A method for detecting Al 3+ Ionic Rhodamine B Grafted Carboxymethyl Cellulose Fluorescent Probe RBCMC

Abstract

The present invention provides an environmentally friendly fluorescent probe RBCMC with high selectivity and high sensitivity. It modifies carboxymethyl cellulose with a rhodamine derivative and successfully realizes the detection of Al<supgt;3+< / supgt; in water. Experiments show that the organic combination of the two endows the fluorescent probe RBCMC with the water solubility of the carboxymethyl cellulose carrier and gives the probe the advantage of specific detection in water. Under the interference of common cations and anions, the fluorescent probe RBCMC exhibits good anti-interference ability, and its lowest detection limit for Al<supgt;3+< / supgt> is 0.239 μM. At the same time, the fluorescent probe RBCMC can be prepared into a hydrogel and successfully applied to the detection of natural water samples. Compared with the prior art, the present invention has low research and development costs, is easy to implement, and has simple operation, and has broad application prospects in the detection of Al<supgt;3+< / supgt> ions.

Description

Technical Field

[0001] The present invention belongs to the field of analytical chemistry, and particularly relates to a method for detecting Al 3+ Preparation and application of fluorescent probes. Background Art

[0002] With the rapid development of science and technology, a large amount of aluminum has appeared in medicines, packaging, food additives and other daily necessities. Excessive use of aluminum has caused serious environmental pollution and caused serious health problems through bioaccumulation, such as Alzheimer's disease, Parkinson's disease, aluminum bone disease, etc. This has a great impact on the 3+ The detection of 27 Al NMR, mass spectrometry (MS), and high performance liquid chromatography (HPLC) have the disadvantages of long response time, expensive equipment, and complex operation. With the development of fluorescence sensing technology, researchers have reported a large number of Al detection based on various fluorophores in recent years. 3+ Chemical sensors. Rhodamine fluorophores are widely used in the detection of metal ions due to their unique spirolactam structure. Unfortunately, most fluorescent sensors need to work in organic solvents, which have the limitations of insufficient water solubility and secondary pollution. Therefore, it is necessary to develop a method that can detect Al in pure water. 3+ Environmentally friendly fluorescent sensors are essential.

[0003] Cellulose comes from natural plants and is an abundant renewable resource. Cellulose is an ideal carrier for the preparation of multifunctional integrated materials due to its good biocompatibility, biodegradability and hydrophilicity. In recent years, fluorescent sensors based on cellulose-based modifications have developed rapidly. Compared with traditional organic small molecule fluorescent sensors, polymer-based fluorescent sensors combine the advantages of organic dyes and cellulose carriers, and have inherent advantages such as excellent processing performance, signal amplification and low detection limit.

[0004] This patent develops a novel method for fixing rhodamine derivatives on a cellulose substrate by using EDC / NHS to mediate the reaction between carboxyl and amino groups. 3+ Fluorescent probe RBCMC with sensitive and selective fluorescence response. The probe detects the target substance by expressing spectral signals through opening and closing rings. It has the characteristics of fast response and high selectivity, and can detect trace amounts of Al in water samples. 3+ At the same time, RBCMC was prepared into hydrogel and successfully applied to the testing of natural water samples. Summary of the invention

[0005] The present invention aims to provide a method for detecting Al 3+ Preparation and application of ionic rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A method for detecting Al 3+ Ionic rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC, the structure of the fluorescent probe is as follows:

[0008]

[0009] The preparation method of the rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC in the present invention comprises the following steps:

