PROTEIN-TEXTILE/PAPER-COMPOSITES AND ARTICLES CONTAINING THE SAME

Abstract

Disclosed herein is a multilayered biopolymeric composite comprising a first crosslinked proteinaceous biopolymer layer disposed on a substrate; where the substrate comprises a fabric, paper, or a combination thereof; and wherein the first crosslinked proteinaceous biopolymer layer and/or the substrate comprises at least one of a nanoclay, a dye, a colorant, a radio-opaque additive, an electrically conductive filler, or a combination thereof.

Claims

1. A multilayered biopolymeric composite comprising: a first crosslinked proteinaceous biopolymer layer disposed on a substrate; where the substrate comprises a fabric, paper, or a combination thereof; and wherein the first crosslinked proteinaceous biopolymer layer and/or the substrate comprises at least one of a nanoclay, a dye, a colorant, a radio-opaque additive, an electrically conductive filler, or a combination thereof.

2. The multilayered biopolymeric composite of claim 1, where the dye is a fluorescent dye that is selected from the group consisting of fluorescein, rhodamine B, rhodamine 6G, sulforhodamine 101, cyanine dyes, BODIPY dyes, Texas Red, Nile Red, coumarin derivatives, eosin Y, erythrosin B, pyrene derivatives, lanthanide-based complexes such as europium and terbium chelates, or a combination thereof.

3. The multilayered biopolymeric composite of claim 1, where the dye is a polyazaindacene, a coumarin, a lanthanide complex, a hydrocarbon and substituted hydrocarbon dye, a polycyclic aromatic hydrocarbon, a scintillation dye, an aryl- and heteroaryl-substituted polyolefin, a carbocyanine dye, a phthalocyanine dye, an oxazine dye, a carbostyryl dye, a porphyrin dye, an acridine dye, an anthraquinone dye, an anthrapyridone dye, a naphtalimide dye, a benzimidazole derivative, an arylmethane dye, an azo dye, a diazonium dye, a nitro dye, a quinone imine dye, a tetrazolium dye, a thiazole dye, a perylene dye, a perinone dye, a bis-benzoxazolylthiophene, a xanthene dye, an indigoid dye, a chromone dyes, a flavones dye, or a combination thereof.

4. The multilayered biopolymeric composite of claim 1, where the dye is a quantum dot; where the quantum dot is a cadmium selenide (CdSe), a cadmium telluride (CdTe), a cadmium sulfide (CdS), a zinc sulfide (ZnS), an indium phosphide (InP), a lead sulfide (PbS) nanocrystal.

5. The multilayered biopolymeric composite of claim 1, where the quantum dot comprises a core-shell structure, and where the core-shell comprises a CdSe core in contact with a ZnS shell or an InP core in contact with a ZnS shell.

6. The multilayered biopolymeric composite of claim 1, wherein the dye and/or the colorant is a fluorescing dye or a fluorescing colorant that fluoresces between 350 to 900 nanometers.

7. The multilayered biopolymeric composite of claim 1, wherein the crosslinked proteinaceous biopolymer layer is electrically conducting with an electrical resistivity less than about 110.sup.11 ohm-cm, an IZOD notched impact strength greater than about 200 Joules per meter (J/m) when measured as per ASTM D 256, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers.

8. The multilayered biopolymeric composite of claim 1, wherein the crosslinked proteinaceous biopolymer layer is radio-opaque to xrays, has an IZOD notched impact strength greater than about 200 Joules per meter (J/m) when measured as per ASTM D 256, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers.

9. The multilayered biopolymeric composite of claim 1, wherein the multilayered biopolymeric composite has a mass attenuation coefficient of 1.9 to 2.2 cm.sup.2/g at 70 keV, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers.

10. The multilayered biopolymeric composite of claim 1, wherein the first crosslinked proteinaceous biopolymer layer comprises at least one of a nanoclay, a dye, a colorant, a radio-opaque additive, an electrically conductive filler, fire retardant or a combination thereof.

11. The multilayered biopolymeric composite of claim 1, wherein the nanoclay is a smectite-type clay or layered phosphate or MXenes.

12. The multilayered biopolymeric composite of claim 1, wherein the nanoclay is intercalated with a proteinaceous biopolymer used in the first crosslinked proteinaceous biopolymer layer.

13. The multilayered biopolymeric composite of claim 1, wherein the first crosslinked proteinaceous biopolymer layer comprises albumin.

14. The multilayered biopolymeric composite of claim 1, wherein the crosslinked proteinaceous biopolymer is crosslinked via an unsaturated carboxylic acid, an amine, a carboxylic acid functionalized with an amine, or a combination thereof.

15. The multilayered biopolymeric composite of claim 6, wherein the amine is a naturally occurring amine or a synthetic amine.

16. The multilayered biopolymeric composite of claim 1, wherein the electrically conducting filler forms a percolating network in at least the first crosslinked proteinaceous biopolymer layer.

17. The multilayered biopolymeric composite of claim 1, wherein the radio-opaque additive is barium sulfate, bismuth sub-carbonate, bismuth oxychloride, bismuth trioxide, tungsten powder, tantalum powder, zirconium oxide, iodine-containing organic compounds, strontium sulfate, strontium carbonate, or a combination thereof.

18. The multilayered biopolymeric composite of claim 13, further comprising a plurality of crosslinked proteinaceous biopolymer layers and a plurality of substrates, where each substrate of the plurality of substrates has a crosslinked proteinaceous biopolymer layer on opposing surfaces.

19. The multilayered biopolymeric composite of claim 1, further comprising a second crosslinked proteinaceous biopolymer layer that is disposed on a surface of the substrate that is opposite of the surface that contacts the first crosslinked proteinaceous biopolymer layer.

20. An article comprising the multilayered biopolymeric composite of claim 1, wherein the article is a space suit, radiation protection clothing, a radiation protection shelter, a bullet proof vest or flame retardant clothing.

