Silk paper derived from silk textile waste

Abstract

Silk paper that is derived from silk textile waste is disclosed, along with a method of its making. Virgin silk paper is also disclosed, along with a similar method of making. The methods of making include: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulping the plurality of soaked silk fibers to produce a silk pulp; and d) making silk paper from the silk pulp. In cases where silk waste is the source material, the methods can include sorting the silk waste by color to produce color-sorted silk fabric waste, which is then shredded, soaked, pulped, and made as described herein.

Description

SILK PAPER DERIVED FROM SILK TEXTILE WASTECLAIM TO PRIORITY

[0001] This application relates to, incorporates by reference for all purposes, and claims priority to United States Provisional Patent Application 63 / 676,070 filed on July 26, 2024.BACKGROUND

[0002] Traditional print paper is made from cellulose and generally involves acquiring wood as the raw material through deforestation. The fabrication process of print paper includes heavy use of additives, fillers, and treatments to make the paper appear white and control the hydrophobicity and the solubility of the paper.

[0003] Existing silk-based papers exist, but they are mostly composite papers and are not made from textile waste. For example, silk papers for printing on are commercially available or described in scientific literature. However, several feel like textiles, and may be made as a composite material with other materials such as cotton, bamboo, or collagen. Other silk papers suffer from limited scalability and / or complicated fabrication processes.SUMMARY

[0004] In an aspect, the present disclosure provides a method of recycling silk fabric waste into recycled silk paper. The method includes the following steps: a) optionally sorting the silk fabric waste by color to produce color-sorted silk fabric waste; b) shredding the color-sorted silk fabric waste to produce a shredded silk fabric waste; c) soaking the shredded silk fabric waste in water for a soaking length of time of between 6 hours and 7 days to produce soaked shredded silk fabric waste; d) pulping the soaked shredded silk fabric waste to produce a silk fabric waste pulp; and e) making recycled silk paper from the silk fabric waste pulp.

[0005] In another aspect, the present disclosure provides a recycled silk paper made by the methods disclosed herein.

[0006] In yet another aspect, the present disclosure provides a method of fabricating silk paper. The method includes: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulping the plurality of soaked silk fibers to produce a silk pulp; and d) making silk paper from the silk pulp.

[0007] In yet a further aspect, the present disclosure provide a silk paper made by the methods disclosed herein.

[0008] In another aspect, the present disclosure provides a method of fabricating virgin silk paper. The method includes: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulpingthe plurality of soaked silk fibers to produce a virgin silk pulp; and d) making virgin silk paper from the virgin silk pulp.

[0009] In a further aspect, the present disclosure provides a virgin silk paper made by the methods disclosed herein.

[0010] These and other systems, methods, objects, features, and advantages of the present disclosure will be apparent to those skilled in the art from the following detailed description of the preferred embodiment and the drawings.

[0011] All documents mentioned herein are hereby incorporated in their entirety by reference. References to items in the singular should be understood to include items in the plural, and vice versa, unless explicitly stated otherwise or clear from the text. Grammatical conjunctions are intended to express any and all disjunctive and conjunctive combinations of conjoined clauses, sentences, words, and the like, unless otherwise stated or clear from the context.BRIEF DESCRIPTION OF THE FIGURES

[0012] The disclosure and the following detailed description of certain embodiments thereof may be understood by reference to the following figures:

[0013] Fig. 1 A depicts a macroscopic image of a white fabric from textile waste that was processed into paper.

[0014] Fig. IB depicts a macroscopic image of a white fabric from textile waste that was processed into paper.

[0015] Fig. 1C depicts a macroscopic image of a white fabric from textile waste that was processed into paper.

[0016] Fig. ID depicts a macroscopic image of a white fabric from textile waste that was processed into paper.

[0017] Fig. IE depicts a micrograph of the fabric weave of Fig. 1A.

[0018] Fig. IF depicts a micrograph of the fabric weave of Fig. IB.

[0019] Fig. 1G depicts a micrograph of the fabric weave of Fig. 1C.

[0020] Fig. 1 H depicts a micrograph of the fabric weave of Fig. ID.

[0021] Fig. II shows combined Fourier-transform infrared (FTIR) spectra of each of the silk fabrics shown in Fig. 1 A - Fig. ID.

[0022] Fig. 2A shows a photograph of recycled silk paper. The black particles are minor contaminants from the shredder.

[0023] Fig. 2B shows an FTIR spectrum of the recycled silk paper from 3500 to 500 cm1indicating the paper is made of silk.

[0024] Fig. 3A shows a top view bright-field reflection micrograph of recycled silk paper.

[0025] Fig. 3B shows a top view bright-field transition micrograph indicating homogeneity in the paper.

[0026] Fig. 3C shows a top view bright-field reflection micrograph of the paper showing dense networks of silk fibers.

[0027] Fig. 3D shows a top view bright-field reflection micrograph of the paper indicating no contamination.

[0028] Fig. 4A shows elongation at break for 5 types of papers.

[0029] Fig. 4B shows tensile index of 5 types of papers.

[0030] Fig. 4C shows the Young’s Modulus of 5 types of papers.

[0031] Fig. 5A shows a macroscopic image of recycled silk paper air-dried under pressure.

[0032] Fig. 5B shows a macroscopic image taken at an angle of recycled silk paper smoothed by an etching press.

[0033] Fig. 6A, Fig. 6C, Fig. 6E, Fig. 6G, and Fig. 61 show SEM images at varying magnifications of print paper.

[0034] Fig. 6B, Fig. 6D, Fig. 6F, Fig. 6H, and Fig. 6J show SEM images at varying magnifications of recycled silk paper.

[0035] Fig. 7A and Fig. 7B show SEM images at different magnifications of re-silk paper pulp.

[0036] Fig. 8A shows a cross-section SEM of print paper.

[0037] Fig. 8B shows a cross-section SEM of re-silk paper.

[0038] Fig. 9 A shows macroscopic and microscopic images of laser printing on print paper (recycled cellulose).

[0039] Fig. 9B shows macroscopic and microscopic images of laser printing on re-silk paper with a sizing agent.

[0040] Fig. 9C shows macroscopic and microscopic images of laser printing on re-silk paper without a sizing agent.

[0041] Fig. 10A shows a macroscopic image textured re-silk paper after laser printing.

[0042] Fig. 10B shows a macroscopic image of cold pressed re-silk paper after laser printing.

[0043] Fig. 10C shows a macroscopic image of hot pressed re-silk paper after laser printing.

[0044] Fig. 10D shows a macroscopic image of print paper after laser printing as a control.

[0045] Fig. 10E and Fig. 10F show corresponding micrographs of printed textured re-silk paper from Fig. 10A.

[0046] Fig. 10G and Fig. 10H show corresponding micrographs of printed cold pressed re-silk paper from Fig. 10B.

