Up-conversion sensor-based perfluorinated compound specificity detection kit and application thereof

Abstract

The invention provides a perfluorinated compound specific detection kit based on an up-conversion sensor. The perfluorinated compound specific detection kit comprises a gold nano material modified by polyethylene glycol-mercaptan and perfluoroalkyl mercaptan and an up-conversion nano material modified by polyethyleneimine, the gold nano material modified by polyethylene glycol-mercaptan and perfluoroalkyl mercaptan is obtained by combining polyethylene glycol-mercaptan and perfluoroalkyl mercaptan with gold nano particles by forming a gold-sulfur bond, the polyethyleneimine modified up-conversion nano material is obtained by directly crosslinking polyethyleneimine on the surface of an up-conversion nano material through a one-step hydrothermal synthesis method. When in use, the gold nano-material modified by polyethylene glycol-mercaptan and perfluoroalkyl mercaptan and the up-conversion nano-material modified by polyethyleneimine are mixed under an acidic condition and then are used for detecting perfluorinated compounds, so that high-sensitivity specific detection of the perfluorinated compounds can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical detection, and particularly relates to a perfluorinated compound specific detection kit based on an upconversion sensor and its application. Background Art

[0002] Perfluorinated compounds are a special class of chemicals that are widely used in lubricants, paints, cosmetics, and fire-fighting foams, etc. They are emerging persistent environmental pollutants with high stability and can exist in the environment for a long time. Among them, perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are the most abundant and common perfluorinated compounds in biota and humans. Currently, PFOA and PFOS have been listed in the Stockholm Convention on Persistent Organic Pollutants and production has been stopped in many countries.

[0003] Therefore, considering their potential toxicity, the effective identification of perfluorinated compounds in food is a key issue related to human life and health. Currently, most of the domestic and foreign standards for the detection of perfluorinated compounds still use traditional instrumental analysis methods, which have defects such as long detection cycles and high detection costs and are difficult to achieve rapid detection. For example, the patent application with the publication number CN112229935A discloses an analytical detection method for perfluorinated compounds. This method first uses polypyrrole nanofiber solid-phase extraction to separate and enrich perfluorinated compounds, and then uses liquid chromatography-tandem mass spectrometry for detection, which can detect perfluorinated compounds contained in food contact materials, food, etc. However, the instruments used in this method are relatively expensive and involve complex sample preparation, and the instrument operation is complex and time-consuming.

[0004] The reference (Sensitive Colorimetric Visualization of Perfluorinated Compounds Using Poly(ethylene glycol) and Perfluorinated Thiols Modified Gold Nanoparticles[J]. Anal.Chem. 2014, 86, 4170-4177) discloses a new sensing strategy that uses gold nanoparticles (Au@PEG-FNPs) modified with a mixture of polyethylene glycol-capped thiol (PEG-thiol) and perfluoroalkyl-capped thiol (F-thiol) as probes to detect perfluorinated compounds (PFCs) in water samples by colorimetric detection. Combined with ultraviolet-visible spectrophotometry, this detection method exhibits excellent sensitivity with a wide linear range for PFCs. Within the set concentration range, the detection limit for long-chain PFCs (perfluoroalkyl chain ≥7) can be as low as 10 μg / L. However, there is still room for improvement in the sensitivity of this detection method.

[0005] The patent application with the publication number CN113308248A discloses the preparation and application of a perfluorooctane sulfonic acid mesoporous molecularly imprinted fluorescence probe based on upconversion materials. In this method, amino-modified NaYF4:Yb,Er is used as the core, N,O-bis(trifluoroacetamide) is used as the functional monomer, cetyltrimethylammonium bromide is used as the porogen, perfluorooctane sulfonic acid is used as the template molecule, tetraethyl orthosilicate is used as the cross-linking agent, and under the initiation of alkaline conditions, a silica thin layer with specific recognition sites for perfluorooctane sulfonic acid is formed on the surface of amino-modified NaYF4:Yb,Er. After removing the template and porogen, a mesoporous molecularly imprinted fluorescence probe material is obtained, and its application in the detection of perfluorooctane sulfonic acid in water has good results. However, the synthesis of molecular imprinting requires a long preparation time (more than 12 hours), and it also requires a complex template removal process, resulting in a slow detection speed.

