A SERS Detection Method for Uranium(VI) Ions Based on the Self-Assembly of Silver Nanoparticles Assisted by Streptavidin
A self-assembled silver nanoparticle aggregate using citrate-stabilized silver nanoparticles and streptavidin enhances uranium(VI) detection sensitivity and stability, overcoming the limitations of existing methods to achieve sub-60 nM detection with improved substrate uniformity and reduced complexity.
Patent Information
- Application Number
- CN202310044573.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-01-30
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2043-01-30
AI Technical Summary
The existing uranyl ion detection methods have problems such as low sensitivity, high cost, complex operation, and easy to be disturbed, making it difficult to achieve quantitative detection and poor stability.
Streptavidin-assisted silver nanoparticles are used to self-assemble the aggregates as wet substrates. The citrate-modified silver nanoparticles and strepavidin molecules are assembled through electrostatic action to form a nanostructure with a gap of 1 to 10 nm, and SERS detection is achieved using local electric field enhancement.
It significantly improves the detection sensitivity and stability of uranyl ions, reduces detection costs, simplifies operating procedures, and is suitable for industrial promotion.
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Figure CN115931826B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of uranyl ion detection, and particularly relates to a SERS detection method for uranyl ions based on the self-assembly of streptavidin-assisted silver nanoparticles. Background Art
[0002] Uranium is a natural radioactive element present in the environment and has important applications in the nuclear industry and weapons. The widespread use of uranium has generated a large amount of nuclear waste, and humans are more likely to come into contact with this harmful metal. Uranium mainly exists in the form of hexavalent uranyl ions (UO2 2+ ) in water, is easily migratory in the earth's crust, and can cause great harm to the environment and human body.
[0003] Detecting uranyl ions in water bodies is a prerequisite for their treatment and purification. Therefore, developing a sensitive and rapid method for detecting uranyl ions is of great significance for preventing uranium pollution, protecting the environment and human health. Traditional instrument-based methods for detecting uranyl ions mainly include X-ray fluorescence spectrometry, inductively coupled plasma mass spectrometry, laser fluorescence method, etc. Although these traditional methods have their own advantages, they also have defects such as expensive instruments, complex pretreatment, time-consuming operation, and being easily interfered by other ions.
[0004] Compared with the above detection methods, Surface-enhanced Raman Spectroscopy (SERS) has the characteristics of high sensitivity, short time consumption, small sample demand, little influence by photobleaching and water, and no need for pretreatment of samples. Moreover, the symmetric stretching vibration of the O=U=O structure in uranyl ions has a strong Raman peak at ~870 cm -1 . Therefore, surface-enhanced Raman spectroscopy is an ideal detection means for the rapid and sensitive detection of uranyl ions in aqueous solutions.
[0005] The SERS detection methods for uranyl ions are mainly realized by preparing different types of SERS substrates, such as silver-doped sol-gel films, nano silver arrays prepared by vapor deposition technology, gold nanostars deposited on amino-oximated polyacrylonitrile pads, Al2O3-coated silver nanorods, nano silver-coupled reduced graphene oxide nanosheets, etc. Such nanostructured substrates (dry substrates) prepared by self-assembly or vapor deposition methods usually require dropping samples onto the substrate surface. However, due to the coffee ring effect and the non-uniformity of the substrate itself, it is difficult to achieve quantitative detection of uranyl ions. In addition, the preparation processes of these dry substrates are all very complex and expensive, increasing the cost of use.
[0006] In previous work, the applicant has reported a wet-state SERS method for directly detecting uranyl ions using citrate-stabilized silver nanosol. Citrate can stabilize silver nanoparticles while acting as a chelating agent to capture uranyl ions, and it can also be used as an internal reference to normalize the Raman signal of uranyl ions, thereby eliminating the adverse effects of the substrate and other external factors. This direct detection method is simple to operate, inexpensive, and user-friendly. The detection limit of this method was calculated to be 60 nM based on three times the standard deviation of the blank. However, due to the interference of background signals and the limitation of enhancement performance, it was difficult to detect the SERS signal of 60 nM uranyl ions in the experiment, and only the SERS signal of 200 nM uranyl ions could be measured. Summary of the Invention
[0007] The object of the present invention is to provide a SERS detection method for uranyl ions based on the self-assembly of streptavidin-assisted silver nanoparticles. The aggregates formed by the self-assembly of streptavidin and citrate-modified silver nanoparticles provided by the present invention through electrostatic interaction are used as a wet-state substrate, which can significantly improve the detection sensitivity and stability of detecting uranyl ions by surface-enhanced Raman spectroscopy.