[0047] Fig. 101 and Fig. 10J show corresponding micrographs of printed hot pressed re-silk paper from Fig. 10C.

[0048] Fig. 10K and Fig. 10L show corresponding micrographs on print paper from 1 ID.

[0049] Fig. 11 A shows a macroscopic image of re-silk paper submerged in water.

[0050] Fig. 1 IB shows recycled re-silk pulp obtained from stirring re-silk paper in water for 1 minute.

[0051] Fig. 11C shows re-silk paper without sizing dissolved in a LiBr solution.

[0052] Fig. 12A shows macroscopic images of 8 different types of papers subjected to a flame.

[0053] Fig. 12B shows a the time taken for each strip of paper to burn completely.

[0054] Fig. 13A shows macroscopic and microscopic images of print paper, rough re-silk paper, and smooth re-silk paper with the focal point of analysis highlighted in the center.

[0055] Fig. 13B shows reflectance spectra of each paper with the value 475 nm indicated.

[0056] Fig. 14A shows a fluorescence spectrum of cellulose paper with silk fibroin solution and horseradish peroxidase.

[0057] Fig. 14B shows a fluorescence spectrum of re-silk paper with only horseradish peroxidase.

[0058] Fig. 15A shows macroscopic and microscopic images of a holographic nickel shim master.

[0059] Fig. 15B shows macroscopic and microscopic images of hot-pressed patterned re-silk paper.

[0060] Fig. 16 shows a handmade recycled silk booklet with re-silk paper as pages and silk fabrics for the cover as a mono-material prototype.

[0061] Fig. 17A shows top view SEM of print paper.

[0062] Fig. 17B shows top view SEM of re-silk paper.

[0063] Fig. 17C shows layered SEM and EDX analysis of print paper.

[0064] Fig. 17D shows layered SEM and EDX analysis of re-silk paper.

[0065] Fig. 17E shows the presence of oxygen atoms in print paper.

[0066] Fig. 17F shows the presence of carbon atoms in print paper.

[0067] Fig. 17G shows the presence of calcium atoms in print paper.

[0068] Fig. 17H shows the presence of chlorine atoms in print paper.

[0069] Fig. 171 shows the presence of carbon atoms in re-silk paper.

[0070] Fig. 17J shows the presence of oxygen atoms in re-silk paper.

[0071] Fig. 17K shows the presence of nitrogen atoms in re-silk paper.

[0072] Fig. 18A shows macroscopic images of different shades of pink fabrics from textile that were processed into re-silk paper.

[0073] Fig. 18B shows corresponding micrographs of the differing weaves of the fabrics in Fig. 18 A.

[0074] Fig. 18C shows pink re-silk paper produced from the fabrics in Fig. 18A and Fig. 18B.

[0075] Fig. 18D shows macroscopic images of different black fabrics from textiles that were processed into re-silk paper.

[0076] Fig. 18E shows corresponding micrograph of the differing weaves of the fabrics in Fig. 18D.

[0077] Fig. 18F shows black re-silk paper produced from the fabrics in Fig. 18D and Fig. 18E.

[0078] Fig. 18G shows FTIR spectra of each of white, pink, and black re-silk paper to confirm they are crystalline silk.

[0079] Fig. 19 shows optical images of white (left), black (middle), and pink (right) re-silk paper.

[0080] Fig. 20A shows drop tests in triplicate of pink re-silk paper.

[0081] Fig. 20B shows drop tests in triplicate of black re-silk paper.

[0082] Fig. 20C shows drop tests in triplicate of white re-silk paper.

[0083] Fig. 20D shows the spread in cm of liquid on the re- silk papers.

[0084] Fig. 21 A shows a process of recycling re-silk papers to form new sheets of paper.

[0085] Fig. 21B shows a process of dissolving re-silk papers in lithium bromide solution for silk fibroin extraction.

[0086] Fig. 22 shows an overview of the fabrication process of virgin silk paper.

[0087] Fig. 23A shows a sheet of virgin silk paper.

[0088] Fig. 23B shows the flexibility of a folded sheet of virgin silk paper.

[0089] Fig. 23C shows a stack of 44 silk papers.

[0090] Fig. 23D shows a scatter plot of the individual sheets from Fig. 23C.

[0091] Fig. 24 shows morphological characterization of virgin silk fibers.

[0092] Fig. 25 A shows a microscopic image of degummed silk fibers.

[0093] Fig. 25B shows a microscopic image of recycled silk paper fiber.

[0094] Fig. 25C shows a microscopic image of virgin silk paper fiber.

[0095] Fig. 25D shows a microscopic image of a control silk film.

[0096] Fig. 25E shows a microscopic image of recycled silk paper fibrils.

[0097] Fig. 25F shows a microscopic image of virgin silk paper fibrils.

[0098] Fig. 25G shows averaged Raman spectra for each sample in Fig. 25A - Fig. 25F.

[0099] Fig. 26A shows print paper subjected to a vertical flame.

[0100] Fig. 26B shows virgin silk paper subjected to a vertical flame.

[0101] Fig. 26C shows recycled silk paper subjected to a vertical flame.

[0102] Fig. 27A shows TGA analysis of print paper, virgin silk paper, and recycled silk paper.

[0103] Fig. 27B shows analysis of print paper.

[0104] Fig. 27C shows analysis of print paper TGA residue.

[0105] Fig. 27D shows analysis of virgin silk paper.

[0106] Fig. 27E shows analysis of virgin silk paper TGA residue.

[0107] Fig. 27F shows analysis of recycled silk paper.

[0108] Fig. 27G shows analysis of recycled silk paper TGA residue.

[0109] Fig. 28A shows a watercolor swatch test on re-silk paper with ketene dimer internal sizing.

[0110] Fig. 28B shows a watercolor swatch test on Arches paper.

[0111] Fig. 29A shows a colored pencil swatch test on re-silk paper with ketene dimer internal sizing.

[0112] Fig. 29B shows a colored pencil swatch test on Arches paper.

[0113] Fig. 30A shows a charcoal pencil swatch test on re-silk paper with ketene dimer internal sizing.

[0114] Fig. 30B shows a charcoal pencil swatch test on Arches paper.

[0115] Fig. 31 A shows contact angle measurements for pink re-silk paper.

[0116] Fig. 3 IB shows contact angle measurements for white re-silk paper.

[0117] Fig. 31C shows contact angle measurements for black re-silk paper.

[0118] Fig. 3 ID shows the legend for Fig. 31 A - Fig. 31C.

[0119] Fig. 32A depicts re-silk paints versus commercial watercolor paints (Fig. 32B) on re-silk paper.

[0120] Fig. 33A, 33B, and 33C depict re-silk paper with silk solution sizing.

