CN113529278B - A kind of cross-linked nanofiber membrane and its preparation method and application - Google Patents

Abstract

The invention discloses a cross-linking type nanofiber membrane and a preparation method and application thereof. The cross-linked nano-fiber membrane provided by the scheme of the invention is suspended on the side chain of the fiber membrane, the fluorescent substance is uniformly distributed, the fiber membrane has large surface area-volume ratio and porosity, the sensing efficiency is high, and the reversibility is good. The preparation method is simple and convenient to operate, the reagents are conventional and easy to obtain, and the production cost is low. The compound can be prepared into a sensor or a kit and the like, and further has good application prospect in heavy metal ion detection.

Description

A kind of cross-linked nanofiber membrane and its preparation method and application

technical field

The invention belongs to the technical field of detection, and in particular relates to a cross-linked nanofiber membrane and a preparation method and application thereof.

Background technique

With the rapid development of social industrialization and urbanization, heavy metal (such as Cu, Fe, Pb, Co, Ni, Hg, etc.) ions are non-degradable pollutants, and the water pollution caused by them has become an important environmental problem. Excessive metal ions can cause serious genetic diseases in the human body. Therefore, accurate, rapid and real-time sensitive monitoring of heavy metals in soil, food and drinking water is very necessary.

Cross-linked fluorescence sensors based on solid-phase platforms have become one of the most effective detection methods due to their flexibility, low cost, and sensitivity. A variety of probe sensors are disclosed in the related art, such as the literature Novel highlyselective and reversible chemosensors based on dual-ratiometric fluorescentelectrospun nanofibers with pH and Fe ³⁺ modulated multicolor fluorescenceemission. (Chen, BY.; Kuo, CC.; et al. ACS Appl Mater Interfaces 2015, 7(4), 2797-808.) discloses a rhodamine-based Fe ³⁺ cross-linked nanofiber probe; document Thermo-responsiveelectrospun nanofibers doped with 1,10-phenanthroline-based fluorescentsensor for metal ion detection. (Lin, HJ.; Chen, CY. Et al. J Mater Sci 51, 1620–1631 (2016).) discloses a cross-linking of 1,10-phenanthroline-based polymetal ions Type nanofiber probe; literature Super Hydrophilic Semi-IPN Fluorescent Poly(N-(2-hydroxyethyl)acrylamide)Hydrogel for Ultrafast,Selective and Long-Term Effective Mercury(II)Detectionin Bacteria-Laden System.(Zhang,D.; Chen, T.; Yang, JT.; et al. ACS Appl. BioMater. 2019, 2, 2, 906–915.) discloses a cross-linked hydrogel probe based on naphthalimide derivatives of Hg ²⁺ Needle. Although these sensors can be used for the detection of metal ions, they have the problems that they are only suitable for the detection of a single metal, the preparation process is complicated, or the detection limit is high although they are suitable for the detection of multiple metal ions.

Based on this, how to design and fabricate a cross-linked nanofiber sensor that can be used for the detection of various metal ions through simple steps, which can be used to continuously monitor the content of various metal ions at low concentrations for a long time. One of the urgent problems to be solved in the field.

SUMMARY OF THE INVENTION

The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention proposes a cross-linked nanofiber membrane, which can be used for the detection of various metal ions.

The present invention also proposes a preparation method of the above-mentioned cross-linked nanofiber membrane.

The present invention also proposes the application of the above-mentioned cross-linked nanofiber membrane.

According to one aspect of the present invention, a cross-linked nanofiber membrane is proposed, and the cross-linked nanofibrous membrane includes components whose structure is shown in the following formula:

Among them, n represents the degree of aggregation, which is a natural number.

The cross-linked nanofiber membrane according to a preferred embodiment of the present invention has at least the following beneficial effects: the substance with a fluorescent group in the cross-linked nanofiber membrane of the solution of the present invention is suspended on the side chain of the fiber membrane, The fluorescent substances are uniformly distributed, the fiber membrane has a large surface area-to-volume ratio and porosity, and the sensing efficiency is high and the reversibility is good.

In some preferred embodiments of the present invention, n is 50000-150000; preferably 16000-20000.

或

中的至少一种，其中，所述R包括

或

中的至少一种。In some preferred embodiments of the present invention, the fluorescent substance with a hydroxyl group includes a naphthalimide compound with a hydroxyl group,

or

At least one of wherein the R includes

or

at least one of them.

