3O4 magnetic microspheres are regularly and uniformly distributed. Additionally, Figure b shows the SEM image of Fe3O4@ZnS-MPS (referring to the Fe3O4@ZnS core-shell magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate prepared in Example 1). Comparing Figures a and b, it can be seen that the ZnS particles modified with thiol groups aggregate on the Fe3O4 surface, making the surface of the Fe3O4 magnetic microspheres irregular and rough. Furthermore, Figure d shows the TEM image of Fe3O4@ZnS-MPS, indicating that the ZnS particles modified with thiol groups have been deposited on the surface of the Fe3O4 magnetic microspheres.

[0065] Example 3: XRD testing of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic fluorescent nanoparticles, and Fe3O4@ZnS-MPS

[0066] XRD testing conditions: Under room temperature conditions, the sample is ground and pressed into a pellet, and the measurement is performed at an angle of 5°-80°.

[0067] Figure 3The images show the XRD patterns of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic fluorescent nanoparticles, and Fe3O4@ZnS-MPS. In the XRD patterns, the Fe3O4 magnetic microspheres exhibit six diffraction peaks near 2θ = 30.1°, 35.6°, 43.1°, 53.7°, 57.1°, and 62.8°, corresponding to the (220), (311), (400), (422), (511), and (440) planes of the Fe3O4 cubic spinel crystal structure, respectively. The Fe3O4@ZnS magnetic fluorescent nanoparticles show three new diffraction peaks near 2θ = 28.9°, 47.7°, and 57.0°, confirming the presence of ZnS crystals in the composite material. The positions of the Fe3O4 diffraction peaks in Fe3O4@ZnS-MPS remained unchanged after modification with both quantum dots and thiol groups, indicating that the magnetic core Fe3O4 did not undergo chemical or structural changes during the coating process. It can be clearly seen that the diffraction peaks before and after functionalization are essentially consistent, indicating that the crystal structure of Fe3O4 did not change during different functionalization processes.

[0068] Example 4: Infrared spectroscopy of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic fluorescent nanoparticles, Fe3O4@ZnS-MPS, and sodium 3-mercapto-1-propanesulfonate.

[0069] FT-IR testing: At room temperature, take an appropriate amount of sample, add potassium bromide, grind and compress into a pellet, and measure the wavenumber (σ) in the range of 500-4000 cm⁻¹. -1 .

[0070] Figure 4 These are the infrared spectra of Fe3O4 magnetic microspheres, Fe3O4@ZnS magnetic fluorescent nanoparticles, Fe3O4@ZnS-MPS, and sodium 3-mercapto-1-propanesulfonate. The infrared spectrum of the Fe3O4 magnetic microspheres can be seen at 584 cm⁻¹. -1 The strong absorption peaks are related to the stretching vibrations of the Fe-O bond. For Fe3O4@ZnS magnetic fluorescent nanoparticles, the peaks corresponding to the stretching vibrations of Fe-O and Zn-S appear at 580 cm⁻¹. -1 and 1018cm -1 Sodium 3-mercapto-1-propanesulfonate at 2600–2500 cm⁻¹ -1 The absorption at 10¹⁸ cm⁻¹ corresponds to the stretching vibration peak of -SH. For Fe₃O₄@ZnS-MPS magnetic fluorescent nanoparticles, this peak is observed at 10¹⁸ cm⁻¹. -1 The Zn-S stretching vibration peaks of thiol-modified Zn are significantly masked at 3000 cm⁻¹. -1 At this point, a new CH peak appears, and the new SO stretching vibration peak is at 1042 cm⁻¹. -1 , and 1178cm -1The peak at this point belongs to the S=O=O symmetric stretching vibration. This proves that the thiol group binds to the surface of the microspheres, and the ligand is successfully modified onto the surface of the microspheres.

[0071] Example 5: XPS test of Fe3O4@ZnS-MPS

[0072] XPS test: Under room temperature conditions, take an appropriate amount of sample, grind it, and measure it.

