Method and application of ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials

Abstract

The present invention discloses a method and application of ratiometric fluorescence detection of iodine ions based on composite nano-gold cluster new materials, belonging to the field of nano-new materials and chemical application technology. Composite nano-gold cluster material His / GSH-AuNCs can be prepared by mixing His-AuNCs and GSH-AuNCs in a certain proportion; at the same excitation wavelength, His / GSH-AuNCs has two emission peaks at 470nm and 620nm. Different concentrations of iodine ions are added to the His / GSH-AuNCs solution, and the change value of the fluorescence intensity ratio of the His / GSH-AuNCs solution (I 470 / I 620 ) / (I 470 / I 620 )0; According to the relationship between the concentration of iodine ion solution and the change value of the fluorescence intensity ratio of His / GSH‑AuNCs solution, a standard curve is drawn to detect the concentration of iodine ions in the iodine ion solution. In addition, the method of the present invention can be applied to the experimental recovery rate of iodine ions in actual samples such as lake water, tap water and human urine. The method of the present invention has high sensitivity and selectivity, is simple and rapid, does not require any pretreatment, and has very broad application prospects in daily life, quality monitoring and biomedical evaluation.

Description

Technical Field

[0001] The invention belongs to the technical field of new nano materials and chemical applications, and specifically relates to a method and application of ratiometric fluorescence detection of iodine ions based on new composite nano-gold cluster materials. Background Art

[0002] As an indispensable trace element for the human body, iodine ions play a vital role in human intellectual development, muscle tissue growth, thyroid function and basal metabolism (Cell Dev. Biol., 2011, 22: 645-652). As a primitive element, iodine can only be taken from outside the human body. Insufficient or excessive iodine intake can lead to serious health problems; therefore, in order to prevent iodine deficiency or excessive intake, it is very necessary and important to monitor the iodide level in human or environmental samples (Nat. Rev. Endocrinol., 2018, 14: 301-316).

[0003] Atomic absorption spectroscopy (J. Anal. At. Spectrom., 2001, 16: 382-389), electrochemical methods (Sensors, 2013, 13: 1984-1997), surface enhanced Raman scattering (Analyst, 2013, 138: 1195-1203), photoluminescence analysis (Chem. Rev., 2018, 354: 98-120.) and other technologies have been used for iodine detection. Among them, nanofluorescence sensors are widely used in the detection and tracking of iodine in various samples due to their high specificity, high sensitivity, rapidity and low cost; however, these nanofluorescence sensors usually require heavy metal ions (such as Hg 2+ 、Ag + , Cu 2+ ) first quenches the fluorescence of the sensor, and then restores the fluorescence of the sensor with iodine ions to detect iodine ions. This indirect detection method usually reduces the accuracy of the detection and increases the difficulty of the detection process. Therefore, it is of great significance to develop a simple, direct, accurate and environmentally friendly iodine ion detection method based on new nano-fluorescent materials.

[0004] Gold nanoclusters (AuNCs), as an excellent optical material, have been widely used in fluorescence sensing, in vitro and in vivo imaging, and nanomedicine due to their unique physicochemical properties, such as high fluorescence, good biocompatibility, and excellent stability (Talanta, 2021, 234: 122623-122642).

[0005] At present, most AuNCs-based fluorescent probes are based on direct changes in fluorescence intensity (enhancement or quenching) to detect targets, and these detection methods are usually greatly affected by factors such as background noise, instruments, matrix and probe concentration (ACSSens., 2017, 2: 748-756). Ratio fluorescence methods overcome these problems well. Ratio fluorescence methods are based on the intensity change ratio of two or more emission peaks of fluorescent probes caused by analytes to detect analytes. The intensity change ratio of two or more peaks directly depends on the concentration of the analyte (Anal. Chem., 2023, 95: 5886-5893); therefore, ratio fluorescence methods have higher accuracy and sensitivity. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for ratiometric fluorescence detection of iodine ions based on a new composite nano-gold cluster material in view of the shortcomings of the above method. The present invention applies iodine ion detection to the new composite nano-gold cluster material while preparing it, and constructs a simple method for detecting iodine ions based on the new material. The method has cheap reagents, simple operation, high sensitivity, good accuracy, and can perform quantitative analysis and detection of trace iodine ions.