[0008] To achieve the above object, the present invention provides the following technical solutions:
[0009] The present invention provides a self-assembled aggregate based on silver nanoparticles, which includes a plurality of citrate-modified silver nanoparticles and a plurality of streptavidin molecules attached to the surface of each citrate-modified silver nanoparticle through electrostatic interaction; the plurality of citrate-modified silver nanoparticles and the plurality of streptavidin molecules self-assemble to form the self-assembled aggregate based on silver nanoparticles.
[0010] Preferably, the particle size of the citrate-modified silver nanoparticles is 50-70 nm.
[0011] Preferably, in the self-assembled aggregate, the gap between adjacent citrate-modified silver nanoparticles is 1-10 nm.
[0012] Preferably, in the self-assembled aggregate, the molar ratio of the streptavidin molecules to the citrate-modified silver nanoparticles is ≥500:1.
[0013] Preferably, the preparation method of the citrate-modified silver nanoparticles includes the following steps:
[0014] Mix water, water-soluble silver salt, and water-soluble citrate, and heat to boiling to obtain citrate-modified silver nanosol;
[0015] Separate the solid and liquid of the citrate-modified silver nanosol to obtain the citrate-modified silver nanoparticles.
[0016] The present invention provides a method for preparing a self-assembled aggregate based on silver nanoparticles as described in the above technical solution, comprising the following steps:
[0017] Prepare a sol by mixing citrate-modified silver nanoparticles and water;
[0018] Mix the sol and streptavidin for self-assembly to obtain the self-assembled aggregate based on silver nanoparticles.
[0019] The present invention provides a method for detecting surface-enhanced Raman spectroscopy of a uranyl ion solution, comprising the following steps:
[0020] Mix a wet substrate and a uranyl ion solution to obtain a test solution; the wet substrate is the self-assembled aggregate based on silver nanoparticles as described in the above technical solution or the self-assembled aggregate based on silver nanoparticles prepared by the preparation method as described in the above technical solution;
[0021] Measure the Raman spectrum of the test solution to obtain the Raman absorption peak intensity of the uranyl ion and the Raman absorption peak intensity of citrate respectively, and obtain the ratio of the Raman absorption peak intensity of the uranyl ion to the Raman absorption peak intensity of citrate, which is denoted as the relative Raman absorption peak intensity of the uranyl ion;
[0022] Substitute the relative Raman absorption peak intensity of the uranyl ion into the uranyl ion concentration-relative Raman absorption peak intensity standard curve or standard equation to obtain the concentration of the uranyl ion solution.
[0023] Preferably, in the Raman spectrum, the Raman absorption peak position of the uranyl ion is 750 cm -1 , and the Raman absorption peak position of citrate is 930 cm -1 .
[0024] Preferably, the linear range of the uranyl ion concentration-relative Raman absorption peak intensity standard curve or standard equation is 1×10 -9 ~1×10 -6 mol / L.
[0025] The present invention provides a self-assembled aggregate based on silver nanoparticles, which includes a plurality of citrate-modified silver nanoparticles and a plurality of streptavidin molecules attached to the surface of each citrate-modified silver nanoparticle through electrostatic interaction; the plurality of citrate-modified silver nanoparticles and the plurality of streptavidin molecules self-assemble to form the self-assembled aggregate based on silver nanoparticles. In the present invention, the streptavidin (SA) is a protein isolated from Streptomyces avidinii bacteria, which has a low isoelectric point (pI≈6) and a positive charge on its surface, and can produce electrostatic interaction with citrate-modified silver nanoparticles, thus undergoing self-assembly to assemble the citrate-modified silver nanoparticles into aggregates, forming a self-assembled aggregate based on silver nanoparticles; using the self-assembled aggregate based on silver nanoparticles provided by the present invention as a wet substrate, the size of the streptavidin molecules in the self-assembled aggregate is 3-6 nm and has a certain rigidity, so that there are gaps between adjacent citrate-modified silver nanoparticles (such as Figure 1 shown), and the existence of the gaps can produce a very strong electromagnetic coupling effect under the action of Raman incident laser, resulting in the enhancement of the local electric field and thus producing a strong SERS enhancement effect, so that the SERS detection of low-concentration uranyl ions can be realized. On the other hand, the existence of the gaps can also effectively prevent the excessive aggregation of citrate-modified silver nanoparticles, providing more space for the citrate on the surface of citrate-modified silver nanoparticles to adsorb uranyl ions, so that more uranyl ions can be adsorbed on the surface of citrate-modified silver nanoparticles, which is beneficial to improving the detection sensitivity of uranyl ions; finally, due to the low isoelectric point of streptavidin and the small amount of positive charge on its surface, it can also avoid causing excessive aggregation of citrate-modified silver nanoparticles, ensuring the stability and uniformity of the entire aggregate sol. As a wet substrate, it is beneficial to improve the stability of the SERS detection of uranyl ions.