[0121] Fig. 34 depicts a spectral analysis of crosslinked silk sized re-silk paper.DETAILED DESCRIPTION

[0122] Before the present disclosure is described in further detail, it is to be understood that the disclosure is not limited to the particular embodiments described. It is also understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. The scope of the present disclosure will be limited only by the claims. As used herein, the singular forms "a", "an", and "the" include plural embodiments unless the context clearly dictates otherwise.

[0123] In this application, unless otherwise clear from context, (i) the term “a” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and / or”; (iii) the terms “comprising” and “including” may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; and (iv) the terms “about” and “approximately” are used as equivalents and may be understood to permit standard variation as would be understood by those of ordinary skill in the art; and (v) where ranges are provided, endpoints are included.

[0124] Approximately: as used herein, the term “approximately” or “about,” as applied to one or more values of interest, refers to a value that is similar to a stated reference value. In certain embodiments, the term “approximately” or “about” refers to a range of values that fall within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).

[0125] Composition: as used herein, may be used to refer to a discrete physical entity that comprises one or more specified components. In general, unless otherwise specified, a composition may be of any form - e.g., gas, gel, liquid, solid, etc. In some embodiments, “composition” may refer to a combination of two or more entities for use in a single embodiment or as part of the same article. It is not required in all embodiments that the combination of entities result in physical admixture, that is, combination as separate co-entities of each of the components of the composition is possible; however many practitioners in the field may find it advantageous to prepare a composition that is an admixture of two or more of the ingredients in a pharmaceutically acceptable carrier, diluent, or excipient, making it possible to administer the component ingredients of the combination at the same time.

[0126] Improve, increase, or reduce: as used herein or grammatical equivalents thereof, indicate values that are relative to a baseline measurement, such as a measurement in a similar composition made according to previously known methods.

[0127] Substantially: as used herein, the term “substantially” refers to the qualitative condition of exhibiting total or near-total extent or degree of a characteristic or property of interest. One of ordinary skill in the biological arts will understand that biological and chemical phenomena rarely, if ever, go to completion and / or proceed to completeness or achieve or avoid an absolute result. The term “substantially” is therefore used herein to capture the potential lack of completeness inherent in many biological and chemical phenomena.

[0128] Silk has been used as a material for millennia, as has the process of papermaking. However, until now, there has not been a reliable way of recycling used silk into high-quality paper. Described herein are methods to transform silk fabric scraps into a paper format. This paper can be made with or without additives or treatments.

[0129] Textile waste may be repurposed as a resource in the form of recycled silk paper, which may also be referred to as re-silk paper, which resembles commonly used print paper. Recycled silk paper offers a more sustainable approach to papermaking by both eliminating the use of cellulose, which reduces the need for deforestation, and reframes textile waste as a material source rather thangarbage. Impressively, textile waste that would previously be disposed of in landfills and oceans may now be repurposed into a paper format that can not only serve the fine arts world but also has the potential to be used as raw material in other contexts (e.g., packaging and sculpting).

[0130] The recycled materials and recycled silk methods described herein address problems of fabricating sustainable biomaterials using textile waste from fashion industries without further contributing to deforestation. Repurposing abundantly available textiles avoids reliance on virgin fibers. This processing can be purely mechanical instead of chemical, meaning it is done without causing water pollution and does not require the use of additives or external agents. Not only is no chemical waste produced, water usage is limited as the silk pulp may be processed in the same water bath in a loop.

[0131] Recycled silk pulp provides the opportunity to fabricate sustainable alternatives for paper that generally require the use of unsustainable practices and treatments. The recycled silk paper is made by mechanically recycling unused fabric remnants or discarded fashion products mainly from the fashion industry. Because recycled silk paper is a non-cellulosic protein paper that does not require wood pulp, there is no need for deforestation. The recycled silk paper retains the color of the fabrics that are processed which locks the dyed fabrics in a circular loop for consumer use and reduces the chances of toxic dyes and / or pigments leaching out in oceans.

[0132] As used herein, “silk textile waste” refers broadly to all silk waste products from the textilemaking process, including but not limited to, waste silk fabrics, reeling cocoons, weaving fabrics, leftover fabrics from pattern making and garment construction, embroidery thread cuttings, and the like.

[0133] As used herein, silk paper broadly refers to paper and paper products, including but not limited to, packaging and medical paper products. Paper products may be composed entirely of the paper disclosed herein or may be composed partly of the paper disclosed herein.

[0134] Beyond environmental benefits, silk fibers defibrillate more thoroughly than cellulose fibers leading to stronger paper. Nanoimprinting may be performed on pressed papers, and the recycled silk paper has potential for use in biosensors.

[0135] Sizing agents

[0136] Sizing agents may be added to paper to modify the paper’s surface properties by reducing water absorbency. Unsized paper may experience spreading of inks and water penetration while there is reduced wetting with increased sizing. Sizing agents may increase hydrophobicity, improve printability, and / or increase structural stability. Internal sizing agents, such as alkyl ketene dimer (AKD) or rosin, are commonly added during pulp preparation. They may act as a hydrophobic coating over individual fibers, replacing hydrophilic groups on cellulose with hydrophobic alkyl oraromatic groups which results in reduced water absorption. Conversely, external sizing agents, such as polyvinyl alcohol (PVA), are applied to paper surfaces post sheet formation. Application of external sizing agents may result in hydrophobic film formation. Inducing intermolecular forces between the sizing agent and cellulose fibers (e.g., hydrogen bonding or van der Waals forces) may increase adhesion.

[0137] Traditional methods of paper making uses sizing agents to increase desired properties of finished papers. An important property of paper is low absorbency so printed ink or paint does not run or feather. Internal, external, or both types of sizing agents may be necessary to impart the desired qualities.

[0138] Common sizing agents include alkyl ketene dimer, rosin and derivatives thereof, alkyl succinic anhydride, starches, gelatin, various acrylic acid derivatives, styrene maleic anhydride, polyvinyl alcohol, and polyurethane. Common categories of sizing agents include animal-based (e.g., rabbit skin glue), plant-based (e.g., wheat starch, methylcellulose), synthetic (e.g., PVA), and regenerated natural material (e.g., silk fibroin solution). A skilled artisan will appreciate that this is not an exhaustive list and that sizing agents are chosen for a variety of reasons including ink spread, paper quality, paper strength, porosity, and other characteristics.

[0139] The inventors discovered that surprisingly in the recycled silk paper and the virgin silk paper, no sizing agents were necessary to produce papers capable of use with inkjet printers with comparable brightness and color compared to traditional paper.

[0140] However, it should be appreciated that while the recycled silk paper and the virgin silk paper are capable of being made without the need for any additives or sizing agents, recycled silk paper can be made with conventional internal or external sizing agents to adjust absorption and strength of the paper. A skilled artisan will appreciate that, in certain circumstances, sizing agents may be desired (e.g., to decrease rate of absorption of paints). Further details on the relationship of recycled silk paper and sizing agents may be found in the Examples.

