阅读说明：本技术 一种交联型纳米纤维膜及其制备方法与应用 (Crosslinking type nanofiber membrane and preparation method and application thereof ) 是由 贾永堂 刘熙 徐乐 谢娟 于 2021-06-21 设计创作，主要内容包括：本发明公开了一种交联型纳米纤维膜及其制备方法与应用。本发明方案的交联型纳米纤维膜中带荧光基团的物质悬挂于纤维膜的侧链上,荧光物质分布均匀,纤维膜具有大的表面积-体积比和孔隙率,传感效率高且可逆性好。其制备方法操作简便,试剂常规易得,生产成本低。可将其制备成传感器或试剂盒等,进而在重金属离子检测中具有良好的应用前景。(The invention discloses a cross-linking type nanofiber membrane and a preparation method and application thereof. The cross-linked nanofiber 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.)

1. A crosslinked nanofiber membrane characterized in that: the crosslinking type nanofiber membrane comprises the following components in structure:

wherein n represents the degree of polymerization and is a natural number; preferably, n is 50000-150000; more preferably 16000-.

2. The cross-linked nanofiber membrane as claimed in claim 1, wherein: the fluorescent substance having a hydroxyl group includes a naphthalimide compound having a hydroxyl group,Wherein R comprises At least one of (1).

3. The cross-linked nanofiber membrane as claimed in claim 1, wherein: the polymer is a water-soluble polymer; preferably, the monomer of the polymer is a compound with a hydroxyl-containing or aldehyde group; more preferably polyvinyl alcohol, polyethylene oxide or polyvinylpyrrolidone.

4. A preparation method of a cross-linking type nanofiber membrane comprises the following steps:

carrying out electrostatic spinning and crosslinking on the mixed solution containing the fluorescent substance and the polymer to obtain the crosslinked nanofiber membrane; wherein the fluorescent substance is a hydroxyl-containing fluorescent substance; the cross-linked nanofiber membrane is a cross-linked nanofiber membrane with a side chain suspended with a fluorescent group.

5. The method for producing a crosslinked nanofiber membrane according to claim 4, characterized in that: the crosslinking is a steam crosslinking method; preferably, the crosslinking agent selected in the crosslinking is an aldehyde crosslinking agent; preferably, the aldehyde crosslinking agent is selected from among dialdehyde compounds; more preferably from glutaraldehyde or glyoxal; more preferably, the volume concentration of the glutaraldehyde is 30% -50%; further preferably, the glutaraldehyde is preheated to 80-90 ℃ before crosslinking, and the crosslinking time is 3-11 h.

6. Use of the cross-linked nanofiber membrane as claimed in any one of claims 1 to 3 or the cross-linked nanofiber membrane prepared by the preparation method as claimed in any one of claims 4 to 5 in heavy metal ion detection.

7. A heavy metal ion detection method is characterized in that: the method comprises the following steps:

s1, adding the cross-linked nanofiber membrane as claimed in any one of claims 1 to 3 or the cross-linked nanofiber membrane prepared by the preparation method as claimed in any one of claims 4 to 5 into a sample to be tested;

s2, detecting the heavy metal ions by observing the change of fluorescence intensity; preferably, the sample to be tested is selected from a solid sample or a liquid sample; further preferably, at least one selected from the group consisting of soil, food and drinking water.

8. The method for detecting heavy metal ions according to claim 7, characterized in that: the heavy metal is at least one selected from Cu, Fe, Ni, Co or Pb.

9. A sensor, characterized by: comprising the cross-linked nanofiber membrane as set forth in any one of claims 1 to 3 or the cross-linked nanofiber membrane prepared by the preparation method as set forth in any one of claims 4 to 5.

10. A kit, characterized in that: comprising the cross-linked nanofiber membrane as set forth in any one of claims 1 to 3 or the cross-linked nanofiber membrane prepared by the preparation method as set forth in any one of claims 4 to 5.

Technical Field

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

Background

With the rapid development of social industrialization and urbanization, heavy metal (such as Cu, Fe, Pb, Co, Ni, Hg, etc.) ions are used as non-degradable pollutants, and the water pollution caused by the non-degradable pollutants is an important environmental problem. An excessive amount of metal ions causes serious genetic diseases in the human body. Therefore, accurate, rapid, real-time and sensitive monitoring of heavy metals in soil, food and drinking water is essential.

