KR20120118681A - Preparation method for highly porous core-shell nanoweb - Google Patents

Abstract

PURPOSE: A method for fabricating a porous coreshell nanoweb is provided to obtain micropores with uniform size and shape and to culture various cells. CONSTITUTION: A method for fabricating a porous coreshell nanoweb comprises: a step of discharging a water soluble polymer solution by an inner nozzle of a metal dual nozzle; and a step of discharging a hydrophobic polymer solution by an outer nozzle of the metal dual nozzle. The coreshell nanofiber spun in the inner and outer nozzles is discharged to a collecting electrode dipped in the water. The water soluble polymer solution is a biocompatible polymer of gelatin, collagen, chitosan, silk, bovine serum albumin(BSA), cellulose, alginic acid, or hyaluronic acid.

Description

Preparation method for highly porous core-shell nanoweb

The present invention relates to a method for producing a porous core shell nanoweb, and more particularly, to a method for manufacturing a porous coreshell nanoweb in which the size and shape of pores are adjusted to be suitable for cell culture.

Electrospinning is one of the methods for producing nanofibers by using an electric force, by applying a high voltage between the injection nozzle and the collection electrode containing the polymer solution or melt and spinning in a thin fiber form. When the electric field is applied, the polymer solution droplets undergo two different electrostatic forces, namely the electrostatic repulsion between the surfaces and the coulomb force of the external electric field. These electrical interactions result in a tensile deformation of the polymer solution droplets, resulting in a cone called the Taylor cone. After that, when the electric field strength of the polymer solution overcomes the surface tension of the solution, the solution is spun and made into nanofibers.

The nanofibers produced are very thin diameters of tens of nanometers to several micrometers, and have a very large surface area per unit mass, flexible, many microcavities generated between fibers, and a large number of fibers per unit area. It can be mixed with other materials and has a big characteristic of dispersion against external stress.

For this reason, nanofibers can be used for filter cultivation, biotissue culture, wound protection healing and uniform regeneration of skin tissue, artificial blood vessels, drug delivery systems, space mirrors, plant insecticides, reinforced composites and the like.

On the other hand, water-soluble polymers such as gelatin, polyvinyl alcohol, and hyaluronic acid are excellent in biocompatibility, and the cores of the above water-soluble polymers are cored because of the occurrence of droplets in the polymer solution during electrospinning or electrospinning due to clogging of the nozzles due to crystallization of the polymers in front of the nozzles. A technology for producing a core-shell nanofiber with an electrospinning device having a double nozzle is proposed, but it uses a thermal induction for phase separation to control the size of micropores. There was a problem that occurred.

Using a water-soluble polymer with high water solubility and excellent biocompatibility as a core, the core shell structure is made of nanofibers, and the porous core shell nanoweb is manufactured by adjusting the size and shape of the pores to be suitable for cell culture. The purpose is to provide a method.

The present invention, in discharging the water-soluble polymer solution to the inner nozzle of the metal double nozzle, and the hydrophobic polymer solution to discharge the external nozzle of the metal double nozzle in the manufacture of the core-shell nanofibers, spun from the inner nozzle and the outer nozzle It provides a method for producing a porous core shell nanoweb, characterized in that the coreshell nanofibers are discharged to a collecting electrode immersed in water.

In another aspect, the present invention provides a porous core-shell nanoweb, characterized in that the aspect ratio of the micropores is 0.8 ~ 1.2.

In addition, the present invention is a metal double nozzle; A water-soluble polymer solution injection pump connected to an internal nozzle of the metal double nozzle; A hydrophobic polymer solution injection pump connected to an outer nozzle of the metal double nozzle; A voltage application device connected to the tip of the metal double nozzle; And a collecting electrode spaced apart from the tip of the metal double nozzle and immersed in water.

Porous core-shell nanoweb prepared by the method of the present invention is less likely to deform or damage the biocompatible polymer by heat, the size of micropores is uniform and the shape is constant, so that a variety of cells, such as cancer cells, fibroblasts, embryonic stem cells It can be used as a matrix for culture.