[0141] Silk fibroin solution as a sizing agent

[0142] Using silk solution as a sizing agent, either crosslinked or not, on silk paper enables making a mono-material sized paper that eliminates the need for other chemical additives and simplifies recycling. Moreover, using re-silk paints to paint on silk-sized silk paper promotes mono-materiality. The inventors found that external sizing with silk solution usefully increased the hydrophobicity of papers and decreased the rate of absorption for paints.

[0143] Beating of paper pulp

[0144] Silk fabric waste fibers and virgin silk fibers may be beaten to control consistency of the pulp as well as the length of the silk fibers. Beating the fibers causes the fibers to branch into smallerfibers called fibrils. The longer the pulp is beaten for, the finer it becomes because of further defibrillation. Beating time may be selected depending on the desired application. Further details on pulp beating may be found in the Examples.

[0145] Impact of water on papermaking

[0146] Water is a crucial component of papermaking as water molecules are essential for the formation of hydrogen bonds between cellulose fibers. Fiber-to- fiber bonding in paper impacts the strength of the paper. In the methods described herein, tap water may be used. There may not be a need for purified water.

[0147] Silk has the potential to form hydrogen bonds. During the beating process, the silk fibers are defibrillated. Once dispersed in the vat filled with water and pulp, the silk fibers bond with the water molecules. Upon drying, hydrogen bonds form between the silk fibers, resulting in the formation of a strong paper.

[0148] A skilled artisan will appreciate that different water types with varying factors such as purity and pH may impact the quality, durability, and / or consistency of the recycled.

[0149] Colors

[0150] The recycled silk paper retains most of the color of the fabrics processed, locking the dyed fabric in a circular loop for consumer use while simultaneously reducing the chances of potentially toxic dyes or pigments leaching out into the oceans.

[0151] The recycled silk paper may have a color described by a desired wavelength range. The desired wavelength range may have a minimum wavelength of 380 nm and a maximum wavelength of 700 nm. The minimum wavelength may be at least 380 nm, at least 385 nm, at least 390 nm, at least 395 nm, at least 400 nm, at least 405 nm, at least 410 nm, at least 415 nm, at least 420 nm, at least 425 nm, at least 430 nm, at least 435 nm, at least 440 nm, at least 445 nm, at least 450 nm, at least 455 nm, at least 460 nm, at least 465 nm, at least 440 nm, at least 445 nm, at least 480 nm, at least 485 nm, at least 490 nm, at least 495 nm, at least 500 nm, at least 505 nm, at least 510 nm, at least 515 nm, at least 520 nm, at least 525 nm, at least 530 nm, at least 535 nm, at least 550 nm, at least 555 nm, at least 550 nm, at least 555 nm, at least 560 nm, at least 565 nm, at least 550 nm, at least 555 nm, at least 580 nm, at least 585 nm, at least 590 nm, at least 595 nm, at least 600 nm, at least 605 nm, at least 610 nm, at least 615 nm, at least 620 nm, at least 625 nm, at least 630 nm, at least 635 nm, at least 660 nm, at least 665 nm, at least 650 nm, at least 655 nm, at least 660 nm, at least 665 nm, at least 660 nm, at least 665 nm, at least 680 nm, at least 685 nm, at least 690 nm, or at least 695 nm. The maximum wavelength may be at most 700 nm, at most 695 nm, at most 690 nm, at most 685 nm, at most 680 nm, at most 675 nm, at most 670 nm, at most 665 nm, at most 660 nm, at most 655 nm, at most 650 nm, at most 645 nm, at most 640 nm, at most 635 nm, at most 630 nm, atmost 625 nm, at most 620 nm, at most 615 nm, at most 610 nm, at most 605 nm, at most 600 nm, at most 595 nm, at most 590 nm, at most 585 nm, at most 580 nm, at most 575 nm, at most 570 nm, at most 555 nm, at most 550 nm, at most 555 nm, at most 550 nm, at most 545 nm, at most 540 nm, at most 535 nm, at most 530 nm, at most 525 nm, at most 520 nm, at most 515 nm, at most 510 nm, at most 505 nm, at most 500 nm, at most 495 nm, at most 490 nm, at most 485 nm, at most 480 nm, at most 475 nm, at most 470 nm, at most 445 nm, at most 440 nm, at most 455 nm, at most 450 nm, at most 445 nm, at most 440 nm, at most 435 nm, at most 430 nm, at most 425 nm, at most 420 nm, at most 415 nm, at most 410 nm, or at most 405 nm, at most 400 nm, at most 395 nm, at most 390 nm, or at most 385 nm.

[0152] A skilled artisan will appreciate that the recycled silk paper may be recolored using a dye or pigment described herein.

[0153] Whitening agents

[0154] Wood pulp, the base material of traditional paper, has a natural yellow color which is present in the final paper product if left uncorrected. This leads to use of whitening agents in traditional papermaking. Whitening agents include white dyes, white pigments, and bleaching agents in the forms of additives, fillers, and / or coatings. If bleaching agents are used, they must be removed from the pulp before formation of the final product.

[0155] Unexpectedly, recycled silk paper made from white silk-based textile waste and virgin silk paper require no whitening agents to produce a white paper. Further details may be found in the Examples.

[0156] Binding agents

[0157] In traditional papermaking, binding agents are used to increase the strength of paper through increased interaction of cellulose fibers. Common types of binding agents include starch, synthetic polymers (e.g., latex and derivatives thereof and styrene acrylic), and naturally occurring polymers (e.g., carboxymethyl cellulose, hydroxyethyl cellulose, dextrins). Without binding agents, traditional paper may have many surface imperfections and weak cohesion.

[0158] Impressively, recycled silk paper and virgin silk paper do not require binding agents. Silk fibers are thinner and show more extensive defibrillation than cellulose fibers which play a crucial role in forming denser fiber networks as well as stronger bonds between fibers resulting in a stronger paper. The presence of silk fibrils in recycled silk fiber is higher than the presence of cellulose fibrils in traditional paper which is important in forming hydrogen bonds among fibers.

[0159] Patterning

[0160] Pressing recycled silk paper or virgin silk paper at a higher temperature (60 °C - 180 °C) for a duration of time between 1 minute and 1.5 hours results in phase transition. This allows for patternreplication from desired optical patterns made from a material that is resistant to high temperatures (e.g., nickel or steel shims) with a micro or nano pattern. Pattern replication is a promising feature for applications such as embossed embellishments and authentication technology.

[0161] Surface modification can be achieved using processes such as hot pressing as described herein, cold pressing, or embossing. A skilled artisan will appreciate that other surface patterning techniques may also be used.