[0007] The method for detecting iodine ions provided by the present invention is characterized in that it comprises the following steps:

[0008] (1) Gold nanoclusters His-AuNCs were synthesized using L-histidine L-His and chloroauric acid as raw materials by a water bath method;

[0009] (2) Gold nanoclusters GSH-AuNCs were synthesized using glutathione GSH and chloroauric acid as raw materials by a water bath method;

[0010] (3) Quantitatively weighing His-AuNCs and GSH-AuNCs solids to prepare composite nanogold cluster His / GSH-AuNCs solution;

[0011] (4) Add iodide ion solution to the His / GSH-AuNCs solution. After the reaction, record the corresponding fluorescence emission spectrum and calculate the fluorescence intensity ratio of the two emission peaks of His / GSH-AuNCs at 470 nm and 620 nm. 470 / I 620 The change value of

[0012] (5) According to the ratio of the iodide ion solution concentration to the fluorescence intensity of the His / GSH-AuNCs solution I 470 / I 620 Change value (I 470 / I 620 ) / (I 470 / I 620)0, and the iodide ion concentration can be detected.

[0013] Specifically, the preparation and treatment method of His-AuNCs described in step (1) is: 7.00 mL, 20 mM chloroauric acid HAuCl4 solution is mixed with 42.00 mL, 100 mM histidine L-His solution, and the mixture is reacted at room temperature for 2 hours; after the reaction is completed, the reaction solution is filtered and dialyzed with a dialysis bag with a molecular weight cutoff of 1000 Da for 24 hours to obtain a pure His-AuNCs solution; the His-AuNCs solution is vacuum freeze-dried to finally obtain a His-AuNCs solid powder.

[0014] Specifically, the synthesis method of GSH-AuNCs described in step (2) is: add 3.00mL, 20mM chloroauric acid HAuCl4 solution and 0.90mL, 100mM glutathione GSH solution to 28.5mL deionized water, and react at 70°C for 24 hours in a dark environment; after the reaction is completed, filter the reaction solution and dialyze it with a dialysis bag with a molecular weight cutoff of 1000Da for 24 hours to obtain a pure GSH-AuNCs solution; vacuum freeze-dry the GSH-AuNCs solution to finally obtain GSH-AuNCs solid powder.

[0015] Specifically, the final concentrations of His-AuNCs and GSH-AuNCs in step (3) are 0.05 mg / mL and 0.03 mg / mL, respectively.

[0016] Specifically, the pH of the His / GSH-AuNCs solution in step (3) is 6.

[0017] Specifically, the reaction time of the iodine ions and His / GSH-AuNCs in step (4) is 2 minutes.

[0018] Specifically, the standard curve described in step (5) is (I 470 / I 620 ) / (I 470 / I 620 )0=0.0542*iodine ion concentration+0.9715.

[0019] Specifically, the iodide ion concentration corresponding to the standard curve described in step (5) is 0-10 uM.

[0020] Specifically, the detection limit of iodide ion concentration is 0.0687uM.

[0021] The second object of the present invention is to provide an application of the above-mentioned method for ratiometric fluorescence detection of iodine ions based on the composite nano-gold cluster new material, that is, to detect the content of iodine ions in actual samples. The actual samples include but are not limited to any one of lake water, tap water, and human urine.

[0022] The technical effect of the present invention is: the present invention uses the fluorescence intensity ratio of His / GSH-AuNCs I 470 / I 620 The concentration of iodide ions is detected by the change value of . The His / GSH-AuNC solution used is a simple mixture of His-AuNC and GSH-AuNC. No further surface modification and passivation are required. The detection of iodide ions can be achieved by controlling the ratio of His-AuNC and GSH-AuNC. This method can be used to detect the content of iodide ions in actual samples such as lake water, tap water and human urine. The method of the present invention has high sensitivity and selectivity, is simple and rapid, does not require any pretreatment, and has very broad application prospects in daily life quality monitoring and biomedical evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the fluorescence emission spectrum of His / GSH-AuNCs in Example 1 (excitation is 340 nm).

