Three Dimensionally and Randomly Oriented Fibrous Structures

Abstract

A randomly-oriented 3-D fibrous structure and a method for making the same. The method involves electrospinning a spinning dope with an electrospinning apparatus, wherein the spinning dope comprises: a solvent; a polymer dissolved in the solvent, wherein the dissolved polymer is in subunits having molecular weights that are about 5 to about 150 kDa; and a surfactant; to form one or more fibers that comprise a polymer-surfactant complex and that arrange randomly and evenly in three dimensions when contacting a collecting board of the electrospinning apparatus thereby forming the randomly-oriented 3-D fibrous structure.

What is claimed is: 
     
         1 . A method of making a randomly-oriented 3-D fibrous structure, the method comprising electrospinning a spinning dope with an electrospinning apparatus, wherein the spinning dope comprises:
 a solvent;   a polymer dissolved in the solvent, wherein the dissolved polymer is in subunits having molecular weights that are about 5 to about 150 kDa; and   a surfactant;   
       to form one or more fibers that comprise a polymer-surfactant complex and that arrange randomly and evenly in three dimensions when contacting a collecting board of the electrospinning apparatus thereby forming the randomly-oriented 3-D fibrous structure. 
     
     
         2 . The method of  claim 1 , wherein the polymer is selected from the group consisting of protein, synthetic polymer, and combinations thereof. 
     
     
         3 . The method of claim of  claim 2 , wherein the protein is selected from the group consisting of plant protein, animal protein, and combinations thereof. 
     
     
         4 . The method of  claim 1 , wherein the spinning dope has a concentration of the surfactant that is about 5 to about 300 percent by weight of the polymer. 
     
     
         5 . The method of  claim 1 , wherein the surfactant is selected from the group consisting of anionic surfactant, cationic surfactant, nonionic surfactant, zwitterionic surfactant, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the solvent is selected from the group consisting of water, phosphate buffered saline (PBS), carbonate buffer, tris-glycine buffer, borate buffer, acetate buffer, n-cyclohexyl-2-aminoethanesulfonic acid (CHES) buffer, citric buffer, ethanol, chloroform, 1,4-dioxane, methanol, ethylene glycol, acetone, ethyl acetate, methyl acetate, hexane, petrol ether, citrus terpenes, diethyl ether, dichloromethane, dimethylformamide (DMF), acetonitrile (MeCN), dimethyl sulfoxide (DMSO), formic acid, n-butanol, isopropanol (IPA), n-propanol, acetic acid, nitromethane, dichloromethane, and combinations thereof. 
     
     
         7 . The method of  claim 1 , wherein:
 the fibers have a fineness that is about 50 nm to about 100 μm;   the randomly-oriented 3-D fibrous structure further comprises interconnected pores having sizes that are about 10 to 2000 μm; and   the randomly-oriented 3-D fibrous structure has a porosity that is about 60 to about 99.9% by volume.   
     
     
         8 . The method of  claim 1 , wherein:
 the polymer consists of a primary polymer and one or more secondary polymers and the spinning dope further comprises a first cross-linker, a sacrificial component, or a combination thereof; or   the method further comprises contacting the fibers with a second solution that comprises a second cross-linker, a surface decorator, or a combination thereof; or   a combination thereof.   
     
     
         9 . The method of  claim 8 , wherein the first cross-linker is at a concentration of about 0.01 mol/L to about 10 mol/L of the spinning dope, and
 wherein the sacrificial component is at a concentration of about 0.5% to about 50% based on the weight of the polymer, and   wherein the second solution has a concentration of the second cross-linker that is about 0.01 mol/L to about 10 mol/L, and   wherein the surface decorator is at concentration of about 0.5% to about 10% based on the weight of the polymer.   
     
     
         10 . The method of  claim 9 , wherein the first and second cross-linkers are independently selected from the group consisting of polycarboxylic acid which contains at least three carboxylic acid groups, oxysucrose, genepin, glutaraldehyde, oxaldehyde, NHS esters, maleimides, carbodiimide, isocyanate, and combinations thereof, and
 wherein the sacrificial component is selected from the group consisting of PEG, egg white protein, zein, wheat gliadin, and combinations thereof, and   wherein the surface decorator is one or more peptides selected from the group consisting of Arg-Gly-Asp (RGD), Ile-Lys-Val-Ala-Val (IKVAV), and Asn-Ser-Gly-Ala-Ile-Thr-Ile-Gly (NSGAITIG).   
     