1 is a schematic view of a nanoweb fabrication apparatus formed from coreshell nanofibers through conventional electrospinning.
Figure 2 is a schematic diagram of a nanoweb manufacturing apparatus formed from coreshell nanofibers through electrospinning according to an embodiment of the present invention.
3 is an electron scanning microscope (SEM) photograph of the 10% gelatin nanofibers prepared in Comparative Example 1.
Figure 4 is a graph showing the particle size distribution of the 10% gelatin nanofibers prepared in Comparative Example 1.
5 is an electron scanning microscope (SEM) photograph of the 10% polycaprolactone nanofibers prepared in Comparative Example 2.
Figure 6 is a graph showing the particle size distribution of the 10% polycaprolactone nanofibers prepared in Comparative Example 2.
7 is an electron scanning microscope (SEM) photograph of gelatin-polycaprolactone coreshell nanofibers prepared using polycaprolactone solutions of various concentrations in Comparative Example 3. FIG. A core shell with a solution of 4% by weight polycaprolactone, B by weight 6% by weight polycaprolactone, C by weight 8% by weight polycaprolactone, D by weight 10% by weight polycaprolactone, E by weight 12% by weight polycaprolactone It is a nanofiber.
FIG. 8 is a graph showing particle size distribution of gelatin-polycaprolactone coreshell nanofibers prepared using polycaprolactone solutions of various concentrations in Comparative Example 3. A core shell with a solution of 4% by weight polycaprolactone, B by weight 6% by weight polycaprolactone, C by weight 8% by weight polycaprolactone, D by weight 10% by weight polycaprolactone, E by weight 12% by weight polycaprolactone It is a nanofiber.
FIG. 9 is a TEM photograph showing that coreshell nanofibers prepared by injecting 8 wt% polycaprolactone solution into an external nozzle among coreshell nanofibers of Comparative Example 3 formed a coreshell structure.
10 is an electron scanning microscope (SEM) photograph of the nanofibers and nanoweb of Comparative Example 3, Comparative Example 4 and Example.
11 is a graph showing the average size of the micropores of the nanoweb of Comparative Example 4 and Example.
12 is a graph showing the aspect ratio of the nanoweb of Comparative Example 4 and Example.

The method for producing a porous core shell nanoweb of the present invention is to use a method for producing a nanoshell of the core shell structure by electrospinning.

Electrospinning refers to a technique that uses fluid dynamics and interaction on a charged surface to produce nanosized fibers, referred to as electrospun fibers, from solution. In general, the formation of electrospun fibers involves providing a solution to a metal nozzle in the body that is in electrical communication with a voltage applying device, where the electrical force is applied to fine fibers that are attached on a groundable surface or at a low voltage other than the body. Helps to form. In electrospinning, the polymer solution or melt provided from the metal nozzle is charged at a higher voltage than the collecting electrode. The electric force overcomes surface tension and causes the fine jet of the polymer solution or melt to move towards the grounded or vice versa charged collection electrode. The spray can spread into a much finer fiber flow before reaching the target and is collected as an interconnected web of small fibers.

In the method for producing a porous core shell nanoweb of the present invention, a metal double nozzle is used to discharge a water-soluble polymer solution into an inner nozzle, and a hydrophobic polymer solution is discharged to an outer nozzle of a double nozzle to prepare core-shell nanofibers. The core shell nanofibers emitted from the inner nozzle and the outer nozzle are discharged to the collecting electrode immersed in water.

1 is a schematic diagram of a conventional core shell nanofiber or nanoweb manufacturing apparatus through electrospinning, Figure 2 is a schematic diagram of a coreshell nanofiber or nanoweb manufacturing apparatus through electrospinning according to an embodiment of the present invention.

In FIG. 1, the nanofibers discharged from the dual nozzle into the core shell structure are collected while being discharged from the air to the collecting electrode. However, in FIG. 2, the collecting electrode is positioned in the water, and the nanofibers discharged in the core shell structure are immersed in the water while being discharged to the collecting electrode. In water, the volatilization of the solvent of the hydrophobic polymer solution forming the shell is controlled as compared to the air, and through the control of the volatilization of the solvent, the surface of the nanofibers or the nanoweb may be formed with a uniform size of micropores.

In the present invention, the temperature of the water in which the collecting electrode through which the core shell nanofibers discharged from the inner nozzle and the outer nozzle are discharged is immersed is 2 to 20 ° C., preferably 4 to 12 ° C., in order to control the solvent volatilization of the hydrophobic polymer solution. When the upper limit is exceeded, volatilization of the solvent proceeds rapidly, and the size of the micropores may increase or the aspect ratio may exceed 1.2. If the lower limit is lower, the stability of the nanofibers decreases and the thickness of the nanofibers decreases, thereby increasing the nanofibers. The physical strength of the web can be reduced.

