CN112808026A

CN112808026A - Nanofiber film and preparation method and application thereof

Info

Publication number: CN112808026A
Application number: CN202011520121.0A
Authority: CN
Inventors: 王东; 李梦; 温海飞; 李昊轩; 李莹; 王雷; 唐本忠
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2020-12-21
Filing date: 2020-12-21
Publication date: 2021-05-18
Anticipated expiration: 2040-12-21
Also published as: CN112808026B

Abstract

The invention discloses a nanofiber membrane and a preparation method and application thereof, wherein the preparation method comprises the following steps: mixing an AIE photosensitizer and a hydrophobic copolymer in an organic solvent, heating and stirring to obtain a spinning solution; and (3) carrying out electrostatic spinning by adopting the spinning solution to prepare the nanofiber membrane. The porous structure of the nanofiber membrane prepared by the invention can realize the adsorption and filtration effects on micro particles or pathogenic aerosol; the fiber film has the capability of generating active oxygen and a mild photothermal conversion effect under sunlight illumination, and can synergistically realize the killing and removing capability of various pathogenic bacteria adsorbed on the surface of the fiber film. The nanofiber membrane is simple to prepare, stable in property, and wide in application prospect in pathogenic bacteria filtration and wearable biological protection, and has a broad-spectrum killing effect on bacteria, fungi and viruses.

Description

Nanofiber film and preparation method and application thereof

Technical Field

The invention relates to the field of wearable biological protection materials, in particular to a nanofiber film and a preparation method and application thereof.

Background

In recent years, outbreaks of various infectious diseases (e.g., H1N1 influenza, middle east respiratory syndrome, Ebola and COVID-19) have had a tremendous impact on the global economic and human health. Many theoretical and practical experiences have shown that wearing personal protective equipment (such as masks and the like) has a positive effect on preventing the spread of respiratory diseases. However, an outbreak of a global pandemic of illness often leads to shortages of supply and demand for personal protective equipment and related raw materials; the random disposal and improper inactivation of the PPE in turn leads to cross-contamination and further spread of the disease. Therefore, the design and preparation of the hybrid material with the functions of filtering and inactivating pathogenic bacteria have very important scientific research value. To achieve this, a method widely used at present is to introduce an antibacterial agent into a thin film material by means of physical doping or chemical modification. However, the existing antibacterial film has some disadvantages: the long contact time is needed to thoroughly kill the surface pathogenic bacteria, the broad-spectrum killing effect on bacteria, fungi and viruses is not achieved, and the large amount of heat generated by the antibacterial material which is killed and killed only by the photo-thermal effect under the sunlight can burn the surface skin of the human body.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

In view of the defects of the prior art, the invention aims to provide a nanofiber membrane as well as a preparation method and application thereof, and aims to solve the problems of long inactivation time consumption, insufficient sterilization broad spectrum, potential skin contact damage, insufficient research on membrane preparation by using an AIE photosensitizer and the like of the conventional antibacterial membrane material.

The technical scheme of the invention is as follows:

a method for preparing a nanofiber membrane, comprising the steps of:

mixing an AIE photosensitizer and a hydrophobic copolymer in an organic solvent, heating and stirring to obtain a spinning solution;

and (3) carrying out electrostatic spinning by adopting the spinning solution to prepare the nanofiber membrane.

The preparation method of the nanofiber membrane is characterized in that the AIE photosensitizer is a small molecule with the functions of generating active oxygen by light sensitization and photo-thermal conversion.

The preparation method of the nanofiber membrane is characterized in that the chemical structural formula of the AIE photosensitizer is shown in the specification

Or

One kind of (1).

The preparation method of the nanofiber membrane comprises the step of preparing a hydrophobic polymer, wherein the hydrophobic polymer is one or more of polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate and polycaprolactone.

The preparation method of the nanofiber membrane comprises the step of preparing a nanofiber membrane, wherein the organic solvent is a mixed solvent of N, N-dimethylformamide and tetrahydrofuran.

