Yarn Reinforced Bacterial Cellulose Hybrid Materials

Abstract

A yarn reinforced bacterial cellulose hybrid composition includes a two-dimensional yarn mesh stretched and embedded within a BC sheet. Such materials are fabricated by providing a bacterial cellulose-producing bacterium; providing a suitable bacteria nutritional medium; culturing the bacterium in the nutritional medium under conditions to produce bacterial cellulose; and providing a two-dimensional yarn mesh having a defined pattern such that the yarn mesh is embedded within the bacterial cellulose.

Claims

1-64. (canceled)

65. A composition comprising: a sheet of bacterial cellulose (BC); and a two-dimensional yarn mesh formed of yarn, wherein the yarn mesh is stretched and embedded within the BC sheet in a single plane parallel to the surfaces of the BC sheet.

66. The composition of claim 65, wherein the yarn comprises one or more filament yarns.

67. The composition of claim 65, wherein the yarn comprises one or more spun or twisted yarns.

68. The composition of claim 65, wherein the yarn is a natural yarn selected from a group consisting of: silk; cotton; flax; and wool.

69. The composition of claim 65, wherein the yarn is woven into the yarn mesh.

70. The composition of claim 65, wherein the yarn is knitted into the yarn mesh.

71. The composition of claim 65, wherein the BC sheet includes only a single yarn mesh embedded therein.

72. The composition of claim 65, further comprising a two-dimensional fiber mesh, wherein the fiber mesh is embedded and stretched within the BC in a plane parallel to the yarn mesh.

73. The composition of claim 65, wherein the composition further comprises a resin.

74. The composition of claim 73, wherein the resin is selected from a group consisting of: a biodegradable resin; a water-soluble resin; and a natural resin,

75. The composition of claim 73, wherein the resin is selected from a group consisting of: polyethylene oxide (PEO); polyvinyl alcohol (PVA); and polyhydroxy alkanoate (PHA).

76. A process for preparing a yarn reinforced bacterial cellulose composite material, the process comprising the steps of: (i) attaching a two-dimensional yarn mesh to a solid support structure located in a liquid tight container such that the yarn mesh is held under tension in a single plane; (ii) contacting the yarn mesh with a cellulose producing bacterial culture in the liquid tight container such that the yarn mesh is parallel to a surface of the cellulose producing bacterial culture; (iii) producing a yarn reinforced bacterial cellulose composite material by maintaining culture conditions that enable production of cellulose by the cellulose producing bacterial culture, wherein the yarn mesh is embedded within the bacterial cellulose composite material.

77. The process of claim 76, wherein the yarn is woven into the yarn mesh.

78. The process of claim 76, wherein the yarn is knitted into the yarn mesh.

79. The process of claim 76, wherein the yarn reinforced bacterial cellulose composite material includes only a single yarn mesh embedded therein.

80. The process of claim 76, further comprising (iv) attaching a two-dimensional fiber mesh to the solid support structure such that the fiber mesh is held under tension in a single plane parallel to the yarn mesh, wherein the producing includes maintaining the culture conditions until both the yarn mesh and the fiber mesh are embedded within the bacterial cellulose composite material.

81. The process of claim 76, further comprising (iv) sterilizing the liquid tight container and the yarn mesh prior to the contacting.

82. A device for preparing a yarn reinforced bacterial cellulose (BC) hybrid material in a static culture, the device comprising: (i) a liquid tight container of between 1 liter and 100 liters with a depth of between 10 mm and 200 mm; (ii) a solid support structure comprising an arrangement of vertically oriented pegs fixed to a lower surface of the container, wherein each vertically oriented peg includes a feature for holding a fiber at a predetermined height above the lower surface of the container; (iii) a yarn arranged in a mesh, held under tension by the solid support structure at the predetermined height.

83. The device of claim 82, wherein the predetermined height is between 5 mm and 50 mm from the lower surface of the container.