The cross-linked fluorescent sensor based on the solid-phase platform has become one of the most effective detection methods due to the advantages of flexibility, low cost, sensitivity and the like. Various probe sensors are disclosed in the related art, such as the Novel high selectivity and reversible chemosensors based on dual-ratio fluorescent sensors with pH and Fe³⁺modulated multicolor fluorescence emission (Chen, BY.; Kuo, CC.; et al. ACS Appl Mater Interfaces 2015,7(4),2797-³⁺The cross-linked nanofiber probe of (3); the literature Thermo-responsive electrospind nanoparticles with 1,10-phenanthroline-based fluorescent sensor for metal ion detection (Lin, HJ.; Chen, CY, Et al. J. Mater Sci 51,1620, 1631 (2016)) discloses a 1,10-phenanthroline based multi-metal ion cross-linked nanofiber probe; the document Super Hydrophtic Semi-IPN Fluorescent Poly (N- (2-hydroxyethyl) acrylamide) Hydrogel for ultra fast, Selective and Long-Term Effective Mercury (II) Detection in bacterial-Laden System (Zhang, D.; Chen, T.; Yang, JT.; et al. ACS appl. Bio Mater.2019,2, 906-²⁺The crosslinked hydrogel probe of (1). Although all the sensors can be used for detecting metal ions, the sensors have the problems that the sensors are only suitable for detecting single metal and the preparation process is complex, or the sensors are suitable for detecting multiple metal ions but the detection limit is high.

Based on this, how to design and prepare a cross-linking type nanofiber sensor capable of being used for detecting various metal ions through simple steps becomes one of the problems to be solved in the detection field, so that the cross-linking type nanofiber sensor is used for continuously monitoring the content of various metal ions under low concentration for a long time.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a cross-linked nanofiber membrane which can be used for detecting various metal ions.

The invention also provides a preparation method of the crosslinking type nanofiber membrane.

The invention also provides application of the crosslinking type nanofiber membrane.

According to one aspect of the present invention, there is provided a cross-linked nanofiber membrane comprising a composition having a structure represented by the following formula:

wherein n represents the degree of polymerization and 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 cross-linked nanofiber 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.

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

In some preferred embodiments of the present invention, the fluorescent substance having a hydroxyl group includes a naphthalimide compound having a hydroxyl group,OrWherein R comprisesOrAt least one of (1).

In some preferred embodiments of the invention, the polymer is a water-soluble polymer; preferably, the monomer of the polymer is a compound with a hydroxyl-containing or 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 cross-linked nanofiber membrane is provided, which comprises the following steps:

carrying out electrostatic spinning and crosslinking on the mixed solution containing the fluorescent substance and the polymer to obtain the crosslinked nanofiber membrane; wherein the fluorescent substance is a hydroxyl-containing fluorescent substance; the cross-linked nanofiber membrane is a cross-linked nanofiber membrane with a side chain suspended with a fluorescent group.

The preparation method according to a preferred embodiment of the present invention has at least the following advantageous effects: the preparation method of the scheme of the invention has the advantages of simple and convenient operation, conventional and easily obtained reagents and low production cost.

In some preferred embodiments of the present invention, the fluorescent substance having a hydroxyl group includes a naphthalimide compound having a hydroxyl group,OrWherein R comprisesOrAt least one of (1).

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

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

In some preferred embodiments of the 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 to the polyvinyl alcohol is 1: 1-100.

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

In some embodiments of the invention, the crosslinking is steam crosslinking.

In some embodiments of the invention, the crosslinking agent selected for crosslinking is an aldehyde crosslinking agent.

In some preferred embodiments of the invention, the aldehyde crosslinker is selected from dialdehyde compounds.

In some preferred embodiments of the invention, the aldehyde crosslinker is selected from glutaraldehyde or glyoxal.

In some preferred embodiments of the invention, the glutaraldehyde is present at a concentration of 30% to 50% by volume.

In some preferred embodiments of the invention, glutaraldehyde is preheated to 80 ℃ to 90 ℃ prior to crosslinking.

In some preferred embodiments of the invention, the crosslinking time is 3 to 11 hours.

According to another aspect of the present invention, an application of the cross-linked nanofiber membrane is provided, wherein the cross-linked nanofiber membrane or the cross-linked nanofiber membrane prepared by the preparation method is used for heavy metal ion detection.

In some embodiments of the present invention, the application is a method for detecting heavy metal ions, comprising the following steps:

s1, adding the cross-linked nanofiber membrane or the cross-linked nanofiber membrane prepared by the preparation method into a sample to be tested;

and S2, detecting the heavy metal ions by observing the change of fluorescence intensity.

The application according to a preferred embodiment of the invention has at least the following advantageous effects: the composite membrane provided by the scheme of the invention can be used for detecting various metal ions and has a lower detection limit on various heavy metal ions, and the detection limit of part of heavy metal ions is as follows: cu²⁺—1.6×10^-3mg/L、Fe³⁺—1.8×10^-3mg/L、Ni²⁺—1.8×10^-3mg/L、Co^{2 +}—1.3×10^-3mg/L、Pb²⁺—2×10^-3mg/L。

In some embodiments of the invention, the sample to be tested is selected from a solid sample or a liquid sample; preferably, at least one selected from the group consisting of soil, food and drinking water. If the sample is a solid sample, the detection method further comprises the step of pretreating the sample to dissolve out heavy metal ions; such as subjecting it to a leaching treatment or the like.