21. A method of manufacturing the multilayered biopolymeric composite of claim 1, the method comprising: mixing an uncrosslinked proteinaceous biopolymer and a crosslinking agent to form a solution; disposing the solution on at least one surface of the substrate; and crosslinking the uncrosslinked proteinaceous biopolymer to form the first crosslinked proteinaceous biopolymer layer on the substrate with the chemical crosslinking agent or physical crosslinking by heating the article to 60 to 80 C. for 5 to 20 minutes.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0010] FIG. 1 is a depiction of the reaction between bovine serum albumin and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to produce the crosslinked proteinaceous biopolymer;

[0011] FIG. 2 is a graph that depicts thermal degradation of uncoated fabric compared with fabric that is coated with crosslinked albumin;

[0012] FIG. 3A depicts the method of manufacturing the crosslinked biopolymer bovine serum albumin (BSA) with the Rhodamine B fluorescent agent;

[0013] FIG. 3B depicts a graph of intensity versus wavelength for BSA containing Rhodamine B;

[0014] FIG. 3C depicts a table that shows the excitation wavelength, the emission wavelength and the quantum yield;

[0015] FIG. 4A depicts the manufacturing of the multilayered biopolymer composite; and

[0016] FIG. 4B depicts a table where the conductivity of each fabric was determined.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Disclosed herein too are methods and apparatus for providing new and useful forms of biopolymeric composites. The biopolymeric composites include a proteinaceous biopolymer that is disposed on flexible substrate. Examples of flexible substrates include fabrics (also referred to herein as textiles), paper, or a combination thereof. Generally, the biopolymeric composite may be particularly useful in applications that call for fluorescence, hydrophobic properties, fire resistant properties, radiation shielding, catalytic properties, radiative cooling, and impact resistance (such as bulletproof materials).

[0018] In an embodiment, the proteinaceous biopolymer serves as a shell for a substrate that comprises woven and non-woven fabrics (hereinafter fabrics) that include synthetic polymers. The substrate may also comprise paper. In other words, the proteinaceous biopolymer encapsulates the substrate (the fabric and/or the paper) and imparts fluorescence, hydrophobic properties, fire resistant properties, radiation shielding, catalytic properties, radiative cooling, and impact resistance (such as bulletproof materials) to the biopolymeric composite. Some of these properties such as fluorescence, radiation shielding, electrical conduction, flame retardancy and the like may be imparted to the substrate or to the shell via additives, while other properties such as impact resistance may be obtained by the appropriate combination of the proteinaceous biopolymer shell with one or more layers of the substrate (i.e., with or without the addition of additives)

[0019] The proteinaceous biopolymer comprises a synthetically created or naturally occurring biomolecule or macromolecule that comprises one or more long chains of amino acid residues. Proteins differ from one another primarily in their sequence of amino acids, which are dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its biological activity as well as its chemical nature. The proteinaceous biopolymer is biodegradable and can be completely recycled during its lifetime.

[0020] The proteinaceous biopolymer is preferably soluble in water or an alcohol. The proteinaceous biopolymer is one that can interact with the substrate via van der Waals forces, or can form hydrogen bonds with the substrate. There may be mechanical interlocking (i.e., friction) that holds the shell (the proteinaceous biopolymer) in place with respect to the substrate. There is no covalent bonding between the substrate and the proteinaceous biopolymer but can be induced if desired.

[0021] Examples of proteins (that form the proteinaceous biopolymer) are glycoproteins, structural proteins, fibrous proteins, enzymes, proteoglycans, peptides, natural polypeptides, synthetic polypeptides, spherical proteins, oligosaccharides, polysaccharides, collagen, gelatin, elastin, zein, wheat gluten, casein, whey, gellan gum, carrageenan, guar gum, Psyllium seed gum, yam starch powder, alginate, seaweed flour, tragacanth gum, karaya gum, curdlan, soy alginic acid, carboxymethylcellulose, agar-agar, carrageenans, locust bean gum, gelatin, alginate, arabinoxylan, arrowroot, Cassia gum, cellulose, gum Arabic, karaya gum, konjac, kuzu, maltodextrin, marshmallow root, pectin, sodium alginate, starch, xanthan gum, b-glucan, fibrinogen, fibrin, thrombin, collagen, elastin, albumin, keratin, laminine, papain, avidin, streptavidin, soybean protein, and the like, or a combination thereof.

[0022] A preferred proteinaceous biopolymer is albumin. Albumins are a class of water-soluble proteins characterized by relatively moderate molecular weight, acidic isoelectric points, and high solubility in aqueous solutions. They are found in both animal and plant sources and serve a variety of biological functions, including transport of endogenous and exogenous substances, regulation of osmotic pressure, and nutrient storage. Albumins include serum albumins, egg-derived albumins, plant derived albumins, milk albumins, or a combination thereof.

[0023] Serum albumins, such as human serum albumin (HSA) and bovine serum albumin (BSA), are major components of blood plasma and function primarily as carrier proteins for fatty acids, hormones, and drugs. Egg-derived albumins, including ovalbumin and ovotransferrin, serve as nutrient reservoirs and exhibit antimicrobial activity. Plant-derived albumins, such as leucosin and patatin, are present in seeds or tubers and may possess enzymatic activity or contribute to nutrient transport. Milk albumins, including -lactalbumin, play roles in lactose biosynthesis and are present in whey protein fractions. The structural and functional diversity of albumins across biological sources enables their use in a wide range of industrial, therapeutic, and research contexts.

[0024] In an embodiment, the proteinaceous biopolymers may be treated with a crosslinking agent (also known as a functionalizing agent) prior to or during the encapsulation of the fabric. The functionalizing agent preferably includes reactive groups. The reactive groups can facilitate free-radical polymerization when activated by electromagnetic radiation, heat transfer, or a combination of electromagnetic radiation and heat transfer. The functionalizing agent preferably includes an unsaturated carboxylic acid or a derivative of an unsaturated carboxylic acid. Amines, succinimidyl esters and carbodiimides may also be used as crosslinking agents to crosslinking the proteinaceous biopolymers via their carboxylic acid groups or thiol groups.

[0025] Examples of unsaturated carboxylic acids include maleic acid, fumaric acid, itaconic acid, acrylic acid, methacrylic acid, crotonic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acids, citraconic acid, or the like, or combinations thereof. Examples of derivatives of unsaturated carboxylic acids are maleic anhydride, acrylic anhydride, methacrylic anhydride, citraconic anhydride, itaconic anhydride, malonic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, pimelic anhydride, suberic anhydride, azelaic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate, or the like, or a combination thereof. A preferred reactive group for functionalizing the proteinaceous biopolymer is a succinic anhydride, a methacrylic anhydride, or a combination thereof.

[0026] As noted above, the proteinaceous biopolymers (e.g., albumins) can be crosslinked with a variety of amines via covalent bond formation to modify their structural and functional properties. Suitable amines include aliphatic primary amines (e.g., methylamine, ethylenediamine), polyamines (e.g., polyethyleneimine, spermidine), secondary amines (e.g., dimethylamine), and, under certain conditions, aromatic amines. The crosslinking may proceed through mechanisms such as amide bond formation via carbodiimide chemistry, Schiff base formation between aldehyde-functionalized albumins and amines, Michael-type addition to activated double bonds, or nucleophilic addition to epoxy groups.

