Nanofluorescent probe SiO2@Tb in detection of Fe in water 3+ Application of the aspect

Abstract

The application discloses a kind of nano fluorescent probes SiO2@Tb in detecting Fe 3+ In aspect application.Nano fluorescent probes SiO2@Tb Fluorescence emission of silica matrix as reference, characteristic emission fluorescence of rare earth terbium ion is quenched by Fe 3+ Ratiometric fluorescent probe is constructed, with self-reference characteristics, which can effectively reduce system error, with high selectivity and sensitivity, strong anti-interference ability, low detection environment requirement, high accuracy, and low detection limit, only 0.0752 μM;Simple instrument and equipment, easy to operate, with potential application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detection of metal ions in water bodies, and particularly relates to a kind of silica / terbium nanohybrid material (SiO2@Tb) as a ratio type fluorescent probe for fluorescent detection of trace Fe 3+ content in water bodies. BACKGROUND

[0002] Nowadays, heavy metal wastewater pollution has become one of the important ways of water environmental pollution in the world, and has become an urgent problem that plagues public health. With the sustained development of China's economy, various heavy metal-containing materials are widely used in various production and processing manufacturing industries, and are discharged into the environment with industrial wastewater. Heavy metals have strong penetration in the environment, and can be continuously accumulated through food chain enrichment, are difficult to be harmlessly treated, and spontaneously degrade very slowly, causing serious threats to organisms, ecosystems and human health and safety.

[0003] Iron is one of the essential trace elements for human body, but the harm of excessive iron to human body cannot be underestimated. Iron ions participate in oxygen transport and synthesis of cytochrome and other enzymes, but if human body absorbs too much iron, it can cause poisoning, and further cause diseases such as liver fibrosis and hepatocyte tumors, causing dysfunction of the body. Long-term drinking of drinking water containing excessive metal iron can cause various diseases in human body, and the residual iron in the environment enters the human body through the food chain, and has a chronic damage effect on the body, and further causes difficult-to-cure diseases such as physical deformity and cancer. Therefore, it is particularly necessary to develop simple, sensitive and rapid iron ion detection technology.

[0004] Currently, various methods exist for detecting iron ions in water, including gas chromatography (GC), high-performance liquid chromatography (HPLC), electrochemical immunoassay, ICP-MS, and ICP-OES. However, these methods often involve expensive and complex equipment, complicated operation, long processing times, and are easily affected by environmental interference, hindering practical applications. In recent years, fluorescent probe detection technology has become an important field in materials science and analytical science, evolving into a crucial tool for detecting heavy metal ions. The advantages of fluorescent probe technology include high sensitivity and selectivity in analyzing trace amounts of substances, simple instrumentation, and the ability to perform real-time in-situ monitoring of target analytes. Among these, ratiometric fluorescent probes are favored due to their excellent fluorescence detection performance. In addition to the advantages of general fluorescent probes, ratiometric fluorescent probes possess two emission bands, one high and one low, forming a ratio relationship, enabling self-calibration and thus improving detection accuracy while reducing background interference. It should be noted that currently used fluorescent probes for detecting iron ions, such as metal-organic frameworks (MOFs) and quantum dots, are all non-ratiometric fluorescent probes. However, these probes are easily affected by environmental background during detection. Therefore, leveraging the advantages of ratiometric fluorescent probe detection technology to develop a sensitive and rapid iron ion fluorescence detection technology holds promise for widespread application. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a nano-fluorescent probe, SiO2@Tb, for detecting Fe in water. 3+ In this application, ratiometric fluorescence sensing is used for detection, featuring simple instrumentation and equipment, and good performance against Fe. 3+ It has the advantages of good selectivity and sensitivity, low detection limit, etc.; moreover, it can eliminate the interference of the environment and other ions during the detection process, and has high accuracy.

[0006] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0007] A nano-fluorescent probe SiO2@Tb is provided for detecting Fe in water. 3+ Applications in this area.

[0008] According to the above scheme, the application is as follows: combining the nano-fluorescent probe SiO2@Tb with Fe... 3+ After mixing with the water to be tested, the mixture was irradiated with ultraviolet light, and the fluorescence emission spectrum was recorded. The fluorescence intensities I at 545 nm and 461 nm were obtained from the emission spectrum. 545 I 461 Find I 545 / I 461 The ratio, based on I 545 / I 461 Calculate the change in Fe in the water body to be tested 3+ .