[0010] Rhodamine B (960 mg, 2 mmol) was dissolved in 40 mL of anhydrous ethanol, and anhydrous ethylenediamine (1.3 ml, 20 mmol) was slowly added dropwise; nitrogen was introduced and reacted at 80°C for 12 hours; and the mixture was extracted three times with 100 ml of saturated brine and 100 ml of 1,2-dichloroethane. Finally, further purification was performed by silica gel column chromatography, with the eluent being CH2Cl2:MeOH=97:3 (V / V), to obtain 960 mg of the product rhodamine B ethylenediamine, with a yield of 90%; sodium carboxymethyl cellulose CMC was dissolved in deionized water, stirred for 12 hours until completely dissolved, and 100 mL of CMC (2 mg / mL) solution was prepared; the pH value was adjusted to 5 by hydrochloric acid solution, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC (958 mg, 5 mmol) was added and stirred for 30 minutes; then, N-hydroxysuccinimide NHS (115 mg, 1 mmol) was added, and the pH value was adjusted to 7.2 by NaOH solution. Finally, rhodamine B ethylenediamine (484 mg, 1 mmol) was dissolved in 5 mL of N, N-dimethylformamide, and added to the above CMC solution, and reacted at room temperature for 20 hours; after the reaction, it was repeatedly centrifuged and washed with ethanol, and dialyzed with deionized water for 2 days until Al was added to the dialyzate. 3+ The solution has no absorption peak under the UV-visible spectrum, and the final product, rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC, is obtained after drying.

[0011] The method for detecting Al 3+ The fluorescent probe RBCMC was used to detect Al in aqueous phase 3+ .

[0012] Compared with the prior art, the present invention has the following significant advantages: (1) the present invention synthesizes an Al 3+The fluorescent probe RBCMC has the advantages of strong selectivity, low detection limit, high sensitivity, reversibility, excellent spectral performance, simple structure, and easy modification. (2) The raw materials used in the present invention are low in cost, the synthesis method is simple, the reaction conditions are mild, and the yield is high. There are few post-processing steps and it is easy to achieve large-scale production. (3) The fluorescent probe involved in the present invention can be made into a hydrogel, which can detect Hg under visible light and ultraviolet conditions. 2+ (4) The fluorescent probe involved in the present invention can selectively detect Al in the aqueous phase. 3+ , and has high sensitivity, and has good application prospects in many fields such as natural environment and biological systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Rhodamine B ethylenediamine (RB) 1 H NMR spectrum (CDCl3, 400MHz)

[0014] Figure 2 ESI mass spectrum of Rhodamine B ethylenediamine (RB)

[0015] Figure 3 Fourier transform infrared spectra of compounds carboxymethyl cellulose (CM), rhodamine B ethylenediamine (RB) and fluorescent probe RBCMC

[0016] Figure 4 Compounds carboxymethyl cellulose (CM), rhodamine B ethylenediamine (RB) and fluorescent probe RBCMC 1 H NMR spectrum (CDCl3, 400MHz)

[0017] Figure 5 (A) Full XPS spectra of CMC and (B) RBCMC; (C) High-resolution spectra of the C1s peak of CMC and (D) RBCMC

[0018] Figure 6 (A) UV absorption spectra of different cations (100 μM) mixed with RBCMC solution (2.0 mg / mL), (B) Fluorescence emission spectra of RBCMC (3.0 mg / mL) in different cation solutions (100 μM). Inset: RBCMC solution and RBCMC+Al 3+ Comparison of solutions (a) under white light (b) under 365nm UV light

[0019] Figure 7 Probe RBCMC to Al 3+ Response time graph of

[0020] Figure 8 Fluorescence spectra of the probe RBCMC in solutions containing (A) different cations and (B) anions

[0021] Fig. 9 (A) Al in aqueous solution 3+ Fluorescence spectra of RBCMC (3.0 mg / mL) when the concentration increases (B) Linear fitting based on the above fluorescence titration test results combined with the Benesi-Hildebrand equation (C) Calculation of the minimum detection limit

[0022] Fig.10 (A) Different concentrations of Al 3+ Fluorescence intensity in RBCMC hydrogel (B) Maximum fluorescence intensity of RBCMC hydrogel and Al 3+ Linear fitting curve of concentration. Illustration: Different concentrations of Al 3+ RBCMC hydrogel images (a) under white light (b) under 365nm UV light

[0023] Fig.11 Effect of RBCMC hydrogel on Al in natural water 3+ Ion detection results DETAILED DESCRIPTION

[0024] (I) Synthesis and structural characterization of the fluorescent probe RBCMC