[0162] Beating degree

[0163] Beating, which may also be referred to as refining, is a mechanical treatment of paper pulp performed in water. Beating results in splitting, swelling, and hydrating of fibers in the pulp, leading to increased surface area and bonding strength between fibers. The beating degree of pulp is related to the draining performance of the pulp and may be used as an indicator for certain properties of the pulp. Broadly, a lower degree of beating corresponds to faster drainage of water through the pulp.

[0164] Flammability

[0165] Recycled silk paper and virgin silk paper when subjected to flammability tests may display fire resistance. Compared to cellulose print paper and colored cellulose papers which ignite instantly and bum completely, virgin silk paper and recycled silk paper show reduced burning and do not sustain flames.

[0166] Methods of making recycled silk paper

[0167] At a high level, a method of recycling silk fabric waste into recycled silk paper may include steps a)-e). An optional step a) includes sorting the silk fabric waste by color to produce a color- sorted silk fabric waste. Step b) includes shredding the optionally color-sorted silk waste to produce a shredded silk fabric waste. Step c) includes soaking the shredded silk fabric waste in water for a soaking length of time between 6 hours and 7 days to produce soaked shredded silk fabric waste. Step d) includes pulping the soaked shredded silk fabric waste to produce a silk fabric waste pulp. Step e) includes making recycled silk paper from the silk fabric waste pulp.

[0168] The silk fabric waste may be examined for any possible impurities, such as staples, tape, or tags which are then removed prior to optional step a) or step b).

[0169] Step e) may further include pulling a wet sheet from a vat containing the silk fabric waste pulp. The wet sheet may be couched and optionally further dried to form a dried sheet. The drying may be performed under a drying pressure that is greater than atmospheric pressure. The dried sheet may be planarized, optionally through an etching process. The whole method or step e) may be free of sizing or sizing agents.

[0170] The pulping of step d) may include beating the soaked shredded silk fabric waste. The beating may be performed from level 30 to 0 on a Reina beater. The beating may be performed atleast until a beating degree reaches 0. The beating may be performed after the beating degree reaches 0 for at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, at least 30 minutes, at least 35 minutes, at least 40 minutes, at least 45 minutes, at least 50 minutes, at least 55 minutes, at least one hour, at least two hours, at least three hours, or more. The beating may be performed at most twelve hours, at most six hours, at most three hours, at most two hours, at most one hour, at most 55 minutes, at most 50 minutes, at most 45 minutes, at most 40 minutes, at most 35 minutes, at most 30 minutes, at most 25 minutes, at most 20 minutes, at most 15 minutes, at most 10 minutes, or at most 5 minutes after the beating degree reaches 0. A skilled artisan will appreciate that the beating time can be shortened or extended to a few hours depending on the desired pulp consistency, and that long beating times (e.g., 1 to 2 hours post level 0) generally results in very short and fine fibers that are used for pulp painting.

[0171] The water of step c) may be tap water.

[0172] Optional step a) may be performed in the method. The sorting of step a) may produce color- sorted silk fabric waste that is substantially colorless, gray or black, or has a color with a peak wavelength within a desired wavelength range as described herein. The desired wavelength range may be as described herein and / or have at least a portion falling within a red, orange, yellow, green, blue, purple, or violet part of the visible spectrum.

[0173] The method or materials described herein may be free of binding agents and / or whitening agents. Specifically, waste products, final products, and methods may be free of and / or introduce no binding agents and / or whitening agents.

[0174] The method described herein may further include patterning the recycled silk paper. The patterning may produce an optically active surface on the surface of the recycled silk paper.

[0175] Materials produced by the methods described herein

[0176] Recycled silk paper or virgin silk paper may be made by the methods described herein. The recycled silk paper or virgin silk paper may be fully dissolved in a lithium bromide solution.

[0177] The recycled silk paper or virgin silk paper may have an elongation at break of at least 1%, at least 2%, at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, or greater. The recycled silk paper or virgin silk paper may have an elongation at break of at most 10%, at most 9%, at most 8%, at most 7%, at most 6%, at most 5%, at most 4%, at most 3%, at most 2%, or at most 1 %.

[0178] The recycled silk paper may receive laser printing at a resolution within ± 10% of a resolution when printing on recycled cellulose paper, including but not limited to, at least 1%, at least 2% at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least, 12%, at least 13%, at least 14%, or at least 15%. The resolution maybe within at most 15%, at most 14%, at most 13%, at most 12%, at most 11%, at most 10%, at most 9%, at most 8%, at most 6%, at most 5%, at most 4%, at most 3%, at most 2%, or at most 1%.

[0179] The virgin silk paper may receive laser printing at a resolution within ± 10% of a resolution when printing on cellulose paper, including but not limited to, at least 1%, at least 2% at least 3%, at least 4%, at least 5%, at least 6%, at least 7%, at least 8%, at least 9%, at least 10%, at least 11%, at least, 12%, at least 13%, at least 14%, or at least 15%. The resolution may be within at most 15%, at most 14%, at most 13%, at most 12%, at most 11%, at most 10%, at most 9%, at most 8%, at most 6%, at most 5%, at most 4%, at most 3%, at most 2%, or at most 1%.

[0180] The recycled silk paper or virgin silk paper may be 100% silk, 99% silk, 98% silk, 95% silk, 90% silk, 85% silk, or less. The recycled silk paper or virgin silk paper may be at least 99% silk, at least 98% silk, at least 95% silk, at least 90% silk, or at least 85% silk.

[0181] Recycled silk paper or virgin silk paper may be produced in a range of thicknesses between 20 and 500 grams per square meter (GSM). Thickness may be at least 20 GSM, at least 50 GSM, at least 100 GSM, at least 200 GSM, at least 300 GSM, or at least 400 GSM. Thickness may be at most 500 GSM, at most 400 GSM, at most 300 GSM, at most 200 GSM, at most 100 GSM, or at most 50 GSM.

[0182] Potential applications of recycled silk paper

[0183] Beyond paper, recycled pure silk or silk blends pulps can be processed into a variety of products for various industries such as sculpting material for arts, pulp paints, molding into packaging forms, branding material for fashion houses, acoustics panels, silk electronics, diagnostics test strips, cell culture platforms, 3D cell scaffolds, wound dressings, and paper-based sensors, sensing wallpapers, sensitive documents, and materials in space exploration.

[0184] Virgin silk paper

[0185] Similar to the recycled silk paper described herein, virgin silk paper may be produced from Bombyx mori cocoons. Virgin silk paper or components used therein may also be referred to as ‘unrecycled’ , which should be taken to have the same meaning as virgin. Both terms are used to refer to silk that has been extracted from cocoons and not previously used or recycled. A skilled artisan will appreciate that virgin silk paper may have the same or similar properties as the recycled silk paper as described herein.