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

The fiber membrane provided by the scheme of the invention can be used for detecting various heavy metal ions, can effectively avoid leaching of small molecular dyes, has low detection limit on various metal ions, and has a good application prospect.

In some embodiments of the invention, the detection method further comprises the step of plotting a standard curve. The scheme of the invention can realize qualitative detection, for example, whether the heavy metal ions are contained is judged by the existence or nonexistence of the change or the intensity of the fluorescence intensity, so that the qualitative detection is realized; and the quantitative detection can also be realized, a standard curve is determined by preparing a standard solution, and the concentration of the heavy metal ions is calculated according to the determined fluorescence intensity value.

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 cross-linked nanofiber membrane can be prepared into sensors, kits and other commercial products, so that the carrying and the use are more convenient.

Drawings

The invention is further described with reference to the following figures and examples, in which:

FIG. 1 shows the cross-linked nanofiber membranes prepared in example 1 of the present invention at different concentrations of Cu²⁺Fluorescence spectra in solution;

FIG. 2 shows the cross-linked nanofiber membranes prepared in example 1 of the present invention at different concentrations of Fe³⁺Fluorescence spectra in solution;

FIG. 3 shows the cross-linked nanofiber membrane prepared in example 1 of the present invention with different Ni concentrations²⁺Fluorescence spectra in solution;

FIG. 4 shows the cross-linked nanofiber membranes prepared in example 1 of the present invention at different Co concentrations²⁺Fluorescence spectra in solution;

FIG. 5 shows the cross-linked nanofiber membranes prepared in example 1 of the present invention at different concentrations of Pb²⁺Fluorescence spectra in solution.

Detailed Description

The concept and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments to fully understand the objects, features and effects of the present invention. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and those skilled in the art can obtain other embodiments without inventive effort based on the embodiments of the present invention, and all embodiments are within the protection scope of the present invention. The test methods used in the examples are all conventional methods unless otherwise specified; the materials, reagents and the like used are commercially available reagents and materials unless otherwise specified.

Example 1

This example prepares a cross-linked nanofiber membrane, which has the following structure:

the preparation principle is as follows:

the reaction process comprises the following steps: two hydroxyl groups on the PVA chain are crosslinked through an acetal reaction, and one hydroxyl group on the PVA chain and a hydroxyl group of the fluorescent substance are crosslinked through the acetal reaction.

The specific process is as follows:

i preparing the naphthalimide monomer. The preparation route comprises the following steps:

the preparation process comprises the following steps:

4-bromo-1, 8-naphthalic anhydride (20g) was charged to a flask containing 360ml of absolute ethanol, followed by ethanolamine (8.82 g). The reaction was stopped by refluxing for 20 h. After the solution was cooled to room temperature, the crude product was obtained by filtration. Recrystallization from methanol/tetrahydrofuran and drying of the filtered product under vacuum at 50 ℃ gave 6-bromo-2- (2-hydroxyethyl) benzo [ de ] isoquinoline-1, 3-dione as a white solid (20g, yield: 87%).

6-bromo-2- (2-hydroxyethyl) benzo [ de ] isoquinoline-1, 3-dione (8g) and N-methylpiperazine (16mL) were added to 35mL of ethylene glycol monomethyl ether and refluxed for 12 h. Stopping the reaction, slowly adding deionized water dropwise until the solution is cooled to room temperature until precipitation occurs, and filtering to obtain a yellow crude product. The anhydrous ethanol was recrystallized, and then filtered to obtain a naphthalimide monomer (7.77g, yield: 91.6%).

ii, mixing the fluorescence detection material (hydroxyl-containing naphthalimide monomer) prepared by the operation with polyvinyl alcohol (Aladdin, 1788 type; alcoholysis degree: 87.0-89.0% (moL/moL); CAS:9002-89-5) according to the mass ratio of 1:14, adding the mixture into deionized water for complete dissolution, heating to 80 ℃, and stirring for 3 hours to obtain a mixed spinning solution with the mass concentration of 10%;

iii electrostatic spinning (voltage 25 kV; jet velocity 0.8 mL/h; receiving distance 15 cm; temperature 25 ℃, humidity 30%; needle specification 21#) to prepare into nanometer fiber membrane;

iv preheating to 90 ℃ by using 50% volume of glutaraldehyde, placing the glutaraldehyde and 30% (v/v) hydrochloric acid solution in a culture dish together (the volume ratio of the glutaraldehyde to the hydrochloric acid solution is 1:4) respectively in a dryer with allochroic silica gel at the bottom, placing the nanofiber membrane prepared by the operation in the dryer, and pumping air in the dryer for 5min by using a vacuum pump (the air pressure is 0.06 MPa). And (3) taking out the nanofiber membrane after crosslinking for 5h, and drying the nanofiber membrane in vacuum at the temperature of 60 ℃ for 12h to obtain the crosslinked nanofiber membrane.