The preparation method of the nanofiber membrane comprises the steps of mixing the AIE photosensitizer and the hydrophobic copolymer in the organic solvent, heating and stirring, wherein the mass ratio of the AIE photosensitizer to the hydrophobic copolymer is 1: 20.

The preparation method of the nanofiber membrane comprises the step of enabling the mass concentration of the AIE photosensitizer in the spinning solution to be less than or equal to 0.2%.

The preparation method of the nanofiber membrane comprises the step of preparing the nanofiber membrane by adopting the spinning solution to carry out electrostatic spinning, wherein the voltage is 12.0-15.0kV, and the electrostatic spinning time is 15min-2 h.

The invention relates to a nanofiber membrane, which is prepared by adopting the preparation method of the nanofiber membrane.

The application of the nanofiber film is characterized in that the nanofiber film is used for preparing wearable biological protection equipment.

Has the advantages that: the invention prepares a novel nanofiber membrane by doping a photosensitizer with AIE characteristics and a hydrophobic copolymer with dielectric properties by an electrostatic spinning method. The porous structure of the nanofiber membrane can realize the adsorption and filtration effects on micro particles or pathogenic aerosol; the composite material has the capacity of sensitizing to generate active oxygen and a mild photo-thermal conversion effect under the sunlight illumination, and can synergistically realize the killing and removing capacity on various pathogenic bacteria adsorbed on the surface of a fiber film.

Drawings

Fig. 1 is a flowchart of a method for preparing a nanofiber membrane according to a preferred embodiment of the present invention.

Fig. 2 is an SEM image and CLSM image of the nanofiber thin film prepared in example 1 of the present invention: (a) and (b) SEM images of undoped and TTVB doped nanofiber films, respectively; (c) and (d) CLSM diagrams of undoped and TTVB doped nanofiber films, respectively.

FIG. 3 is a fiber diameter distribution diagram of the nanofiber membrane prepared in example 1 of the present invention: (a) and (b) results for undoped and TTVB doped nanofiber films, respectively.

FIG. 4 shows the results of water contact angle measurements of NM and TTVB @ NM of nanofiber films prepared in example 1 of the present invention at room temperature.

Fig. 5 shows the uv-vis absorption spectrum (a) and the fluorescence emission spectrum (b) of the solid powder of the nanofiber film TTVB @ NM and the dopant TTVB prepared in example 1 of the present invention.

Fig. 6 is a schematic diagram (a) and a graph (b) of the photo-thermal conversion of active oxygen generation of the nanofiber film NM and TTVB @ NM under simulated sunlight according to example 1 of the present invention.

FIG. 7 shows the filtration efficiency and pressure drop test (a) and the permeability test (b) for TTVB @ NM coated meltblown webs having different thicknesses obtained from example 1 of the present invention.

FIG. 8 shows the results of the killing tests of the nanofiber membranes NM and TTVB @ NM prepared in example 1 of the present invention on different pathogenic bacteria (gram positive bacteria-Staphylococcus aureus S. aureus, gram negative bacteria-Escherichia coli E. coli, fungi-Candida albicans C. albicans and viruses-M13 bacteriophage) in liquid droplets in the dark and under simulated sunlight.

Fig. 9 shows the interception and filtration effects of the nanofiber membranes NM and TTVB @ NM prepared in example 1 of the present invention on different pathogenic bacteria (gram-positive bacteria-staphylococcus aureus s.aureus, gram-negative bacteria-escherichia coli e.coli, fungi-candida albicans) in aerosol: (a) coli-containing aerosol is sprayed on the surface of a fiber film, and then bacteria on the upper surface and the lower surface of the fiber film are respectively collected and coated; (b) SEM analysis results of different pathogenic bacteria adsorbed and intercepted on the surface of the fiber membrane.

