A bimodal sensor and methods of making and using the same

Abstract

The application discloses a bimodal sensor and a preparation method and application thereof. The bimodal sensor comprises functionalized nano-gold, which comprises nano-gold; the surface of the nano-gold is decorated with 4-mercaptobenzoic acid and thymine; and the thymine is decorated by cysteamine. The functionalized nano-gold can realize specific identification of mercury ions in substrates such as food and medicine, and then realize bimodal detection result output of colorimetry / surface enhanced Raman spectroscopy, so as to achieve the purpose of self-correction detection, improve the selectivity, accuracy and efficiency of detection, and can be applied to the detection of mercury ions in natural environment, food, medicine and cosmetics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy metal analysis, in particular to a bimodal sensor and a preparation method and application thereof. BACKGROUND

[0002] Mercury is a common contaminant in food, which has high toxicity, especially methylmercury, can accumulate through the food chain, and poses a serious threat to human health. The toxicity of mercury mainly manifests as neurotoxicity and kidney damage, and long-term exposure can also cause damage to the immune system and reproductive system. At present, the detection methods of mercury in food mainly include atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, etc. These methods have high sensitivity and accuracy, but have the disadvantages of complex operation, high cost, long detection period, etc., which are difficult to meet the needs of on-site rapid detection. Therefore, it is essential to develop an accurate and sensitive detection method to ensure food safety.

[0003] In recent years, sensor technology has attracted widespread attention in the field of heavy metal ion detection in food due to its simple operation, high sensitivity, and good selectivity. However, due to the insufficient detection accuracy of a single sensor, its practicality and reliability in complex food samples are often limited, and standardized detection methods need to be used for comparative analysis to verify its accuracy. Multi-modal sensors have become an effective strategy to improve detection accuracy through self-calibration steps. SUMMARY

[0004] The present application aims to solve at least one of the above technical problems in the prior art. To this end, the purpose of the present application is to provide a bimodal sensor and a preparation method and application thereof.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is:

[0006] In a first aspect of the present application, a functionalized gold nanoparticle is provided, comprising gold nanoparticles; the surface of the gold nanoparticles is modified with 4-mercaptobenzoic acid and thymine; the thymine is modified by cysteamine.

[0007] In the present application, 4-mercaptobenzoic acid (4-MBA) and cysteamine (Cy) are modified on the surface of gold nanoparticles (AuNPs) through Au-S bonds, and thymine (T) is modified on the surface of gold nanoparticles through a -CO-NH- bond between cysteamine and thymine, forming a bimodal sensor.

[0008] In some embodiments of the present application, after the surface of the gold nanoparticles is modified with 4-mercaptobenzoic acid, thymine is modified by cysteamine.

[0009] In some embodiments of the present application, the nano-gold surface is modified by cysteamine to modify thymine, and then modified by 4-mercaptobenzoic acid.

[0010] In the present application, thymine is used as a recognition receptor, and can recognize target substances by colorimetry when applied. Meanwhile, 4-mercaptobenzoic acid can introduce Raman signal probe molecules into the sensor, so that the target substances can be quantified indirectly through the Raman signal intensity of 4-mercaptobenzoic acid, without interfering with the colorimetric recognition, and realizing the dual-mode (colorimetric and surface-enhanced Raman) signal output of the sensor.

[0011] In some embodiments of the present application, the molar ratio of the nano-gold to the 4-mercaptobenzoic acid is 1:100-4:25.

[0012] In some embodiments of the present application, the molar ratio of the nano-gold to the cysteamine is 20-20000:1.

[0013] In some embodiments of the present application, the molar ratio of the cysteamine to the thymine is 3:100-1:2.

[0014] In some embodiments of the present application, the average particle size of the nano-gold is 35-55 nm.

[0015] In a second aspect of the present application, a preparation method of the functionalized nano-gold is provided, comprising the following steps:

[0016] The nano-gold, 4-mercaptobenzoic acid, cysteamine and thymine are reacted to prepare the functionalized nano-gold.

[0017] In some embodiments of the present application, the nano-gold solution is reacted with the 4-mercaptobenzoic acid solution to prepare AuNPs / 4-MBA; then reacted with the cysteamine solution to prepare AuNPs / 4-MBA / Cy; and then cross-linked with thymine to prepare AuNPs / 4-MBA / Cy / T complex, i.e. the functionalized nano-gold.