     
         11 . The method of  claim 1 , wherein the polymer is a protein and the method further comprises aging the dissolved protein at an aging temperature that is about 20 to about 90° C. for an aging duration that is about 0.5 to about 48 hours before conducting the electrospinning. 
     
     
         12 . The method of  claim 1 , further comprising contacting the fibers with a coagulation solution that comprises a coagulant to modify the water stability and mechanical properties of the fibers. 
     
     
         13 . The method of  claim 12 , wherein the coagulant is selected from the group consisting of methanol, ethanol, sodium sulfate and acetic acid, acetone, sulfuric acid, hydrochloric acid, and combinations thereof. 
     
     
         14 . A method of making a randomly-oriented 3-D fibrous structure, the method comprising electrospinning a spinning dope with an electrospinning apparatus, wherein the spinning dope comprises:
 a solvent;   a polymer dissolved in the solvent, wherein the dissolved polymer is in subunits having molecular weights that are about 10 to about 50 kDa, and wherein the polymer is selected from the group consisting of protein, synthetic polymer, and combinations thereof; and   an anionic surfactant at about 5 to about 300 percent by weight of the polymer;   
       to form one or more fibers of a fineness that is about 50 nm to about 100 μm and that comprise a polymer-surfactant complex and that arrange randomly and evenly in three dimensions when contacting a collecting board of the electrospinning apparatus thereby forming the randomly-oriented 3-D fibrous structure that further comprises interconnected pores having sizes that are about 10 to 2000 μm and that has a porosity that is about 60 to about 99.9% by volume. 
     
     
         15 . A randomly-oriented 3-D fibrous structure comprising:
 one or more fibers that comprise a polymer-surfactant complex, wherein the fiber(s) have lengths that are at least about 100 nm and finenesses that are about 50 nm to about 100 μm, and are arranged randomly and evenly in three dimensions throughout the randomly-oriented 3-D fibrous structure; and   interconnected pores having sizes that are about 10 to 2,000 μm, wherein the pores comprise about 60 to about 99.9% by volume of the randomly-oriented 3-D fibrous structure.   
     
     
         16 . The randomly-oriented 3-D fibrous structure of  claim 15 , wherein:
 the fineness of the one or more fibers is about 50 nm to about 20 μm; and   the interconnected pores have sizes that are about 100 to 1,000 μm, wherein the pores comprise about 90 to about 99.9% by volume of the randomly-oriented 3-D fibrous structure.   
     
     
         17 . The randomly-oriented 3-D fibrous structure of  claim 15 , wherein the polymer-surfactant complex is formed via electrospinning of a spinning dope that comprises a solvent; a polymer dissolved in the solvent, wherein the dissolved polymer is in subunits having molecular weights that are about 5 to about 150 kDa; and a surfactant. 
     
     
         18 . The randomly-oriented 3-D fibrous structure of  claim 17 , wherein the surfactant is selected from the group consisting of anionic surfactant, cationic surfactant, nonionic surfactant, zwitterionic surfactant, and combinations thereof; and wherein the polymer is selected from the group consisting of protein, synthetic polymer, and combinations thereof. 
     
     
         19 . The randomly-oriented 3-D fibrous structure of  claim 18 , wherein the protein is selected from the group consisting of plant protein, animal protein, and combinations thereof. 
     
     
         20 . The randomly-oriented 3-D fibrous structure of  claim 19 , wherein:
 the plant protein is selected from the group consisting of wheat gluten, wheat gliadin, wheat glutenin, soy protein, camelina protein, peanut protein, canola protein, sorghum protein, rice protein, millet protein, sunflower seed protein, pumpkin seed protein, mung bean protein, red bean protein, chickpea protein, green pea protein, and combinations thereof;   the animal protein is selected from chicken feather, egg white, wool keratin, casein, silk, fibrin, collagen, gelatin, hair keratin, horn keratin, nail keratin, whey protein, and combinations thereof; and   the synthetic polymer is selected from the group consisting of polyethylene glycol (PEG), poly lactic acid (PLA), poly glycolic acid (PGA), polyhydroxyalkanoates (PHAs), poly(lactic-co-glycolic acid) (PLGA), poly-3-hydroxybutyrate (PHB), polyhydroxyvalerate (PHV), polyhydroxyhexanoate (PHH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and combinations thereof.