Fig. 10 shows the inactivation effect of the nanofiber membranes NM and TTVB @ NM prepared in example 1 of the present invention on aerosols containing mixed pathogenic bacteria (gram-positive bacteria-staphylococcus aureus s.aureus, gram-negative bacteria-escherichia coli e.coli, fungi-candida albicans) in dark and natural sunlight: (a) and (b) the test results after 5min and 10min of illumination respectively.

Detailed Description

The invention provides a nanofiber membrane and a preparation method and application thereof, and the invention is further described in detail below in order to make the purpose, technical scheme and effect of the invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Photosensitizers having Aggregation Induced Emission (AIE) properties have been attracting attention as a novel antibacterial material. AIE photosensitizers have higher ROS generation efficiency in the aggregate state than traditional aggregation-induced quenching (ACQ) molecules. In addition, through reasonable design and adjustment of the framework structure of the AIE molecule or the donor motif, the absorption spectrum of the AIE molecule can be adjusted to a white light range and the AIE molecule has a moderate photothermal effect to assist ROS in killing pathogenic bacteria without causing burn to normal skin. However, current studies of sterilization based on AIE photosensitizer mainly focus on solution level or mouse wound infection treatment, and studies of antibacterial interface preparation technology at solid film level are rarely reported.

Based on this, the present invention provides a method for preparing a nanofiber membrane, as shown in fig. 1, which comprises the steps of:

s10, mixing the AIE photosensitizer and the hydrophobic copolymer in an organic solvent, heating and stirring to obtain a spinning solution;

and S20, performing electrostatic spinning by using the spinning solution to obtain the nanofiber membrane.

In this embodiment, a novel nanofiber membrane is prepared by doping a photosensitizer with AIE characteristics and a hydrophobic copolymer with dielectric properties by an electrospinning method. The porous structure of the nanofiber membrane can realize the adsorption and filtration effects on micro particles or pathogenic aerosol; the fiber film has the capability of generating active oxygen and a mild photothermal conversion effect under sunlight illumination, and can synergistically realize the killing and removing capability of various pathogenic bacteria adsorbed on the surface of the fiber film. The nanofiber membrane is simple to prepare, stable in property, and wide in application prospect in pathogenic bacteria filtration and wearable biological protection, and has a broad-spectrum killing effect on bacteria, fungi and viruses.

In some embodiments, the AIE photosensitizer and the hydrophobic copolymer are dissolved in an organic solvent at a mass ratio of 1:20 and stirred at 45 ℃ in the absence of light for 16h to produce a spinning solution. In this example, the organic solvent was a mixed solvent of N, N-Dimethylformamide (DMF) and Tetrahydrofuran (THF). In the spinning solution prepared in this example, the AIE photosensitizer has a black quantum concentration of 0.2% or less.

In some embodiments, the hydrophobic polymer may be selected from, but is not limited to, at least one of polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and polycaprolactone.

In some embodiments, the AIE photosensitizer is a small molecule with light sensitization to generate active oxygen and photothermal conversion. By way of example, the AIE photosensitizer has the chemical formula

Or

One kind of (1).

In some embodiments, during electrospinning, the extrusion rate of the spinning solution is 1.0mL/h, the syringe volume is 5mL, the needle size is 21G, the distance from the end of the needle to the spinning collection metal plate is 15cm, the voltage is 12.0-15.0kV, and the electrospinning time is 15min-2 h.

In some embodiments, after electrospinning to produce the nanofiber membrane, the nanofiber membrane is also subjected to vacuum drying and pasteurization to obtain a sterile membrane suitable for biological testing. In this embodiment, the method for vacuum drying the nanofiber film comprises: vacuum drying at 45 deg.C for 12 hr, and sealing in a self-sealing bag; the pasteurization method comprises the following steps: and (5) blowing a drying box at 65 ℃ for 30 min.

In some embodiments, the nanofiber membrane is prepared by the preparation method of the nanofiber membrane.