The water-soluble polymer constituting the core in the nanoweb formed from the nanoshell of the coreshell structure of the present invention is at least one biocompatible polymer selected from gelatin, collagen, chitosan, silk, bovine serum albumin (BSA), cellulose, alginic acid and hyaluronic acid. It is preferable.

As a solvent of the water-soluble polymer solution of the present invention, any solvent selected from acetic acid, a lower alcohol having 1 to 4 carbon atoms, water, or two or more mixed solvents is preferable, and more preferably acetic acid, ethanol, methanol which is advantageous in electrospinning properties. Or a mixed solvent of these and water, and in the case of a mixed solvent of acetic acid, ethanol or methanol and water, the mixing ratio of water is 0 to 30% by weight, preferably 1 to 20% by weight, more preferably 1 to 10% by weight.

The content of the water-soluble polymer in the water-soluble polymer solution of the present invention is 2 to 20% by weight, preferably 5 to 15% by weight, more preferably 8 to 12% by weight. If the upper limit is exceeded, electrospinning is difficult, and below the lower limit, it is difficult to control the size or shape of the micropores.

The hydrophobic polymer forming the shell in the nanoweb formed from the nanofibers of the core-shell structure of the present invention is polycaprolactone (PCL), polymethyl methacrylate (PMMA), polystyrene (PS), polyacrylonitrile (PAN), It is preferably at least one polymer selected from polyvinylidene fluoride (PVdF), polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA) and polyvinyl alcohol (PVA).

The solvent of the hydrophobic polymer solution of the present invention is preferably at least one volatile solvent selected from chloroform, dichloromethane, tetrahydrofuran, cyclohexane, acetonitrile and dimethylformamide, or at least two mixed solvents.

The hydrophobic polymer content in the hydrophobic polymer solution of the present invention is 2 to 15% by weight, preferably 5 to 12% by weight, most preferably 8 to 10% by weight. When the upper limit is exceeded, the thickness of the core-shell nanofibers or nanowebs is increased, so that the size and pore amount of the micropores is rather reduced, and the size and shape of the pores are less than the lower limit, and the electrospinning characteristics may be lowered.

The porous core shell nanoweb of the present invention prepared by the above method has an aspect ratio of micropores of 1 to 1.3, preferably 1 to 1.2, and an average micropore size of 0.5 to 20 μm, preferably Is 0.7 to 10 µm, more preferably 0.8 to 5 µm.

In addition, the porous core-shell nanoweb manufacturing apparatus of the present invention is a metal double nozzle; A water-soluble polymer solution injection pump connected to an internal nozzle of the metal double nozzle; A hydrophobic polymer solution injection pump connected to an outer nozzle of the metal double nozzle; A voltage application device connected to the tip of the metal double nozzle; And a collecting electrode spaced apart from the tip of the metal double nozzle and immersed in water.

It is preferable that the injection speed of the water-soluble polymer solution discharged from the inner nozzle is 0.1 to 1 ml / hour, and the injection speed of the hydrophobic polymer solution discharged from the outer nozzle is 0.5 to 2.0 ml / hour. The voltage applied for electrospinning may vary depending on the type and concentration of the polymer solution constituting the core and shell, but may be 5 to 25 kW, and is preferably 7 to 20 kW. Also, the distance between the tip of the nozzle and the collecting electrode can be up to 5-25 cm, preferably in the range of 10-15 cm.

Hereinafter, the present invention will be described more specifically with reference to the following examples. However, the following examples are provided only to aid understanding of the present invention, and the scope of the present invention is not limited to the following examples.

Comparative example  1: Preparation of 10% Gelatin Nanofibers

An electrospinning device consisting of a 30 GA stainless steel nozzle, an infusion pump, a voltage applicator, and a collecting electrode (stainless steel foil sheet) was used. The distance between the nozzle and the bottom stainless steel foil sheet was 12 cm and a potential difference of 14 kV occurred between the nozzle and the collecting electrode.

10 wt% gelatin and 90 wt% acetic acid were mixed and stirred at room temperature for 4 hours to prepare a gelatin solution. Then, 10 mL of the gelatin solution was fed to the nozzle by an injection pump at a flow rate of 0.4 mL / h, and then the collecting electrode. 10% gelatin nanofibers were prepared while being discharged.