84. The device of claim 82, wherein the liquid tight container has an irregular shape.

Description

FIGURES

[0054] The invention is described herein with reference to the accompanying drawings. It is to be understood that in some instances, various aspects of the invention may be shown exaggerated or enlarged to facilitate an understanding of the invention.

[0055] FIG. 1 depicts two examples of warping frame support pegs.

[0056] FIG. 2 depicts an example of spun yarns held in place on a warping frame support peg at a notch.

[0057] FIG. 3 depicts an angled view of one embodiment of an assembled warping frame with multiple support pegs and an example of applied single yarn scaffold.

[0058] FIG. 4 depicts an example of a warping frame with an irregular shape and rectangular pegs.

[0059] FIG. 5 depicts an example of a warping frame with a square shape and rectangular pegs.

[0060] FIG. 6 depicts an example of a warping frame with a circle shape, and round pegs.

[0061] FIG. 7 depicts an example of an embodiment where a single yarn is arranged directly on the warping frame.

[0062] FIG. 8 depicts an example of an embodiment where a multiple different yarns are arranged directly on the warping frame.

[0063] FIG. 9 is a perspective view of one embodiment of a fermentation container.

[0064] FIG. 10 is the top view of one embodiment of a fermentation container.

[0065] FIG. 11 is the side view of one embodiment of a fermentation container.

[0066] FIG. 12 shows perspective view of positioning of warping frame placement in fermentation container.

[0067] FIG. 13 shows top view of positioning of warping frame placement in fermentation container.

[0068] FIG. 14 is a side view of the of fermentation container with inoculated media and warping frame in starting setup.

[0069] FIG. 15 is a side view of the of fermentation container and pellicle growth after 2-4 days.

[0070] FIG. 16 is a side view of the of fermentation container and pellicle growth after 4-8 days.

[0071] FIG. 17 is a side view of the fermentation container and pellicle growth after 7-15 days, or when material is fully-grown.

[0072] FIG. 18 shows the top view of one embodiment of a scaffold fixed to a warping frame before being added to growth/fermentation container for BC production.

[0073] FIG. 19 shows the top view of fully grown BC-textile hybrid pellicle removed from growth/fermentation container.

[0074] FIG. 20 shows a cross section of one embodiment of the BC-textile hybrid material (wet) where yarns are concentrated at the midpoint of the pellicle.

[0075] FIG. 21 shows a cross section of one embodiment of the BC-textile hybrid material (wet) where yarns are concentrated at bottom of the pellicle.

[0076] FIG. 22 shows a cross section of one embodiment of the BC-textile hybrid material (wet) where yarns are spread throughout thickness of the pellicle.

[0077] FIG. 23 shows a cross section of one embodiment of the BC-textile hybrid material (wet) where yarns are spread throughout thickness of the pellicle, and parts of the yarn extend outside of the pellicle.

DETAILED DESCRIPTION

[0078] For clarity of disclosure, and not by way of limitation, the detailed description of the invention and process for producing it are divided into the subsections set forth below.

[0079] Pattern, in reference to the pattern of fibers is a non-random and intentional arrangement of fibers in one, multiple or a combination of directions. In an embodiment, a pattern of fibers comprises a mesh of fibers, such as a mesh of yarn, which can be woven, knitted, or the like.

1. Warping Frame and Scaffold Preparation

[0080] The purpose of the warping frame is to provide support to the scaffold or matrix of yarns during scaffold assembly as well as during fermentation stage and hybrid material production. The warping frame is composed of a base with fixed or adjustable pegs and/or raised supports.

[0081] FIG. 1 shows examples of two embodiments of pegs 1, 2. Peg 1 depicts a round peg that is fixed to the base 4 with nut and bolt. Peg 2 depicts a laser cut peg with a rectangular cross section, which is fixed with glue to the base 4. The cross section and height of the pegs/supports 1, 2 can be adjusted according to desired design/placement of scaffold within BC matrix. What is important is that a yarn or multiple yarns can be easily fixed in one or more places 3 on the support 1, 2. FIG. 2 depicts one embodiment of a spun yarn 10, or yarn composed of twisted fibers, fixed to a preferred peg embodiment 2 where a notch 3 holds the yarn 10 in place.