[0006] Therefore, it is urgent to study a rapid and accurate perfluorinated compound detection method to improve the detection speed and sensitivity. Summary of the Invention

[0007] To solve the above technical problems existing in the prior art, the present invention provides a perfluorinated compound specific detection kit based on an upconversion sensor and its application. By means of nano-controlled self-assembly, an upconversion fluorescence donor and a gold nano acceptor are prepared, and perfluoroalkylthiol is used as the recognition element to achieve highly sensitive and specific detection of perfluorinated compounds.

[0008] The present invention provides a perfluorinated compound specific detection kit based on an upconversion sensor, including:

[0009] Gold nanomaterials modified with polyethylene glycol-thiol and perfluoroalkylthiol, which are obtained by combining polyethylene glycol-thiol and perfluoroalkylthiol with gold nanoparticles through the formation of gold-sulfur bonds, and the perfluoroalkylthiol is HS(CH2) 11 -O-(CH2)2-(CF2)5-CF3;

[0010] Upconversion nanomaterials modified with polyethyleneimine, which are obtained by directly cross-linking polyethyleneimine on the surface of upconversion nanomaterials through a one-step hydrothermal synthesis method;

[0011] When in use, the gold nanomaterials modified with polyethylene glycol-thiol and perfluoroalkylthiol are mixed with the upconversion nanomaterials modified with polyethyleneimine under acidic conditions and then used for the detection of perfluorinated compounds.

[0012] Preferably, the upconversion nanomaterials are inorganic sodium fluoride nanocrystals doped with erbium, ytterbium, and yttrium elements.

[0013] Preferably, the ratio of the polyethylene glycol-thiol and perfluoroalkylthiol modified gold nanomaterials to the polyethyleneimine modified upconversion nanomaterials is 10.72 - 16.08 μmol ∶ 5 - 7 mg.

[0014] Preferably, the method for preparing the polyethylene glycol-thiol and perfluoroalkylthiol modified gold nanomaterials comprises the following steps:

[0015] (1) Mix chloroauric acid, polyethylene glycol-thiol, and a reducing agent in a solvent for reaction. The polyethylene glycol-thiol is modified on the surface of the reduced gold nanoparticles through gold-sulfur bonds to obtain a polyethylene glycol-thiol modified gold nanoparticle solution;

[0016] (2) Then add perfluoroalkylthiol to the above-mentioned polyethylene glycol-thiol modified gold nanoparticle solution. The perfluoroalkylthiol is modified on the surface of the polyethylene glycol-thiol modified gold nanoparticles through gold-sulfur bonds, and the polyethylene glycol-thiol and perfluoroalkylthiol modified gold nanomaterials are separated.

[0017] More preferably, the ratio of polyethylene glycol-thiol, perfluoroalkylthiol, and chloroauric acid is 1.5 - 2.0 mg ∶ 0.2 - 0.3 mg ∶ 3 - 5 μmol.

[0018] More preferably, the reducing agent is sodium borohydride; the solvent is ethanol.

[0019] Preferably, the method for preparing the polyacetimide modified upconversion nanomaterials comprises the following steps:

[0020] (1) Dissolve sodium chloride and polyacetimide in polyethylene glycol A to obtain solution 1;

[0021] (2) Then add solution 1 to a methanol solution containing yttrium chloride hexahydrate, ytterbium chloride hexahydrate, and erbium chloride hexahydrate and stir to mix, obtaining solution 2;

[0022] (3) Dissolve ammonium fluoride in polyethylene glycol B to obtain solution 3, and then mix solution 2 and solution 3 evenly to obtain solution 4;

[0023] (4) Transfer solution 4 to a reaction kettle, and through crystal growth and dissolution reaction and the modification of polyacetimide on the surface of the upconversion nanomaterial crystals, the polyacetimide modified upconversion nanomaterials are obtained.

[0024] Further preferably, the dosage ratio of sodium chloride, polyacetylimide and polyethylene glycol A is 0.08 - 0.2 g∶0.3 - 0.5 g∶16 - 30 mL; the dosage ratio of yttrium chloride hexahydrate, ytterbium chloride hexahydrate, erbium chloride hexahydrate and methanol is 0.2 - 0.3 g∶0.07 - 0.08 g∶0.007 - 0.008 g∶8 - 15 mL; the dosage ratio of ammonium fluoride and polyethylene glycol B is 6.24 g∶8 - 15 mL; the volume ratio of polyethylene glycol A, methanol and polyethylene glycol B is 2∶1∶1.