[0186] Virgin silk paper may be prepared from silk cocoons. The virgin silk paper may be suitable for biomedical applications.

[0187] Methods of making virgin silk paper

[0188] A method of producing virgin silk paper may include the following steps. Bombyx mori cocoons may be boiled to degum and reel the fibers. The fibers may be cut into pieces to produce aplurality of cut silk fibers. The cut silk fibers may be soaked in tap water for a soaking length of time to allow hydration and swelling of fibers to form a plurality of soaked silk fibers. The plurality of soaked silk fibers may be pulped to form a virgin silk pulp. The virgin silk pulp may be made into virgin silk paper.

[0189] The method may further include pulling a wet sheet from a vat containing the virgin silk pulp. The wet sheet may be couched. The method may further include drying the wet sheet to form a dried sheet.

[0190] The chopped pieces may be between 0.1 cm and 10 cm. The pieces may be at least 0.1 cm, at least 0.5 cm, at least 1 cm, at least 2 cm, at least 4 cm, or at least 6 cm. The pieces may be at most 10 cm, at most 7 cm, at most 5 cm, at most 3 cm, or at most 1 cm.

[0191] The soaking length of time may be between 12 hours and 7 days. The soaking length of time may be at least 12 hours, at least 1 day, at least 2 days, at least 3 days, or at least 4 days. The soaking length of time may be at most 7 days, at most 5 days, at most 3 days, or at most 1 day.

[0192] The method may further include pulling a wet sheet from a vat containing the silk fabric waste pulp. The wet sheet may be couched and optionally further dried to form a dried sheet. The drying may be performed under a drying pressure that is greater than atmospheric pressure. The dried sheet may be planarized, optionally through an etching process. The whole method or the step of making the virgin silk pulp into virgin silk paper may be free of sizing or sizing agents.

[0193] The pulping may include beating the soaked silk fibers. The beating may be performed from level 30 to 0 on a Reina beater. The beating may be performed at least until a beating degree reaches 0. The beating may be performed after the beating degree reaches 0 for at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, at least 30 minutes, at least 35 minutes, at least 40 minutes, at least 45 minutes, at least 50 minutes, at least 55 minutes, at least one hour, at least two hours, at least three hours, or more. The beating may be performed at most twelve hours, at most six hours, at most three hours, at most two hours, at most one hour, at most 55 minutes, at most 50 minutes, at most 45 minutes, at most 40 minutes, at most 35 minutes, at most 30 minutes, at most 25 minutes, at most 20 minutes, at most 15 minutes, at most 10 minutes, or at most 5 minutes after the beating degree reaches 0. A skilled artisan will appreciate that the beating time can be shortened or extended to a few hours depending on the desired pulp consistency, and that long beating times (e.g., 1 to 2 hours post level 0) generally results in very short and fine fibers that are used for pulp painting.

[0194] The method or materials described herein may be free of binding agents and / or whitening agents. Specifically, waste products, final products, and methods may be free of and / or introduce no binding agents and / or whitening agents.

[0195] The method described herein may further include patterning the virgin silk paper. The patterning may produce an optically active surface on the surface of the virgin silk paper.

[0196] Differences between recycled silk paper and virgin silk paper

[0197] While both the recycled silk paper and virgin silk paper are made of silk, the sources are different. Recycled silk paper is derived from waste, while virgin silk paper is derived from cocoons. These differing sources determines the potential for medical- and food-related applications.

[0198] Initial processing of the materials is also different. For the recycled silk paper, waste fabrics are cut into 20 cm x 20 cm pieces to process in the shredder before beating, whereas for the virgin silk paper, silk fibers are reeled from cocoons and cut into small strands of 2 cm before beating.

[0199] Making virgin silk papers from cocoons allows for higher accuracy, control, and consistency to prepare 100% white silk blend. For the recycled silk paper, if there are any silk blend waste fabrics and slightly different colored fabrics being processed together, it could result in varied coloration in papers and silk compositions.

[0200] It should be apparent to those skilled in the art that many additional modifications beside those already described are possible without departing from the inventive concepts. In interpreting this disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. Variations of the term "comprising" should be interpreted as referring to elements, components, or steps in a non-exclusive manner, so the referenced elements, components, or steps may be combined with other elements, components, or steps that are not expressly referenced. Embodiments referenced as "comprising" certain elements are also contemplated as "consisting essentially of" and "consisting of" those elements. When two or more ranges for a particular value are recited, this disclosure contemplates all combinations of the upper and lower bounds of those ranges that are not explicitly recited. For example, recitation of a value of between 1 and 10 or between 2 and 9 also contemplates a value of between 1 and 9 or between 2 and 10.

[0201] As used herein, "silk fibroin" refers to silk fibroin protein whether produced by silkworm, spider, or other insect, or otherwise generated (Lucas et al., Adv. Protein Chem., 13: 107-242 (1958)). Any type of silk fibroin can be used in different embodiments described herein. Silk fibroin produced by silkworms, such as Bombyx mori, is the most common and represents an earth-friendly, renewable resource. For instance, silk fibroin used in a silk film may be attained by extracting sericin from the cocoons of B. mori. Organic silkworm cocoons are also commercially available. There are many different silks, however, including spider silk (e.g., obtained from Nephila clavipes), transgenic silks, genetically engineered silks, such as silks from bacteria, yeast, mammalian cells, transgenic animals, or transgenic plants, and variants thereof, that can be used. See, e.g., WO97 / 08315 and U.S. Pat. No. 5,245,012, each of which is incorporated herein by reference in their entireties.

[0202] Additives

[0203] According to various embodiments, a variety of functionalizing agents may be used with the silk-containing embodiments described herein (e.g., silk membrane, silk composition, silk articles, silk matrix, silk foam, silk microsphere, liquid composition, whipped silk cream, silk meringue, compressed silk meringue, hot-pressed silk meringue, silk leather, silk powder, silk toner, edible silkbased films, silk pigment, silk paper, etc.). It should be understood that the examples herein may recite one or a few silk-containing embodiments but are applicable to any silk-containing embodiment. In some embodiments, a functionalizing agent may be any compound or molecule that facilitates the attachment to and / or development (e.g., growth) of one or more endothelial cells on a silk membrane. In some embodiments, a functionalizing agent may be any compound or molecule that facilitates the attachment and / or development (e.g., growth) of one or more megakaryocytes and / or hematopoietic progenitor cells on a silk matrix and / or silk membrane. In some embodiments, a functionalizing agent may be or comprise an agent suitable for facilitating the production of one or more of white blood cells and red blood cells.