[0082] FIG. 3 shows one embodiment of an assembled warping frame 12 with multiple support pegs 2 with yarn 10 fixed at the notch 3 in each peg. The yarn 10 is stretched between the notches 3 of pegs 2 to be under tension so that the yarn 10 does not hang down between pegs 2. As a result, the yarn 10 forms a two-dimensional mesh located in a single plane at an elevation above the base 4 corresponding to the elevation of the notches 3.

[0083] FIG. 4 depicts an example of a warping frame 12 with an irregular shape and rectangular pegs 2. FIG. 5 depicts an example of a warping frame 12 with a square shape and rectangular pegs 2. FIG. 6 depicts an example of a warping frame 12 with a circle shape, and round pegs 1. There is no limit in shape, size or positioning of base plate and pegs for warping frame embodiments.

[0084] The material composition of one warping frame 12 embodiment is acrylic.

[0085] In another embodiment, stainless steel is used.

[0086] The only limiting factor of the material composition of the warping frame 12 is it should be as inert as possible as to not corrode, rust or react with the liquid chemical composition of the media or material processing solutions such as but not limited to NaOH solution, bleach, or solvents. The material should also not be harmful to living organisms such as bacteria or fungi. Also for many sterilization and finishing treatments it may need to withstand high heats.

[0087] Yarn 10 is applied to the warping frame 12 by hand in one embodiment but in other embodiments by machine, robotic arm or automated thread placement mechanism.

[0088] In another embodiment, the fibers comprising the yarn are transparent.

[0089] In another embodiment, the yarn is conductive.

[0090] In another embodiment, the fibers comprise a natural cellulose-based or protein-based material.

[0091] In another embodiment, the natural cellulose-based material is selected from the group consisting of cotton, linen, flax, sisal, ramie, hemp, kenaf, jute, bamboo, banana, pineapple, kapok, and combinations thereof. Any other natural cellulose fibers known in the art can also be used.

[0092] In another embodiment, the natural protein-based material is selected from the group consisting of wool, silk, angora, cashmere, mohair, alpaca, milk protein, spider silk, and soy protein and combinations thereof.

[0093] In another embodiment, the fibers comprise a polymeric material. In another embodiment, the polymeric material is cellulose acetate, nylon, rayon, modacrylic, olefin, acrylic, polyester, polylactic acid, polylactic-co-glycolic acid (PLGA), polyurethane, aramid (e.g. KEVLAR), or ultrahigh molecular weight polyethylene, (e.g. SPECTRA or DYNEEMA). In another embodiment, the fibers comprise carbon (e.g., carbon fiber) or glass (e.g., fiberglass).

[0094] The scaffold could be comprised of a single yarn and fiber type or could contain multiple different yarns in a single hybrid material. The arrangement of the yarns could be prefabricated through other textile production methods such as weaving or knitting and fixed to warping frame or can be arranged directly onto warping frame in single or multiple axes weave pattern. FIG. 7 depicts an example of an embodiment where a single yarn 10 is arranged directly on the warping frame 12. FIG. 8 depicts an example of an embodiment where a multiple different yarns 10A, 10B, 10C are arranged directly on the warping frame 12.

[0095] As yarns often contain contaminants and/or other microbes or can easily become contaminated during handling. For this reason, it is important to sterilize the frame and yarn after yarn is applied to the frame, and/or prevent pre-sterilized elements from being contaminated during assembly. Sterilization method depends on the composition of the warping frame as well as the yarn used. Sterilization methods include but are not limited to soaking in ethanol or bleach solution, dry heat, autoclave, exposure to UV light, or other chemical sterilization methods.