[0025] (ii) Fluorescent probe RBCMC for Al 3+ Selective responsiveness

[0026] (III) Probe RBCMC to Al 3+ Response time

[0027] (IV) Probe RBCMC to Al 3+ Anti-interference ability of detection

[0028] (V) Probe RBCMC detection of Al 3+ Sensitivity

[0029] (VI) Application of RBCMC hydrogel probe

[0030] (VII) Effect of RBCMC hydrogel on Al in real environmental water samples 3+ Detection capabilities

[0031] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] Synthesis and structural characterization of fluorescent probe RBCMC

[0034] Rhodamine B (960 mg, 2 mmol) was dissolved in 40 mL of anhydrous ethanol, and anhydrous ethylenediamine (1.3 ml, 20 mmol) was slowly added dropwise; nitrogen was introduced and reacted at 80°C for 12 hours; and the mixture was extracted three times with 100 ml of saturated brine and 100 ml of 1,2-dichloroethane. Finally, further purification was performed by silica gel column chromatography, with the eluent being CH2Cl2:MeOH=97:3 (V / V), to obtain 960 mg of the product rhodamine B ethylenediamine, with a yield of 90%; sodium carboxymethyl cellulose CMC was dissolved in deionized water, stirred for 12 hours until completely dissolved, and 100 mL of CMC (2 mg / mL) solution was prepared; the pH value was adjusted to 5 by hydrochloric acid solution, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC (958 mg, 5 mmol) was added and stirred for 30 minutes; then, N-hydroxysuccinimide NHS (115 mg, 1 mmol) was added, and the pH value was adjusted to 7.2 by NaOH solution. Finally, rhodamine B ethylenediamine (484 mg, 1 mmol) was dissolved in 5 mL of N, N-dimethylformamide, and added to the above CMC solution, and reacted at room temperature for 20 hours; after the reaction, it was repeatedly centrifuged and washed with ethanol, and dialyzed with deionized water for 2 days until Al was added to the dialyzate. 3+ The solution has no absorption peak under the UV-visible spectrum, and the final product, rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC, is obtained after drying.

[0035] The specific synthesis path is as follows:

[0036]

[0037] Among them, compound RB 1 H NMR spectrum and ESI mass spectrum are shown in the appendix of the instruction manual. Figure 1 , 2.

[0038] Instructions attached Figure 3 The FT-IR spectra of RB, CMC and RBCMC are shown in Figure 2. The characteristic peaks of CMC and RBCMC are at 3500 cm -1 (OH), 2900cm -1 (CH), 1610cm -1 (C=O), 1030cm -1 (CO). Compared with the infrared spectrum of CMC, RBCMC has a -1 , 1680cm -1 , 1520cm -1 New absorption peaks nearby are clearly visible, which are the methylene peak (-CH2) on the rhodamine derivative, the benzene ring (C=C) and the newly generated amide peak (C=ON) in the synthesis. These indicate that the rhodamine derivative has been successfully grafted onto CMC.

[0039] Instructions attached Figure 4 The compounds carboxymethyl cellulose (CM), rhodamine B ethylenediamine (RB) and the fluorescent probe RBCMC 1 H NMR spectrum. The data of RBCMC showed the peaks of 2-ethylamino group of rhodamine derivative at 1.08ppm and 3.15ppm, which indicated that the rhodamine derivative was successfully grafted onto CMC. Figure 5 (A) is the XPS spectrum of CMC. The two peaks near 285.9eV and 531.9eV correspond to C1s and O1s. Figure 5 (B) is the XPS spectrum of RBCMC. The two peaks at 285.3eV and 533.2eV correspond to C1s and O1s, but a new peak appears at 399.3eV, indicating that the amide reaction is successful. Figure 5 (C, D) High-resolution spectra of the C1S peak. The increase in the atomic concentration of CC and OC=O / NC=O signals in the high-resolution spectrum of RBCMC compared to CMC can be attributed to the introduction of rhodamine amide groups on the surface of CMC. FT-IR spectra, 1 The data of H NMR and XPS spectra showed that the rhodamine derivative was successfully grafted onto CMC.

[0040] Example 2

[0041] Fluorescent probe RBCMC for Al 3+ Selective responsiveness

[0042] Fluorescence spectroscopy was used to further investigate the effect of RBCMC on Al 3+ specific response capability.