[0026] In the present invention, further, in the aggregate, the gap between adjacent citrate-modified silver nanoparticles is 1-10 nm. In the present invention, when the gap is 1-10 nm, the region formed by the gap (referred to as "hot spot") can produce a very strong electromagnetic coupling effect under the action of Raman incident laser, resulting in the enhancement of the local electric field and thus producing a strong SERS enhancement effect, so that the SERS detection of low-concentration uranyl ions can be realized.
[0027] The present invention provides a surface-enhanced Raman spectroscopy detection method for uranyl ion solutions, comprising the following steps: mixing a wet substrate and a uranyl ion solution to obtain a solution to be detected; the wet substrate is a self-assembled aggregate based on silver nanoparticles described in the above technical solution or a self-assembled aggregate based on silver nanoparticles prepared by the preparation method described in the above technical solution; measuring the Raman spectrum of the solution to be detected, respectively obtaining the Raman absorption peak intensity of uranyl ions and the Raman absorption peak intensity of citrate, and obtaining the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate, which is denoted as the relative Raman absorption peak intensity of uranyl ions; substituting the relative Raman absorption peak intensity of uranyl ions into the standard curve or standard equation of uranyl ion concentration-relative Raman absorption peak intensity to obtain the concentration of the uranyl ion solution. The detection method provided by the present invention uses a self-assembled aggregate based on silver nanoparticles as the wet substrate, which can significantly improve the detection sensitivity and stability of detecting uranyl ions by SERS; and the operation is simple, which is suitable for industrial promotion. Description of the Drawings
[0028] Figure 1 Schematic diagram of the SERS detection method for uranyl ions based on the self-assembled aggregate of silver nanoparticles provided by the embodiment of the present invention;
[0029] Figure 2 SERS signal spectra of UO2 under different reaction time conditions with the self-assembled aggregate of silver nanoparticles prepared in Example 1 of the present invention as the wet substrate; 2+
[0030] Figure 3 SERS signal spectra of UO2 measured continuously 5 times with the self-assembled aggregate of silver nanoparticles prepared in Example 1 of the present invention as the wet substrate; 2+
[0031] Figure 4 SERS signal spectra of UO2 with different concentrations with the self-assembled aggregate of silver nanoparticles prepared in Example 1 of the present invention as the wet substrate; 2+
[0032] Figure 5 Relationship diagram between the relative Raman intensity of uranyl ions at 750 cm and citrate at 930 cm and the uranyl ion concentration with the self-assembled aggregate of silver nanoparticles prepared in Example 1 of the present invention as the wet substrate; -1 -1
[0033] Figure 6 Selectivity test diagram for the detection of UO2 with the self-assembled aggregate of silver nanoparticles prepared in Example 1 of the present invention as the wet substrate; 2+ Detailed implementation mode
[0034] The present invention provides a self-assembled aggregate based on silver nanoparticles, which includes a plurality of citrate-modified silver nanoparticles and a plurality of streptavidin molecules attached to the surface of each of the citrate-modified silver nanoparticles through electrostatic interaction; the plurality of citrate-modified silver nanoparticles and the plurality of streptavidin molecules self-assemble to form the self-assembled aggregate based on silver nanoparticles.
[0035] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well-known to those skilled in the art.