[0073] The elemental composition of the Fe3O4@ZnS-MPS nanocomposite material was investigated by XPS analysis. Figure 5 The five peaks at 1019.2 eV, 709.8 eV, 529.6 eV, 282.7 eV, and 159.2 eV were composed of Zn 2p, Fe 2p, O 1s, C 1s, and S 2p, respectively, confirming the successful synthesis of the Fe3O4@ZnS-MPS nanocomposite material. Figure 5 b indicates that Fe 3+ 2p 3 / 2 and Fe 3+ 2p 1 / 2 The binding energies are located at 710.8 and 725.0 eV, respectively, and bimodal fitting of Fe 2p yields Fe energies located at 708.7 and 721.6 eV, respectively. 2+ 2p 3 / 2 and Fe 2+ 2p 1 / 2 The binding energy indicates the presence of Fe3O4 in the nanocomposite material. Figure 5 From c, we can know that Zn 2p 3 / 2 With Zn 2p 1 / 2 The binding energy difference between them is 22.5 eV, indicating that the metallic Zn supported on the catalyst mainly exists in the +2 valence state. The values ​​are located at 159.5 eV and 160.7 eV (…). Figure 5 The peaks in d) are attributed to metal sulfides S from ZnS. 2- (2p 3 / 2 and S 2p 1 / 2 ).

[0074] Example 6: Magnetic property testing of Fe3O4 magnetic microspheres and Fe3O4@ZnS-MPS

[0075] VSM test: Under room temperature conditions, take an appropriate amount of sample, weigh it in milligrams using a precision balance, and tightly wrap it in soft paper to form a small ball for measurement.

[0076] Figure 6The figures show the hysteresis loop curves of Fe3O4 magnetic microspheres and Fe3O4@ZnS-MPS. The saturation magnetization of the Fe3O4 magnetic microspheres is 64.52 emu / g, while the magnetic saturation value of the Fe3O4@ZnS-MPS nanocomposite is 47.09 emu / g. The magnetization in the nanocomposite is reduced due to the diamagnetic effect of the thick, thiol-modified ZnS layer surrounding the Fe3O4 magnetic microspheres. 2+ The ion redistribution may also have led to a decrease in the saturation magnetization of the composite material. However, it still exhibits typical superparamagnetism, which meets the experimental requirements for removing Ag. + It still exhibits excellent magnetic properties (see...) Figure 6 illustration).

[0077] Example 7: Thermogravimetric analysis of Fe3O4@ZnS-MPS

[0078] To investigate the thermal properties of the samples, a thermogravimetric analyzer (TGA) was used. Thermal properties are an important indicator for evaluating hybrid materials, and different synthesis methods result in different thermal properties. The TGA curves of Fe3O4@ZnS-MPS were measured under a nitrogen atmosphere at a heating rate of 10 °C / min. The results are as follows: Figure 7 As shown. Figure 7 Overall, the weight loss rates of the products were not very high. The weight loss rate of Fe3O4 was only about 8%. The weight loss was reduced after modification with ZnS, which was due to the loss of water contained in ZnS. After modification with MPS, the weight loss rate reached 17%, indicating that the polymer in the sample had been completely removed. Therefore, thermogravimetric analysis further confirms that the thiol groups have been modified onto the surface of Fe3O4 magnetic microspheres.

[0079] Example 8: Effect of pH on the ability of Fe3O4@ZnS-MPS to recognize silver ions

[0080] The pH value of the solution is one of the important parameters affecting the detection capability of the probe. From... Figure 8 As can be seen, the fluorescence intensity of the probe itself did not change significantly within the pH range of 4.8-9. The addition of silver ions did not affect the degree of fluorescence intensity quenching by pH. Therefore, this invention selected a common neutral liquid with a pH of 7.0 as the experimental standard.