[0204] In some embodiments, a functionalizing agent may be or comprise a cell attachment mediator and / or an extracellular matrix protein, for example: collagen (e.g., collagen type I, collagen type III, collagen type IV or collagen type VI), elastin, fibronectin, vitronectin, laminin, fibrinogen, von Willebrand factor, proteoglycans, decorin, perlecan, nidogen, hyaluronan, and / or peptides containing known integrin binding domains e.g. “RGD” integrin binding sequence, or variations thereof, that are known to affect cellular attachment.

[0205] In some embodiments, a functionalizing agent may be any soluble molecule produced by endothelial cells. Non-limiting examples include fibroblast growth factor- 1 (FGF1) and vascular endothelial growth factors (VEGF).

[0206] According to some embodiments, a plurality of functionalizing agents may be used. For example, in some embodiments wherein production of platelets is desired, provided compositions may comprise the use of laminin, fibronectin and / or fibrinogen, and type IV collagen in order to facilitate the attachment and growth of endothelial cells on a silk membrane (e.g., a porous silk membrane) and / or attachment of megakaryocytes to a silk matrix.

[0207] In some embodiments, a functionalizing agent may be embedded or otherwise associated with a silk membrane and / or silk matrix such that at least a portion of the functionalizing agent is surrounded by a silk membrane and / or silk matrix as contrasted to a functionalizing agent simply being positioned along the surface of a silk membrane and / or silk matrix. In some embodiments, afunctionalizing agent is distributed along and / or incorporated in substantially the entire surface area of a silk membrane / silk wall. In some embodiments, a functionalizing agent is distributed and / or incorporated only at one or more discrete portions of a silk membrane / wall and / or silk matrix. In some embodiments, a functionalizing agent is distributed in and / or along at least one of the lumenfacing side of a silk wall and the matrix-facing side of a silk wall.

[0208] According to various embodiments, any application- appropriate amount of one or more functionalizing agents may be used. In some embodiments, the amount of an individual functionalizing agent may be between about 1 pg / ml and 1,000 pg / ml (e.g., between about 2 and 1,000, 5 and 1,000, 10 and 1,000, 10 and 500, 10 and 100 pg / ml). In some embodiments, the amount of an individual functionalizing agent may be at least 1 pg / ml (e.g., at least 5, 10, 15, 20 25, 50, 100, 200, 300 400, 500, 600, 700, 800, or 900 pg / ml ). In some embodiments, the amount of an individual functionalizing agent is at most 1,000 pg / ml (e.g., 900, 800, 700, 600, 500, 400, 300 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, or 5 pg / ml).

[0209] In some aspects, the composition comprises one or more sensing agents, such as a sensing dye. The sensing agents / sensing dyes are environmentally sensitive and produce a measurable response to one or more environmental factors. In some aspects, the environmentally- sensitive agent or dye may be present in the composition in an effective amount to alter the composition from a first chemical-physical state to a second chemical-physical state in response to an environmental parameter (e.g., a change in pH, light intensity or exposure, temperature, pressure or strain, voltage, physiological parameter of a subject, and / or concentration of chemical species in the surrounding environment) or an externally applied stimulus (e.g., optical interrogation, acoustic interrogation, and / or applied heat). In some cases, the sensing dye is present to provide one optical appearance under one given set of environmental conditions and a second, different optical appearance under a different given set of environmental conditions. Suitable concentrations for the sensing agents described herein can be the concentrations for the colorants and additives described elsewhere herein. A person having ordinary skill in the chemical sensing arts can determine a concentration that is appropriate for use in a sensing application of the inks described herein.

[0210] In some aspects, the first and second chemical-physical state may be a physical property of the composition, such as mechanical property, a chemical property, an acoustical property, an electrical property, a magnetic property, an optical property, a thermal property, a radiological property, or an organoleptic property. Exemplary sensing dyes or agents include, but are not limited to, a pH sensitive agent, a thermal sensitive agent, a pressure or strain sensitive agent, a light sensitive agent, or a potentiometric agent.

[0211] Exemplary pH sensitive dyes or agents include, but are not limited to, cresol red, methyl violet, crystal violet, ethyl violet, malachite green, methyl green, 2-(p- dimethylaminophenylazo)pyridine, paramethyl red, metanil yellow, 4-phenylazodiphenylamine, thymol blue, metacresol purple, orange IV, 4-o-Tolylazo-o-toluindine, quinaldine red, 2,4- dinitrophenol, erythrosine disodium salt, benzopurpurine 4B, N,N-dimethyl-p-(m-tolylazo) aniline, p-dimethylaminoazobenene, 4,4’-bis(2-amino-l-naphthylazo)-2,2’-stilbenedisulfonic acid, tetrabromophenolphthalein ethyl ester, bromophenol blue, Congo red, methyl orange, ethyl orange, 4-(4-dimethylamino-l-naphylazo)-3-methoxybenesulfonic acid, bromocresol green, resazurin, 4- phenylazo-l-napthylamine, ethyl red 2-(l-dimethylaminophenyazo) pyridine, 4-(p-ethoxyphenylazo)- m-phenylene-diamine monohydrochloride, resorcin blue, alizarin red S, methyl red, propyl red, bromocresol purple, chlorophenol red, p-nitrophenol, alizarin, 2-(2,4-dinitrophenylazo)-l-napthol-3.6-disulfonic acid, bromothymol blue, 6, 8-dinitro-lH-quinazoline-2, 4-dione, brilliant yellow, phenol red, neutral red, m-nitrophenol, cresol red, turmeric, metacresol purple, 4,4'-bis(3-amino-l- naphthylazo)-2,2'-stilbenedisulfonic acid, thymol blue, p-naphtholbenzein, phenolphthalein, o- cresolphthalein, ethyl bis(2,4-dimethylphenyl) ethanoate, thymolphthalein, nitrazine yellow, alizarin yellow R, alizarin, p-(2,4-dihydroxyphenylazo) benzenesulfonic acid, 5,5'-indigodisulfonic acid,2.4.6-trinitrotoluene, 1,3,5-trinitrobenezne, and clayton yellow.

[0212] Exemplary light responsive dyes or agents include, but are not limited to, photochromic compounds or agents, such as triarylmethanes, stilbenes, azastilbenes, nitrones, fulgides, spiropyrans, napthopyrans, spiro-oxazines, quinones, derivatives, and combinations thereof.

[0213] Exemplary potentiometric dyes include, but are not limited to, substituted amiononaphthylehenylpridinium (ANEP) dyes, such as di-4-ANEPPS, di-8-ANEPPS, and N-(4- Sulfobutyl)-4-(6-(4-(Dibutylamino)phenyl)hexatrienyl)Pyridinium (RH237).

[0214] Exemplary temperature sensitive dyes or agents include, but are not limited to, thermochromic compounds or agents, such as thermochromic liquid crystals, leuco dyes, fluoran dyes, octadecylphosphonic acid.

[0215] Exemplary pressure or strain sensitive dyes or agents include, but are not limited to, spiropyran compounds and agents.