[0025] The present invention also provides the application of the above-mentioned perfluorinated compound specific detection kit based on the upconversion sensor in the detection of perfluorinated compounds.

[0026] The present invention provides a method for specifically detecting perfluorinated compounds based on an upconversion sensor. This method uses the above-mentioned perfluorinated compound specific detection kit based on the upconversion sensor, and includes the following steps: Before detection, first mix and incubate the polyethylene glycol-thiol and perfluoroalkylthiol modified gold nanomaterials with the polyethyleneimine modified upconversion nanomaterials under acidic conditions to obtain a specific detection system. During detection, perform ion pair extraction and methyl tert-butyl ether extraction on the sample to be detected, take the supernatant after purification and add it to the specific detection system, measure the fluorescence intensity signal characteristic value of the detection system, and calculate the content of perfluorinated compounds in the sample by referring to the standard curve.

[0027] Preferably, the method for establishing the standard curve is as follows: Gradient dilute a perfluorinated compound standard solution with a known concentration, then use the above-mentioned perfluorinated compound specific detection kit based on the upconversion sensor for detection, obtain the fluorescence intensity signal characteristic values of perfluorinated compounds at different known concentrations, and obtain the standard curve through linear fitting.

[0028] Preferably, the perfluorinated compounds are perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), perfluorobutyric acid (PFBA) or perfluorononanoic acid (PFNA). The present invention takes PFOS as an example to detect perfluorinated compounds, and is equally applicable to the detection of other perfluorinated compounds.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] (1) The present invention discloses a specific detection method of perfluorinated compounds in an environment based on an upconversion fluorescence nanosensor, which detects perfluorinated compounds based on a luminescent sensor based on upconversion and gold nanoparticles. Upconversion nanoparticles are used as fluorescence donors, gold nanoparticles are used as fluorescence acceptors, and a specific perfluorinated compound detection system based on the fluorescence inner filter effect is established. When perfluorinated compounds are not present, the gold nanoparticles are in a dispersed state, and their absorption peaks and upconversion emission peaks overlap to quench the upconversion luminescence through the fluorescence inner filter effect; when perfluorinated compounds are present, they bind to the perfluoroalkyl long chains on the surface of the gold nanoparticles through fluorine-fluorine forces, induce gold nanoparticle aggregation, decrease the absorption peak, and restore the donor fluorescence. Therefore, a highly specific perfluorinated compound concentration detection system is constructed through the change in the fluorescence intensity of the sensor.

[0031] (2) The specific detection kit constructed by the present invention and the specifically designed upconversion nanomaterial-gold nanofluorescence detection system have strong fluorescence responsiveness to perfluorinated compounds, can effectively eliminate background fluorescence and interference from other molecules, have high specificity for the detection of perfluorinated compounds, and can achieve high-sensitivity detection of the content of perfluorinated compounds, overcoming the defects of traditional instrumental analysis methods such as high cost, cumbersome operation and low detection sensitivity, which is crucial to ensuring environmental safety and human life and health.

[0032] (3) The linear concentration range of the perfluorinated compound concentration and the fluorescence intensity signal value established by the present invention is 200-10 5 nM, has a wide linear detection range, and the detection limit LOD is 3.3pM, which can meet the high-sensitivity detection of the content of perfluorinated compounds; and the present invention greatly shortens the time required for preparing the detection system, improves the detection speed, and has good versatility and application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a characterization diagram of the prepared nanomaterial; wherein, Figure 1 A in the figure is the transmission electron microscope image of the upconversion nanoparticles. Figure 1 B in the figure is a transmission electron microscope image of gold nanoparticles.

[0034] Figure 2 The preparation process and detection principle of the PFOS-specific detection system based on upconversion sensors; UCNPs are core upconversion nanomaterials, PEI is poly(ethyleneimine); AuNPs are gold nanoparticles, polyethylene glycol-thiol (PEG-SH) and perfluoroalkylthiol (F-SH) are their surface polymers; PFCs are perfluorinated compounds.