[0024] Figure 2 This is the TEM image of His / GSH-AuNCs in Example 1.

[0025] Figure 3 This is the particle size distribution diagram of His / GSH-AuNCs in Example 1.

[0026] Figure 4 The fluorescence intensity ratio change value (I 470 / I 620 ) / (I 470 / I 620 )0 affects the bar chart.

[0027] Figure 5 The fluorescence intensity ratio change value (I 470 / I 620 ) / (I 470 / I 620 )0 affects the bar chart.

[0028] Figure 6 The fluorescence spectra of the His / GSH-AuNCs solution in Example 2 when different concentrations of iodine ions were added.

[0029] Figure 7 is the change value of the ratio of the iodide ion solution concentration to the fluorescence intensity of the His / GSH-AuNCs solution in Example 2 (I 470 / I 620 ) / (I 470 / I 620 )0.

[0030] Figure 8 The fluorescence spectra of the His / GSH-AuNCs solution in Example 3 added with deionized water and lake water sample 1.

[0031] Fig. 9 The fluorescence spectra of the His / GSH-AuNCs solution added to deionized water and lake water sample 2 in Example 3 are shown.

[0032] Fig.10 The fluorescence spectra of the His / GSH-AuNCs solution in Example 3 added with deionized water and tap water sample 1.

[0033] Fig.11 The fluorescence spectra of the His / GSH-AuNCs solution in Example 3 added with deionized water and tap water sample 2.

[0034] Fig.12 This is the fluorescence spectrum of the His / GSH-AuNCs solution in Example 3 added with deionized water and human urine sample 1.

[0035] Fig.13 This is the fluorescence spectrum of the His / GSH-AuNCs solution in Example 3 added with deionized water and human urine sample 2. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with specific embodiments and drawings, but they are not intended to limit the present invention.

[0037] Example 1, Preparation of His / GSH-AuNCs solution.

[0038] Preparation of His-AuNCs: Mix 7.00 mL of 20 mM chloroauric acid (HAuCl4) solution with 42.00 mL of 100 mM histidine (L-His) solution and react at room temperature for 2 hours; after the reaction is completed, filter the reaction solution and dialyze it with a dialysis bag (molecular weight cutoff: 1000 Da) for 24 hours to obtain a pure His-AuNCs solution; vacuum freeze-dry the His-AuNCs solution to finally obtain His-AuNCs solid powder.

[0039] Preparation of GSH-AuNCs: 3.00 mL of 20 mM chloroauric acid (HAuCl4) solution and 0.90 mL of 100 mM glutathione (GSH) solution were added to 28.5 mL of deionized water, and reacted at 70°C for 24 hours in a dark environment. After the reaction was completed, the reaction solution was filtered and dialyzed with a dialysis bag (molecular weight cutoff: 1000 Da) for 24 hours to obtain a pure GSH-AuNCs solution. The GSH-AuNCs solution was vacuum freeze-dried to finally obtain GSH-AuNCs solid powder.

[0040] Preparation of His / GSH-AuNCs solution: Quantitatively weigh His-AuNCs and GSH-AuNCs solids to prepare His / GSH-AuNCs solution, so that the final concentrations of His-AuNCs and GSH-AuNCs are 0.05 mg / mL and 0.03 mg / mL respectively; adjust the solution pH to about 6. The fluorescence spectrum of His / GSH-AuNCs was measured by fluorescence spectrophotometer ( Figure 1 ).from Figure 1 It can be seen that His / GSH-AuNCs have two fluorescence emission peaks (excitation peak: 340nm), and the emission peak positions are 470nm and 620nm respectively. TEM characterization of His / GSH-AuNCs ( Figure 2 ), from the particle size distribution diagram ( Figure 3 ) It can be seen that the average diameter of His / GSH-AuNCs is 8.43 nm.