[0036] The self-assembled aggregate based on silver nanoparticles provided by the present invention includes a plurality of citrate-modified silver nanoparticles.
[0037] In the present invention, the particle size of the citrate-modified silver nanoparticles is preferably 50-70 nm, more preferably 55-65 nm.
[0038] In the present invention, the preparation method of the citrate-modified silver nanoparticles preferably includes the following steps:
[0039] Mix water, a water-soluble silver salt and a water-soluble citrate, and heat to boiling to obtain a citrate-modified silver nano sol;
[0040] Separate the solid and liquid of the citrate-modified silver nano sol to obtain the citrate-modified silver nanoparticles.
[0041] In the present invention, water, a water-soluble silver salt and a water-soluble citrate are mixed (hereinafter referred to as the first mixing), and heated to boiling to obtain a citrate-modified silver nano sol.
[0042] In the present invention, the water-soluble silver salt is specifically preferably silver nitrate.
[0043] In the present invention, the water-soluble citrate is specifically preferably trisodium citrate dihydrate.
[0044] In the present invention, the molar ratio of the water-soluble silver salt to the water-soluble citrate is preferably 1:(0.7-0.75), more preferably 1:(0.72-0.74).
[0045] In the present invention, the volume ratio of water to the mass of the water-soluble silver salt is preferably 50 mL:9 mg.
[0046] In the present invention, during the first mixing, the water-soluble citrate is preferably mixed in the form of an aqueous solution of the water-soluble citrate. During the first mixing, the volume of the aqueous solution of the water-soluble citrate is preferably 2 mL, and the molar concentration of the aqueous solution of the water-soluble citrate is preferably 38.8 mmol / L.
[0047] In the present invention, the first mixing preferably includes the following steps: dissolving the water-soluble silver salt in water to obtain a water-soluble silver salt solution; heating the water-soluble silver salt solution to boiling; and stirring and mixing the boiling water-soluble silver salt solution and the water-soluble citrate.
[0048] In the present invention, the temperature for heating to boiling is preferably 100 °C, and the holding time for heating to boiling is 30 min.
[0049] After obtaining the citrate-modified silver nanosol, the present invention separates the solid and liquid of the citrate-modified silver nanosol to obtain the citrate-modified silver nanoparticles.
[0050] The present invention preferably separates the solid and liquid of the citrate-modified silver nanosol cooled to room temperature.
[0051] In the present invention, the solid-liquid separation is preferably centrifugation, and the rotation speed of the centrifugation is preferably 6000 r / min.
[0052] The present invention preferably takes the solid-phase product of the solid-liquid separation as the citrate-modified silver nanoparticles.
[0053] The self-assembled aggregate based on silver nanoparticles provided by the present invention includes a plurality of streptavidin molecules attached to the surface of each of the citrate-modified silver nanoparticles through electrostatic interaction.
[0054] In the present invention, the size of the streptavidin molecule is preferably 3 - 6 nm.
[0055] In the present invention, in the aggregate, the molar ratio of the streptavidin molecule to the citrate-modified silver nanoparticle is preferably ≥500:1.
[0056] In the present invention, a plurality of the citrate-modified silver nanoparticles and a plurality of the streptavidin molecules self-assemble to form the self-assembled aggregate based on silver nanoparticles: a plurality of the streptavidin molecules are attached to the surface of a plurality of the citrate-modified silver nanoparticles through electrostatic interaction, causing the plurality of citrate-modified silver nanoparticles to approach each other to form the aggregate.
[0057] In the present invention, in the aggregate, the gap between adjacent citrate-modified silver nanoparticles is preferably 1 - 10 nm.
[0058] The self-assembled aggregates based on silver nanoparticles provided by the present invention preferably exist in the form of a hydrogel.
[0059] The present invention provides a method for preparing the self-assembled aggregates based on silver nanoparticles as described in the above technical solution, comprising the following steps:
[0060] Prepare a sol by mixing citrate-modified silver nanoparticles and water;
[0061] Mix the sol and streptavidin for self-assembly to obtain the self-assembled aggregates based on silver nanoparticles.