[0009] Preferably, the wavelength of the ultraviolet excitation light used in the ultraviolet irradiation is 210-330 nm, more preferably 237 nm.

[0010] According to the above scheme, the specific steps used are as follows:

[0011] 1) Ultrasonic dispersion of the nanofluorescent probe SiO2@Tb in deionized water to obtain a uniformly dispersed suspension; the ratio of the fluorescent probe to deionized water is 1 mg: 5-30 mL;

[0012] 2) Mix V1 mL of the suspension obtained in step 1) with V2 mL of the water body to be detected uniformly; record the emission spectrum by means of a fluorescence spectrometer, and obtain the fluorescence intensities I 545 , 461 and I 545 at 545 nm and 461 nm from the emission spectrum; obtain the concentration N μM of Fe 461 from the working curve, and further calculate the content C μM of Fe 3+ in the water body to be detected by using formula (1); wherein the working curve is obtained by plotting the I 3+ / I 545 ratio and the iron ion content as coordinates; 461

[0013] C = (V1+V2)*N / V2 (1).

[0014] According to the above scheme, V1 mL is 1-5 mL.

[0015] According to the above scheme, the working curve is plotted according to the following steps:

[0016] 1) Prepare a 0.1 mM Fe 3+ aqueous solution using deionized water as the solvent;

[0017] 2) Ultrasonic dispersion of the nanofluorescent probe SiO2@Tb in deionized water to obtain a uniformly dispersed suspension; the ratio of the fluorescent probe to deionized water is 1 mg: 5-30 mL;

[0018] 3) Take 2 mL of the SiO2@Tb suspension in a cuvette, turn on the fluorescence spectrometer, and record the emission spectrum under ultraviolet excitation; sequentially add 20 μL, 20 μL, 20 μL, 20 μL, 20 μL, 20 μL, 40 μL, 40 μL, 40 μL, 40 μL, 40 μL of the above Fe 3+ aqueous solution, mix uniformly, and record the emission spectrum of the suspension;

[0019] ​4) Analyzing the data to obtain the fluorescence intensity I at 545 nm and 461 nm from the emission spectrum 545 , 461 , Obtaining the I 545 / I 461 ratio; making a curve of the I 545 / I 461 ratio versus the iron ion content, and linearly fitting the curve to obtain a working curve for the ratio-type fluorescence detection of trace Fe 3+ in water.

[0020] According to the above scheme, the nano-fluorescent probe SiO2@Tb has the structural feature that the terbium coordination compound is bonded on the surface of the nanometer silicon dioxide through a chemical bond. Preferably, the chemical bond is an amide bond.

[0021] According to the above scheme, in the nano-fluorescent probe SiO2@Tb, the particle size of the nanometer silicon dioxide is 5-100 nm.

[0022] According to the above scheme, the preparation steps of the nano-fluorescent probe SiO2@Tb are as follows:

[0023] The nanometer silicon dioxide is used as a raw material to react with an amine propyl silane coupling agent to prepare an amino-modified silicon dioxide nanosphere; then the amino-modified silicon dioxide nanosphere is reacted with an aromatic carboxylic acid or a derivative thereof to prepare a carboxyl-modified silicon dioxide nanosphere; and finally, the carboxyl-modified silicon dioxide nanosphere is subjected to a coordination reaction with a rare earth ion Tb 3+ to obtain the nano-fluorescent probe SiO2@Tb.

[0024] Preferably, the amine silane coupling agent is amine propyl trimethoxysilane and / or amine propyl triethoxysilane.

[0025] Preferably, the aromatic carboxylic acid is one or more of terephthalic acid, phthalic acid, isophthalic acid, and 4,4'-dicarboxy biphenyl; and the aromatic carboxylic acid derivative is benzene tricarboxylic anhydride or pyromellitic anhydride.

[0026] The present application has the following beneficial effects:

[0027] 1. The present application uses the nano-hybrid material SiO2@Tb to detect Fe 3+ in water, which has good selectivity and sensitivity for Fe 3+ , a low detection limit of only 0.0752 µM, and can eliminate the interference of the environment and other ions during the detection process, and has high accuracy, simple instrument equipment, and convenient operation, and has potential application prospects.