[0035] Figure 3 is the principle diagram of upconversion fluorescence quenching; Figure 3 A in the figure is the absorption spectrum of gold nanoparticles and the fluorescence emission spectrum of upconversion nanoparticles;Figure 3 In it, B is the luminescence decay curve before and after the mixing of upconversion nanoparticles and gold nanoparticles.

[0036] Figure 4 It is the fluorescence response result diagram of the detection system for different concentrations of PFOS; among them, Figure 4 In it, A is the spectrogram of the detection system under different PFOS concentrations, Figure 4 In it, B is the standard curve diagram fitted with the PFOS concentration and the characteristic value of the fluorescence signal of the detection system.

[0037] Figure 5 It is the performance evaluation result diagram of the upconversion detection system; among them, Figure 5 In it, A is the molecular structure model of the target and interfering components; Figure 5 In it, B is the selectivity test result diagram. Specific implementation mode

[0038] Example 1

[0039] A specific detection method for perfluorinated compounds in food based on an upconversion fluorescence nanosensor, and the specific preparation steps are as follows:

[0040] I. Preparation of polyimide-modified upconversion nanoparticles

[0041] Accurately weigh 0.14 g of sodium chloride and 0.4 g of polyimide (MW = 20000, the same below) and stir in 18.0 mL of polyethylene glycol (MW = 5000, the same below). Then accurately weigh 0.2366 g of yttrium chloride hexahydrate, 0.0775 g of ytterbium chloride hexahydrate, and 0.0076 g of erbium chloride hexahydrate, dissolve them in 9 mL of methanol, and add them to the above mixture, and continue to stir for 30 min. When it is observed that the solution becomes transparent, dissolve 0.231 g of ammonium fluoride in 9 mL of polyethylene glycol and add it to the above transparent liquid, and stir at room temperature for 10 min. Put the mixture into a 50 mL high-pressure reaction kettle with a polytetrafluoroethylene liner and react at 200 °C for 1.5 hours. After natural cooling, wash with ethanol and dry in vacuum to obtain polyimide-modified upconversion nanoparticles.

[0042] Figure 1 In it, A is the transmission electron micrograph of the prepared polyimide-modified upconversion nanoparticles. It can be seen from the figure that the prepared upconversion nanoparticles have uniform particle size, a diameter of about 20 nm, and good dispersibility.

[0043] II. Preparation of polyethylene glycol-thiol and perfluoroalkyl thiol-modified gold nanoparticles

[0044] Add 1.872 mg of polyethylene glycol-thiol (HS(CH2) 11 -(OCH2CH2)n -OH, n = 6), and after mixing, 1 mL of freshly prepared sodium borohydride solution (concentration 0.1 M, solvent ethanol) was added to the mixture, and the color of the solution immediately turned dark red. Stir for 30 min to obtain a polyethylene glycol-modified gold nanoparticle solution. 0.275 mg of perfluoroalkyl thiol (HS(CH2) 11 -O-(CH2)2-(CF2)5-CF3) was added to the above polyethylene glycol-modified gold nanoparticle solution and left standing overnight. Then, it was evaporated to about 1 mL under a nitrogen atmosphere and then redispersed with 40 mL of deionized water and stored at room temperature for later use.

[0045] Figure 1 Figure B in shows the transmission electron microscope image of the prepared gold nanoparticles. It can be seen from the figure that the gold nanoparticles have a uniform particle size, with a diameter of about 15 nm and good dispersibility.

[0046] III. Establishment of the specific detection system

[0047] The gold nanoprobe (gold nanoparticles modified with polyethylene glycol and perfluoroalkyl thiol) prepared in the above steps and the upconversion nanoprobe (upconversion nanoparticles modified with polyimide) were mixed in a certain proportion. By adding PFOS and then performing fluorescence quenching and recovery experiments on the system, the recognition effect of the system on PFOS was investigated, which is the specific detection system. The specific operation steps are as follows: 6 mg of upconversion nanoparticles modified with polyimide prepared in the above steps were dissolved in 300 μL of acetic acid buffer solution with pH = 4, and 100 μL of the above-prepared aqueous solution of gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol (containing 13.4 μmol of gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol) was added. The solution obtained after mixing evenly is the specific detection system.