[0018] In some embodiments of the present application, the nano-gold solution is reacted with the cysteamine solution to prepare AuNPs / Cy; then cross-linked with thymine to prepare AuNPs / Cy / T; and then reacted with the 4-mercaptobenzoic acid solution to prepare AuNPs / Cy / T / 4-MBA complex, i.e. the functionalized nano-gold.

[0019] In some embodiments of the present application, the cross-linking reaction is carried out under the action of a cross-linking agent, and the cross-linking agent includes 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride / N-hydroxysuccinimide (EDC / NHS).

[0020] In some embodiments of the present invention, thymine-1-acetic acid is reacted with cysteine ​​in the presence of a crosslinking agent to modify thymine.

[0021] In some embodiments of the present invention, the concentration of the gold nanoparticles is 0.1–0.4 mmol / L; for example, 0.2–0.3 mmol / L.

[0022] In some embodiments of the present invention, the concentration of the 4-mercaptobenzoic acid is 25.0–40.0 mmol / L; for example, 30.0–35.0 mmol / L.

[0023] In some embodiments of the present invention, the concentration of cysteine ​​is 0.03 to 0.1 mmol / L; for example, 0.04 to 0.08 mmol / L.

[0024] In some embodiments of the present invention, the concentration of thymidine carboxylic acid is 0.2–1.0 mmol / L; for example, 0.3–0.8 mmol / L.

[0025] In some embodiments of the present invention, the volume ratio of the mixed gold nanoparticle solution, cysteine ​​solution, thymine carboxylic acid solution and 4-mercaptobenzoic acid solution is 2:0.01:0.01:0.5 to 15:0.1:0.1:1.5; such as 6:0.01:0.01:0.8 to 12:0.05:0.05:1.2.

[0026] In some embodiments of the present invention, the concentration of the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1–20 mmol / L; for example, 5–15 mmol / L.

[0027] In some embodiments of the present invention, the concentration of the N-hydroxysuccinimide is 1–20 mmol / L; for example, 5–15 mmol / L.

[0028] In some embodiments of the present invention, the molar concentration ratio of thymine to EDC is 0.2:1 to 1.0:20.0.

[0029] In some embodiments of the present invention, the molar ratio of thymine to NHS is 0.2:1 to 1.0:20.0.

[0030] In some embodiments of the present invention, the nano-gold can be commercially available; or it can be prepared according to the preparation method described in the present invention.

[0031] In some embodiments of the present invention, the preparation method of the gold nanoparticles includes the following steps: subjecting a gold salt to a reducing agent in a hydrothermal reaction to obtain the gold nanoparticles.

[0032] In some embodiments of the present invention, the molar concentration ratio of the gold salt to the reducing agent is 0.1:0.25 to 0.4:0.45.

[0033] In some embodiments of the present invention, the concentration of the gold salt is 0.5% to 6% (w / v).

[0034] In some embodiments of the present invention, the concentration of the reducing agent is 0.5% to 7% (w / v).

[0035] In some embodiments of the present invention, the gold salt includes at least one of chloroauric acid, gold nitrate, gold sulfate, gold acetate, and gold cyanide.

[0036] In some embodiments of the present invention, the reducing agent includes at least one of sodium citrate, ascorbic acid, sodium bisulfite, sodium thiosulfate, ferrous sulfate, glucose, sodium borohydride, and ethylene glycol.

[0037] In some embodiments of the present invention, the hydrothermal reaction temperature is 90–150°C; the reaction time is 5–30 min.

[0038] A third aspect of the present invention provides a dual-modal sensor comprising the aforementioned functionalized gold nanoparticles.

[0039] In some embodiments of the present invention, the dual-modal sensor further includes a solvent, such as water.

[0040] In some embodiments of the present invention, the mass concentration of functionalized gold nanoparticles in the dual-modal sensor is at least 0.1 mmol / L, such as 0.1 to 0.4 mmol / L.

[0041] In a fourth aspect, the present invention provides a reagent kit for detecting mercury ions, comprising a housing containing a sample vial, a cuvette, and a quartz array having the aforementioned dual-modal sensor; the quartz array may have dimensions of 35.0 × 50.0 × 2.0 mm.

[0042] A fifth aspect of the present invention provides an application of the functionalized gold nanoparticles, the dual-modal sensor, or the reagent kit for detecting mercury ions in mercury ion detection.