The nanofiber film prepared by the method has a porous structure formed by randomly and crossly arranging a plurality of layers of nanofibers, the diameter distribution of the nanofibers is 554 +/-100 nm, and the water contact angle under the room temperature condition is about 137.3 degrees.

In some embodiments, the application of the nanofiber membrane is also provided, and the nanofiber membrane is used for preparing wearable biological protection equipment. The nanofiber membrane can be used for adsorbing and filtering pathogenic bacteria and killing and removing the pathogenic bacteria under sunlight.

The following is a further explanation of the preparation method and properties of a nanofiber membrane of the present invention by means of specific examples:

example 1

(1) Adding 3.6g of polyvinylidene fluoride PVDF-HFP particles and 0.18g of AIE photosensitizer TTVB powder into 10mL of mixed solvent of N, N-Dimethylformamide (DMF) and Tetrahydrofuran (THF), and magnetically stirring for 16h under the constant temperature condition of maintaining 45 ℃ to obtain uniform spinning solution containing polyvinylidene fluoride and AIE photosensitizer;

(2) during electrostatic spinning, a 5mL injector and a 21G stainless steel needle are used, the applied voltage is 15kV, the receiving distance is 15cm, and the spinning time is 30min, so that a primary nanofiber film is obtained;

(3) placing the nanofiber film in a vacuum drying oven, setting the temperature to be 45 ℃, drying for 12 hours to remove residual solvent, and then placing the nanofiber film in a self-sealing bag for sealed storage; before carrying out biological experiments, carrying out pasteurization, and specifically comprising the following steps: and (5) blowing a drying box at 65 ℃ for 30 min.

The micro-morphology and the surface hydrophilicity and hydrophobicity of the AIE molecule doped nanofiber membrane prepared in the embodiment are tested:

the microscopic morphology of the nanofiber film TTVB @ NM prepared in this example was tested with a field emission Scanning Electron Microscope (SEM) and a Confocal Laser Scanning Microscope (CLSM) and compared to the undoped film NM. SEM test results are shown in FIGS. 2(a) and 2(b), the doping of TTVB does not affect the morphology of the fiber, and NM and TTVB @ NM both have a porous structure formed by randomly and crossly arranging a plurality of layers of nano fibers; the CLSM test results in fig. 2(c) and 2(d) show that TTVB can be uniformly distributed in the fiber, and no agglomeration or precipitation occurs; the results in FIG. 3 show that the fiber diameter distribution of NM is 479 + -110 NM and the fiber diameter distribution of TTVB @ NM is 554 + -100 NM, with doping of TTVB resulting in a slight increase in fiber diameter.

In fig. 4, the water contact angle results of NM and TTVB @ NM measured at room temperature are 140.9 ° and 139.3 °, respectively, which shows that the hydrophobicity of both is almost equivalent, and the surface hydrophilicity and hydrophobicity of NM is not affected by doping of TTVB.

The photophysical properties of the AIE molecule-doped nanofiber thin films prepared in this example were tested:

the absorption and emission spectra of TTVB @ NM were characterized by uv-vis and fluorescence emission spectrometers and compared to the properties of the solid powder of dopant TTVB. As shown in FIG. 5, the photophysical properties of TTVB are not changed after the doped nano-fiber film enters the nano-fiber film, and the TTVB @ NM has stronger absorption in the visible light region (400-700NM), which is beneficial to the photo-sterilization research of the doped nano-fiber film under sunlight.

The ability of TTVB @ NM to generate active oxygen under simulated sunlight was studied using DCFH as a probe and compared to undoped thin film NM. DCFH fluoresces green under the oxidation of active oxygen, and as a result, TTVB @ NM produces a large amount of active oxygen, and NM does not produce active oxygen due to the absence of a dopant photosensitizer, as shown in FIG. 6 (a).