[0081] Example 9: Fe3O4@ZnS-MPS with Ag addition + Fluorescence tests before and after

[0082] Fluorescence intensity test: At room temperature, take an appropriate amount of sample and dissolve it in phosphate buffer solution. For fluorescence spectroscopy test, select an excitation wavelength of 370 nm and a spectral range of 400-500 nm.

[0083] Figure 9A comparison of the fluorescence characteristic spectra of Fe3O4@ZnS-MPS before and after the addition of Ag+. Figure 9 It can be seen that Ag + The addition of Ag can significantly quench Fe3O4@ZnS-MPS; the inset shows the addition of Ag. + Transmission electron microscopy (TEM) images of Fe3O4@ZnS-MPS before and after clearly showing Ag. + It has been loaded and dispersed on the surface of Fe3O4@ZnS-MPS magnetic fluorescent nanoparticles. The Fe3O4@ZnS-MPS nanoparticles themselves have good dispersibility and are almost spherical. Ag + Complexation with sodium 3-mercapto-1-propanesulfonate on the Fe3O4@ZnS surface leads to probe aggregation, resulting in significant fluorescence quenching.

[0084] Example 10: Testing the response range and concentration gradient of Fe3O4@ZnS-MPS to silver ions

[0085] Figure 10 It can be seen that, along with Ag in the solution + With increasing concentration, the fluorescence intensity gradually decreases, especially in Ag concentrations of 0-100 μM. + Within the concentration range, Ag + The concentration of the silver ion showed a linear relationship with the fluorescence intensity, with a detection limit of 7.04 μM. According to the World Health Organization (WHO) regulations on silver ion content, the concentration of silver ions in drinking water should not exceed 0.05 mg / L, and the concentration of silver ions in the human body should be below 0.05 mg / L (0.46 μM / L), which perfectly matches the detection range of the magnetic fluorescent nanoparticles of this invention. Therefore, the nanoparticles of this invention can accurately determine the content of silver ions.

[0086] Example 11: Test of the selectivity and anti-interference capability of Fe3O4@ZnS-MPS

[0087] High selectivity is essential for sensors. Therefore, under the same conditions, the magnetic fluorescent composite material was examined for its susceptibility to Ag by screening the reactions of relevant analytes. + The results showed that Ag exhibited selectivity. + The fluorescence quenching effect is the best; although other ions show weak quenching, it is obviously negligible compared to silver ions. Figure 11 a). To further investigate the ability of magnetic fluorescent nanoparticles to recognize silver ions in the presence of other metal ions, and to simultaneously examine the anti-interference ability of the nanoparticles, when one equivalent amount of silver ions was added to one equivalent amount of other ions in a solution (400 μM Ag), + Co 2+ Ni 2+ Al3+ Cu 2+ Zn 2+ Cd 2+ Fe 3+ Fe 2+ K + Ca 2+ Na + Pb 2+ Hg 2+ Other ions did not affect the detection of silver ions by the magnetic fluorescent nanoparticles. Fluorescence emission spectroscopy well demonstrates this. Figure 11 b) Common metal ions in the environment will not significantly interfere with the qualitative and quantitative detection of silver ions by particles.

[0088] Example 12: Effect of initial Ag+ concentration on the adsorption capacity and removal rate of Fe3O4@ZnS-MPS + The effect of initial concentration on adsorption efficiency is as follows: Figure 12 Adsorption analysis showed that, with the initial Ag... +

[0089] With increasing concentration, the adsorption capacity of Fe3O4@ZnS-MPS gradually increases. This is because the increased initial concentration enhances the adsorption driving force and ion mass transfer rate, and the binding sites on the adsorbent surface are gradually oxidized by Ag. + The adsorption capacity is increased by occupying space. Ag in solution + The removal rate reached 99.62% at 100 μM and then gradually decreased. This is because the amount of adsorbent in the solution was constant, which was Ag. + The available adsorption sites are also limited; when the heavy metal concentration is low, almost all Ag... + All can bind to adsorption sites, achieving a high removal rate. However, as adsorption gradually reaches equilibrium, the adsorption effect of the adsorbent on free metal ions in the solution decreases, leading to a reduction in the removal rate. When Ag... + When the concentration changed from 300 μM to 600 μM, the removal rate decreased from 99.54% to 93.54%, while the adsorption capacity increased from 322.496 mg / g to 606.112 mg / g. Taking all factors into account, Ag... + The optimal result can be obtained at a concentration of around 400 μM at the intersection point.