[0028] 2. In the present application, under ultraviolet light excitation, the fluorescence emission of the silicon dioxide matrix of SiO2@Tb is used as a reference, and the characteristic emission fluorescence of the rare earth terbium ion is detected by Fe 3+The quenched ratio-type fluorescent probe has self-reference characteristics, can greatly reduce system error, has good selectivity, and has strong anti-interference ability, and can effectively avoid interference from the environment and other common cations. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The fluorescence emission spectrum diagram of the SiO2@Tb ratio-type fluorescent probe in the embodiment of the application for metal cation selectivity experiment.

[0030] Figure 2 The influence of different kinds of cations on I 545 / I 461 of the SiO2@Tb fluorescent probe in the embodiment of the application.

[0031] Figure 3 The fluorescence emission spectrum diagram of the SiO2@Tb fluorescent probe in the embodiment of the application for Fe 3+ concentration gradient titration experiment.

[0032] Figure 4 The relationship diagram of the concentration of Fe 3+ and I 545 / I 461 of the SiO2@Tb fluorescent probe in the embodiment of the application.

[0033] Figure 5 The fluorescence spectrum diagram of the SiO2@Tb fluorescent probe in the embodiment of the application for Fe 3+ anti-interference experiment.

[0034] Figure 6 The I 3+ / I 545 ratio histogram in the Fe 461 anti-interference experiment of the SiO2@Tb fluorescent probe in the embodiment of the application.

[0035] Figure 7 The excitation spectrum of the fluorescence of the SiO2@Tb fluorescent probe and the ultraviolet absorption spectrum of different cations in the embodiment of the application. DETAILED DESCRIPTION

[0036] The application will be further described below through specific embodiments and in conjunction with the drawings.

[0037] The reagents and materials used in the following embodiments can be obtained from commercial channels if not specifically stated.

[0038] Embodiment 1:

[0039] A preparation of a ratio-type fluorescent probe SiO2@Tb is provided, comprising the following steps:

[0040] 1) 0.5 g of nano-SiO2 with particle size of 9 nm was ultrasonically dispersed in 50 mL of ethanol, and then 0.1 mL of 3-aminopropyltriethoxysilane (APTES) was added and reacted for 24 h. After the reaction was completed, the obtained product was centrifuged at high speed to obtain amino-modified silica nanoparticles (SiO2@NH2).

[0041] 2) The prepared amino-modified silica nanoparticles were ultrasonically dispersed in 50 mL of tetrahydrofuran, 0.1 g of trimellitic anhydride (TMA) was added, and the mixture was stirred at room temperature for 8 h. The product was centrifuged at high speed, and then washed with tetrahydrofuran and ethanol solution to remove unreacted TMA, thereby obtaining carboxyl-modified silica nanoparticles (SiO2@COOH).

[0042] 3) The prepared carboxyl-modified silica nanoparticles were ultrasonically dispersed in 30 mL of ethanol, and then an appropriate amount of triethylamine solution was added to adjust the pH; 0.1 mL of 0.1 mol / L Tb 3+ aqueous solution was added, and the mixture was stirred at room temperature for 8 h. After the reaction was completed, the obtained product was centrifuged at high speed, and then washed with ethanol and acetone to remove uncoordinated Tb 3+ , thereby obtaining a silica / terbium nano-hybrid material (SiO2@Tb).

[0043] Example 2: Selective experiment

[0044] 1) Preparation of sample suspension: the prepared nano-fluorescent probe SiO2@Tb (1 mg) was ultrasonically dispersed in 10 mL of deionized water to obtain a uniformly dispersed SiO2@Tb suspension.

[0045] 2) Different metal cation aqueous solutions with a concentration of 0.01 M were respectively prepared, and the cations were Fe 3+ , Na + , K + , Ba 2+ , Mg 2+ , Ca 2+ , Fe 2+ , Mn 2+ , and Co 2+ .