[0062] In the present invention, when preparing the sol by mixing citrate-modified silver nanoparticles and water, and when mixing the sol and streptavidin, streptavidin preferably forms the mixture in the form of an aqueous streptavidin solution, and the mass concentration of the aqueous streptavidin solution is preferably 1.5 mg / mL; the volume ratio of the sol to the aqueous streptavidin solution is preferably 9:1×10 -3 .
[0063] In the present invention, when the sol and streptavidin are mixed, multiple citrate-modified silver nanoparticles and multiple streptavidin molecules in the sol self-assemble through electrostatic interaction to form the self-assembled aggregates based on silver nanoparticles.
[0064] The present invention provides a method for surface-enhanced Raman spectroscopy detection of a uranyl ion solution, comprising the following steps:
[0065] Mix a wet substrate and a uranyl ion solution to obtain a test solution; the wet substrate is the self-assembled aggregates based on silver nanoparticles as described in the above technical solution or the self-assembled aggregates based on silver nanoparticles prepared by the preparation method as described in the above technical solution;
[0066] Measure the Raman spectrum of the test solution, respectively obtain the Raman absorption peak intensity of uranyl ions and the Raman absorption peak intensity of citrate, and obtain the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate, which is denoted as the relative Raman absorption peak intensity of uranyl ions;
[0067] Substitute the relative Raman absorption peak intensity of uranyl ions into a uranyl ion concentration-relative Raman absorption peak intensity standard curve or standard equation to obtain the concentration of the uranyl ion solution.
[0068] The present invention mixes a wet substrate and a uranyl ion solution to obtain a test solution; the wet substrate is the self-assembled aggregates based on silver nanoparticles as described in the above technical solution or the self-assembled aggregates based on silver nanoparticles prepared by the preparation method as described in the above technical solution.
[0069] In the present invention, the uranyl ion solution is specifically preferably an aqueous solution of uranyl ions.
[0070] As one or more embodiments of the present invention, the uranyl ion solution includes Cd 2+ , Zn 2+ , Ni 2+ , Ce 3+ , Cu 2 + , Co 2+ and La 3+ or one or more of them.
[0071] In the present invention, the volume ratio of the wet substrate to the uranyl ion solution is preferably (9 - 9.1):1.
[0072] In the present invention, the temperature for mixing the wet substrate and the uranyl ion solution is preferably room temperature, and the mixing time of the wet substrate and the uranyl ion solution is preferably ≥30 min, more preferably 30 min.
[0073] In the present invention, when the wet substrate and the uranyl ion solution are mixed, the uranyl ions in the uranyl ion solution are adsorbed on the surface of the citrate - modified silver nanoparticles.
[0074] To obtain the test solution, the present invention measures the Raman spectrum of the test solution, respectively obtains the Raman absorption peak intensity of uranyl ions and the Raman absorption peak intensity of citrate, and obtains the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate, which is denoted as the relative Raman absorption peak intensity of uranyl ions.
[0075] In the present invention, in the Raman spectrum, the Raman absorption peak position of the uranyl ions is preferably 750 cm -1 , and the Raman absorption peak position of the citrate is preferably 930 cm -1 .
[0076] In the present invention, the relative Raman absorption peak intensity of uranyl ions is the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate.
[0077] After obtaining the relative Raman absorption peak intensity of uranyl ions, the present invention substitutes the relative Raman absorption peak intensity of uranyl ions into the uranyl ion concentration - relative Raman absorption peak intensity standard curve or standard equation to obtain the concentration of the uranyl ion solution.
[0078] In the present invention, the method for obtaining the uranyl ion concentration - relative Raman absorption peak intensity standard curve preferably includes the following steps:
[0079] A series of standard solutions are obtained by using a series of uranyl ion solutions with known concentrations according to the method for obtaining the solution to be measured described above; the molar concentrations of the series of uranyl ion solutions with known concentrations are specifically preferably: 1×10 -9 mol / L, 5×10 -9 mol / L, 1×10 -8 mol / L, 1×10 -7 mol / L, 1×10 -6 mol / L;
[0080] The Raman spectra of the series of standard solutions are measured, and the Raman absorption peak intensities of uranyl ions and the Raman absorption peak intensities of citrate ions in the series of standard solutions are obtained respectively, and the ratios of the Raman absorption peak intensities of uranyl ions to the Raman absorption peak intensities of citrate ions in the series of standard solutions are obtained, which are denoted as the standard relative Raman absorption peak intensities of a series of uranyl ions;
[0081] Taking the standard relative Raman absorption peak intensities of the series of uranyl ions as the dependent variable and the concentrations of uranyl ions in the corresponding series of uranyl ion solutions with known concentrations as the independent variable, a standard curve of uranyl ion concentration - relative Raman absorption peak intensity is plotted.