[0043] In this invention, mercury ions lack a Raman signal. In the functionalized gold nanoparticles or dual-modal sensor, 4-mercaptobenzoic acid serves as a Raman signal probe molecule, enabling quantification of mercury ions based on Raman signal intensity, thus addressing the issue of mercury ions lacking a Raman signal. Simultaneously, the presence of 4-mercaptobenzoic acid does not interfere with colorimetric recognition of mercury ions. Thymine specifically recognizes and adsorbs mercury ions. Utilizing the unique localized surface plasmon resonance properties of gold nanoparticles, a color change is achieved, enhancing the surface-enhanced Raman spectroscopy signal, thereby realizing dual-signal output of colorimetry and surface-enhanced Raman spectroscopy. This dual-signal output further reduces the interference of complex matrices in actual samples on the results and promotes mutual verification, thereby improving the accuracy, reliability, and diversity of detection, enabling on-site detection and rapid screening of actual samples through colorimetry and surface-enhanced Raman spectroscopy.

[0044] A sixth aspect of the present invention provides a method for detecting mercury ions, comprising the following steps:

[0045] Mercury ions are detected using the aforementioned functionalized gold nanoparticles or the aforementioned dual-modal sensor.

[0046] In some embodiments of the present invention, the detection is colorimetric / surface-enhanced Raman spectroscopy detection.

[0047] In some embodiments of the present invention, the mercury ion detection method includes the following steps: using the functionalized gold nanoparticles or the dual-modal sensor to detect the ultraviolet-visible spectrum and surface-enhanced Raman spectrum of mercury ions in a control solution and a test solution containing mercury ions at different standard concentrations, respectively, and using the external standard method to determine the mercury ion content in the test solution.

[0048] In some embodiments of the present invention, the mercury ion detection method includes the following steps:

[0049] (1) Using the functionalized gold nanoparticles or the dual-modal sensor, construct standard working curves between mercury ions of different standard concentrations and Raman / colorimetric signal intensities;

[0050] (2) Mix the functionalized gold nanoparticles or the dual-modal sensor with the mercury ion-containing analyte, obtain the Raman / colorimetric signal intensity, and perform qualitative analysis; and / or, perform quantitative analysis using the standard working curve.

[0051] In some embodiments of the present invention, standard working curves between the intensity of characteristic absorption peaks in the ultraviolet-visible spectra of mercury ions at different standard concentrations in the range of 400–700 nm (e.g., 500–600 nm, 510–560 nm, 520–540 nm, 530–535 nm, 530–533 nm) are constructed using the functionalized gold nanoparticles or the dual-modal sensor described above.

[0052] In some embodiments of the present invention, the functionalized gold nanoparticles or the dual-modal sensor described above are used to construct mercury ion concentrations of different standard concentrations in the range of 400–2000 cm⁻¹. -1 (e.g., 700-1500cm) -1 900~1200cm -1 1000~1100cm -1 1060~1090cm -1 1070~1080cm -1 The standard working curve between the Raman characteristic peak intensities at () is used.

[0053] In some embodiments of the present invention, in step (2), the mixing time is 10 to 40 minutes, such as 15 to 30 minutes.

[0054] In some embodiments of the present invention, the functionalized gold nanoparticles or the dual-modal sensor are mixed with a mercury ion-containing analyte to obtain the intensity of the characteristic absorption peaks in the ultraviolet-visible spectrum at 400–700 nm (e.g., 500–600 nm, 510–560 nm, 520–540 nm, 530–535 nm, 530–533 nm) and the intensity of the characteristic absorption peaks at 400–2000 cm⁻¹. -1 (e.g., 700-1500cm) -1 900~1200cm -1 1000~1100cm -1 1060~1090cm -1 1070~1080cm -1 Qualitative analysis is performed by measuring the intensity of the Raman characteristic peak at ( ); and / or, quantitative analysis is performed using the standard working curve.

[0055] In some embodiments of the present invention, the concentration of mercury ions in the test sample is at least 1.0 μg / L.

[0056] In some embodiments of the present invention, the standard concentration ranges from 1.0 to 500.0 μg / L, such as 5.0 to 400.0 μg / L.

[0057] In some embodiments of the present invention, the molar concentration ratio of the functionalized gold nanoparticles or the dual-modal sensor to mercury ions is 40 to 81000:1.

[0058] In some embodiments of the present invention, the test sample includes samples derived from at least one of food, pharmaceuticals, cosmetics, soil, and water.