Next, we tested TTVB @ NM for its ability to convert light to heat under simulated sunlight and compared it to undoped thin film NM. As shown in FIG. 6(b), NM and TTVB @ NM increased in temperature from 25 ℃ to 30 ℃ and 38 ℃ in the light, respectively, and TTVB @ NM exhibited a superior photothermal conversion effect, and this temperature could help kill pathogenic bacteria by promoting their volatilization and did not cause skin burn due to excessive temperature.

The filtration properties and air permeability of the AIE molecule doped nanofiber membranes prepared in this example were tested:

for ease of testing, the electrospun films used in this experiment were pre-spun onto a meltblown sheet having a thickness of about 150 μm and the properties of the films were compared for different spun thicknesses, with spinning times of 0, 15min, 30min, 60min and 90min, respectively. During the test of the filtration properties, the aerosol particles used by us were ultrafine particles of NaCl having an average particle size of 260nm and the aerosol flow rate was 85L/min. As shown in fig. 7(a), when the electrospinning time exceeds 30min, the filtration efficiency of the membrane is more than 99%, which satisfies the requirement of the filtration efficiency of the N99 mask on the market; the pressure drop result shows that when the spinning time is within 30min, the pressure drop value can meet the requirement of an N99 mask (less than 350 Pa). The permeability results in figure 7(b) show that TTVB @ NM has a permeability of 50-200mm/s, which is comparable or better than the new wearable materials reported in the literature.

The ability of the AIE molecule-doped nanofiber membrane prepared in this example to kill pathogenic bacteria in solution was tested:

in this part of the test, we used four different pathogenic bacteria (gram positive bacteria-staphylococcus aureus s. aureus; gram negative bacteria-escherichia coli e. coli; fungi-candida albicans c. albicans and virus-M13 bacteriophage) to verify the broad spectrum bactericidal properties of the AIE molecule doped nanofiber membrane TTVB @ NM. We prepared dispersions of different pathogenic bacteria separately and dropped 10. mu.L of the pathogenic bacteria dispersion to the surface of NM or TTVB @ NM, and then the films carrying the pathogenic bacteria were placed in the dark or under simulated sunlight (65 mW/cm)²) After 15min, 30min or 1h, the pathogenic bacteria on the surface of the film are collected by washing with PBS and the survival rate of the pathogenic bacteria is calculated by using a plate counting method. As shown in fig. 8, the thin film NM without dopant had no killing effect on both bacteria and fungi in dark and light, and their survival rates were all above 80%; TTVB @ NM has no killing effect on gram-negative bacteria and fungi in a dark place, and the killing effect on gram-positive bacteria is about 30 percent; TTVB @ NM has good killing effect on gram-positive bacteria, gram-negative bacteria and fungi under the irradiation of light, and the survival rates of the three are below 10%. For viruses, NM itself has a certain killing effect on M13 phage under illumination, but TTVB @ NM has a better sterilization effect under illumination, and the inhibition rate is more than 80%.

The ability of the AIE molecule doped nanofiber membrane prepared in this example to filter and kill pathogenic bacteria in aerosol was tested:

during the actual transmission of infectious diseases, aerosols are more contagious and pathogenic due to longer diffusion distances and longer floating times in the air. Therefore, exploring the ability of the nanofiber membrane to filter and kill pathogenic bacteria in aerosols is crucial to developing new antibacterial membrane materials. In this test, an aerosol generating device (atomizer) was used to produce pathogen aerosols ranging in size from 1 μm to 5 μm to simulate aerosols produced by a human in sneezing or coughing.

First, we tested the filtration and interception of pathogenic aerosols by fibrous membranes. Coli (e.coli) onto TTVB @ NM surface for 10s, and then we collected the bacteria on and below the fiber membrane with PBS and plated. As a result, as shown in FIG. 9(a), a large amount of bacteria were intercepted on the TTVB @ NM surface, while no bacteria were present under the cellophane. Subsequently, we sprayed aerosols of different pathogenic bacteria (gram positive bacteria-staphylococcus aureus s. aureus, gram negative bacteria-escherichia coli and fungi-candida albicans) on the nanofiber membrane and observed using a field emission Scanning Electron Microscope (SEM), as shown in fig. 9b), we can observe that gram positive bacteria, gram negative bacteria and fungi are all intercepted and adsorbed on the surface of the nanofiber membrane.