[0090] Although the present invention has been described with reference to the above embodiments, it should be understood that the present invention may be further modified and varied without departing from the spirit of the present invention, and all such modifications and variations are within the protection scope of the present invention.

Claims

1. A magnetic fluorescent nanosensor with a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate, characterized in that: Fe3O4 magnetic microspheres were prepared by a solvothermal method, and Fe3O4 was coated with quantum dots ZnS by chemical precipitation. Fe3O4@ZnS was then modified with sodium 3-mercapto-1-propanesulfonate to prepare thiol-functionalized magnetic fluorescent microspheres. The fabrication of the Fe3O4@ZnS core-shell magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate includes the following steps: ①Preparation of Fe3O4 magnetic microspheres FeCl3•6H2O was placed in a container, ethylene glycol was added, and the mixture was heated and stirred until it was fully dissolved to obtain a clear black solution. Then, sodium acetate and a surfactant were added to the solution, and after stirring for a certain period of time, a reddish-brown viscous solution was obtained. The solution was then transferred to a polytetrafluoroethylene reactor. The reactor was placed in a stainless steel jacket and sealed. After being placed in a drying oven for hydrothermal reaction for a certain period of time, it was taken out and allowed to cool naturally for a certain period of time. After opening the reactor lid, the upper clear liquid was removed, and the black precipitate at the bottom was collected. Then, it was washed with deionized water to obtain Fe3O4 nanomagnetic microspheres. Water was then added to make a dispersion for the next step of magnetic microsphere surface modification. ②Preparation of Fe3O4@ZnS magnetic fluorescent nanoparticles Take the Fe3O4 nanomagnetic microsphere dispersion obtained in step ①, add deionized water, add a small amount of ammonia to maintain pH stability, and stir for a certain time under constant temperature heating water bath; dissolve Zn(Ac)2·2H2O in deionized water and transfer it to Fe3O4 solution, slowly add Na2S·9H2O solution to Fe3O4 mixed solution, when the Na2S·9H2O solution is completely added, ZnS quantum dots will form on the surface of Fe3O4, stir for a certain time under constant temperature heating water bath, and wash with magnetic water until the aqueous solution is clear to prepare Fe3O4@ZnS magnetic fluorescent nanoparticles; ③ Fabrication of Fe3O4@ZnS core-shell magnetic fluorescent nanosensors modified with sodium 3-mercapto-1-propanesulfonate Fe3O4@ZnS magnetic fluorescent nanoparticles were dispersed in water, and then an aqueous solution of sodium 3-mercapto-1-propanesulfonate was added. The mixture was heated in a water bath and stirred in the dark for a certain period of time. Then, water was magnetically absorbed until the aqueous solution was clear, thus preparing a core-shell structured magnetic fluorescent nanosensor of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate.