[0041] Example 2: Drawing of the standard curve for detecting iodide ions using His / GSH-AuNCs.

[0042] Take 28 4 mL centrifuge tubes, mark them as 1-28, add 2.97 mL of the His / GSH-AuNCs solution prepared by the above method to the 28 centrifuge tubes, and then add 30 uL of deionized water or 30 uL of 7.5 mM different anions and cations to the centrifuge tubes respectively. - 、NO3 - 、F - 、HCO3 - 、S2O3 2- 、CO3 2- Br - 、C2O4 2- 、SO4 2- 、HPO4 2- , Cl - 、H2PO4 - BrO3 - ,I - 、Co 2+ , Ca 2+ , Cu2+ , K + , Ba 2+ NH4 + 、Ni 2+ Mg 2+ 、Na + 、Zn 2+ , Fe 2+ , Fe 3+ , Mn 2+ (Zn 2+ , Fe 2+ , Fe 3 + , Mn 2+ ions were added together with an equal amount of sodium ethylenediaminetetraacetate). After reacting for 2 minutes, the solutions in each centrifuge tube were tested in turn in a fluorescence spectrophotometer, and the change value of the His / GSH-AuNCs fluorescence intensity ratio (I 470 / I 620 ) / (I 470 / I 620 )0, such as Figure 4 and 5 As shown. Figure 4 and 5 It can be seen that the change value of the fluorescence intensity ratio of His / GSH-AuNCs (I 470 / I 620 ) / (I 470 / I 620 )0 only responded to iodide ions, indicating that His / GSH-AuNCs have high selectivity for iodide ions.

[0043] Take 8 4mL centrifuge tubes, mark them as 1-8, add 2.97mL of the His / GSH-AuNCs solution prepared by the above method to the 8 centrifuge tubes, and then add 30uL of deionized water or 30uL of iodine ion solution with concentrations of 0.1mM, 0.2mM, 0.3mM, 0.5mM, 0.6mM, 0.8mM, and 1mM to the centrifuge tubes respectively. After reacting for 2 minutes, the solutions in each centrifuge tube are tested in a fluorescence spectrophotometer in turn, and the change value of the His / GSH-AuNCs fluorescence intensity ratio (I 470 / I 620 ) / (I 470 / I 620 )0( Figure 6 ). According to the change value of the ratio of the iodide ion solution concentration to the fluorescence intensity of the His / GSH-AuNCs solution (I 470 / I 620 ) / (I 470 / I 620 )0 to draw a standard curve ( Figure 7), and the iodide ion concentration can be detected according to the standard curve.

[0044] Example 3, experimental recovery rate of iodide ions detected by His / GSH-AuNCs in actual samples.

[0045] Take 7 4mL centrifuge tubes, mark them as 1-7, add 2.97mL of the His / GSH-AuNCs solution prepared by the above method to the 7 centrifuge tubes, and then add 30uL of deionized water or 30uL of lake water sample 1 (containing 0.5mM iodine ions), 30uL of lake water sample 2 (containing 1mM iodine ions), 30uL of tap water sample 1 (containing 0.5mM iodine ions), 30uL of tap water sample 2 (containing 1mM iodine ions), 30uL of human urine sample 1 (containing 0.5mM iodine ions), and 30uL of human urine sample 2 (containing 1mM iodine ions) to the centrifuge tubes respectively. After reacting for 2 minutes, the solutions in each centrifuge tube were tested in a fluorescence spectrophotometer in turn, and the change value of the His / GSH-AuNCs fluorescence intensity ratio (I 470 / I 620 ) / (I 470 / I 620 )0( Figure 8-13 ). The iodine ion experimental recovery rate and relative standard deviation (RSD) in each sample were calculated based on the standard curve. The results are shown in Table 1.