[0059] The beneficial effects of this invention are:

[0060] The functionalized gold nanoparticles of this invention can specifically identify mercury ions in matrices such as food and pharmaceuticals, thereby achieving dual-modal detection results output by colorimetric / surface-enhanced Raman spectroscopy, achieving the purpose of self-calibration detection, improving the selectivity, accuracy and efficiency of detection, and can be applied to the detection of mercury ions in natural environment, food, pharmaceuticals and cosmetics.

[0061] The method for synthesizing functionalized gold nanoprobes of this invention is simple, uses readily available and economical raw materials, and is easy to operate.

[0062] This invention utilizes the unique localized surface plasmon resonance properties of gold nanoparticles to cause color changes and enhance surface-enhanced Raman spectroscopy signals, thereby achieving dual signal output of colorimetric and surface-enhanced Raman spectroscopy.

[0063] This invention provides a method for detecting mercury ions using functionalized gold nanoparticles, with a detection limit of up to 1.2 μg / L. Attached Figure Description

[0064] Figure 1 This is the UV-Vis absorption spectrum response diagram of functionalized gold nanoparticles for quantitative analysis of mercury ions in Example 1 of the present invention.

[0065] Figure 2 This is the working curve for the quantitative detection of mercury ions by ultraviolet-visible absorption spectroscopy using functionalized gold nanoparticles in Example 1 of the present invention.

[0066] Figure 3 This is the SERS response diagram of functionalized gold nanoparticles for quantitative analysis of mercury ions in Example 1 of the present invention.

[0067] Figure 4 This is the working curve for the quantitative SERS detection of mercury ions by functionalized gold nanoparticles in Example 1 of the present invention.

[0068] Figure 5 The above are SERS images of functionalized gold nanoparticles from Examples 1 and 2 of this invention.

[0069] Figure 6 This is a comparison diagram of SERS of functionalized gold nanoparticles recognizing mercury ions in Example 1 of the present invention.

[0070] Figure 7 This is a bar chart showing the UV-Vis spectrophotometric response of thymine-functionalized gold nanoparticles with different concentrations to mercury ions in Example 3 of the present invention.

[0071] Figure 8 The bar chart shows the surface-enhanced Raman spectroscopy response of thymine-functionalized gold nanoparticles with different concentrations to mercury ions in Example 3 of this invention.

[0072] Figure 9This is a bar chart showing the selective UV-Vis spectrophotometric response of functionalized gold nanoparticles to mercury ions in Example 1 of the present invention.

[0073] Figure 10 This is a bar chart showing the UV-Vis spectrophotometric response of functionalized gold nanoparticles to mercury ions in Example 1 of the present invention.

[0074] Figure 11 This is a bar chart showing the selective surface-enhanced Raman spectroscopy response of functionalized gold nanoparticles to mercury ions in Example 1 of the present invention.

[0075] Figure 12 This is a bar chart showing the surface-enhanced Raman spectroscopy response of functionalized gold nanoparticles to mercury ions in Example 1 of the present invention. Detailed Implementation

[0076] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0077] Example 1

[0078] This embodiment prepares a functionalized gold nanoparticle, and the specific process is as follows:

[0079] S1: Preparation of the nano-gold solution: Measure 99.0 mL of deionized water into a 250 mL Erlenmeyer flask, add 1.0 mL of 1% (w / v) chloroauric acid solution and mix well. Heat to boiling. Then quickly add 1.0 mL of 1% (w / v) anhydrous sodium citrate solution and stir the mixture at boiling for 15 min. After the reaction is complete, cool to room temperature and store at 4°C for later use.

[0080] S2: Preparation of Functionalized Gold Nanoparticles: 1.0 mL of 4-mercaptobenzoic acid (5.0 mg / L) was added to 10.0 mL of the gold nanoparticle solution prepared in S1 and mixed to form an AuNPs / 4-MBA mixed solution. Then, 10.0 μL of cysteamine (50.0 μmol / L) was added to the above mixed solution and stirred and incubated for 1 h. After centrifugation at 5000 rpm / 10 min, the supernatant was removed, and 1 mL of water was added to reconstitute the solution to obtain AuNPs / 4-MBA / Cy. Subsequently, 1.0 mL of thymine-1-acetic acid (0.1 mmol / L) was mixed with 1.0 mL of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride / N-hydroxysuccinimide solution (EDC / NHS, 10.0 mmol / L) and placed at room temperature to activate the -COOH group. Next, 10.0 μL of carboxyl-activated thymine-1-acetic acid was added to 1.0 mL of AuNPs / 4-MBA / Cy, and then the mixture was shaken and incubated at room temperature for 4 h to obtain the final AuNPs / 4-MBA / Cy / T complex mixed solution.