2. A method for preparing a Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate, characterized in that, Includes the following steps: ①Preparation of Fe3O4 magnetic microspheres FeCl3•6H2O was placed in a container, ethylene glycol was added, and the mixture was heated and stirred at T1℃ to fully dissolve it, resulting in a clear black solution. Then, sodium acetate and a surfactant were added to the solution, and after stirring for t1 hours, a reddish-brown viscous solution was obtained. The solution was then transferred to a polytetrafluoroethylene reactor, which was placed in a stainless steel jacket and sealed. After hydrothermal reaction at T2℃ for t2 hours, the reactor was removed and allowed to cool naturally for t3 hours. After opening the reactor lid, the supernatant was removed, and the black precipitate at the bottom was collected. The precipitate was then washed with deionized water to obtain Fe3O4 magnetic nanospheres. Water was then added to prepare a dispersion for the next step of preparing Fe3O4@ZnS magnetic fluorescent nanoparticles. ②Preparation of Fe3O4@ZnS magnetic fluorescent nanoparticles Take the Fe3O4 nanomagnetic microsphere dispersion obtained in step ①, add deionized water, add a small amount of ammonia to maintain pH stability, and stir in a constant temperature water bath at T3℃ for t4 hours; dissolve Zn(Ac)2·2H2O in deionized water and transfer it to the Fe3O4 solution, and slowly add Na2S·9H2O solution to the Fe3O4 mixed solution. When the Na2S·9H2O solution is completely added, ZnS quantum dots will form on the surface of Fe3O4. Stir in a constant temperature water bath at T4℃ for t5 hours, and wash with magnetic water until the aqueous solution is clear to prepare Fe3O4@ZnS magnetic fluorescent nanoparticles; ③ Fabrication of Fe3O4@ZnS core-shell magnetic fluorescent nanosensors modified with sodium 3-mercapto-1-propanesulfonate Fe3O4@ZnS magnetic fluorescent nanoparticles were dispersed in water, and then an aqueous solution of sodium 3-mercapto-1-propanesulfonate was added. The mixture was stirred in a water bath at 5°C in the dark for 6 hours. Then, water was magnetically absorbed until the aqueous solution was clear, thus preparing a core-shell structured magnetic fluorescent nanosensor of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate.

3. The method for preparing a magnetic fluorescent nanosensor with a core-shell structure of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate as described in claim 2, characterized in that, T1= 80-90; t1=0.5-1; T2=160-200; t2=10-12; t3=12-13; T3= 80; t4=0.5-1; T4=70-80; t5=6-7; T5=40-60; t6=3-4.

4. The method for preparing a magnetic fluorescent nanosensor with a core-shell structure of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate as described in claim 2, characterized in that, In steps ①-③, the molar ratios of each component are as follows: FeCl3·6H2O: sodium acetate = 1:0.3-1:0.8; Zn(Ac)2·2H2O: Na2S·9H2O = 1:0.5-1:2; Fe3O4@ZnS: sodium 3-mercapto-1-propanesulfonate = 1:1-1.5:

1.

5. The application of the magnetic fluorescent nanosensor with a core-shell structure of Fe3O4@ZnS modified with sodium 3-mercapto-1-propanesulfonate prepared by the method described in any one of claims 2-4 in the measurement, detection, screening, separation of silver ions, and magnetic resonance imaging or fluorescence imaging.

6. A magnetic fluorescent nanosensor composition for measuring, detecting, screening or separating silver ions, comprising the magnetic fluorescent nanosensor with a Fe3O4@ZnS core-shell structure modified with sodium 3-mercapto-1-propanesulfonate as described in claim 1.

7. The magnetic fluorescent nanosensor composition for measuring, detecting, screening, or separating silver ions as described in claim 6, characterized in that, The magnetic fluorescent nanosensor composition further comprises a solvent, an acid, a base, a buffer solution, or a combination thereof.

8. A method for detecting the presence of silver ions in a sample or determining the content of silver ions in a sample, comprising: a) The product that forms a fluorescence change when the Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate as described in claim 1 is brought into contact with a sample; b) Determine the fluorescence properties of the product.

9. A method for separating silver ions from a sample, comprising: a) Contact the Fe3O4@ZnS core-shell structured magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate as described in claim 1 with the sample; b) Separation of the sample from the Fe3O4@ZnS core-shell structure magnetic fluorescent nanosensor modified with sodium 3-mercapto-1-propanesulfonate was achieved under an external magnetic field.

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