Example 2

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: the fluorescent detection material and polyvinyl alcohol were added to deionized water, then heated to 90 ℃ by a constant temperature magnetic stirrer and stirred continuously until completely dissolved (less than 3 h).

Example 3

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: the mass ratio of the fluorescent detection material (hydroxyl-containing naphthalimide monomer) to the polyvinyl alcohol is 1:1, 1:10, 1:20, 1:50 or 1: 100.

Example 4

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: the solute concentration of the mixed solution is 5% or 15%.

Example 5

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: the glutaraldehyde concentration is 30% or 40%.

Example 6

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: preheating to 85 ℃ or 90 ℃ before crosslinking.

Example 7

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: the crosslinking time is 3h or 11 h.

Example 8

This example prepared a cross-linked nanofiber membrane, which differs from example 1 in that: the polymer is polyethylene oxide.

Test examples

The test example tests the detection performance of the composite films prepared in examples 1 to 8. Wherein: with Cu²⁺For example, the prepared nanofiber membrane was cut into a rectangle having a size of 1cm 2cm, and soaked in a cuvette containing 2mL of deionized water for 5min, and then the fiber membrane was subjected to fluorescence intensity test using an RF-6000 fluorescence spectrometer. Subsequently adding 1-10 drops of Cu into the cuvette²⁺Adding one drop of metal ion solution, mixing with the water solution in the cuvette for 5-10min, and measuring the fluorescence intensity.

Other metal ions (Fe)³⁺、Ni²⁺、Co²⁺、Pb²⁺) Test method of (2) and Cu²⁺The same is true. The concentration of the metal ion solution to be measured is 0-2 mg/L.

In example 1, the composite membrane prepared therein was used for different concentrations of Cu²⁺、Fe³⁺、Ni²⁺、Co²⁺、Pb²⁺The detection effect of (2) is shown in fig. 1 to 5.

As can be seen from the figure, the fluorescence intensity of the fiber membrane is increased along with the increase of the concentration of the metal ions in the aqueous solution, the fluorescence sensing curve of the composite membrane to the metal ions is obtained through linear fitting of the fluorescence spectrum, and the detection limit of each metal ion is respectively calculated to be Cu according to the formula (3 sigma/k)²⁺—1.6×10^-3mg/L、Fe³⁺—1.8×10^-3mg/L、Ni²⁺—1.8×10^-3mg/L、Co²⁺—1.3×10^-3mg/L、Pb²⁺—2×10^-3mg/L。

The fiber membrane prepared in the embodiment 1 is repeatedly used for detecting metal ions, and after the fiber membrane is repeatedly used for 10 times, the effect is not obviously different, so that the fiber membrane provided by the scheme of the invention can be stably and repeatedly used.

The result shows that the detection limit of the composite membrane (side chain suspended fluorescence unit cross-linked nanofiber membrane) prepared by the embodiment of the invention on metal ions is lower than the limit value of most of the existing reports, and the composite membrane has good metal ion concentration sensing characteristic.

The fluorescence intensity of the fiber membranes prepared in example 2 and used for detecting metal ions with the same concentration is equivalent to that of example 1, and the dissolution time is reduced with the increase of temperature, but the effect is not greatly different. However, since an excessively high temperature accelerates the evaporation of water and increases the solution concentration, it is usually preferred to use 80 to 90 ℃.

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

The diameter of the fiber membrane prepared in example 4 increased as the mass concentration of the mixed solution increased. When the mass concentration is 5%, the diameter is smaller than that of the fiber in the embodiment 1; at a mass concentration of 15%, the diameter was larger than that of the fiber in example 1.

In examples 5 and 6, with the increase of the concentration of the glutaraldehyde or the increase of the preheating temperature, the content of glutaraldehyde vapor increases, the hydrophilicity of the fiber membrane is reduced, and the detection efficiency is reduced.

In example 7, the hydrophilicity of the fiber membrane decreased with the increase of the correlation time, and the detection efficiency decreased.

The performance of the fiber membrane obtained in example 8 was comparable to that of example 1, thereby showing that the polymer as a carrier had a small influence on the detection effect.

Wherein both ends are connected to other atoms through oxygen.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.