In some preferred embodiments of the present invention, the polymer is a water-soluble polymer; preferably, the monomer of the polymer is a compound with a hydroxyl group or an aldehyde group; more preferably, polyvinyl alcohol (PVA ), polyethylene oxide (PEO) or polyvinylpyrrolidone (PVP).

According to another aspect of the present invention, a method for preparing the above-mentioned cross-linked nanofiber membrane is proposed, comprising the following steps:

The cross-linked nanofiber membrane is obtained by taking the mixed solution containing the fluorescent substance and the polymer, electrospinning and cross-linking; wherein, the fluorescent substance is a hydroxyl-containing fluorescent substance; the cross-linked nanofiber The membrane is a cross-linked nanofiber membrane with fluorescent groups suspended on its side chains.

The preparation method according to a preferred embodiment of the present invention has at least the following beneficial effects: the preparation method of the scheme of the present invention is easy to operate, conventional reagents are readily available, and the production cost is low.

或

中的至少一种，其中，所述R包括

或

中的至少一种。In some preferred embodiments of the present invention, the fluorescent substance with a hydroxyl group includes a naphthalimide compound with a hydroxyl group,

or

At least one of wherein the R includes

or

at least one of them.

In some preferred embodiments of the present invention, the polymer is a water-soluble polymer.

In some preferred embodiments of the present invention, the monomer of the polymer is a compound with a hydroxyl group or an aldehyde group.

In some preferred embodiments of the present invention, the polymer is polyvinyl alcohol, polyethylene oxide (PEO) or polyvinylpyrrolidone (PVP).

In some embodiments of the present invention, the mass ratio of the fluorescent substance and the polyvinyl alcohol is 1:1-100.

In some embodiments of the present invention, the mass percentage concentration of the solute in the mixed solution containing the fluorescent substance and the polymer is 5%-15%.

In some embodiments of the present invention, the crosslinking is a steam crosslinking method.

In some embodiments of the present invention, the cross-linking agent selected in the cross-linking is an aldehyde cross-linking agent.

In some preferred embodiments of the present invention, the aldehyde-based crosslinking agent is selected from dialdehyde-based compounds.

In some preferred embodiments of the present invention, the aldehyde-based crosslinking agent is selected from glutaraldehyde or glyoxal.

In some preferred embodiments of the present invention, the volume concentration of the glutaraldehyde is 30%-50%.

In some preferred embodiments of the present invention, glutaraldehyde is preheated to 80°C-90°C prior to crosslinking.

In some preferred embodiments of the present invention, the cross-linking time is 3-11 h.

According to a further aspect of the present invention, an application of the above-mentioned cross-linked nanofiber membrane is proposed, and the application is to use the above-mentioned cross-linked nanofiber membrane or the cross-linked nanofiber membrane prepared by the above preparation method for heavy metal ion detection .

In some embodiments of the present invention, the application is a heavy metal ion detection method, comprising the following steps:

S1, adding the above-mentioned cross-linked nanofiber membrane or the cross-linked nanofiber membrane obtained by the above preparation method to the sample to be tested;

S2. Detect the heavy metal ions by observing changes in fluorescence intensity.

According to the application of a preferred embodiment of the present invention, it has at least the following beneficial effects: the composite membrane of the solution of the present invention can be used for the detection of various metal ions and has a lower detection limit for various heavy metal ions. The detection limits are as follows: Cu ²⁺ -1.6×10 ^-3 mg/L, Fe ³⁺ -1.8×10 ^-3 mg/L, Ni ²⁺ -1.8×10 ^-3 mg/L, Co ^{2 +} -1.3×10 ^-3 mg/L, Pb ²⁺ -2×10 ^-3 mg/L.

In some embodiments of the present invention, the sample to be tested is selected from solid samples or liquid samples; preferably, it is selected from at least one of soil, food and drinking water. If it is a solid sample, the detection method further includes the step of pre-processing the sample to dissolve the heavy metal ions; for example, leaching the sample.

In some embodiments of the present invention, the heavy metal is selected from at least one of Cu, Fe, Ni, Co or Pb.

The fiber membrane of the scheme of the present invention can be used for the detection of various heavy metal ions, which can effectively avoid the leaching of small molecular dyes, and has low detection limits for various metal ions, and has good application prospects.