[0046] 3) Detection method: 2 mL of the prepared SiO2@Tb suspension in 1) was taken into a cuvette, and different metal cation aqueous solutions (0.01 M, 20 μL) prepared in 2) were added, respectively. The fluorescence spectrometer was opened, and the fluorescence emission spectrum was recorded under excitation of ultraviolet light at a wavelength of 237 nm. The fluorescence intensities I 545 and I 461 at 545 nm and 461 nm were obtained from the emission spectrum, and I545 / I 461 ratio.

[0047] Figure 1 , Figure 2 The fluorescence spectrum and I of the SiO2@Tb fluorescent probe used in Example 2 for the selective experiment of metal cations. 545 / I 461 The ratio is shown in the graph. As can be seen from the graph, when Fe is added... 3+ At that time, Tb 3+ The characteristic emission peak at 545 nm was rapidly quenched, while other cations showed little or no quenching. The fluorescence intensity at 461 nm remained almost unchanged before and after the addition of all quenchers. Based on this phenomenon, the ratio of fluorescence intensity at 545 nm to 461 nm was calculated, revealing that only the addition of Fe... 3+ After I 545 / I 461 The ratio decreased significantly, while the I ratio decreased after the addition of other cations to the suspension. 545 / I 461 Ratio and I when blank 545 / I 461 The ratio remains essentially unchanged or changes only slightly. This indicates that the fluorescent probe provided by this invention is effective for Fe... 3+ It exhibits extremely high selectivity, and the ratiometric fluorescent probe used in this invention possesses self-reference characteristics, greatly reducing systematic errors and resulting in high detection accuracy. It can be used as a fluorescent sensor for the efficient detection of Fe. 3+ .

[0048] Example 3: Titration experiment to obtain working curve

[0049] 1) Preparation of SiO2@Tb suspension: Same as in Example 2.

[0050] 2) Prepare Fe with a concentration of 0.1 mM. 3+ Solution.

[0051] 3) Titration experiment: Take 2.0 mL of the SiO2@Tb suspension prepared in step 1) into a cuvette, turn on the fluorescence spectrometer, and record the emission spectrum under ultraviolet light excitation. Then add 20 μL, 20 μL, 20 μL, 20 μL, 20 μL, 20 μL, 40 μL, 40 μL, 40 μL, 40 μL, 40 μL, and 40 μL of Fe in sequence. 3+ Aqueous solution (0.1 mM) was mixed thoroughly, excited using a 237 nm excitation wavelength, and the emission spectrum was recorded. The fluorescence intensity of the SiO2@Tb suspension was recorded, and Ig was calculated. 545 / I 461 The ratio, in I 545 / I 461 The ratio of Fe3+ The concentration of Fe3+ was plotted and data fitting was performed to obtain the linear equation (2):

[0052] y = 8.74886 - 0.35993[C] (2)

[0053] wherein y: fluorescence emission intensity I 545 / I 461 ratio; [C]: Fe 3+ content.

[0054] Figure 3 、 Figure 4 The fluorescence spectrum of the titration experiment of SiO2-Tb ratio type fluorescent detection of Fe 3+ and the relationship between Fe 3+ content and I 545 / I 461 ratio change map, after data fitting can be obtained, in the lower detection range (0-16 μM), Fe 3+ content and I 545 / I 461 ratio between the good linear correlation (R 2 = 0.99375), indicating that SiO2@Tb to take the ratio of fluorescence detection of Fe 3+ in water has high sensitivity and accuracy. At the same time, the fitting line is SiO2@Tb as a fluorescent probe for fluorescence detection of Fe 3+ working curve, using the curve can be obtained in the target detection liquid Fe 3+ content. In addition, according to equation (3) can be obtained its detection limit is 0.0752 μM.

[0055] LOD = 3σ / K (3)

[0056] wherein σ: standard deviation; K: I 545 / I 461 and the corresponding slope of the analyte concentration.

[0057] Finally, under the excitation of 254 nm ultraviolet light, it was found that the luminescence of SiO2@Tb suspension changed from bright green to blue before and after adding Fe 3+ solution, the bright green fluorescence is the characteristic emission of Tb 3+ , after adding Fe 3+ , the green fluorescence emitted by Tb 3+ is quenched, and the observed blue fluorescence is the matrix emission of SiO2.

[0058] Example 4: sample detection

[0059] 1) Preparation of SiO2@Tb suspension: the same as example 2.