[0048] The preparation method and detection principle of the PFOS-specific detection system based on the upconversion sensor are as Figure 2 shown. In the specific detection system, gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol are mixed with upconversion nanoparticles modified with polyimide. Due to the overlap of the absorption peak of the gold nanoparticles and the emission peak of the upconversion nanoparticles, the fluorescence acceptor quenches the upconversion luminescence. When PFOS is added, the long-chain perfluoroalkyl groups on the surface of the gold nanoparticles bind to the fluorine groups of PFOS, inducing a decrease in the absorption peak of the aggregated gold nanoparticles, resulting in the recovery of the upconversion fluorescence. The schematic diagram of the upconversion fluorescence quenching is as Figure 3 shown in Figure A in. The fluorescence emission spectrum of the upconversion nanoparticles was measured using a fluorescence spectrometer, and the absorption spectrum of the gold nanoparticles was measured using a spectrophotometer. The absorption peak of the gold nanoparticles overlaps with the upconversion emission peak at 540 nm, which can quench the upconversion emission peak. Figure 3In [reference], B is the luminescence decay curve of the upconversion nanoparticles before and after mixing with gold nanoparticles measured by a fluorescence spectrometer. As can be seen from Figure 3 B in [reference], the presence of gold nanoparticles has little effect on the upconversion fluorescence lifetime, indicating that fluorescence quenching is caused by the occurrence of fluorescence inner filter effect.

[0049] Example 2

[0050] A specific detection method for perfluorinated compounds in food based on an upconversion fluorescence nanosensor, and the specific preparation steps are as follows:

[0051] I. Preparation of polyimide-modified upconversion nanoparticles

[0052] Accurately weigh 0.08 g of sodium chloride and 0.3 g of polyimide (MW = 20000) and stir in 16.0 mL of polyethylene glycol-thiol (MW = 5000). Then accurately weigh 0.2 g of yttrium chloride hexahydrate, 0.07 g of ytterbium chloride hexahydrate, and 0.007 g of erbium chloride hexahydrate, dissolve them in 8 mL of methanol, and add them to the above mixture, and continue stirring for 30 min. When the solution becomes transparent, dissolve 0.231 g of ammonium fluoride in 8 mL of polyethylene glycol-thiol and add it to the above transparent liquid, and stir at room temperature for 10 min. Put the mixture into a 50 mL high-pressure reaction kettle with a polytetrafluoroethylene liner, and react at 200 °C for 1.5 hours. After natural cooling, wash with ethanol and vacuum dry to obtain polyimide-modified upconversion nanoparticles.

[0053] II. Preparation of polyethylene glycol-thiol and perfluoroalkylthiol-modified gold nanoparticles

[0054] Add 1.5 mg of polyethylene glycol-thiol to 30 mL of a 0.1 mM chloroauric acid solution. After mixing, add 1 mL of freshly prepared sodium borohydride (0.1 M) solution to the mixture, and the color of the solution immediately turns dark red. Stir for 30 min to obtain a polyethylene glycol-modified gold nanoparticle solution. Add 0.2 mg of perfluoroalkylthiol to the above polyethylene glycol-modified gold nanoparticle solution and let it stand overnight. Then, evaporate to about 1 mL under a nitrogen atmosphere, and then redisperse with 40 mL of deionized water and store at room temperature for later use.

[0055] III. Establishment of a specific detection system

[0056] Mix the gold nanoprobes (gold nanoparticles modified with polyethylene glycol and perfluoroalkyl thiol) and upconversion nanoprobes (upconversion nanoparticles modified with polyimide) prepared in the above steps in a certain proportion. By adding PFOS and then performing fluorescence quenching and recovery tests on the system, the recognition effect of the system on PFOS is investigated, which is the specific detection system. The specific operation steps are as follows: Dissolve 5 mg of the upconversion nanoparticles modified with polyimide prepared in the above steps in 300 μL of acetic acid buffer solution with pH = 4, add 80 μL of the aqueous gold nanoparticle solution modified with polyethylene glycol-thiol and perfluoroalkyl thiol prepared above (containing 10.72 μmol of gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol), and the resulting solution after mixing evenly is the specific detection system.