[0082] In the present invention, the method for obtaining the standard equation of uranyl ion concentration - relative Raman absorption peak intensity preferably includes the following steps: linearly simulating the standard curve of uranyl ion concentration - relative Raman absorption peak intensity to obtain the standard equation of uranyl ion concentration - relative Raman absorption peak intensity.
[0083] In the present invention, the linear range of the standard curve or standard equation of uranyl ion concentration - relative Raman absorption peak intensity is 1×10 -9 ~1×10 -6 mol / L.
[0084] The present invention proposes a method for SERS detection by first using positively charged streptavidin to assemble silver nanoparticles to form a stable substrate and then using citrate ions to adsorb uranyl ions, which can greatly improve the detection sensitivity of uranyl ions. Streptavidin (SA) is a protein isolated from Streptomyces avidinii bacteria. It has a low isoelectric point (pI≈6) and a positive charge on its surface, and can produce electrostatic interaction with citrate - modified silver nanoparticles to assemble and aggregate the silver nanoparticles into a substrate. As Figure 1As shown, a nano-gap structure region with a size of 1 - 10 nm is formed between the nanoparticles and their aggregates. Under the action of incident laser, a very strong electromagnetic coupling effect can occur, which will lead to the enhancement of the local electric field and produce a strong SERS enhancement effect. These regions are also vividly called "hot spots". According to the results of crystal diffraction and atomic force microscope imaging, the size of a single streptavidin is 3 - 6 nm, which is just within the structural gap size of the "hot spot" effect. This size is much larger than the linker such as inorganic salts, inorganic acids and organic amines. And because the isoelectric point of streptavidin is low and the surface has few positive charges, it can avoid causing excessive aggregation of the metal sol, ensuring the stability and uniformity of the whole solution. In addition, streptavidin has a certain rigidity. The scale of 3 - 6 nm not only forms a large number of "hot spots" between the aggregated particles, but also provides space for the adsorption of uranyl ions by citrate on the particle surface, which is beneficial to improving the detection sensitivity and stability of uranyl ions.
[0085] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.
[0086] Example 1
[0087] Dissolve 18 mg of AgNO3 in 100 mL of water, and then heat it to boiling; then quickly stir and add 2 mL of 38.8 mM aqueous sodium citrate solution; keep the resulting mixture boiling for 30 minutes, and then stir and cool it at room temperature to obtain a citrate-modified silver nanoparticle colloid. The particle size of the citrate-modified silver nanoparticles in the citrate-modified silver colloid is about 60 nm;
[0088] Take 9 mL of the citrate-modified AgNP colloid solution, add 1 μL of 1.5 mg / mL streptavidin aqueous solution to the citrate-modified AgNP colloid solution to form an aggregate colloid, and then add 1 mL of 10 -6 mol / L uranyl ion aqueous solution. After mixing for 1 min, 10 min, 15 min, 30 min and 35 min respectively, collect Raman spectra. The results are as Figure 2 shown:
[0089] As Figure 2 shown, when the concentration of UO2 2+ is 1×10 -6 M, the SERS peak position (750 cm 2+ ) of UO2 -1 increases with the increase of the reaction time and reaches stability at 30 min. After that, the peak intensity hardly changes with the increase of the reaction time. 30 min is selected as the reaction duration for subsequent experiments.
[0090] Example 2
[0091] Dissolve 18 mg of AgNO3 in 100 mL of water, and then heat to boiling; then quickly stir and add 2 mL of 38.8 mM aqueous sodium citrate solution; keep the resulting mixture boiling for 30 minutes, and then cool with stirring at room temperature to obtain a citrate-modified silver nanoparticle colloid. The particle size of the citrate-modified silver nanoparticles in the citrate-modified silver colloid is about 60 nm;
[0092] Take 5 tubes of 9 mL of citrate-modified AgNP colloid solution, add 1 μL of 1.5 mg / mL aqueous streptavidin solution to each of the 5 tubes of citrate-modified AgNP colloid solution to form an aggregate colloid, and then add 1 mL of 10 - 5 mol / L uranyl ion aqueous solution, mix for 30 min, and obtain 5 tubes of reaction solutions after the reaction; measure the Raman spectra of the obtained 5 tubes of reaction solutions, and the results are as Figure 3 shown:
[0093] It is shown by Figure 3 that the relative standard deviation (RSD) of the Raman spectra of the 5 tubes of reaction solutions is within 10%, ensuring the stability of the analytical detection.