In some embodiments of the present invention, the detection method further includes the step of drawing a standard curve. The scheme of the present invention can realize qualitative detection, such as determining whether heavy metal ions are contained in the fluorescence intensity or not, thereby realizing qualitative detection; it can also realize quantitative detection, by preparing a standard solution, measuring a standard curve, and then according to The measured fluorescence intensity value was used to calculate the concentration of heavy metal ions.

In some embodiments of the present invention, the application is a sensor, comprising the above-mentioned cross-linked nanofiber membrane or the cross-linked nanofiber membrane prepared by the above-mentioned preparation method.

In some embodiments of the present invention, the application is a kit comprising the above-mentioned cross-linked nanofiber membrane or the cross-linked nanofiber membrane prepared by the above-mentioned preparation method.

The above-mentioned cross-linked nanofiber membrane can be prepared into commercial products such as sensors or kits, making it more convenient to carry and use.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, wherein:

Fig. 1 is the fluorescence spectrogram of the cross-linked nanofiber membrane prepared in Example 1 of the present invention in different concentrations of Cu ²⁺ solution;

Fig. 2 is the fluorescence spectrum of the cross-linked nanofiber membrane prepared in Example 1 of the present invention in Fe ³⁺ solutions of different concentrations;

Fig. 3 is the fluorescence spectrum of the cross-linked nanofiber membrane obtained in Example 1 of the present invention in different concentrations of Ni ²⁺ solutions;

Fig. 4 is the fluorescence spectrum of the cross-linked nanofiber membrane prepared in Example 1 of the present invention in different concentrations of Co ²⁺ solutions;

FIG. 5 is a fluorescence spectrum of the cross-linked nanofiber membrane prepared in Example 1 of the present invention in different concentrations of Pb ²⁺ solutions.

Detailed ways

The concept of the present invention and the technical effects produced will be clearly and completely described below with reference to the embodiments, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts are all within the scope of The scope of protection of the present invention. The test methods used in the examples are conventional methods unless otherwise specified; the materials, reagents, etc. used, unless otherwise specified, can be obtained from commercial sources.

Example 1

In this example, a cross-linked nanofiber membrane is prepared, and the structure is as follows:

Its preparation principle is as follows:

The reaction process includes: cross-linking between two hydroxyl groups on the PVA chain through acetal reaction and cross-linking between one hydroxyl group on the PVA chain and the hydroxyl group of the fluorescent substance through acetal reaction.

The specific process is:

i Preparation of naphthalimide monomer. Its preparation route process is as follows:

The specific preparation process is:

4-Bromo-1,8-naphthalenedicarboxylic anhydride (20 g) was added to a flask containing 360 ml of absolute ethanol, followed by ethanolamine (8.82 g). Refluxed for 20h to stop the reaction. After the solution was cooled to room temperature, the crude product was obtained by filtration. It was recrystallized from methanol/tetrahydrofuran, and the filtered product was dried under vacuum at 50°C to obtain 6-bromo-2-(2-hydroxyethyl)benzo[de]isoquinoline-1,3-dione (20 g) as a white solid. , yield: 87%).

6-Bromo-2-(2-hydroxyethyl)benzo[de]isoquinoline-1,3-dione (8g) and N-methylpiperazine (16mL) were added to 35ml ethylene glycol monomethyl In ether, refluxed for 12h. The reaction was stopped, deionized water was slowly added dropwise after the solution was cooled to room temperature until precipitation appeared, and the yellow crude product was obtained by filtration. Recrystallization from absolute ethanol, followed by filtration gave naphthalimide monomer (7.77 g, yield: 91.6%).

ii Combine the fluorescent detection material (hydroxyl-containing naphthalimide monomer) and polyvinyl alcohol (Aladdin, 1788 type; alcoholysis degree: 87.0-89.0% (moL/moL); CAS: 9002 -89-5) Mix in a ratio of 1:14 by mass, add in deionized water to dissolve completely, heat to 80°C and stir for 3h to obtain a mixed spinning solution with a mass concentration of 10%;

iii Electrospinning (voltage 25kV; jet rate 0.8mL/h; receiving distance 15cm; temperature 25°C; humidity 30%; needle size 21#) was prepared into a nanofiber membrane;

iv Preheat to 90°C with glutaraldehyde with a volume fraction of 50%, and place it in a petri dish with a 30% (v/v) hydrochloric acid solution (the volume ratio of the two is 1:4). In a desiccator of discolored silica gel, the nanofiber membrane obtained by the above operation was placed in the desiccator, and the air in the desiccator was extracted by a vacuum pump for 5 min (air pressure was 0.06 MPa). After cross-linking for 5 h, the nanofiber membrane was taken out and vacuum-dried at 60 °C for 12 h to obtain a cross-linked nanofiber membrane.