[0027] Suitable crosslinking agents include primary amines, secondary amines, tertiary amines, moieties containing carboxylic acids that are functionalized with amines and/or thiols or a combination thereof. The amines may, for example, be linear or cyclic amines. Preferred amines are primary amines, secondary amines, or a combination thereof. Examples of primary amines include methylamine, ethylamine, propylamine, ethylenediamine, monoethanolamine, ethylpropylamino carbodiimide, and the like, or a combination thereof. Examples of secondary amines include dialkylamines such as dimethylamine, diethylamine, dipropylamine, dibutylamine, diethanolamine, and the like, or a combination thereof.

[0028] Naturally occurring amines may also be used to crosslink proteins through covalent interactions with reactive functional groups such as carboxyl, aldehyde, or hydroxyl moieties present on the biopolymer. These amines may serve as crosslinking agents by forming amide, imine, or other covalent linkages under appropriate reaction conditions. Examples of naturally occurring amines include lysine, putrescine, cadaverine, spermidine, spermine, or a combination thereof. Lysine, an amino acid with a primary F-amino group, can directly participate in crosslinking through carbodiimide-mediated coupling or reaction with aldehydes. Polyamines such as putrescine and cadaverine, which contain multiple primary amine groups, can bridge protein molecules to form crosslinked networks. Similarly, spermidine and spermine, which contain both primary and secondary amine groups, offer multiple reactive sites for crosslinking and stabilization of protein structures.

[0029] In an embodiment, amine-functionalized carboxylic acids may be used as crosslinking agents. The carboxylic acid present in these crosslinking agents facilitate aligning with thiols, amines, and other carboxylic acids present in the proteinaceous biopolymers. Amine-functionalized carboxylic acids enable crosslinking with proteins by presenting complementary functional groups that align with reactive residues on the protein surface. The carboxyl group can be activated, for instance using carbodiimide chemistry, to form covalent amide bonds with nucleophilic amine groups on lysine side chains or N-termini of the protein. The amine group on the functionalized molecule may also react with electrophilic groups such as aldehydes or activated esters to form Schiff bases or amide linkages. The alignment is driven by electrostatic interactions and hydrogen bonding, which facilitate proximity between reactive groups and enhance crosslinking efficiency. The alignment and reaction depend on the chemistry employed, particularly targeting lysine (s-amino), aspartic/glutamic acid (carboxyl), cysteine (thiol), or N-terminal residues of the protein. Examples include aminopolycarboxylic acids (APCAs) such as iminodiacetic acid, aspartic acid, ethylenediaminetetraacetic acid, hyaluronic acid, and the like, or a combination thereof.

[0030] Crosslinking agents are optional and may be used in amounts of 1 wt % to 15 wt %, preferably 2 wt % to 8 wt % or more, based on a total weight of the composition and the desired degree of crosslinking for a targeted application of the end product. The composition referred to herein is the weight of the solid proteinaceous biopolymer after crosslinking and functionalizing are completed (and all solvents are extracted from the wet composition to form the solid proteinaceous biopolymer).

[0031] In an embodiment, the proteinaceous biopolymer may optionally be functionalized with a secondary functionalizing agent that may contain one or more substituents that can provide the proteinaceous biopolymer with various desirable properties. One desirable property is hydrophobicity. Suitable substituents present in the secondary functionalizing agent includes one or more alkyl groups, oxygen, nitrogen, sulfur or phosphorus. In an embodiment, the substituent may include an alkyl having 4 to 20 carbon atoms, preferably 7 to 12 carbon atoms.

[0032] An exemplary secondary functionalizing agent is an alkylsuccinic anhydride having 8 to 18 carbon atoms. The functionalizing agent may be added in an amount of 1 to 10 wt %, preferably 2 to 5 wt %, based on a total weight of the proteinaceous biopolymer.

[0033] Buffering agents may be added to the proteinaceous biopolymer to stabilize the protein in solution and to maintain an optimal pH environment. The proteinaceous biopolymer (e.g., albumin) is sensitive to pH fluctuations. Buffers help maintain a slightly acidic to neutral pH (around pH 6-7.4), which preserves albumin's structural integrity and solubility. An example of a buffer is (10-50 mM) potassium mono/dibasic phosphate buffer, sodium carbonate buffer, mesylate buffer, Tris buffer, or acetate buffer or a combination thereof. Gluconic acid can be added in variable amounts to the proteinaceous biopolymer to increase or decrease the molecular weight between crosslinks. Addition of gluconic acid and its derivatives can result in the crosslinked biopolymer being elastomeric (having an elastic modulus of less than 100 megapascals (MPa)) or being highly crosslinked (in which case the elastic modulus is greater than 100 MPa). The elastic modulus is measured as per ASTM D 638.

[0034] The buffering (5-50 mM) agent may be added in amounts of 0.0002 to 0.002 wt %, based on a total weight of the proteinaceous biopolymer.

[0035] Preferred proteinaceous biopolymers include bovine serum albumin (BSA), ovalbumin, whey, papain, or a combination thereof. The proteinaceous biopolymers can be used in amounts of 5 to 90 wt %, preferably 10 to 50 wt %, and more preferably 15 to 45 wt %, based on a total weight of the composition.

[0036] As noted above, the proteinaceous biopolymer may be applied as a coating to a substrate to form the multilayered composite. The coating is prepared by mixing the proteinaceous biopolymer with a solvent, an optional cross-linking agent, an optional secondary functionalizing agent, and any other additives to form a solution. The solution is then coated onto the substrate (e.g., fabric and/or paper) to produce a wet multilayered composite. The solvent is removed to create the crosslinked proteinaceous biopolymer disposed on the substrate.

[0037] As noted above, there are a wide variety of properties that may be imparted to the multilayered composite by the addition of suitable additives to the multilayered composite. The substrate will first be described followed by the addition of the additives to the multilayered composite.

[0038] In one embodiment, the woven or non-woven fabric (used as the substrate) may comprise a naturally occurring fiber such as cotton, silk, jute, hemp, coir, bamboo, abaca, coir, lyocell, modal, sisal, and the like, or a combination thereof. In another embodiment, the woven or non-woven fabric may comprise a synthetic organic polymer. Organic polymers that are present in one, two or three dimensional articles are listed below.