[0081] The prepared AuNPs / 4-MBA / Cy / T complex mixed solution was stored in a refrigerator at 4°C.

[0082] Example 2

[0083] This embodiment prepares a functionalized gold nanoparticle, and the specific process is as follows:

[0084] S1: A nano-gold solution was prepared according to the preparation method of S1 in Example 1;

[0085] S2: Preparation of Functionalized Gold Nanoparticles: 10.0 μL of cysteamine (50.0 μmol / L) was added to 10.0 mL of gold nanoparticle solution, and the mixture was incubated with shaking for 1 h to form AuNPs / Cy. Subsequently, 1.0 mL of thymidine-1-acetic acid (0.5 mmol / L) was mixed with 1.0 mL of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride / N-hydroxysuccinimide solution (EDC / NHS, 10.0 mmol / L) and incubated at room temperature for 1 h to activate the -COOH group. Next, 10.0 μL of carboxyl-activated thymidine-1-acetic acid was added to 10.0 mL of AuNPs / Cy, and the mixture was then incubated with shaking at room temperature for 4 h to obtain the final AuNPs / Cy / T mixed solution. Then, centrifuge at 5000 rpm for 10 min, remove the supernatant, add 1.0 mL of 4-mercaptobenzoic acid (5.0 mg / L) to reconstitute, and obtain the final AuNPs / Cy / T / 4-MBA mixed solution.

[0086] The prepared AuNPs / Cy / T / 4-MBA mixed solution was stored in a refrigerator at 4°C.

[0087] Example 3

[0088] This embodiment prepares a functionalized gold nanoparticle, and the specific process is as follows:

[0089] S1: A nano-gold solution was prepared according to the preparation method of S1 in Example 1;

[0090] S2: Preparation of thymidine carboxylic acid-functionalized gold nanoparticles at different concentrations: 1.0 mL of 4-mercaptobenzoic acid (5.0 mg / L) was added to 10.0 mL of the gold nanoparticle solution prepared in S1 and mixed to form an AuNPs / 4-MBA mixed solution. Then, 10.0 μL of cysteamine (50.0 μmol / L) was added to the above mixed solution and stirred and incubated for 1 h. After centrifugation at 5000 rpm / 10 min, the supernatant was removed, and 1 mL of water was added to reconstitute the solution to obtain AuNPs / 4-MBA / Cy. Subsequently, 1.0 mL of thymine-1-acetic acid (different concentrations: 0.05, 0.2, 0.4, 0.5, 0.75 mmol / L) was mixed with 1.0 mL of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride / N-hydroxysuccinimide solution (EDC / NHS, 10.0 mmol / L) and placed at room temperature to activate the -COOH group. Next, 10.0 μL of carboxyl-activated thymine-1-acetic acid was added to 1.0 mL of AuNPs / 4-MBA / Cy, and then the mixture was incubated with shaking at room temperature for 4 h to obtain the final AuNPs / 4-MBA / Cy / T complex mixture.

[0091] Example 4

[0092] This embodiment establishes a colorimetric standard curve for mercury ions. The specific process is as follows:

[0093] 200 μL of the functionalized gold nanoparticle solution prepared in Example 1 was mixed with 100 μL of standard mercury ion solutions at concentrations of 5.0 μg / L, 10.0 μg / L, 100.0 μg / L, 200.0 μg / L, 300.0 μg / L, and 400.0 μg / L at a ratio of 2:1 (v / v) and incubated for 25 minutes. The mixture was then transferred to a cuvette, and the UV-Vis absorption intensity was scanned in the wavelength range of 450 nm to 600 nm. The intensity of the characteristic absorption peak at 531.0 nm, representing the concentration relationship between the thymine carboxylic acid-functionalized gold nanoparticle solution and the standard mercury ion solution, was obtained to establish a colorimetric standard curve.

[0094] The working curves for colorimetric standard detection and quantitative detection of functionalized gold nanoparticle probes and mercury ion concentrations are shown below. Figure 1 , Figure 2As shown, the thymine carboxylic acid-functionalized gold nanoparticle probe exhibits a good linear relationship with mercury ion concentration in the range of 5.0 μg / L to 400.0 μg / L, with a correlation coefficient R0 of [value missing]. 2 The value is 0.9938, and the linear equation is y. A0-A =0.00021x+0.016, detection limit is 2.4μg / L.