We then tested the ability of the fibrous membranes to inactivate pathogenic aerosols. We prepared an aerosol containing mixed pathogens (gram positive bacteria-staphylococcus aureus s. aureus, gram negative bacteria-escherichia coli e. coli and fungi-candida albicans, virus-M13 phage) and sprayed it on a nanofiber film for 20 s. Then the film with the aerosol is respectively placed in the dark or under natural sunlight for illumination for 5min or 10min (outdoor temperature: 26 ℃ C.; sunlight intensity: 83 mW/cm)²) Then, the pathogenic bacteria on the surface of the fiber membrane were collected and the survival rate of the pathogenic bacteria was calculated using a plate count method. The results are shown in FIG. 10 without dopingNM of the miscellaneous agent has almost no killing ability under the irradiation of sunlight; TTVB @ NM has a certain killing capacity to various pathogenic bacteria in a dark place, and is attributed to the bactericidal capacity of positive charges in a TTVB structure; TTVB @ NM has strong bactericidal capacity under the irradiation of sunlight, can inhibit 99 percent of activities of gram-positive bacteria, gram-negative bacteria and M13 bacteriophage within 5min, and inhibit 90 percent of activities of fungi within 10 min. We believe that this inhibitory and inactivating capacity is derived primarily from ROS produced by TTVB @ NM under solar illumination, and that in addition the photothermal efficiency also aids in killing pathogenic bacteria by promoting aerosol volatilization.

In conclusion, the novel nanofiber film is prepared by doping the photosensitizer TTVB with AIE characteristic and the hydrophobic copolymer PVDF-HFP with dielectric property by an electrostatic spinning method. The porous structure of the nanofiber membrane can realize the adsorption and filtration effects on micro particles or pathogenic aerosol; the composite material has the capacity of sensitizing to generate active oxygen and a mild photo-thermal conversion effect under the sunlight illumination, and can synergistically realize the killing and removing capacity on various pathogenic bacteria adsorbed on the surface of a fiber film.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims

1. A method for preparing a nanofiber membrane is characterized by comprising the following steps:

2. The method of claim 1, wherein the AIE photosensitizer is a small molecule having functions of light sensitization to generate active oxygen and light-heat conversion.

3. The method for preparing nanofiber membrane as claimed in claim 1, wherein the AIE photosensitizer has a chemical formula of

Or

One kind of (1).

4. The method for preparing the nanofiber membrane as claimed in claim 1, wherein the hydrophobic polymer is one or more of polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate and polycaprolactone.

5. The method for preparing a nanofiber membrane as claimed in claim 1, wherein the organic solvent is a mixed solvent of N, N-dimethylformamide and tetrahydrofuran.

6. The method for preparing the nanofiber membrane as claimed in claim 1, wherein in the step of mixing the AIE photosensitizer and the hydrophobic copolymer in the organic solvent and heating and stirring, the mass ratio of the AIE photosensitizer to the hydrophobic copolymer is 1: 20.

7. The method for preparing nanofiber membrane as claimed in claim 1, wherein the mass concentration of AIE photosensitizer in the spinning solution is 0.2% or less.

8. The method for preparing the nanofiber membrane as claimed in claim 1, wherein in the step of preparing the nanofiber membrane by electrospinning using the spinning solution, the voltage is 12.0-15.0kV, and the electrospinning time is 15min-2 h.

9. A nanofiber membrane prepared by the method for preparing a nanofiber membrane as claimed in any one of claims 1 to 8.

10. Use of a nanofibre membrane according to claim 9 for the preparation of wearable bio-protective devices.