[0039] The polymer (that is used in the fabric and in the paper) may be a thermoplastic polymer, a blend of thermoplastic polymers, a thermosetting polymer, or a blend of a thermoplastic polymer with a thermosetting polymer. The organic polymer may also be a blend of polymers, copolymers, terpolymers, or a combination thereof. The organic polymer can also be an oligomer, a homopolymer, a copolymer, a block copolymer, an alternating block copolymer, a random polymer, a random copolymer, a random block copolymer, a graft copolymer, a star block copolymer, a dendrimer, a polyelectrolyte (polymers that have some repeat groups that contain electrolytes), a polyampholyte (a polyelectrolyte having both cationic and anionic repeat groups), an ionomer, or the like, or a combination thereof.

[0040] Examples of thermoplastic polymers present in the fabric includes polyacetals, polyacrylics, polycarbonates, polyalkyds, polystyrenes, polyolefins, polyesters, polyamides, polyaramides, polyamideimides, polyarylates, polyurethanes, epoxies, phenolics, silicones, polyarylsulfones, polyethersulfones, polyphenylene sulfides, polysulfones, polyimides, polyetherimides, polytetrafluoroethylenes, polyetherketones, polyether ether ketones, polyether ketone ketones, polybenzoxazoles, polyoxadiazoles, polybenzothiazinophenothiazines, polybenzothiazoles, polypyrazinoquinoxalines, polypyromellitimides, polyguinoxalines, polybenzimidazoles, polyoxindoles, polyoxoisoindolines, polydioxoisoindolines, polytriazines, polypyridazines, polypiperazines, polypyridines, polypiperidines, polytriazoles, polypyrazoles, polycarboranes, polyoxabicyclononanes, polydibenzofurans, polyphthalides, polyacetals, polyanhydrides, polyvinyl ethers, polyvinyl thioethers, polyvinyl alcohols, polyvinyl ketones, polyvinyl halides, polyvinyl nitriles, polyvinyl esters, polysulfonates, polysulfides, polythioesters, polysulfones, polysulfonamides, polyureas, polyphosphazenes, polysilazanes, polypropylenes, polyethylenes, polyethylene terephthalates, polyvinylidene fluorides, polysiloxanes, or the like, or a combination thereof.

[0041] Examples of polyelectrolytes present in the substrate include polystyrene sulfonic acid, polyacrylic acid, pectin, carrageenan, alginates, carboxymethylcellulose, polyvinylpyrrolidone, polyethyleneimine, polyols, or the like, or a combination thereof.

[0042] Examples of thermosetting polymers present in the substrate include epoxy polymers, unsaturated polyester polymers, polyimide polymers, bismaleimide polymers, bismaleimide triazine polymers, cyanate ester polymers, vinyl polymers, benzoxazine polymers, benzocyclobutene polymers, acrylics, alkyds, phenol-formaldehyde polymers, novolacs, resoles, melamine-formaldehyde polymers, urea-formaldehyde polymers, hydroxymethylfurans, isocyanates, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, unsaturated polyesterimides, or the like, or a combination thereof.

[0043] The substrate may also include paper, cellulose fibers, cellulose nanoparticles and paper products. Papers include a material made from cellulose fibers derived from wood, rags, or other sources, wood pulp, cotton, jute, bagasse, bamboo, or the like. It is primarily used for writing, printing, drawing, and packaging.

[0044] The substrate is coated with the biopolymer to form the multilayered biopolymeric composite. The biopolymer is first dissolved in a suitable solvent to form a biopolymer solution (hereinafter solution). The optional crosslinking agent, the optional secondary functionalizing agent, and other additives that impart fluorescence, radio-opacity, impact strength, and the like may be added to the solution prior to the solution being applied to the substrate. The biopolymeric solution is dried after application to the substrate to form a layer of proteinaceous biopolymer on the substrate. Multiple applications of solution may be conducted to thicken the layer of the proteinaceous biopolymer. The proteinaceous biopolymer may be added to one or both sides of the substrate to form the multilayered biopolymeric composite. Multiple layers of the coated substrate are stratified with additional addition of the biopolymer and the crosslinking agent to rigidify and further strengthen the product.

[0045] In an embodiment, the substrate is present in the biopolymeric composite in an amount of 10 to 95 wt %, preferably 15 to 85 wt % and more preferably 20 to 70 wt % of the biopolymeric composite.

[0046] Solvents used for dissolving the proteinaceous biopolymer to form a solution include water, alcohols, ketones, and the like. Alcohols include methanol, ethanol, butanol, propanol, or a combination thereof. Solvents that are not toxic to living beings are preferred. Water and ethanol are preferred solvents. The proteinaceous biopolymer may be present in the solution in an amount of 10 to 80 wt %, preferably 25 to 60 wt %, based on a total weight of the biopolymer and the solvent.

[0047] Plasticizers may also be added to the biopolymer solution. Plasticizers may form hydrogen or electrostatic bonds with the proteinaceous biopolymer that increases the amount of free and freezing bond water retained in the biopolymer. Examples of plasticizers include glycerol, glycerin, glyceryl oleate, oleyl alcohol, polyethylene glycol (e.g., PEG-4, PEG-6, PEG-8, PEG-12, PEG-16, PEG-20, PEG-32, PEG-75), stearic acid, oleic acid, sodium lactate, and the like, or a combination thereof.

[0048] In some embodiments, the biopolymer solution may further comprise one or more humectants. Generally, a humectant is a water-soluble solvent and any one of a group of hygroscopic substances with hydrating properties, i.e., used to keep things moist. They often are a molecule with several hydrophilic groups, most often hydroxyl groups; however, amines and carboxyl groups, sometimes esterified, can be used as well.

[0049] Non-limiting examples of some humectants include propylene glycol (E1520), hexylene glycol, and butylene glycol; glyceryl triacetate (E1518); vinyl alcohol; neoagarobiose; glycerol/glycerin, sorbitol (E420), xylitol, maltitol (E965), polymeric polyols (e.g., polydextrose (E1200)), quillaia (E999), urea, aloe vera gel, MP diol, alpha hydroxy acids (e.g., lactic acid), and the like, or a combination thereof.

[0050] Surfactants may also be added to the biopolymer solution. Surfactants may be amphoteric surfactants, anionic surfactants, cationic surfactants, zwitterionic surfactants, or a combination thereof. An example of a surfactant is sodium dodecyl sulfate.