[0057] Example 3

[0058] A specific detection method for perfluorinated compounds in food based on an upconversion fluorescence nanosensor, and the specific preparation steps are as follows:

[0059] I. Preparation of upconversion nanoparticles modified with polyimide

[0060] Accurately weigh 0.2 g of sodium chloride and 0.5 g of polyimide (MW = 20000) and stir in 30 mL of polyethylene glycol-thiol (MW = 5000). Then accurately weigh 0.3 g of yttrium chloride hexahydrate, 0.08 g of ytterbium chloride hexahydrate, and 0.008 g of erbium chloride hexahydrate, dissolve them in 15 mL of methanol, and add them to the above mixture, and continue stirring for 30 min. When it is observed that the solution becomes transparent, dissolve 0.231 g of ammonium fluoride in 15 mL of polyethylene glycol-thiol and add it to the above transparent liquid, and stir at room temperature for 10 min. Put the mixture into a 50 mL high-pressure reaction kettle with a polytetrafluoroethylene lining, and react at 200 °C for 1.5 hours. After natural cooling, wash with ethanol and vacuum dry to obtain upconversion nanoparticles modified with polyimide.

[0061] II. Preparation of gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol

[0062] Add 2 mg of polyethylene glycol-thiol to 50 mL of chloroauric acid solution with a concentration of 0.1 mM. After mixing, add 1 mL of freshly prepared sodium borohydride (0.1 M) solution to the mixture, and the color of the solution immediately turns dark red. Stir for 30 min to obtain a gold nanoparticle solution modified with polyethylene glycol. Add 0.3 mg of perfluoroalkyl thiol to the above gold nanoparticle solution modified with polyethylene glycol and let it stand overnight. Then, evaporate to about 1 mL under a nitrogen atmosphere, and then redisperse with 40 mL of deionized water and store at room temperature for later use.

[0063] III. Establishment of a specific detection system

[0064] Mix the gold nanoprobe (gold nanoparticles modified with polyethylene glycol and perfluoroalkyl thiol) and the upconversion nanoprobe (upconversion nanoparticles modified with polyimide) prepared in the above steps in a certain proportion. By adding PFOS and then conducting fluorescence quenching and recovery tests on the system, the recognition effect of the system on PFOS is investigated, which is the specific detection system. The specific operation steps are as follows: Dissolve 7 mg of the upconversion nanoparticles modified with polyimide prepared in the above steps in 300 μL of acetic acid buffer solution with pH = 4, and add 120 μL of the aqueous solution of gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol prepared above (containing 16.08 μmol of gold nanoparticles modified with polyethylene glycol-thiol and perfluoroalkyl thiol). The solution obtained after mixing evenly is the specific detection system.

[0065] Example 4

[0066] Establish a detection standard curve for perfluorinated compounds. The specific preparation steps are as follows:

[0067] (1) Determine the fluorescence intensity signal characteristic values of the PFOS standard solution: Prepare 13 specific detection systems according to the method of Example 1. Add 0.2 mL of PFOS standard solutions with concentrations of 1 nM, 10 nM, 50 nM, 75 nM, 100 nM, 200 nM, 300 nM, 400 nM, 500 nM, 1000 nM, 5000 nM, 10 4 nM, and 10 5 nM to them respectively to obtain test solutions with different concentrations. One concentration of PFOS solution corresponds to one specific detection system, and the two are in a one-to-one correspondence. Then determine the fluorescence intensity signal characteristic value Y of the specific detection system added with PFOS solutions with different concentrations. Figure 4 In [reference], A is the fluorescence signal of the detection system at different PFOS concentrations. It can be seen from the figure that the fluorescence intensity of the specific detection system is the highest at a wavelength of 540 nm. Therefore, measure the fluorescence intensity value at 540 nm under the excitation light with a wavelength of 980 nm; and as the PFOS concentration increases, the fluorescence intensity of the detection system also increases.

[0068] (2) Establish a PFOS detection standard curve: Establish the relationship between the logarithm of the PFOS concentration (c) and the fluorescence intensity signal characteristic value Y. The PFOS detection standard curve is obtained through linear fitting as shown in Figure 4 In [reference], B. The logarithm of the PFOS concentration and the fluorescence intensity signal characteristic value show a linear relationship in the concentration range of 200 - 10 5 nM, and deviate from the linear curve in the range of 10 - 200 nM. Therefore, in the range of 200 - 10 5The linear equation obtained within the nM linear range is Y = 256.86log(c) + 286.86, and the coefficient of determination R 2 = 0.986. The detection limit is calculated to be 3.3 pM according to the formula LOD = 3σ / K (where σ is the standard deviation of 10 blank experiments and K is the slope of the standard curve).