An electron scanning microscope (SEM) photograph of the prepared 10% gelatin nanofibers is shown in FIG. 3, and a graph of particle size distribution of the prepared nanofibers is shown in FIG. 4.

Comparative example  2: 10% Polycaprolactone ( PCL Manufacture of nanofibers

10% by weight of polycaprolactone was mixed with 90% by weight of chloroform and stirred for 4 hours to prepare a 10% caprolactone solution, and the solution was prepared using the same electrospinach as in Comparative Example 1 to 10% polycaprolactone nano Fibers were prepared. However, the potential difference between the nozzle and the collecting electrode was 7 kV.

An electron scanning microscope (SEM) photograph of the prepared 10% polycaprolactone nanofibers is shown in FIG. 5, and a graph of particle size distribution of the prepared nanofibers is shown in FIG. 6.

Comparative example  3: gelatin Polycaprolactone Core shell  Preparation of Nanofibers

10 wt% gelatin was mixed with 90 wt% acetic acid and stirred for 4 hours to prepare a gelatin solution.

Polycaprolactone was mixed with acetic acid at concentrations of 4, 6, 8, 10 and 12% by weight, respectively, and stirred for 4 hours to prepare respective polycaprolactone solutions.

In order to manufacture a core-shell nanofibers, an electrospinning device having a double nozzle was used as shown in FIG. 1. The double nozzle consisted of the outer nozzle and the inner nozzle, the diameter of the outer nozzle was 0.70 mm, and the diameter of the inner nozzle was 0.40 mm. The potential difference between the collection electrode and the nozzle tip was 17, 16, 15, 13 and 12 kV voltages respectively in 4, 6, 8, 10 and 12 wt% polycaprolactone solutions. When manufacturing the nanofibers, the distance between the nozzle and the collecting electrode was maintained at a distance of 12 cm, and the flow rate was adjusted to 0.4 mL / h of core and 0.4 mL / h of shell (PCL).

A core shell nanofiber having a gelatin core and a polycaprolactone shell was prepared by preparing a core by injecting the gelatine solution into a 10 mL syringe and injecting it with an internal nozzle to inject a 10 mL polycaprolactone solution into an external nozzle.

Electron scanning microscope (SEM) photographs of coreshell nanofibers using various concentrations of polycaprolactone prepared are shown in FIG. 7, and a graph of particle size distribution of the prepared nanofibers is shown in FIG. 8.

The coreshell nanofibers prepared by injecting 8 wt% polycaprolactone solution into the outer nozzle of the coreshell nanofibers were confirmed by TEM photographs to form a coreshell structure (FIG. 9).

Example Gelatin Polycaprolactone Core shell  Porous Core Shell Nanoweb of  Produce

10 wt% gelatin was mixed with 90 wt% acetic acid and stirred for 4 hours to prepare a gelatin solution.

Polycaprolactone was mixed with chloroform at a concentration of 6% by weight, and stirred for 4 hours to prepare a polycaprolactone solution dissolved in a volatile solvent.

In order to manufacture a core-shell nanofibers, an electrospinning device having a double nozzle was used as shown in FIG. 2. The collecting electrode was immersed in water at 10 ° C. so that the discharged core-shell nanofibers could be directly immersed in water. The double nozzle consisted of the outer nozzle and the inner nozzle, the diameter of the outer nozzle was 0.70 mm, and the diameter of the inner nozzle was 0.40 mm. The potential difference between the collecting electrode and the nozzle tip used a 17 kV voltage, respectively. When manufacturing the nanofibers, the distance between the nozzle and the collecting electrode was maintained at a distance of 12 cm, and the flow rate was adjusted to 0.4 mL / h of core and 0.4 mL / h of shell (PCL).

A core core is formed from a core shell nanofiber having a gelatin core and a polycaprolactone shell by making a shell by injecting the gelatin solution into a 10 mL syringe and injecting it with an internal nozzle to inject a 10 mL polycaprolactone solution into an external nozzle. Nanowebs were prepared.

Comparative example  4: 6% Polycaprolactone ( PCL Manufacture of nanofibers

6% by weight of polycaprolactone was mixed with 94% by weight of chloroform and stirred for 4 hours to prepare a 6% caprolactone solution, using the same electrospinning value as that of Comparative Example 1, but the collection electrode was In the same manner as used for the system immersed in water. The potential difference between the nozzle and the collecting electrode was 10 kV.