[0060] 2) Take 2 mL of the suspension in step 1 in a cuvette, add 50 μL of Fe 3+ aqueous solution (the content of Fe 3+ is 0.0967 mM as detected by ICP-MS), and mix well. Turn on the fluorescence spectrometer, record the emission spectrum after adding Fe 3+ ions, and obtain the fluorescence intensities at 545 nm and 461 nm. Calculate the I 545 / I 461 ratio to be 7.893. Further calculate the content of Fe 3+ in the detection system to be 2.378 μM by using the following formula (2). Further calculate the content of Fe 3+ in 50 μL of Fe 3+ aqueous solution added to be 0.0974 mM by using formula (1). Within the error range, the test results of the test method provided by the application and ICP-MS are consistent, which confirms that the test results of the method are reliable, true and effective.

[0061] Example 5: Anti-interference experiment

[0062] 1) Preparation of SiO2@Tb suspension: the same as in Example 2.

[0063] 2) Prepare aqueous solutions of different metal cations with a concentration of 0.01 M, and the cations are Fe 3+ , Na + , K + , Ba 2+ , Mg 2+ , Ca 2+ , Fe 2+ , Mn 2+ , and Co 2+ .

[0064] 3) Anti-interference experiment: take 2 mL of the SiO2@Tb suspension prepared in 1) in a cuvette, add other metal ions (0.01 M, 20 μL, except Fe 3+ ) with the same concentration to the SiO2@Tb suspension, then add Fe 3+ solution (0.01 M, 20 μL), and record the luminescence emission spectrum of the blank suspension, after adding the interference ions, and after adding Fe 3+ solution under the excitation of ultraviolet light at 237 nm, respectively. Then record the fluorescence intensity change of the SiO2@Tb suspension and calculate the I 545 / I 461 ratio for data analysis.

[0065] Figure 5 、 Figure 6The ratio of SiO2@Tb in Example 5 for the selective detection of Fe 3+ The anti-interference fluorescence spectrum of SiO2@Tb and I 545 / I 461 ratio histogram. When the interfering cations are added, the luminescence intensity of the suspension and I 545 / I 461 are basically unchanged, and when Fe 3+ is added again, the luminescence intensity of the suspension at 545 nm is significantly greatly reduced, I 545 / I 461 ratio is basically not interfered by other metal cations. It is shown that SiO2@Tb does not interfere with other cations when the selective detection of Fe 3+ is carried out by the ratio, and can effectively avoid the interference from the environment, has strong selectivity and high sensitivity.

[0066] Example 6: Discussion on the reasons for excellent selectivity and anti-interference ability

[0067] 1) Preparation of SiO2@Tb suspension: the same as Example 2.

[0068] 2) Prepare aqueous solutions of different metal cations with a concentration of 0.01 M, and the cations are Fe 3+ , Na + , K + , Ba 2+ , Mg 2+ , Ca 2+ , Fe 2+ , Mn 2+ , and Co 2+ .

[0069] 3) Take 2 mL of the SiO2@Tb suspension prepared in 1) in a cuvette, select 545 nm as the emission wavelength, and record the fluorescence excitation spectrum of the SiO2@Tb suspension.

[0070] 4) Take 2 mL of the same concentration of different metal ions (0.01 M) prepared in 2) in a cuvette, turn on the ultraviolet spectrometer, and record the ultraviolet absorption spectrum of the SiO2@Tb suspension.

[0071] Figure 7 The fluorescence excitation spectrum of SiO2@Tb suspension in Example 6 and the ultraviolet absorption spectrum of different metal ions. It can be found from the figure that Fe 3+ has a strong ultraviolet absorption and is highly overlapped with the fluorescence excitation spectrum of SiO2@Tb. However, other cations have almost no absorption and are almost not overlapped with the fluorescence excitation spectrum of SiO2@Tb, indicating that SiO2@Tb and Fe 3+The energy absorption competition between them promotes fluorescence quenching, that is, the quenching mechanism is ultraviolet absorption competition mechanism, and SiO2@Tb is also given for detecting Fe 3+ The reason why the application has excellent selectivity and anti-interference ability.

[0072] In summary, the above examples demonstrate that the ratio type fluorescence detection of Fe 3+ in water provided by the application has the following advantages: simple instrument equipment, low detection limit, high selectivity and sensitivity, excellent anti-environmental interference ability, and reliable detection results.