Example 2

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that: the fluorescent detection material and polyvinyl alcohol are added to deionized water, and then heated to 90°C by a constant temperature magnetic stirrer and stirred continuously until Complete dissolution (less than 3h).

Example 3

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that the fluorescence detection material (hydroxyl-containing naphthalimide monomer) and polyvinyl alcohol are in a mass ratio of 1:1, 1 : 10, 1:20, 1:50 or 1:100.

Example 4

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that the solute concentration of the mixed solution is 5% or 15%.

Example 5

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that the concentration of glutaraldehyde is 30% or 40%.

Example 6

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that it is preheated to 85° C. or 90° C. before cross-linking.

Example 7

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that the cross-linking time is 3h or 11h.

Example 8

In this example, a cross-linked nanofiber membrane is prepared, which is different from Example 1 in that the polymer is polyethylene oxide.

Test example

This test example tests the detection performance of the composite films prepared in Examples 1-8. Among them: Take Cu ²⁺ as an example, cut the prepared nanofiber membrane into a rectangle with a size of 1cm 2cm, and soak it in a cuvette with 2mL deionized water for 5min, and then use RF-6000 fluorescence spectrometer to analyze the fiber membrane Perform a fluorescence intensity test. Then add 1-10 drops of Cu ²⁺ solution to the cuvette, and after each additional drop of metal ion solution, mix it thoroughly with the aqueous solution in the cuvette for 5-10 minutes, and then measure its fluorescence intensity.

The test methods for other metal ions (Fe ³⁺ , Ni ²⁺ , Co ²⁺ , Pb ²⁺ ) are the same as those for Cu ²⁺ . The concentration of the measured metal ion solution is 0-2 mg/L.

The detection effects of the composite membrane prepared in Example 1 on Cu ²⁺ , Fe ³⁺ , Ni ²⁺ , Co ²⁺ , and Pb ²⁺ with different concentrations are shown in FIGS. 1 to 5 .

It can be seen from the figure that with the increase of the concentration of metal ions in the aqueous solution, the fluorescence intensity of the fiber membrane also increases. Through the linear fitting of the fluorescence spectrum, the fluorescence sensing curve of the composite membrane for metal ions is obtained. (3σ/k), the detection limits of each metal ion were calculated as Cu ²⁺ -1.6×10 ^-3 mg/L, Fe ³⁺ -1.8×10 ^-3 mg/L, Ni ²⁺ -1.8×10 ^-3 mg/L, Co ²⁺ -1.3×10 ^-3 mg/L, Pb ²⁺ -2×10 ^-3 mg/L.

The fiber membrane prepared in the above Example 1 was repeatedly used for the detection of metal ions. After 10 repetitions, there was no significant difference in its effect. Therefore, the fiber membrane of the present invention can be used repeatedly stably.

The results show that the detection limit of metal ions of the composite membrane (cross-linked nanofiber membrane with pendant fluorescent units on the side chain) prepared in the embodiment of the present invention is lower than the limit of most existing reports, and has good metal ion concentration sensing. characteristic.

The fluorescence intensities of the fiber membranes prepared in Example 2 under different mass ratios to the detection of metal ions of the same concentration are comparable to those in Example 1. With the increase of temperature, the dissolution time decreases, but the effect is not much different. However, if the temperature is too high, the evaporation of water will be accelerated, and the concentration of the solution will be too large. Therefore, it is usually 80-90 °C.

The fluorescence intensity of the fiber membranes prepared in Example 3 under different mass ratios detected by the same concentration of metal ions increases gradually with the increase of the mass ratio.

The diameter of the fiber membrane prepared in Example 4 increased with the increase of the mass concentration of the mixed solution. When the mass concentration is 5%, the diameter is smaller than the fiber diameter in Example 1; when the mass concentration is 15%, the diameter is larger than the fiber diameter in Example 1.

In Examples 5 and 6, as the concentration of glutaraldehyde increases or the preheating temperature increases, the content of glutaraldehyde vapor increases, the hydrophilicity of the fiber membrane decreases, and the detection efficiency decreases.

In Example 7, as the correlation time increased, the hydrophilicity of the fiber membrane decreased, and the detection efficiency decreased.