[0069] Example 5

[0070] Detection of perfluorinated compounds in food samples.

[0071] Weigh 4 g of fish oil sample, and then add 1, 1000, 10 5 nM of PFOS respectively. Then mix 2 mL of tetrabutylammonium sulfate solution (0.5 M, pH = 10) with 2 mL of sodium carbonate (0.25 M). After the reaction, extract twice with 5 mL of MTBE. After the sample is concentrated under nitrogen, it is dissolved in a water:acetonitrile (v:v = 6:4) mixture. Take 0.4 mL and add it to the specific detection system constructed in Example 1, and measure the characteristic value of the fluorescence intensity signal of the specific detection system. Calculate the content of PFOS in the food sample through the PFOS detection standard curve established in Example 2.

[0072] Table 1 Results of detecting PFOS content in fish oil spiked samples by the method of the present invention

[0073]

[0074] As can be seen from Table 1, the detection results are close to the added amounts, the detection recovery rate exceeds 100%, and the relative standard deviation is less than 1.73%. All these results indicate that the PFOS detection method proposed in this study has excellent accuracy and practicability in the detection of actual fish oil samples.

[0075] Comparative Example 1

[0076] The detection of PFOS content usually uses high performance liquid chromatography - mass spectrometry coupling technology in the standard. To further evaluate the accuracy of the method of the present invention, the results of detecting PFOS content by the method of the present invention and the standard method were compared in the study. The specific operation is as follows: Analyze three fish oil samples randomly spiked with different unknown concentrations of PFOS using the specific detection system constructed in Example 1. After measuring the fluorescence intensity, substitute the fluorescence value into the standard curve equation to calculate the content of PFOS. At the same time, detect the same samples by high performance liquid chromatography, calculate the PFOS content of the random samples, and compare the significant differences between the high performance liquid chromatography detection results and the fluorescence detection results.

[0077] Table 2 Comparison of the results of detecting PFOS content in random samples by the method of the present invention and the standard method (unit, μM)

[0078]

[0079] As can be seen from Table 2, the detection results of the two methods are relatively close. The test analysis results show that the P value is 0.39, which is much greater than 0.05, indicating that there is no significant difference between the PFOS fluorescence detection method and the high performance liquid chromatography method. All of the above results indicate that the PFOS detection method proposed in this study has excellent accuracy.

[0080] Detection Example 1

[0081] Detection of the specificity and anti-interference ability of perfluorinated compounds.

[0082] n-Octanoic acid, 1-hexadecylamine, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), tridecanoic acid, 1,2-dodecanediol, and n-decanoic acid were used in the method of the present invention to evaluate its selectivity. Specifically, the specificity detection system constructed in Example 1 was adopted. The results are as Figure 5 shown. Only the target PFOS can cause a significant change in the fluorescence signal. Thus, it can be seen that the detection method constructed in the present invention has high specificity for PFOS.

Claims

1. A perfluorinated compound specific detection kit based on an upconversion sensor, characterized in that, Comprising: Gold nanomaterials modified with polyethylene glycol-thiol and perfluoroalkyl thiol are obtained by binding polyethylene glycol-thiol and perfluoroalkyl thiol to gold nanoparticles through the formation of gold-sulfur bonds. The perfluoroalkyl thiol is HS(CH2) 11 -O-(CH2)2-(CF2)5-CF3; A polyethyleneimine-modified upconversion nanomaterial, which is obtained by directly crosslinking polyethyleneimine on the surface of the upconversion nanomaterial through a one-step hydrothermal synthesis method; When in use, the polyethylene glycol-thiol and perfluoroalkylthiol-modified gold nanomaterial and the polyethyleneimine-modified upconversion nanomaterial are mixed under acidic conditions and then used for detecting perfluorinated compounds.

2. The perfluorinated compound specific detection kit based on an upconversion sensor according to claim 1, wherein The upconversion nanomaterial is an inorganic sodium fluoride nanocrystal doped with erbium, ytterbium and yttrium elements.

3. The perfluorinated compound specific detection kit based on an upconversion sensor according to claim 1, wherein, The ratio of the polyethylene glycol-thiol and perfluoroalkylthiol-modified gold nanomaterial to the polyethyleneimine-modified upconversion nanomaterial is 10.72 - 16.08 μmol∶5 - 7 mg.