[0094] Example 3
[0095] Dissolve 18 mg of AgNO3 in 100 mL of water, and then heat to boiling; then quickly stir and add 2 mL of 38.8 mM aqueous sodium citrate solution; keep the resulting mixture boiling for 30 minutes, and then cool with stirring at room temperature to obtain a citrate-modified silver nanoparticle colloid. The particle size of the citrate-modified silver nanoparticles in the citrate-modified silver colloid is about 60 nm;
[0096] Add 8 mL of the citrate-modified silver nanoparticle colloid to a centrifuge tube, centrifuge at a speed of 6000 revolutions per minute, remove the supernatant to obtain citrate-modified silver nanoparticles; add 2 mL of water to the citrate-modified silver nanoparticles to disperse the citrate-modified silver nanoparticles to obtain a citrate-modified AgNP colloid solution (stock solution);
[0097] Take 9 mL of the citrate-modified AgNP colloid solution, add 1 μL of 1.5 mg / mL aqueous streptavidin solution to form an aggregate colloid;
[0098] Under room temperature conditions, add 1 mL of a series of uranyl ion aqueous solutions with known molar concentrations (molar concentrations are 1×10 -9 mol / L, 5×10 -9 mol / L, 1×10 -8mol / L, 1×10 -7 mol / L, 1×10 -6 mol / L), mix for 30 min, and a series of standard reaction solutions are obtained after the reaction ends;
[0099] Measure the Raman spectra of a series of standard reaction solutions respectively. The specific Raman spectra are as Figure 4 shown, Figure 5 indicating that under the same reaction conditions, the SERS signals of UO2 with different concentrations, within the concentration range of 1×10 2+ ~1×10 2+ M for UO2, the stretching vibration peak intensity of UO2 increases step by step with the increase of the concentration of UO2. At a concentration of 5×10 -9 ~1×10 -6 M, obvious signal peaks can still be observed. 2 + 2+ -9 M concentration, obvious signal peaks can still be observed.
[0100] Respectively obtain the Raman absorption peak intensities of uranyl ions at 750 cm -1 and citrate at 930 cm -1 in a series of standard reaction solutions; divide the Raman absorption peak intensity of uranyl ions at 750 cm -1 by the Raman absorption peak intensity of citrate at 930 cm -1 to obtain the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate in a series of standard solutions, which is recorded as the standard relative Raman absorption peak intensity of a series of uranyl ions; use the standard relative Raman absorption peak intensity of the series of uranyl ions as the dependent variable and the concentration of uranyl ions in a series of known concentration uranyl ion solutions as the independent variable to plot the uranyl ion concentration - relative Raman absorption peak intensity standard curve, as Figure 5 shown, there is a good linear relationship between the relative Raman intensity and the uranyl ion concentration in the range of 1×10 - 9 M~1×10 -6 M.