[0046] Table 1

[0047]

[0048] As shown in Table 1, for lake water samples, the experimental recovery rate and relative standard deviation RSD of iodine ions in 30uL lake water samples containing 0.5mM iodine ions were 107.8% and 2.15% respectively. The experimental recovery rate and relative standard deviation RSD of iodine ions in 30uL lake water samples containing 1mM iodine ions were 92.8% and 1.14% respectively. For tap water samples, the experimental recovery rate and relative standard deviation RSD of iodine ions in 30uL tap water samples containing 0.5mM iodine ions were 92.1% and 1.37% respectively. The experimental recovery rate and relative standard deviation RSD of iodine ions in 30uL tap water samples containing 1mM iodine ions were 96.7% and 0.59% respectively. For human urine samples, the experimental recovery rate and relative standard deviation RSD of iodine ions in 30uL human urine samples containing 0.5mM iodine ions were 94.2% and 1.32% respectively. The iodide ion experimental recovery rate and relative standard deviation (RSD) of 30uL human urine sample containing 1mM iodide ion were 95.4% and 0.46%, respectively.

Claims

1. A method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials, characterized in that The steps include: (1) Gold nanoclusters His-AuNCs were synthesized using L-histidine L-His and chloroauric acid as raw materials by a water bath method; (2) Gold nanoclusters GSH-AuNCs were synthesized using glutathione GSH and chloroauric acid as raw materials by a water bath method; (3) Quantitatively weighing His-AuNCs and GSH-AuNCs solids to prepare composite nanogold cluster His / GSH-AuNCs solution; (4) Add iodide ion solution to the His / GSH-AuNCs solution. After the reaction, record the corresponding fluorescence emission spectrum and calculate the fluorescence intensity ratio of the two emission peaks of His / GSH-AuNCs at 470 nm and 620 nm. 470 / I 620 The change value of (5) According to the ratio of the iodide ion solution concentration to the fluorescence intensity of the His / GSH-AuNCs solution I 470 / I 620 Change value (I 470 / I 620 ) / (I 470 / I 620 )0, the standard curve can be drawn, that is, the iodine ion concentration can be detected; The synthesis method of His-AuNCs in step (1) is as follows: 7.00 mL of 20 mM chloroauric acid HAuCl4 solution is mixed with 42.00 mL of 100 mM histidine L-His solution, and the mixture is reacted at room temperature for 2 hours; after the reaction is completed, the reaction solution is filtered and dialyzed with a dialysis bag with a molecular weight cutoff of 1000 Da for 24 hours to obtain a pure His-AuNCs solution; The His-AuNCs solution was freeze-dried in vacuum to obtain His-AuNCs solid powder; The synthesis method of GSH-AuNCs in step (2) is as follows: 3.00 mL of 20 mM chloroauric acid HAuCl4 solution and 0.90 mL of 100 mM glutathione GSH solution are added to 28.5 mL of deionized water, and the mixture is reacted at 70° C. for 24 hours in a dark environment; after the reaction is completed, the reaction solution is filtered and dialyzed with a dialysis bag with a molecular weight cutoff of 1000 Da for 24 hours to obtain a pure GSH-AuNCs solution; The GSH-AuNCs solution was freeze-dried in vacuum to obtain GSH-AuNCs solid powder; The final concentrations of His-AuNCs and GSH-AuNCs in step (3) are 0.05 mg / mL and 0.03 mg / mL, respectively.

2. The method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials according to claim 1, characterized in that: The pH of the His / GSH-AuNCs solution in step (3) is 6.

3. The method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials according to claim 1, characterized in that: The reaction time of the iodine ions and His / GSH-AuNCs in step (4) is 2 minutes.

4. The method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials according to claim 1, characterized in that: The standard curve described in step (5) is (I 470 / I 620 ) / (I 470 / I 620 )0=0.0542*iodine ion concentration+0.9715.

5. The method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials according to claim 1, characterized in that: The iodide ion concentration corresponding to the standard curve described in step (5) is 0-10uM.

6. The method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials according to claim 1, characterized in that: The detection limit of iodide ion concentration is 0.0687uM.

7. Application of the method for ratiometric fluorescence detection of iodide ions based on composite nano-gold cluster new materials according to any one of claims 1 to 6, characterized in that: This method was used to detect the experimental recovery of iodide ions in actual samples.

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