[0095] Example 5

[0096] In this embodiment, a quasi-curve for surface-enhanced Raman spectroscopy of mercury ions is established. The specific process is as follows:

[0097] 200 μL of the functionalized gold nanoparticle solution prepared in Example 1 was mixed with standard mercury ion solutions at concentrations of 1.0 μg / L, 5.0 μg / L, 150.0 μg / L, 300.0 μg / L, 450.0 μg / L, and 1000.0 μg / L at a ratio of 2:1 (v / v) and incubated for 25 minutes. Surface-enhanced Raman spectroscopy was then performed to determine the concentration relationship between the functionalized gold nanoparticle solution and the standard mercury ion solution. The Raman spectroscopy parameters were: excitation wavelength 785 nm, power 168 mW, exposure time 5 s, and acquisition range 200–2000 cm⁻¹. -1 The characteristic Raman shift of 4-mercaptobenzoic acid was obtained at 1077.0 cm⁻¹. -1 The relationship between peak value and mercury ion concentration was investigated to establish a standard curve for surface-enhanced Raman spectroscopy.

[0098] Standard detection plots and working curves for the surface-enhanced Raman spectroscopy of functionalized gold nanoparticle probes and mercury ion concentrations are shown below. Figure 3 , Figure 4 As shown, the functionalized gold nanoparticle probe exhibits a good linear relationship with mercury ion concentration in the range of 1.0 to 1000.0 μg / L, and the correlation coefficient R of the working curve is [value missing]. 2 The value is 0.9933, and the linear equation is y. SERS =47.87x + 5405.86, detection limit is 1.2 μg / L.

[0099] Test case

[0100] This experimental example demonstrates Raman spectroscopy testing of the functionalized gold nanoparticles prepared in Examples 1 and 2. The specific procedure is as follows:

[0101] 300 μL of the functionalized gold nanoparticle solution prepared in Examples 1 and 2 was mixed with 100 μL of a standard mercury ion solution with a concentration of 300.0 μg / L at a ratio of 2:1 (v / v) and incubated for 25 min. The mixture was then transferred to a custom quartz array for surface-enhanced Raman spectroscopy to determine the concentration relationship between the functionalized gold nanoparticle solution and the standard mercury ion solution.

[0102] The results are as followsFigure 5 As shown, the position of 4-mercaptobenzoic acid modification has no effect on the detection results.

[0103] Example 6

[0104] This embodiment performs mercury ion detection, and the specific process is as follows:

[0105] 200 μL of the functionalized gold nanoparticle solution prepared in Example 1 was mixed with 100 μL of a standard mercury ion solution with a concentration of 300.0 μg / L at a ratio of 2:1 (v / v) and incubated for 25 min. The mixture was then transferred to a custom quartz array for surface-enhanced Raman spectroscopy to determine the concentration relationship between the functionalized gold nanoparticle solution and the standard mercury ion solution.

[0106] The results are as follows Figure 6 As shown, the Raman spectral intensity of the functionalized gold nanoparticles increases after recognizing mercury ions, thus proving the successful synthesis of the functionalized gold nanoparticles and their ability to quantitatively detect mercury ions.

[0107] Example 7

[0108] This embodiment performs mercury ion detection, and the specific process is as follows:

[0109] 200 μL of thymidine carboxylic acid-functionalized gold nanoparticles of different concentrations prepared in Example 3 and 100 μL of a 300.0 μg / L standard mercury ion solution were mixed at a ratio of 2:1 (v / v) and incubated for 25 minutes. The mixture was then transferred to a cuvette and a custom-made quartz array, and its UV-Vis absorption intensity was scanned in the wavelength range of 450 nm to 600 nm and 200–2000 cm⁻¹, respectively. -1 Scan its Raman intensity within the range.

[0110] The results are as follows Figure 7 , Figure 8 As can be seen, thymidine carboxylic acid-functionalized gold nanoparticles of different concentrations can effectively recognize mercury ions, with a concentration of 0.5 mmol / L being the optimal condition.