[0101] At room temperature, add 1 mL of an aqueous solution of uranyl ions with an unknown molar concentration to the aggregate colloid, mix for 30 min, and a test reaction solution is obtained after the reaction ends; measure the Raman spectrum of the test reaction solution, and respectively obtain the Raman absorption peak intensities of uranyl ions at 750 cm -1 and citrate at 930 cm -1 in the test reaction solution; divide the Raman absorption peak intensity of uranyl ions at 750 cm -1 by the Raman absorption peak intensity of citrate at 930 cm -1 The Raman absorption peak intensity was obtained, and the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate ions in the solution to be measured was recorded as the relative Raman absorption peak intensity. The relative Raman absorption peak intensity was substituted into Figure 5 the standard curve of uranyl ion concentration - relative Raman absorption peak intensity shown in
[0102] Example 4
[0103] 9 mL of the citrate-modified AgNP colloidal solution prepared in Example 1 was taken, 1 μL of a 1.5 mg / mL streptavidin aqueous solution was added to the citrate-modified AgNP colloidal solution to form an aggregate colloid, and then 1 mL of an aqueous solution containing 10 - 5 mol / L of uranyl ions and 1×10 -4 mol / L of interfering ions (Cd 2+ , Zn 2+ , Ni 2+ , Ce 3+ , Cu 2+ , Co 2+ and La 3+ ) was added. After mixing for 30 min, the Raman spectrum was collected. The results are shown in Figure 6:
[0104] Figure 6 It shows that Cd 2+ , Zn 2+ , Ni 2+ , Ce 3+ , Cu 2+ , Co 2+ and La 3+ interfering ions did not produce obvious signal enhancement, indicating that the aggregate colloid formed by the streptavidin aqueous solution provided by the present invention has good selectivity for the SERS detection of UO2 2+ .
[0105] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. Other embodiments can be obtained without creative efforts based on this embodiment, and these embodiments all fall within the protection scope of the present invention.
Claims
1. A surface-enhanced Raman spectroscopy detection method for uranyl ion solution, characterized in that Comprising the following steps: Mix a wet substrate and a uranyl ion solution to obtain a solution to be measured; the wet substrate is a self-assembled aggregate based on silver nanoparticles, The self-assembled aggregate based on silver nanoparticles comprises a plurality of citrate-modified silver nanoparticles and a plurality of streptavidin molecules attached to the surface of each of the citrate-modified silver nanoparticles through electrostatic interaction; A plurality of the citrate-modified silver nanoparticles and a plurality of the streptavidin molecules self-assemble to form the self-assembled aggregate based on silver nanoparticles; Measure the Raman spectrum of the solution to be measured, respectively obtain the Raman absorption peak intensity of uranyl ions and the Raman absorption peak intensity of citrate, and obtain the ratio of the Raman absorption peak intensity of uranyl ions to the Raman absorption peak intensity of citrate, denoted as the relative Raman absorption peak intensity of uranyl ions; Substitute the relative Raman absorption peak intensity of the uranyl ions into the standard curve or standard equation of uranyl ion concentration - relative Raman absorption peak intensity to obtain the concentration of the uranyl ion solution.
2. The surface enhanced Raman spectroscopy detection method for uranyl ion solution according to claim 1, characterized in that The particle size of the citrate-modified silver nanoparticles is 50 - 70 nm.
3. The surface-enhanced Raman spectroscopy detection method for uranyl ion solution according to claim 1 or 2, characterized in that In the self-assembled aggregate, the gap between adjacent citrate-modified silver nanoparticles is 1 - 10 nm.
4. The surface-enhanced Raman spectroscopy detection method for uranyl ion solution according to claim 1 or 2, characterized in that, In the self-assembled aggregate, the molar ratio of the streptavidin molecules to the citrate-modified silver nanoparticles is ≥500:
1.
5. The surface-enhanced Raman spectroscopy detection method for uranyl ion solution according to claim 1 or 2, characterized in that, The preparation method of the citrate-modified silver nanoparticles comprises the following steps: Mix water, a water-soluble silver salt and a water-soluble citrate, heat to boiling, and obtain a citrate-modified silver nano-sol; Perform solid-liquid separation on the citrate-modified silver nano-sol to obtain the citrate-modified silver nanoparticles.
6. The surface-enhanced Raman spectroscopy detection method for uranyl ion solution according to claim 1, characterized in that, The preparation method of the self-assembled aggregate based on silver nanoparticles comprises the following steps: Configure the citrate-modified silver nanoparticles and water into a sol; Mix the sol and streptavidin for self-assembly to obtain the self-assembled aggregate based on silver nanoparticles.
7. The surface-enhanced Raman spectroscopy detection method according to claim 1, wherein In the Raman spectrum, the Raman absorption peak position of the uranyl ion is 750 cm -1 , and the Raman absorption peak position of the citrate is 930 cm -1 .
8. The surface-enhanced Raman spectroscopy detection method according to claim 1, wherein The linear range of the standard curve or standard equation of the uranyl ion concentration - relative Raman absorption peak intensity is 1×10 -9 ~1×10 -6 mol / L.