4. The perfluorinated compound specific detection kit based on an upconversion sensor according to claim 1, wherein The preparation method of the polyethylene glycol-thiol and perfluoroalkylthiol-modified gold nanomaterial comprises the following steps: (1) Mixing chloroauric acid, polyethylene glycol-thiol and a reducing agent in a solvent for reaction, and polyethylene glycol-thiol is modified on the surface of the reduced gold nanoparticles through gold-sulfur bonds to obtain a polyethylene glycol-thiol-modified gold nanosolution; (2) Then adding perfluoroalkylthiol to the above polyethylene glycol-thiol-modified gold nanosolution, and perfluoroalkylthiol is modified on the surface of the polyethylene glycol-thiol-modified gold nanoparticles through gold-sulfur bonds, and the polyethylene glycol-thiol and perfluoroalkylthiol-modified gold nanomaterial is separated.

5. The perfluorinated compound-specific detection kit based on an upconversion sensor according to claim 4, wherein The ratio of the raw materials polyethylene glycol-thiol, perfluoroalkylthiol and chloroauric acid is 1.5 - 2.0 mg∶0.2 - 0.3 mg∶3 - 5 μmol; the reducing agent is sodium borohydride.

6. The perfluorinated compound specific detection kit based on an upconversion sensor according to claim 1, wherein The preparation method of the polyacetimide-modified upconversion nanomaterial comprises the following steps: (1) Dissolving sodium chloride and polyacetimide in polyethylene glycol A to obtain solution 1; (2) Then adding solution 1 to a methanol solution containing yttrium chloride hexahydrate, ytterbium chloride hexahydrate and erbium chloride hexahydrate and stirring and mixing to obtain solution 2; (3) Dissolving ammonium fluoride in polyethylene glycol B to obtain solution 3, and then mixing solution 2 and solution 3 evenly to obtain solution 4; (4) Transferring solution 4 to a reaction kettle, and obtaining the polyacetimide-modified upconversion nanomaterial through crystal growth and dissolution reaction and the modification of polyacetimide on the surface of the upconversion nanomaterial crystal.

7. The perfluorinated compound specific detection kit based on an upconversion sensor according to claim 6, wherein The dosage ratio of the sodium chloride, polyacetimide and polyethylene glycol A is 0.08 - 0.2 g∶0.3 - 0.5 g∶16 - 30 mL; the dosage ratio of the yttrium chloride hexahydrate, ytterbium chloride hexahydrate, erbium chloride hexahydrate and methanol is 0.2 - 0.3 g∶0.07 - 0.08 g∶0.007 - 0.008 g∶8 - 15 mL; the dosage ratio of the ammonium fluoride and polyethylene glycol B is 6.24 g∶8 - 15 mL; the volume ratio of the polyethylene glycol A, methanol and polyethylene glycol B is 2∶1∶1.

8. Application of the perfluorinated compound-specific detection kit based on the upconversion sensor according to any one of claims 1 to 7 in the detection of perfluorinated compounds.

9. A method for specific detection of perfluorinated compounds based on an upconversion sensor, characterized in that, Using the perfluorinated compound specific detection kit based on the upconversion sensor according to any one of claims 1 to 7, the method comprises the following steps: Before detection, uniformly mix the polyethylene glycol-thiol and perfluoroalkyl thiol modified gold nanomaterials with the polyethyleneimine modified upconversion nanomaterials under acidic conditions to obtain a specific detection system. During detection, perform ion pair extraction and methyl tert-butyl ether extraction on the sample to be detected, take the supernatant, purify it, and then add it to the specific detection system. Measure the fluorescence intensity signal characteristic value of the detection system, and calculate the content of perfluorinated compounds in the sample by referring to the standard curve.

10. The perfluorinated compound specific detection method based on an upconversion sensor according to claim 9, characterized in that, The method for establishing the standard curve is as follows: Gradiently dilute the perfluorinated compound standard solution with a known concentration, and then use the perfluorinated compound specific detection kit based on the upconversion sensor for detection to obtain the fluorescence intensity signal characteristic values of perfluorinated compounds at different known concentrations. The standard curve is obtained by linear fitting.

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