[0043] Fifteen common metal ions (Ag(I), Al(III), Cd(II), Co(II), Cu(II), Fe(II), Fe(III), Hg(II), K(I), Li(I), Mg(II), Na(I), Ni(II), Pb(II), and Zn(II)) were selected to explore the specific response performance of RBCMC in aqueous solution.

[0044] The results of the UV absorption experiment are shown in the attached Figure 6 (A) When testing RBCMC system solutions containing different types of metal ions, only Al 3+The system solution produced an ultraviolet absorption peak at 560nm, which indicated that RBCMC had specific response ability. Studies have shown that the probe-specific response may be attributed to the coordination geometry and conformation of the sensor and the size of the metal ion. The organic combination of carboxymethyl cellulose (CMC) and rhodamine ethylenediamine (RB) changed the electron cloud and metal ion coordination effect on the probe, thus giving the RBCMC modified material the ability to respond specifically.

[0045] Fluorescence spectroscopy was used to further investigate the effect of RBCMC on Al 3+ The specific response ability of Figure 6 (B). Through testing, the fluorescence spectrum of RBCMC system liquid containing other common metal ions (Ag(I), Cd(II), Co(II), Cu(II), Fe(II), Fe(III), Hg(II), K(I), Li(I), Mg(II), Na(I), Ni(II), Pb(II), Zn(II), etc.) will not change significantly. However, when detecting the RBCMC system liquid containing Al(III), the position of the fluorescence peak shifted significantly (582 to 589.5) and the fluorescence intensity was significantly enhanced (42 to 1005). In addition, RBCMC also exhibits the characteristics of naked eye detection, and specific detection can be achieved by color change without the aid of analytical instruments. As shown in the attached Figure 6 As shown in the small image (A), when RBCMC solution is added to the system solution containing Al(III), the color of the solution changes significantly to pink. With the help of UV absorption spectrum and fluorescence spectrum data, it is not difficult to find that RBCMC has a good specific response ability in water.

[0046] Example 3

[0047] Probe RBCMC to Al 3+ response time.

[0048] Add 100 μL of Al to 3 mL of probe RBCMC solution. 3+ (5nM) solution, and the fluorescence intensity was measured once a minute. The results are shown in the attached Figure 7 It can be seen that when Al 3+ After the addition, the fluorescence intensity of the probe RBCMC solution increased rapidly, increasing 21 times (31 to 666) within five minutes, and then slowly increased and reached the highest value after 20 minutes, and then remained unchanged. It can be seen that the probe RBCMC can detect Al relatively quickly. 3+ .

[0049] Example 4

[0050] Probe RBCMC to Al 3+ Anti-interference ability of detection

[0051] As attached Figure 8 As shown in (A), the anti-interference ability of the probe RBCMC was investigated. The fluorescence value of the RBCMC system solution containing competitive ions was measured by fluorescence spectroscopy, and then Al 3+ The fluorescence value of the solution was measured. By comparing the two, it can be found that the solution containing only the probe and the competitive ion has only weak fluorescence that can be ignored, while the solution containing Al 3+ Later, the probe RBCMC produced strong fluorescence. This indicates that when Al 3+ When coexisting with other competing ions, it does not affect the probe's sensitivity to Al 3+ The probe RBCMC has good anti-interference ability. Figure 8 As shown in (B), the anion pair probe RBCMC was also detected to detect Al 3+ The probe RBCMC detects Al in solutions containing various anions. 3+ , its fluorescence intensity is not disturbed too much and can exist stably. All these indicate that the probe RBCMC has high anti-interference ability and can be used in the natural environment.

[0052] Example 5

[0053] Probe RBCMC detection of Al 3+ Sensitivity

[0054] As attached Fig. 9 As shown in (A), the sensitivity of the probe RBCMC was investigated by quantitative analysis of the samples by fluorescence titration. 3+ The fluorescence intensity of the RBCMC system solution was negligible. 3+ Concentration, each time Al is added 3+ The sample was left to stand for 10 minutes before measuring the fluorescence intensity. 3+ As the concentration gradually increases, the fluorescence intensity of the sample also gradually increases, the position of the fluorescence peak red-shifts from 582nm to 589.5nm, and the color of the sample changes from colorless to pink. These phenomena can be attributed to the complexation of metal ions with RBCMC, inducing the ring-opening of the spirolactam structure of rhodamine B to emit strong fluorescence.