Experimental Example  1: Morphological comparison

10% gelatin core of Comparative Example 3, coreshell nanofiber made of 4% polycaprolactone shell and not immersed in water, nanoweb made of 6% polycaprolactone of Comparative Example 4 and immersed in water, Example The shape of the nanoweb formed from coreshell nanofibers made of 10% gelatin core, 6% polycaprolactone shell and prepared by immersion in water is shown in FIG. 10 by electron scanning microscope.

Each sample was coated with platinum (5 wt% on activated carbon) with a turbo sputter coater. At this time, the SEM image required a high voltage of 20 KV. The core shell structure of the nanofibers was confirmed by a transmission electron microscope (JEM-2100F). At this time, a high voltage of 200KV, a dark current of 95, and a discharge current of 126 were used.

The core shell nanofibers composed of a gelatin core and a polycaprolactone cell prepared without immersion in water of Comparative Example 3 exhibited no micropores without forming a web, and made of 6% polycaprolactone of Comparative Example 4 The nanoweb immersed in water forms a web by combining nanofibers, but the micropores are not uniform and have a long elongated shape. The core is made of 10% gelatin core, 6% polycaprolactone shell, and is immersed in water. The nanoweb formed from the shell nanofibers was able to confirm that micropores of uniform size and shape were formed.

The average size of the micropores of the nanoweb of Comparative Example 4 and Example is shown in FIG. 11 and the aspect ratio in FIG. 12. Although the size of the micropores of the nanoweb of Comparative Example 4 and Example was not significantly different, the aspect ratio of the comparative example is 2.85, but the example was found to be close to the circle at 1.0.

Claims (12)

In preparing a core-shell nanofiber by discharging a water-soluble polymer solution to the inner nozzle of the metal double nozzle, and a hydrophobic polymer solution to the outer nozzle of the metal double nozzle, the core shell nanofiber spun from the inner nozzle and the outer nozzle Method for producing a porous core-shell nanoweb, characterized in that for discharging to a collecting electrode immersed in water.
The method of claim 1, wherein the temperature of the water in which the collecting electrode through which the core shell nanofibers emitted from the inner nozzle and the outer nozzle are discharged is immersed is 2 to 20 ° C.
The method of claim 2, wherein the temperature of the water in which the collecting electrode through which the core shell nanofibers radiated from the inner nozzle and the outer nozzle are discharged is immersed is 4 to 12 ° C.
The porous core shell of claim 1, wherein the water-soluble polymer of the water-soluble polymer solution is at least one biocompatible polymer selected from gelatin, collagen, chitosan, silk, bovine serum albumin (BSA), cellulose, alginic acid, and hyaluronic acid. Method for preparing nanoweb.
The method of claim 1, wherein the solvent of the water-soluble polymer solution is any one solvent selected from acetic acid, a lower alcohol having 1 to 4 carbon atoms, water, or two or more mixed solvents.
The method of claim 1, wherein the content of the water-soluble polymer in the water-soluble polymer solution is 2 to 20% by weight.
According to claim 1, wherein the hydrophobic polymer of the hydrophobic polymer solution is polycaprolactone (PCL), polymethyl methacrylate (PMMA), polystyrene (PS), polyacrylonitrile (PAN), polyvinylidene fluoride (PVdF ), Polyethylene oxide (PEO), polyvinylpyrrolidone (PVP), polyacrylic acid (PAA) and polyvinyl alcohol (PVA) is a method for producing a porous core shell nanoweb, characterized in that at least one polymer.
The method of claim 1, wherein the solvent of the hydrophobic polymer solution is at least one volatile solvent selected from chloroform, dichloromethane, tetrahydrofuran, cyclohexane, acetonitrile and dimethylformamide or two or more mixed solvents Method for producing a porous core shell nanoweb.
The method of claim 1, wherein the hydrophobic polymer content in the hydrophobic polymer solution is 2 to 15% by weight.
10. A porous core-shell nanoweb prepared by the method of any one of claims 1 to 9, characterized in that the aspect ratio of the micropores is 1 to 1.3.
The porous core shell nanoweb of claim 10, wherein the average size of the micropores is 0.5 to 20 µm.
Metal double nozzles; A water-soluble polymer solution injection pump connected to an internal nozzle of the metal double nozzle; A hydrophobic polymer solution injection pump connected to an outer nozzle of the metal double nozzle; A voltage application device connected to the tip of the metal double nozzle; And a collecting electrode spaced apart from the tip of the metal double nozzle and immersed in water.

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