[0051] Various additives may be added to the mixture of proteinaceous biopolymers and fabric prior to blending. These additives include fillers such as, for example, natural and synthetic clays, reinforcing agents, dyes, carbon black and colorants, glass beads, elastomers, impact modifiers, gelling agents, crushed tires, antioxidants, antiozonants, flame-retardants, thermal-stabilizers, mold release agents, and the like, or a combination thereof.

[0052] Preferred additives include electrically conducting fillers, dyes and colorants (including fluorescent dyes and colorants), radio-opaque fillers, nanoclays, or a combination thereof.

[0053] In an embodiment, the multilayered biopolymeric composite may be rendered electrically conducting by adding electrically conducting fillers such as metal particles, carbonaceous particles, electrically conducting ceramic particles, intrinsically conducting fillers, or a combination thereof to the proteinaceous biopolymer. Metal particles include particulate or fibrous particles of copper, aluminum, steel, or a combination thereof. Carbonaceous particles include carbon black, Keltjen black, carbon nanotubes (single wall, double wall, multiwall carbon nanotubes, or a combination thereof), graphite particles and/or platelets, graphite oxide particles, graphene sheets, carbon fibers derived from pitch or polyacrylonitrile, or a combination thereof. Electrically conducting ceramic particles include indium tin oxide, antimony tin oxide, lanthanum-doped strontium titanate (SLT), yttrium-doped strontium titanate (SYT), or a combination thereof. Intrinsically electrically conducting polymer fillers include polyaniline, polythiophene, polyacetylene, polypyrrole, or a combination thereof. In an embodiment, the intrinsically conducting polymers may be used neutralized with an acid (e.g., dodecylbenzene sulfonic acid). Details of some of these electrically conductive fillers are provided below.

[0054] SWNTs used in the composition may be produced by laser-evaporation of graphite, carbon arc synthesis or the high-pressure carbon monoxide conversion process (HIPCO) process. These SWNTs generally have a single wall comprising a graphene sheet with outer diameters of about 0.7 to about 2.4 nanometers (nm). SWNTs having aspect ratios of greater than or equal to about 5, preferably greater than or equal to about 100, more preferably greater than or equal to about 1000 are generally utilized in the composition. While the SWNTs are generally closed structures having hemispherical caps at each end of the respective tubes, it is envisioned that SWNTs having a single open end or both open ends may also be used. The SWNTs generally comprise a central portion, which is hollow, but may be filled with amorphous carbon.

[0055] In another embodiment, the SWNTs may comprise a mixture of metallic nanotubes and semi-conducting nanotubes. Metallic nanotubes are those that display electrical characteristics similar to metals, while the semi-conducting nanotubes are those, which are electrically semi-conducting. In general, the manner in which the graphene sheet is rolled up produces nanotubes of various helical structures. Zigzag and armchair nanotubes constitute two possible confirmations. In order to minimize the quantity of SWNTs utilized in the composition, it is generally desirable to have the composition comprise as large a fraction of metallic SWNTs.

[0056] MWNTs derived from processes such as laser ablation and carbon arc synthesis that are not directed at the production of SWNTs, may also be used in the compositions. MWNTs have at least two graphene layers bound around an inner hollow core. Hemispherical caps generally close both ends of the MWNTs, but it may be desirable to use MWNTs having only one hemispherical cap or MWNTs, which are devoid of both caps. MWNTs generally have diameters of about 2 to about 50 nm.

[0057] Carbon black having a high surface area is preferred for use in the electrode. Carbon black (subtypes are acetylene black, channel black, furnace black, lamp black and thermal black) is a material produced by the incomplete combustion of coal and coal tar, vegetable matter, or petroleum products, including fuel oil, fluid catalytic cracking tar, and ethylene cracking in a limited supply of air. Carbon black is a form of paracrystalline carbon that has a high surface-area-to-volume ratio, albeit lower than that of activated carbon. Carbon black having a surface area of 50 to 1000 m.sup.2/gm may be used the composition.

[0058] Activated carbon also called activated charcoal, is a form of carbon that has a surface area in excess of 3,000 m.sup.2/gm as determined by gas adsorption. It can be used in conjunction with other electrically conducting carbonaceous elements listed herewith.

[0059] Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. Graphene that is added to the slurry may be in the form of individual graphene sheets or in the form of a plurality of loosely connected graphene sheets. Each atom in a graphene sheet is connected to its three nearest neighbors by -bonds and a delocalised -bond, which contributes to a valence band that extends over the whole sheet. This is the same type of bonding seen in carbon nanotubes and polycyclic aromatic hydrocarbons, and in fullerenes and glassy carbon. The valence band is touched by a conduction band, making graphene a semi-metal with unusual electronic properties that are best described by theories for massless relativistic particles.

[0060] Graphite particles may also be used in the electrically conducting composition. Graphite is a natural manifestation of pure carbon with a hexagonal crystal structure that is arranged in several parallel levels, called graphene layers. In short, graphite particles comprise a plurality of graphene sheets that are arranged to be parallel to each other. This anisotropic structure gives the graphite special properties, such as electrical conductivity or a particular strength along the individual layers. It is extremely heat-resistant with a sublimation point of over 3,800 C., thermally highly conductive and chemically inert.

[0061] Graphite oxide (GO), sometimes called graphene oxide, graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers and acids for resolving of extra metals. The maximally oxidized bulk product is a yellow solid with a C:O ratio between 2.1:1 and 2.9:1, that retains the layer structure of graphite but with a much larger and irregular spacing. The bulk material spontaneously disperses in basic solutions or can be dispersed by sonication in polar solvents to yield monomolecular sheets, known as graphene oxide by analogy to graphene, the single-layer form of graphite. Graphene oxide sheets exist in the form of strong paper-like materials, membranes, thin films, and composite materials and can be used in the composition.

[0062] The electrically conducting fillers are added in amounts of 0.5 to 20 wt %, preferably 2 to 15 wt %, preferably 3 to 10 wt %, based on a total weight of the biopolymeric layer (in the multilayered biopolymeric composite). It is desirable for the electrically conducting fillers to form a percolating network through the volume of the proteinaceous biopolymer. Combinations of the foregoing electrically conductive materials may be used in the composition. Compositions containing electrically conducting fillers may be electrically conducting. The compositions that contain electrically conducting fillers may be used in electrostatic discharge applications, electromagnetic dissipation applications and electrically conductive applications.

[0063] The electrically conducting filler may be added to the substrate, the biopolymer layer, or to both the substrate and the biopolymer layer. In an embodiment, the multilayered biopolymeric composite with electrically conducting filler disposed therein may be used for electromagnetic shielding, electrostatic dissipation, and the like.