[0111] Example 8

[0112] This embodiment conducts a mercury ion detection interference experiment, the specific process of which is as follows:

[0113] Prepare different metals (K) at a concentration of 5.0 mg / L. + Mg 2+ Na + Ca 2+ Ba 2+ Cu 2+ Co 2+ Fe 3+ Al 3+ Cr3+ A solution containing 10 metal ions and a 50 μg / L mercury ion solution were prepared. 200 μL of the functionalized gold nanoparticle probe solution prepared in Example 1 and 100 μL of different metal solutions with a concentration of 5.0 mg / L were mixed at a ratio of 2:1 (v / v) and incubated for 25 min. Following the test methods of Examples 3 and 4, the functionalized gold nanoparticle probe and K were measured. + Mg 2+ Na + Ca 2+ Ba 2+ Cu 2+ Co 2+ Fe 3 + Al 3+ Cr 3+ UV-Vis absorption spectra and surface-enhanced Raman spectra of metal ion solutions.

[0114] Prepare a mixed solution of different metals at a concentration of 5.0 mg / L and a metal ion mixture at a concentration of 50 μg / L mercury ions (K). + +Hg 2 + Mg 2+ +Hg 2+ Na + +Hg 2+ Ca 2+ +Hg 2+ Ba 2+ +Hg 2+ Cu 2+ +Hg 2+ Co 2+ +Hg 2+ Fe 3+ +Hg 2+ Al 3+ +Hg 2+ Cr 3+ +Hg 2 + Ten kinds of mixed metal ions were used. 200 μL of the functionalized gold nanoparticle probe solution prepared in Example 1 was mixed with 100 μL of the above-mentioned mixed solutions of different metal ions at a ratio of 2:1 (v / v) and incubated for 25 min. UV-Vis and surface-enhanced Raman spectroscopy were then performed. Following the test methods of Examples 3 and 4, the ability of the functionalized gold nanoparticle probe to react with K was determined. + +Hg 2 + Mg 2+ +Hg 2+ Na + +Hg 2+ Ca 2+ +Hg2+ Ba 2+ +Hg 2+ Cu 2+ +Hg 2+ Co 2+ +Hg 2+ Fe 3+ +Hg 2+ Al 3+ +Hg 2+ Cr 3+ +Hg 2 + UV-Vis absorption spectrum and surface-enhanced Raman spectrum of a mixed solution of metal ions.

[0115] The relationship between functionalized gold nanoparticle probes and the UV-Vis and surface-enhanced Raman spectra of mercury ions and the tested metal ions is shown in the figure. Figures 9 to 12 , Figure 9 , Figure 10 This is a bar chart showing the UV-Vis spectrophotometric response of interfering substances and mercury ions. Figure 11 , Figure 12 This is a bar chart showing the surface-enhanced Raman (SMR) spectral responses of the interfering substances and mercury ions. The tests show that the UV-Vis absorption and SMR intensities of the functionalized gold nanoparticle probe solution with 10 metal ions are very weak, while the UV-Vis absorption and SMR intensities of the mercury ion solution are significantly enhanced. Furthermore, the presence of metal ions does not interfere with the recognition of mercury ions. Therefore, the functionalized gold nanoparticle probe exhibits excellent selectivity for mercury ion recognition in the presence of the tested metal ions.

[0116] Example 9

[0117] The specific process for detecting mercury ions in food in this embodiment is as follows:

[0118] Before spiking, the milk, yogurt, and dairy beverage samples were pretreated to remove easily adsorbed proteins. 2.5 mL of each of the purchased skim milk, yogurt, and dairy beverage were treated with 1.0 mL of trichloroacetic acid (30%, v / v), and the proteins were removed by vortexing for 5 min. Then, the samples were centrifuged at 10000 rpm for 15 min, and the supernatant was collected and filtered through a 0.22 μm nylon membrane. The samples were then spiked. Specifically, the clarified solution of the treated samples was diluted 10 times with water (mercury ions were not detected in any of the samples), and a mercury ion standard solution was added to prepare spiked concentrations of 10.0 μg / L, 50.0 μg / L, and 300.0 μg / L. Following the methods in Examples 3 and 4, UV-Vis spectrophotometry and surface-enhanced Raman spectroscopy were used for detection. Three consecutive tests were performed, and the average value and relative standard deviation of the UV-Vis absorption peak at 531 nm were calculated for the three data points. These values ​​were then substituted into the UV-Vis spectrophotometric standard curve for mercury ion concentration to obtain the mercury ion concentration in the spiked samples. The 1077 cm⁻¹ value was also calculated for the three data points. -1 The average value and relative deviation of the Raman characteristic peaks are substituted into the concentration standard curve of mercury ions by surface-enhanced Raman spectroscopy to obtain the concentration of mercury ions in the spiked sample.