2. Bacteria and Culture Media for BC Production

[0096] Methods are provided herein for producing bacterial cellulose (BC). In one embodiment, the method comprises providing a bacterium wherein the bacterium is a bacterial cellulose-producing bacterium; providing a bacteria nutritional medium; culturing the bacterium in the bacteria nutritional medium under conditions to produce BC.

[0097] Many strains of bacteria that synthesize cellulose can be used to synthesize BC including but not limited to Komagataeibacter rhaeticus, Acetobacter xylinum, or genetically modified versions of BC secreting genus. In a preferred embodiment, Komagataeibacter rhaeticus is used.

[0098] In one embodiment, Acetobacter xylinum, ATCC 23769, can be used (American Type Culture Collection (ATCC), Manassas, Va.).

[0099] In other embodiments, the following can be used.

[0100] Gluconacetobacter hansenii ATCC 53582

[0101] Gluconacetobacter xylinus ATCC 23767

[0102] Acetobacter pasteurianus ATCC 10245

[0103] Acetobacter liquefaciens ATCC 14835

[0104] Any culture medium known in the art to support the selected bacteria can be used. For example, culture media that can be used can consist of 5-50 g/l, of one or more carbon sources (e.g., stachyose, raffinose, glucose, sucrose, fructose, mannitol, galactose, maltose), 5 g/L yeast extract and 5 g/L tryptone. In one embodiment, 25 g/L is used. Any small sugar known in the art can also be used. For example, HS-glucose media for culturing Komagataeibacter rhaeticus as described in Florea et al., Engineering control of bacterial cellulose production using a genetic toolkit and a new cellulose-producing strain. PNAS 113 (24), May 2016. In a preferred embodiment, media is prepared using a solution of pure coconut water with 1% volume of Aspall's organic Cyder Vinegar. The coconut water media is sterilized in microwave as it cannot be autoclaved.

[0105] In one embodiment a liquid medium is used, in another embodiment the growth medium may be a gel.

3. Growth/Fermentation Container Design and Preparation

[0106] Details are provided here for building a device for preparing a bacterial cellulose (BC) hybrid material, the device comprising of: a container suitable for culturing bacterium capable of producing cellulose in a suitable medium under conditions to produce BC; and a structure for containing and/or fixing a fiber or multiple fibers in a pattern such that the fiber is interwoven with the BC.

[0107] The fermentation container should be made out of an inert and easily sterilized material. In a preferred embodiment, the container is clear glass to allow for better monitoring of fermentation/growth but in other embodiments is opaque. FIGS. 9-11 show top (FIG. 10), side (FIG. 11) and perspective (FIG. 9) views of one embodiment of a fermentation container 20. Import features include two separate sections, a material production compartment 21 and a media addition compartment 22. These are separated by a divider 23 that prevents liquid from flowing easily between the areas except for through a narrow opening 24 at the bottom of the divider. The shape of the container and subsequent compartments can be changed to suit desired size and shape of hybrid pellicle. The pellicle will take on the shape of the material production compartment 21. Container 20 has a lid 25 to protect from contamination by other organisms during fermentation but that allows or promotes oxygen flow to the culture.

[0108] In one embodiment, a paper towel is used as a lid.

[0109] In another embodiment, a sterile cloth is used as a lid.

[0110] In another embodiment, lid is sealed onto container with tube inserted to control gas flow in and out of the container.

[0111] In another embodiment, container is to be sterilized prior to growth. Sterilization methods include but are not limited to soaking in ethanol or bleach solution, dry heat, autoclave, exposure to UV light, or other chemical sterilization methods. Most effective sterilization method should be determined based on material composition of the container.