Claims

1. A nanofluorescent probe SiO2@Tb for detecting Fe in water 3+ Its application in this area is characterized by, The application involves combining the nano-fluorescent probe SiO2@Tb with Fe... 3+ After mixing with the water to be tested, the mixture was irradiated with ultraviolet light, and the fluorescence emission spectrum was recorded. The fluorescence intensities I at 545 nm and 461 nm were obtained from the emission spectrum. 545 I 461 Find I 545 / I 461 The ratio, based on I 545 / I 461 Calculate the change in Fe in the water body to be tested 3+ ;in: The structure of the nano-fluorescent probe SiO2@Tb is characterized by terbium coordination compounds being bonded to the surface of nano-silica via amide bonds.

2. The application according to claim 1, characterized in that, The wavelength of the ultraviolet excitation light used during ultraviolet irradiation is 210 nm-330 nm.

3. The application according to claim 1, characterized in that, The specific steps for using this application are as follows: 1) The nano-fluorescent probe SiO2@Tb was ultrasonically dispersed in deionized water to obtain a uniformly dispersed suspension; the ratio of fluorescent probe to deionized water was 1 mg: 5-30 mL. 2) Mix V1 mL of the suspension obtained in step 1) with V2 mL of the water to be tested thoroughly; record its emission spectrum using a fluorescence spectrometer, and obtain the fluorescence intensity I at 545 nm and 461 nm from the emission spectrum. 545 I 461 Find I 545 / I 461 Ratio; Fe obtained from the working curve 3+ The concentration of Fe in the water body to be tested (N μM) can be calculated using formula (1). 3+ The content of C μM; The working curve is based on I 545 / I 461 The ratio and iron ion content were plotted on a coordinate system. C=(V1+V2) N / V2(1)。 4. The application according to claim 3, characterized in that, V1mL is 1-5mL.

5. The application according to claim 3, characterized in that, The steps for plotting the working curve are as follows: 1) Using deionized water as a solvent, prepare a 0.1 mM Fe solution. 3+ Aqueous solution; 2) The nano-fluorescent probe SiO2@Tb was ultrasonically dispersed in deionized water to obtain a uniformly dispersed suspension; the ratio of fluorescent probe to deionized water was 1 mg: 5-30 mL. 3) Take 2 mL of SiO2@Tb suspension in a cuvette, turn on the fluorescence spectrometer, and record the emission spectrum under ultraviolet light excitation; then add 20 μL, 20 μL, 20 μL, 20 μL, 20 μL, 20 μL, 40 μL, 40 μL, 40 μL, 40 μL, 40 μL, and 40 μL of the above Fe... 3+ Mix the aqueous solution thoroughly and record the emission spectrum of the suspension. 4) Analyze the data and obtain the fluorescence intensity I at 545 nm and 461 nm from the emission spectrum. 545 I 461 Find I 545 / I 461 Ratio; make I 545 / I 461 The relationship curve between the ratio and the iron ion content was obtained, and a linear fit was performed on it to obtain the ratio-based fluorescence detection method for trace Fe in water. 3+ The working curve.

6. The application according to claim 1, characterized in that, In the nano-fluorescent probe SiO2@Tb, the particle size of the nano-silica is 5~100nm.

7. The application according to claim 1, characterized in that, The preparation steps of the SiO2@Tb nanofluorescent probe are as follows: Amino-modified silica nanospheres were prepared by reacting nano-silica with an aminopropylsilane coupling agent; then, carboxyl-modified silica nanospheres were prepared by reacting with aromatic carboxylic acids or their derivatives; finally, rare earth ions (Tb) were reacted with the nano-silica. 3+ A coordination reaction was carried out to prepare the nano-fluorescent probe SiO2@Tb.

8. The application according to claim 7, characterized in that, The aminopropylsilane coupling agent is aminopropyltrimethoxysilane and / or aminopropyltriethoxysilane; the aromatic carboxylic acid is one or more of terephthalic acid, phthalic acid, isophthalic acid and 4,4'-dicarboxylic biphenyl; the aromatic carboxylic acid derivative is phenyltrimeric anhydride or pyromellitic anhydride.

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