[0119] The recoveries calculated by UV-Vis spectrophotometry were 90.0–105.6%, with relative standard deviations (RSDs) of 0.2–4.8%; the recoveries calculated by surface-enhanced Raman spectroscopy were 91.0–101.7%, with RSDs of 0.5–2.8%. These results demonstrate that the detection results from UV-Vis spectrophotometry and surface-enhanced Raman spectroscopy can achieve self-calibration, improving the accuracy of the detection.

[0120] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A dual-modal functionalized gold nanoparticle for colorimetric / surface-enhanced Raman spectroscopy detection of mercury ions, characterized in that: The invention includes gold nanoparticles; the surface of the gold nanoparticles is modified with 4-mercaptobenzoic acid and thymine; the thymine is modified on the surface of the gold nanoparticles by cysteine.

2. The dual-modal functionalized gold nanoparticles for mercury ion detection using colorimetric / surface-enhanced Raman spectroscopy as described in claim 1, characterized in that: The surface of the gold nanoparticles is modified with 4-mercaptobenzoic acid, and then thymine is modified with cysteine; or the surface of the gold nanoparticles is modified with thymine by cysteine ​​and then modified with 4-mercaptobenzoic acid.

3. The dual-modal functionalized gold nanoparticles for mercury ion detection using colorimetric / surface-enhanced Raman spectroscopy as described in claim 1, characterized in that: The dual-modal functionalized gold nanoparticles for mercury ion detection using colorimetric / surface-enhanced Raman spectroscopy satisfy at least one of the following conditions: (1) The molar ratio of the nano-gold to the 4-mercaptobenzoic acid is 1:100~4:25; (2) The molar ratio of the nano-gold to the cysteine ​​is 20~20000:1; (3) The molar ratio of cysteine ​​to thymine is 3:100 to 1:2; (4) The average particle size of the gold nanoparticles is 35~55 nm.

4. A method for preparing dual-modal functionalized gold nanoparticles for mercury ion detection using colorimetric / surface-enhanced Raman spectroscopy, as described in any one of claims 1 to 3, characterized in that, Includes the following steps: The dual-modal functionalized gold nanoparticles for mercury ion detection, namely gold nanoparticles, 4-mercaptobenzoic acid, cysteine, and thymine, were prepared by reacting them with gold nanoparticles, 4-mercaptobenzoic acid, cysteine, and thymine.

5. A dual-modal sensor, characterized in that: This includes the dual-modal functionalized gold nanoparticles for colorimetric / surface-enhanced Raman spectroscopy detection of mercury ions as described in any one of claims 1 to 3.

6. A kit for detecting mercury ions, characterized in that: The device includes a housing, which contains a sample vial, a cuvette, and a quartz array that contain the dual-modal sensor as described in claim 5.

7. A method for detecting mercury ions, characterized in that, The method includes the following steps: using the dual-modal functionalized gold nanoparticles for mercury ion detection as described in any one of claims 1 to 3, the dual-modal sensor as described in claim 5, or the mercury ion detection kit as described in claim 6 to detect mercury ions.

8. The method for detecting mercury ions according to claim 7, characterized in that: The mercury ion detection method includes the following steps: using the dual-modal functionalized gold nanoparticles for mercury ion detection (colorimetric / surface-enhanced Raman spectroscopy), the dual-modal sensor, or the mercury ion detection kit to detect the ultraviolet-visible and surface-enhanced Raman spectra of mercury ions in a control solution and a test solution containing mercury ions at different standard concentrations, respectively, and using the external standard method to determine the mercury ion content in the test solution.

9. The method for detecting mercury ions according to claim 8, characterized in that: The mercury ion detection method includes the following steps: (1) constructing standard working curves between mercury ions of different standard concentrations and Raman / colorimetric signal intensities using the dual-modal functionalized gold nanoparticles for mercury ion detection using colorimetric / surface-enhanced Raman spectroscopy, the dual-modal sensor, or the mercury ion detection kit; (2) mixing the dual-modal functionalized gold nanoparticles for mercury ion detection using colorimetric / surface-enhanced Raman spectroscopy, the dual-modal sensor, or the mercury ion detection kit with a mercury ion-containing analyte, obtaining the Raman / colorimetric signal intensity, and performing qualitative analysis; and / or, performing quantitative analysis using the standard working curves.

10. The method for detecting mercury ions according to claim 9, characterized in that: Obtain the intensity of the characteristic absorption peaks in the UV-Vis spectrum from 400 to 700 nm and from 400 to 2000 cm⁻¹ -1 The intensity of the Raman characteristic peak at that location.

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