4. Hybrid Textile-BC Pellicle Production

[0112] FIGS. 12 and 13 show top (FIG. 13) and perspective (FIG. 12) views of how the assembled scaffold/warping frame 12 is placed within fermentation container 20. FIG. 14 shows the side view of set up fermentation container 20 where number 10 indicates the yarn scaffold and number 26 indicates the media. Once warping frame 12 is in place in the material production compartment 21, prepared media and starter bacteria culture 26 are added slowly into media addition compartment 22. As indicated by arrow 28, the media and bacteria 26 travel through the gap 24 at the bottom of the barrier 23 until liquid media equalizes and reaches the predetermined fill line 27 in all compartments. It is important that the container 20 remains level throughout full fermentation stage.

[0113] FIG. 15 shows BC pellicle growth after 2-4 days, number 30 indicates visible layer of BC. Arrow 28 indicates how media 26 in all compartments remains at equilibrium during fermentation.

[0114] FIG. 16 shows BC pellicle 30 after 4-8 days when surface of the pellicle reaches the scaffold and starts to incorporate the yarns 10 into its structure.

[0115] Media 26 is continually added in small amounts to media addition compartment 22 throughout fermentation so that media 26 remains at fill line 27 in equilibrium throughout entire fermentation. This provides conditions for the pellicle 30 in the material production area 21 to grow evenly with minimal imperfections.

[0116] A pellicle also forms in the media addition compartment 22 but usually will grow unevenly or in layers as the addition of media disturbs its growth.

[0117] In another embodiment, media 26 is applied in the form of a fine mist to the top (or oxygen exposed side) of the growing pellicle 30 to help stimulate growth.

[0118] FIG. 17 shows final BC-textile hybrid pellicle 30 after yarns 10 are fully incorporated, usually within 7 to 15 days depending on growth conditions. Hybrid pellicle 30 is still fixed in place on warping frame 12 at the end of this phase. In one embodiment the hybrid pellicle 30 is removed gently from the warping frame before post processing. In another embodiment it remains on the frame for post processing.

[0119] When removed from the frame 12, both BC fibers and fibers characterizing the yarns might shift slightly but yarns 10 should still remain completely or partly fixed within the BC matrix. FIG. 18 shows the top view of one embodiment of a scaffold comprised of a yarn 10 fixed to a warping frame 12 before being added to growth/fermentation container for BC production. FIG. 19 shows the top view of the fully grown BC-textile hybrid pellicle 30 removed from growth/fermentation container and warping frame, number 10 indicates area where yarn fibers are concentrated and 32 denotes BC growth between the yarns and fibers of the yarns and where growth was not inhibited by shape of the container other means.

[0120] FIG. 20 shows a cross section of one embodiment of the BC-textile hybrid material 40 (wet) where yarns 10 are concentrated at the midpoint of the BC pellicle 30.

[0121] FIG. 21 shows a cross section of one embodiment of the BC-textile hybrid material 40 (wet) where yarns 10 are concentrated at bottom of the pellicle 30.

[0122] FIG. 22 shows a cross section of one embodiment of the BC-textile hybrid material 40 (wet) where yarns 10 are spread throughout thickness of the pellicle 30. In an embodiment, the yarns 10 are multiple different yarns as shown in FIG. 8.

[0123] FIG. 23 shows a cross section of one embodiment of the BC-textile hybrid material 40 (wet) where yarns 10 are spread throughout thickness of the pellicle, and parts of the yarn extend outside of the pellicle 30.

[0124] Wash BC crude pellicle successively with water and 1% (w/v), aqueous NaOH, and then remove all microbial product contaminants by deionized water (BC wet pellicle).

[0125] The hybrid material could be bleached or dyed, dried pure, plasticized using any commercially available plasticizers such as glycerol or impregnated with resin to form a composite.

[0126] Remove water from the BC either by pressing, air dry, oven dry or freeze dry (for BC film), or combination there of.

[0127] In one embodiment the material is impregnated with resin.

[0128] In another embodiment, the resin is transparent.

[0129] In another embodiment, the resin is selected from the group consisting of natural resin, plant-based resin and non-toxic resin.

[0130] In another embodiment, the resin is biodegradable.

[0131] In another embodiment, the resin is water-soluble.