[0064] The biopolymer layer is preferably electrically conducting with an electrical resistivity less than about 110.sup.11 ohm-cm, preferably less than 110.sup.5 ohm-cm and an IZOD notched impact strength greater than about 200 Joules per meter (J/m), preferably greater than 300 J/m when measured as per ASTM D 256.

[0065] A dye or colorant may be added to the multilayered biopolymeric composite. It may be added to the substrate, the biopolymer layer, or to both the substrate and the biopolymer layer. In an embodiment, the dye or colorant may be a fluorescent dye or colorant. A colorant refers to any substance that imparts color to a material. This includes both dyes and pigments, as well as other coloring agents. Colorants can be either soluble or insoluble in the medium in which they are applied. A dye is a specific type of colorant that is soluble in the application medium or becomes soluble during the application process. Dyes typically penetrate and bind at the molecular level to the substrate.

[0066] Examples of dyes are polyazaindacenes and/or coumarins, lanthanide complexes, hydrocarbon and substituted hydrocarbon dyes, polycyclic aromatic hydrocarbons, scintillation dyes (e.g., oxazoles and oxadiazoles), aryl- and heteroaryl-substituted polyolefins (C.sub.2-C.sub.8 olefin portion), carbocyanine dyes, phthalocyanine dyes and pigments, oxazine dyes, carbostyryl dyes, porphyrin dyes, acridine dyes, anthraquinone dyes, anthrapyridone dyes, naphtalimide dyes, benzimidazole derivatives, arylmethane dyes, azo dyes, diazonium dyes, nitro dyes, quinone imine dyes, tetrazolium dyes, thiazole dyes, perylene dyes, perinone dyes, bis-benzoxazolylthiophene (BBOT), xanthene dyes (e.g., thioxanthene dyes), indigoid dyes (e.g., thioindigoid dyes), chromones dyes, flavones dyes, as well as derivatives comprising at least one of the luminescent tags disclosed herein, or a combination thereof. Luminescent tags also include anti-Stokes shift dyes that absorb in the near infrared wavelength and emit in the visible wavelength.

[0067] Exemplary dyes and colorants are fluorescent dyes and colorants. Fluorescent dyes and colorants are compounds capable of absorbing light at a specific excitation wavelength and re-emitting it at a longer emission wavelength, thereby producing a detectable fluorescent signal. These materials are widely employed in applications such as imaging, labeling, sensing, and diagnostics due to their high sensitivity, tunable emission profiles, and compatibility with various substrates and matrices. Fluorescent dyes may include organic molecules, such as rhodamines, fluoresceins, and cyanines, as well as inorganic complexes like quantum dots or lanthanide chelates. Colorants, which may be pigments or soluble dyes, can also exhibit fluorescent properties when appropriately engineered or selected. In certain embodiments, the fluorescent dye or colorant may be covalently attached to a target molecule, encapsulated within a carrier, or incorporated into a polymeric matrix to achieve desired performance characteristics, such as stability, brightness, or controlled release.

[0068] Examples of fluorescent dyes and colorants include fluorescein, rhodamine B, rhodamine 6G, sulforhodamine 101, cyanine dyes (e.g., Cy3, Cy5, Cy7), BODIPY dyes, Texas Red, Nile Red, coumarin derivatives, eosin Y, erythrosin B, pyrene derivatives, and lanthanide-based complexes such as europium and terbium chelates. Rhodamine B and rhodamine 6G are preferred.

[0069] Quantum dots may also be used to produce colors in the multilayered biopolymeric composite. The quantum dots may be added to the substrate, the biopolymer layer, or to both the substrate and the biopolymer layer. Quantum dots are nanoscale semiconductor particles that exhibit size-dependent optical and electronic properties due to quantum confinement effects. They have diameters of 2 to 10 nanometers. Quantum dots can absorb light and re-emit it at specific wavelengths, with the emission color tunable by controlling the particle size. Suitable quantum dots include, but are not limited to, cadmium selenide (CdSe), cadmium telluride (CdTe), cadmium sulfide (CdS), zinc sulfide (ZnS), indium phosphide (InP), and lead sulfide (PbS) nanocrystals. In certain embodiments, the quantum dots may be core-shell structures, such as CdSe/ZnS or InP/ZnS, which enhance photostability and quantum yield. The quantum dots may be incorporated into the biopolymer in free form, encapsulated within a matrix that is chemically different from the biopolymer or compatible with it, or surface-functionalized with ligands or polymers to facilitate compatibility with the biopolymer to enable targeted binding or dispersion.

[0070] The fluorescing multilayered biopolymeric composite emits light at specific wavelengths that depend on their chemical structure and excitation conditions. Emission wavelengths fall within the ultraviolet (UV), visible, and near-infrared (NIR) spectral regions, generally ranging from 350 nm to 900 nanometers (nm), preferably 500 to 650 nm, and more preferably 540 to 600 nm.

[0071] Any of the dyes or colorants listed above may be added in amounts of 0.0005 to 20 wt %, preferably 0.001 to 15 wt %, preferably 0.01 to 10 wt %, based on a total weight of the biopolymeric layer (in the multilayered biopolymeric composite).

[0072] The biopolymer layer is preferably electrically conducting with an electrical resistivity less than about 110.sup.11 ohm-cm, preferably less than 110.sup.5 ohm-cm and an IZOD notched impact strength greater than about 200 Joules per meter (J/m), preferably greater than 300 J/m when measured as per ASTM D 256, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers.

[0073] In another embodiment, the multilayered biopolymeric composite is preferably electrically conducting with an electrical resistivity less than about 110.sup.11 ohm-cm, preferably less than 110.sup.5 ohm-cm and an IZOD notched impact strength greater than about 200 Joules per meter (J/m), preferably greater than 300 J/m when measured as per ASTM D 256, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers.

[0074] The electrical resistivity is measured by taking a molded dogbone sample of the biopolymer (that contain a conductive filler), fracturing it at a certain length, coating the fractured ends with conductive silver paint and taking conductivity readings at the opposing fractured ends using a voltammeter. The conductivity is then converted into resisitivity.

[0075] In an embodiment, the multilayered biopolymeric composite may be used in radiation protective suits in lieu of lead protective suits. They are lower in weight than lead suits while providing the same protective capabilities. In certain embodiments, the radio-opaque filler may be used in particulate, granular, or nanoparticulate form and dispersed uniformly within biopolymeric layer. The concentration and particle size of the radio-opaque filler may be adjusted to achieve the desired balance of radiopacity, mechanical strength, and processability.