The properties of the fiber membrane prepared in Example 8 were comparable to those in Example 1, which indicated that the polymer used as the carrier had little influence on the detection effect.

中代表两端通过氧与其他原子连接。

The middle represents that the two ends are connected to other atoms through oxygen.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and within the scope of knowledge possessed by those of ordinary skill in the art, various Variety. Furthermore, the embodiments of the present invention and features in the embodiments may be combined with each other without conflict.

Claims (21)

1. A cross-linked nanofiber membrane, characterized in that: the cross-linked nanofiber membrane comprises a composition whose structure is shown in the following formula:

Among them, n represents the degree of aggregation, which is a natural number. 2 . The cross-linked nanofiber membrane according to claim 1 , wherein n is 50,000 to 150,000. 3 . 3 . The cross-linked nanofiber membrane according to claim 1 , wherein n is 16000-20000. 4 . 4 . The cross-linked nanofiber membrane according to claim 1 , wherein the hydroxyl-bearing fluorescent substance comprises a hydroxyl-bearing naphthalimide compound, 4 .

At least one of wherein the R includes

at least one of them. 5 . The cross-linked nanofiber membrane according to claim 1 , wherein the polymer is a water-soluble polymer. 6 . 6 . The cross-linked nanofiber membrane according to claim 5 , wherein the monomer of the polymer is a compound with a hydroxyl group or an aldehyde group. 7 . 7 . The cross-linked nanofiber membrane according to claim 5 , wherein the polymer is polyvinyl alcohol, polyethylene oxide or polyvinylpyrrolidone. 8 . 8. A preparation method of a cross-linked nanofiber membrane, comprising the steps: The cross-linked nanofiber membrane is obtained by taking a mixed solution containing a fluorescent substance and a polymer, electrospinning and cross-linking; wherein, the fluorescent substance is a hydroxyl-containing fluorescent substance; the cross-linked nanofiber membrane It is a cross-linked nanofiber membrane with fluorescent groups suspended on its side chains. 9 . The method for preparing a cross-linked nanofiber membrane according to claim 8 , wherein the cross-linking is a steam cross-linking method. 10 . 10 . The method for preparing a cross-linked nanofiber membrane according to claim 9 , wherein the cross-linking agent selected in the cross-linking is an aldehyde cross-linking agent. 11 . 11 . The method for preparing a cross-linked nanofiber membrane according to claim 10 , wherein the aldehyde-based cross-linking agent is selected from dialdehyde compounds. 12 . 12 . The method for preparing a cross-linked nanofiber membrane according to claim 11 , wherein the aldehyde cross-linking agent is selected from glutaraldehyde or glyoxal. 13 . 13 . The method for preparing a cross-linked nanofiber membrane according to claim 12 , wherein the volume concentration of the glutaraldehyde is 30%-50%. 14 . 14. The method for preparing a cross-linked nanofiber membrane according to claim 9, wherein the steam cross-linking method comprises the steps of: preheating glutaraldehyde to 80°C-90°C before cross-linking, The cross-linking time is 3-11h. 15. The cross-linked nanofiber membrane according to any one of claims 1 to 7 or the crosslinked nanofiber membrane obtained by the preparation method according to any one of claims 8 to 14 in heavy metal ion detection application. 16. A heavy metal ion detection method, is characterized in that: comprise the steps: S1. Add the cross-linked nanofiber membrane according to any one of claims 1 to 7 or the cross-linked nanofiber membrane prepared by the preparation method according to any one of claims 8 to 14 to the sample to be tested middle; S2. Detect the heavy metal ions by observing changes in fluorescence intensity. 17. The heavy metal ion detection method according to claim 16, wherein the sample to be tested is selected from a solid sample or a liquid sample. 18. The heavy metal ion detection method according to claim 17, wherein the sample to be tested is selected from at least one of soil, food and drinking water. 19. The heavy metal ion detection method according to claim 16, wherein the heavy metal is selected from at least one of Cu, Fe, Ni, Co or Pb. 20. A sensor, characterized in that it comprises a cross-linked nanofiber membrane prepared by the cross-linked nanofiber membrane according to any one of claims 1 to 7 or the preparation method according to any one of claims 8 to 14 type nanofiber membrane. 21. A test kit, characterized in that: comprising the cross-linked nanofiber membrane as claimed in any one of claims 1 to 7 or the cross-linked nanofiber membrane prepared by the preparation method as claimed in any one of claims 8 to 14 Linked nanofiber membranes.

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