[0055] As attached Fig. 9 As shown in (B), the linear fitting of the above fluorescence titration test results combined with the Benesi-Hildebrand equation was performed to calculate the relationship between the probe RBCMC and Al 3+ The binding constant is 1.92*10 4 M -1 This indicates that the probe RBCMC has a high stability when coordinated with metal ions. Fig. 9As shown in (C), the lowest detection limit can be obtained by linear fitting based on the fluorescence titration experimental results combined with the following formula. The lowest detection limit of the probe RBCMC is calculated to be 0.239 μM.

[0056]

[0057] Detection limit = 3SD / S

[0058] Where SD is the standard deviation of fluorescence values ​​detected 10 times with only blank solution; S is Al 3+ The slope of the calibration curve of metal ion concentration versus fluorescence intensity.

[0059] Example 6

[0060] Application of RBCMC hydrogel probe

[0061] The modified RBCMC material was prepared into a hydrogel and successfully 3+ As shown in the attached Fig.10 (A) As shown in Figure 2, RBCMC hydrogels tested different concentrations of Al 3+ As Al 3+ The fluorescence emission intensity of RBCMC hydrogels was related to the concentration of Al 3+ These results indicate that RBCMC hydrogel can be used as a detection method for Al 3+ of sensors.

[0062] Example 7

[0063] Effect of RBCMC hydrogel on Al in real environmental water samples 3+ Detection capabilities

[0064] Water samples were collected from Xuanwu Lake and Zixi Lake in Nanjing, Jiangsu Province, and solid impurities were simply treated by centrifugal filtration. 3+ Added into real water samples, the fluorescence intensity was measured by fluorescence spectroscopy to obtain the recovered Al 3+ The analysis data of real water samples are provided by Fig.11 It can be seen that the two different environmental water samples have different concentrations of Al 3+ The recovery rate was about 90%-95%. This shows that RBCMC hydrogel can effectively protect Al even in complex environmental water samples. 3+ The recovery rate remains at a high level and can be used to detect trace Al in real environmental water samples. 3+ .

Claims

1. A method for detecting Al 3+ The structure of the ionic rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC is as follows 2. A method for detecting Al as claimed in claim 1 3+ The preparation method of ionic rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC comprises the following steps: Dissolve 960 mg of rhodamine B in 40 mL of anhydrous ethanol and slowly add 1.3 ml of anhydrous ethylenediamine; Nitrogen was introduced and the mixture was reacted at 80°C for 12 hours. The mixture was extracted three times with 100 ml of saturated saline and 100 ml of 1,2-dichloroethane, and further purified by silica gel column chromatography. A mixed solution of CH2Cl2:MeOH with a volume ratio of 97:3 was used as the eluent to obtain 960 mg of the product rhodamine B ethylenediamine RB with a yield of 90%. Sodium carboxymethyl cellulose CMC was dissolved in deionized water and stirred for 12 hours until completely dissolved to prepare 100 mL of a CMC solution with a concentration of 2 mg / mL. The pH value was adjusted to 5 with a hydrochloric acid solution, and 958 mg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC was added and stirred for 30 minutes. Then 115 mg of N-hydroxysuccinimide NHS was added, and the pH value was adjusted to 7.2 with a NaOH solution. Finally, 484 mg of rhodamine B ethylenediamine was dissolved in 5 mL N, N-dimethylformamide, and added to the above CMC solution, reacted at room temperature for 20 hours; after the reaction, repeatedly centrifuged and washed with ethanol, and dialyzed with deionized water for 2 days until Al was added to the dialysate. 3+ The solution has no absorption peak under the UV-visible spectrum, and the final product, rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC, is obtained after drying. The specific synthesis route is as follows:

3. A method for detecting Al as claimed in claim 1 3+ The application of ionic rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC is characterized by: The rhodamine B grafted carboxymethyl cellulose fluorescent probe RBCMC described in claim 1 is used to detect Al in the aqueous phase 3+ ion.

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