[0076] The proteinaceous biopolymeric layer may include radio-opaque fillers that are dispersed in the substrate, the biopolymeric layer, or in both the biopolymeric layer and the substrate. Radio-opaque fillers may be incorporated into the multilayered biopolymeric composite to attenuate X-rays and to provide protection to the wearer against damage from radiation. Examples of radio-opaque fillers include barium sulfate (BaSO4), bismuth sub-carbonate, bismuth oxychloride, bismuth trioxide, tungsten powder, tantalum powder, zirconium oxide (zirconia), iodine-containing organic compounds, strontium-containing compounds such as strontium sulfate or strontium carbonate, or the like, or a combination thereof.

[0077] Radiation protective suits that contain radio-opaque fillers may be used in nuclear facilities, in space vehicles, in outer space, and so on. The radio-opaque fillers may be added in amounts of 0.5 to 60 wt %, preferably 2 to 50 wt %, preferably 3 to 40 wt %, preferably 4 to 10 wt %, based on a total weight of the biopolymeric layer (in the multilayered biopolymeric composite). In an embodiment, the crosslinked proteinaceous biopolymer layer is radio-opaque to xrays, has an IZOD notched impact strength greater than about 200 Joules per meter (J/m) when measured as per ASTM D 256, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers. The multilayered biopolymeric composite has a mass attenuation coefficient of 1.9 to 2.2 cm.sup.2/g at 70 keV, due to the presence of high-Z barium sulfate, while at the same time exhibiting fluorescence at wavelengths between 540 and 600 nanometers. A reasonable value for the mass attenuation coefficient (/) of barium sulfate (BaSO.sub.4) at 70 keV is approximately 1.9 to 2.2 cm.sup.2/g.

[0078] In an embodiment, the multilayered biopolymeric composite may be used in flame retardant suits. The solution which contains the proteinaceous biopolymer along with optional cross-linking agents, optional functionalizing agents, and flame retardants may be applied as a coating onto fabric or paper to facilitate flame retardancy.

[0079] Flame retardant fillers enhance thermal stability and reduce flammability by inhibiting ignition, suppressing flame propagation, or promoting char formation. Examples of suitable flame retardant fillers include aluminum hydroxide (ATH), magnesium hydroxide (MDH), ammonium polyphosphate (APP), zinc borate, red phosphorus, expandable graphite, melamine cyanurate, and hydrated aluminosilicates such as huntite and hydromagnesite. These fillers may act through endothermic decomposition, formation of a protective barrier, or release of inert gases that dilute flammable volatiles. In certain embodiments, the flame retardant filler may be used in conjunction with synergists such as antimony trioxide or metal oxides to enhance performance. The flame retardant filler may be incorporated as a powder, flake, or particulate dispersion, and may be surface-modified to improve compatibility with the polymer matrix or enhance dispersion uniformity.

[0080] Phosphorus containing flame retardants are desired. Phosphorus-containing flame retardants promote char formation and inhibiting combustion through the release of phosphoric acid derivatives during thermal decomposition. Examples of suitable phosphorus-based flame retardants include ammonium polyphosphate (APP), red phosphorus, aluminum diethylphosphinate, melamine polyphosphate, tris(2-chloroethyl) phosphate (TCEP), tris(2-butoxyethyl) phosphate (TBEP), tricresyl phosphate (TCP), resorcinol bis(diphenyl phosphate) (RDP), bisphenol A bis(diphenyl phosphate) (BDP), or a combination thereof. These compounds may function in the gas phase by interfering with flame chemistry or in the condensed phase by facilitating the formation of a protective carbonaceous char layer. In certain embodiments, the phosphorus flame retardant may be used alone or in combination with synergists such as nitrogen-containing compounds or metal oxides to enhance efficacy. Examples of nitrogen-containing compounds include melamine, urea, dicyandiamide, guanidine, cyanamide, ammonium chloride, ammonium sulfate, ethylenediamine, hexamethylenetetramine, polyethylenimine, or a combination thereof. The selected flame retardant may be incorporated into the biopolymer layer or in the substrate as a powder, liquid, or encapsulated form.

[0081] The flame retardant fillers may be added in amounts of 0.5 to 10 wt %, preferably 2 to 8 wt %, preferably 3 to 7 wt %, preferably 4 to 6 wt %, based on a total weight of the biopolymeric layer (in the multilayered biopolymeric composite).

[0082] In an embodiment, nanoclays and 2-dimensional materials (Zr(IV)phosphate, MXenes) may be added to the biopolymer solution to be exfoliated by the proteinaceous biopolymer. These layered materials may be used to reinforce the biopolymer or impart cooling effect. The stiffness (e.g., Youngs modulus) as measured by ASTM D 638 can be changed by varying the amount of nanoclays added to the proteinaceous biopolymer. Nanoclays, such as montmorillonite, are layered silicate materials that can be exfoliated into individual platelets when dispersed in suitable media. Exfoliation of nanoclays can be facilitated by proteins such as albumin, which possess amphiphilic and charged regions capable of intercalating between the clay layers. The interaction of bioproteins with nanoclays disrupts the electrostatic and van der Waals forces holding the layers together, leading to delamination and stabilization of the individual platelets in aqueous dispersions. This protein-mediated exfoliation process enables the formation of bio-nanocomposites with enhanced surface area, improved colloidal stability, and potential for functionalization through the reactive amino acid residues present in the protein. Addition of MoS.sub.2, (0.001 to 0.05 wt %) for example, enhanced the cooling of the product when wet by as much as 8 C. when compared to its surroundings.

[0083] Natural and synthetic smectite-type clays may be used in exfoliated or intercalated forms for various applications. Examples of nanoclays that may be exfoliated by the bioproteins include montmorillonite, hectorite, saponite, laponite, nontronite, beidellite, stevensite, or a combination thereof.

[0084] The nanoclays may be added in amounts of 0.5 to 10 wt %, preferably 2 to 8 wt %, preferably 3 to 7 wt %, preferably 4 to 6 wt %, based on a total weight of the biopolymeric layer (in the multilayered biopolymeric composite).

[0085] In one embodiment, the proteinaceous biopolymer, the solvent, the crosslinking agent, optional secondary functionalizing agents, surfactants, additives (e.g., dyes, colorants and flame retardants) and the like may be blended to form a solution. The blending of the proteinaceous biopolymer and solvent can be conducted in a blender such as for example, single or multiple screw extruders, a Buss kneader, a Henschel, helicones, a Ross mixer, a Banbury, roll mills, and then like, or a combination thereof.