[0132] In another embodiment, the natural or plant-based resin is a soy-based resin.

[0133] In another embodiment, the resin is a petroleum-based resin.

[0134] In another embodiment, the petroleum-based resin is an epoxy, vinyl, or unsaturated polyester-based resin.

[0135] In another embodiment, the resin is polyethylene oxide (PEO).

[0136] In another embodiment, the resin is polyvinyl alcohol (PVA).

[0137] In another embodiment, the resin is polyhydroxy alkanoate (PHA).

Example Protocol

[0138] Listed below is an example protocol for the production of one embodiment of the invention.

[0139] Media solution is prepared using pure coconut water with 1% volume of Aspall's organic Cyder Vinegar. Media is sterilized by microwaving in a covered glass container (but not sealed). For 500 ml of solution it is heated in the microwave for 6 minutes then allowed to cool (still covered) naturally to room temperature (22-25 degrees Celsius).

[0140] Bacteria Used is Komagataeibacter rhaeticus.

[0141] Starter culture is prepared in small sterilized glass jar (5 cm diameter) by adding bacteria to about 3 cm depth of sterilized media solution. It is covered with a paper towel and culture is left static at 22 degrees C. for about 7 days or at least until a pellicle of about 6 mm is formed at the surface.

[0142] Construct warping frame using laser cut acrylic base and support pegs. See FIG. 2 for shape of example peg. In this example, 3 mm thick sheet of clear acrylic is used for the pegs and 5 mm clear acrylic for the base. Each peg is identical with a height of 40 mm and notch at height of 25 mm. Base is 150 mm150 mm square with 40, 3 mm by 4 mm, rectangular holes, 10 on each side of the square at a distance of 9 mm apart. 40 pegs are secured to the based by insertion into the holes and fixed perpendicular to the base using dichloromethane. See FIG. 18 for reference of peg spacing.

[0143] Apply 16/2 organic cotton yarn directly to the warping frame by fixing yarn to each peg at its notch. The thread is tied off at first and last peg to avoid unraveling. See FIG. 18 for reference of yarn arrangement in this example.

[0144] See FIGS. 9-11 as reference for growth/fermentation container design. Whereas the outside of the container is made of clear vacuum formed plastic and the divider laser cut acrylic.

[0145] The assembled frame and container are both sterilized by short soak in ethanol and air dried (covered) until ethanol fully evaporates.

[0146] See FIGS. 12-13 as reference for how the frame is placed into the growth container.

[0147] The entire contents of starter culture jar are carefully (to avoid contamination) added to the media addition compartment of the container and sterilized media is added to the same side slowly until equilibrium at fill line is met (see FIG. 14). In this example the fill line is set at a height of 23 mm or 2 mm below yarn scaffold.

[0148] Container is covered with a paper towel and left static on a level surface. Incubate at 22-25 degrees Celsius. Throughout fermentation process the media level will drop and it is imperative it is monitored and media be added (to media addition compartment only) throughout growth so media level stays at equilibrium at fill line (number 27 in FIGS. 14-17).

[0149] Allow fermentation to occur for 10-15 days or until yarn is fully incorporated into (e.g., embedded within) the BC and hybrid pellicle is about 6 mm thick.

[0150] Remove frame from container but leave pellicle on warping frame.

[0151] Wash BC crude pellicle successively with water and 1% (w/v), aqueous NaOH at room temperature C. for 15 min, and then remove all microbial product contaminants by deionized water (BC wet pellicle).

[0152] Then soak pellicle in water and 5% (w/v), aqueous glycerol solution for 8 hours.

[0153] Remove pellicle carefully from frame and press out excess water by placing it between 2 sheets of fine metal mesh and wooden boards to which even pressure is applied. Let further air dry until about 2 mm thick. Place between two sheets of wax paper, surround with paper towel and place between 20 mm plywood boards. Apply even pressure using nuts and bolts to clamp boards together and leave until hybrid material is fully dried.