[0086] The solution is disposed on a substrate (e.g., fabric, paper, or a combination thereof) and forms a biopolymer shell on the substrate upon undergoing crosslinking. No covalent or ionic bonds are formed between the substrate and the biopolymer shell. The biopolymer shell may form a physical interpenetrating network through the substrate. The biopolymer shell is held in position on the substrate by mechanical interlocking with the substrate. In an embodiment, the biopolymer shell interpenetrates with the substrate.

[0087] The biopolymer shell may have a thickness of 1 micrometer to 5 millimeters, preferably 10 micrometers to 2 millimeters, and preferably 20 micrometers to 1 millimeter.

[0088] Multiple coatings of the biopolymer may be applied to the substrate. Multiple layers the substrate may also be used in the multilayered biopolymeric composite. In other words, the multilayered biopolymeric composite may contain alternating layers of the biopolymer and the substrate. The multilayered biopolymeric composite may have a thickness of 1 millimeter to 10 millimeters. It may be used as a bullet proof, impact resistant shield if desired. The multilayered biopolymeric composite has an impact resistance of 800 to 900 Joules per meter when measured as per ASTM D 256.

[0089] In an embodiment, the multilayered biopolymeric composite has a surface area greater than 25 square centimeter (cm2), preferably greater than 50 cm2, preferably greater than 1 square meter (m2), preferably greater than 2 m2, and preferably greater than 10 m2. The surface area is measured in at least two directions that are perpendicular to the thickness of the multilayered biopolymeric composite. The two directions can be the length and the width of the multilayered biopolymeric composite.

[0090] In an embodiment, the biopolymer solution may be converted into a foam that may be used for scavenging metallic (and metallic salt) contaminants that can otherwise pollute drinking water and other solutions (such as those used in clean room operations, where contaminants are not desired). In order to form a foam, the proteinaceous material may be dissolved in a solvent along with a crosslinking agent to form a solution. The solution is then whipped at high speed as the biopolymer undergoes crosslinking to form a crosslinked foam. The crosslinked foam may be an elastic (flexible) foam or a rigid foam depending upon the amount of crosslinking agent added to the solution. The crosslinked foam may then be added to a contaminated solution to remove contaminants that bond with reactive or functional groups (carboxylic acid groups, amines, thiols, and the like) on the surface of the foam.

[0091] The composite disclosed herein may be used as a space suit, radiation protection clothing, a radiation protection shelter, a bullet proof vest, sports clothing (motorcycling protective equipment, automobile racing equipment, personal protective equipment) or flame retardant clothing.

[0092] The composition and a method of manufacturing the composition is exemplified by the following non-limiting example.

EXAMPLE

Example 1

[0093] This example was conducted to demonstrate the increase in degradation temperature that the disposing of a biopolymer composition on a fabric substrate (that comprises 65 wt % polyester and 35 wt % cotton). A proteinaceous biopolymer (e.g., bovine serum albumin or ovalbumin) is activated with a crosslinking agent ethyl propyl amino carbodiimide (EDC). The coating is disposed on a sheet of fabric and when the crosslinking reaction is completed, the fabric with the crosslinked proteinaceous biopolymer disposed thereon is subjected to thermogravimetric analysis (TGA) at a rate of 10 C/minute to determine the degradation point. FIG. 1 is a depiction of the reaction between bovine serum albumin and EDC to produce the crosslinked protein.

[0094] FIG. 2 is a graph that depicts the degradation of uncoated fabric compared with fabric that is coated with crosslinked albumin. The decomposition temperatures show a decreasing trend across the three samples, with the BSA/EDC fabric composite having the lowest decomposition temperature. This thermal stability trend indicates that the addition of BSA to the fabric accelerates degradation. The addition of a crosslinking agent to the BSA fabric composite further lowers the decomposition temperature.

Example 2

[0095] This example is conducted to demonstrate that fluorescing additives can be added to the crosslinked proteinaceous biopolymer. Rhodamine B was added to the biopolymer prior to crosslinking. FIG. 3A depicts the method of manufacturing the crosslinked biopolymer (BSA) with the Rhodamine B fluorescent agent, while FIG. 3B depicts a graph of intensity versus wavelength for BSA containing Rhodamine B. The graph shows that the intensity of fluorescing increases with the increase in the concentration of the fluorescent agent. The peak fluorescence occurs between 570 and 580 nanometers. UV light (long wave 365 nm) was used to investigate the fluorescence. FIG. 3C depicts a table that shows the excitation wavelength, the emission wavelength and the quantum yield.

Example 3

[0096] This example is conducted to demonstrate the manufacturing of an electrically conducting multilayered biopolymer composite. FIG. 4A depicts the manufacturing of the multilayered biopolymer composite. Graphene and carbon nanotubes are used as the electrically conductive filler. The BSA solution with the graphene and the carbon nanotubes is deposited on a fabric. The repetitive coatings are disposed on the fabric in this manner. FIG. 4B depicts a table where the conductivity of each fabric was determined. All samples were determined to be electrically conductive.

[0097] All statements herein reciting principles, aspects, and embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure.

[0098] Various other components may be included and called upon for providing for aspects of the teachings herein. For example, additional materials, combinations of materials and/or omission of materials may be used to provide for added embodiments that are within the scope of the teachings herein. Adequacy of any particular element for practice of the teachings herein is to be judged from the perspective of a designer, manufacturer, seller, user, system operator or other similarly interested party, and such limitations are to be perceived according to the standards of the interested party.

[0099] In the disclosure hereof any element expressed as a means for performing a specified function is intended to encompass any way of performing that function including, for example, a) a combination of circuit elements and associated hardware which perform that function or b) software in any form, including, therefore, firmware, microcode or the like as set forth herein, combined with appropriate circuitry for executing that software to perform the function. Applicants thus regard any means which can provide those functionalities as equivalent to those shown herein. No functional language used in claims appended herein is to be construed as invoking 35 U.S.C. 112(f) interpretations as means-plus-function language unless specifically expressed as such by use of the words means for or steps for within the respective claim.

[0100] When introducing elements of the present invention or the embodiment(s) thereof, the articles a, an, and the are intended to mean that there are one or more of the elements. Similarly, the adjective another, when used to introduce an element, is intended to mean one or more elements. The terms including and having are intended to be inclusive such that there may be additional elements other than the listed elements. The term exemplary is not intended to be construed as a superlative example but merely one of many possible examples.

[0101] While the invention has been described with reference to some embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.