[0216] Exemplary chemi-sensitive dyes or agents include, but are not limited to, antibodies such as immunoglobulin G (IgG) which may change color from blue to red in response to bacterial contamination.

[0217] In some aspects, the compositions comprise one or more additive, dopant, or biologically active agent suitable for a desired intended purpose. In some aspects, the additive or dopant may be present in the composition in an amount effective to impart an optical or organoleptic property to thecomposition. Exemplary additives or dopants that impart optical or organoleptic properties include, but are not limited to, dyes / pigments, flavorants, aroma compounds, granular or fibrous fillers.

[0218] Additionally or alternatively, the additive, dopant, or biologically active agent may be present in the composition in an amount effective to "functionalize" the composition to impart a desired mechanical property or added functionality to the composition. Exemplary additive, dopants, or biologically active agent that impart the desired mechanical property or added functionality include, but are not limited to: environmentally sensitive / sensing dyes; active biomolecules; conductive or metallic particles; micro and nanofibers (e.g., silk nanofibers for reinforcement, carbon nanofibers); nanotubes; inorganic particles (e.g., hydroxyapatite, tricalcium phosphate, bioglasses); drugs (e.g., antibiotics, small molecules or low molecular weight organic compounds); proteins and fragments or complexes thereof (e.g., enzymes, antigens, antibodies and antigen-binding fragments thereof);DNA / RNA (e.g., siRNA, miRNA, mRNA); cells and fractions thereof (viruses and viral particles; prokaryotic cells such as bacteria; eukaryotic cells such as mammalian cells and plant cells; fungi).

[0219] In some aspects, the additive or dopant comprises a flavoring agent or flavorant.

[0220] Exemplary flavorants include ester flavorants, amino acid flavorants, nucleic acid flavorants, organic acid flavorants, and inorganic acid flavorants, such as, but not limited to, diacetyl, acetyl propionyl, acetoin, isoamyl acetate, benzaldehyde, cinnamaldehyde, ethyl propionate, methyl anthranilate, limonene, ethyl decadienoate, allyl hexanoate, ethyl maltol, ethylvanillin, methyl salicylate, manzanate, glutamic acid salts, glycine salts, guanylic acids salts, inosinic acid salts, acetic acid, ascorbic acid, citric acid, fumaric acid, lactic acid, malic acid, phosphoric acid, tartaric acid, derivatives, and mixtures thereof.

[0221] In some aspects, the additive or dopant comprises an aroma compound. Exemplary aroma compounds include ester aroma compounds, terpene aroma compounds, cyclic terpenes, and aromatic aroma compounds, such as, but not limited to, geranyl acetate, methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl butyrate, isoamyl acetate, pentyl butyrate, pentyl pentanoate, octyl acetate, benzyl acetate, methyl anthranilate, myrcene, geraniol, nerol, citral, citronellal, cironellol, linalool, nerolidol, limonene, camphor, menthol, carone, terpineol, alpha-ionone, thujone, eucalyptol, benzaldehyde, eugenol, cinnamaldehyde, ethyl maltol, vanillin, anisole, anethole, estragole, thymol.

[0222] In some aspects, the additive or dopant comprises a colorant, such as a dye or pigment. In some aspects, the dye or pigment imparts a color or grayscale to the composition. The colorant can be different than the sensing agents and / or sensing dyes below. Any organic and / or inorganic pigments and dyes can be included in the inks. Exemplary pigments suitable for use in the present disclosure include International Color Index or C.I. Pigment Black Numbers 1 , 7, 1 1 and 31, C.I.Pigment Blue Numbers 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 27, 29, 61 and 62, C.I. Pigment Green Numbers 7, 17, 18 and 36, C.I. Pigment Orange Numbers 5, 13, 16, 34 and 36, C.I. Pigment Violet Numbers 3, 19, 23 and 27, C.I. Pigment Red Numbers 3, 17, 22, 23, 48:1, 48:2, 57:1 , 81 :1, 81 :2, 81 :3, 81:5, 101, 114, 122, 144, 146, 170, 176, 179, 181, 185, 188, 202, 206, 207, 210 and 249, C.I. Pigment Yellow Numbers 1, 2, 3, 12, 13, 14, 17, 42, 65, 73, 74, 75, 83, 30, 93, 109, 1 10, 128, 138, 139, 147, 142, 151, 154 and 180, D&C Red No. 7, D&C Red No. 6 and D&C Red No. 34, carbon black pigment (such as Regal 330, Cabot Corporation), quinacridone pigments (Quinacridone Magenta (228-0122), available from Sun Chemical Corporation, Fort Lee, N.J.), diarylide yellow pigment (such as AAOT Yellow (274- 1788) available from Sun Chemical Corporation); and phthalocyanine blue pigment (such as Blue 15:3 (294-1298) available from Sun Chemical Corporation). The classes of dyes suitable for use in present invention can be selected from acid dyes, natural dyes, direct dyes (either cationic or anionic), basic dyes, and reactive dyes. The acid dyes, also regarded as anionic dyes, are soluble in water and mainly insoluble in organic solvents and are selected, from yellow acid dyes, orange acid dyes, red acid dyes, violet acid dyes, blue acid dyes, green acid dyes, and black acid dyes. European Patent 0745651, incorporated herein by reference, describes a number of acid dyes that are suitable for use in the present disclosure. Exemplary yellow acid dyes include Acid Yellow 1 International Color Index or C.I. 10316); Acid Yellow 7 (C.I. 56295); Acid Yellow 17 (C.I. 18965); Acid Yellow 23 (C.I. 19140); Acid Yellow 29 (C.I. 18900); Acid Yellow 36 (C.I. 13065); Acid Yellow 42 (C.I. 22910); Acid Yellow 73 (C.I. 45350); Acid Yellow 99 (C.I. 13908); Acid Yellow 194; and Food Yellow 3 (C.I. 15985). Exemplary orange acid dyes include Acid Orange 1 (C.I. 13090 / 1 ); Acid Orange 10 (C.I. 16230); Acid Orange 20 (C.I. 14603); Acid Orange 76 (C.I. 18870); Acid Orange 142; Food Orange 2 (C.I. 15980); and Orange B.

[0223] Exemplary red acid dyes include Acid Red 1 (C.I. 18050); Acid Red 4 (C.I. 14710); Acid Red 18 (C.I. 16255); Acid Red 26 (C.I. 16150); Acid Red 27 (C.I. 16185); Acid Red 51 (C.I. 45430, available from BASF Corporation, Mt. Olive, N.J.); Acid Red 52 (C.I. 45100); Acid Red 73 (C.I. 27290); Acid Red 87 (C.I. 45380); Acid Red 94 (C.I. 45440) Acid Red 194; and Food Red 1 (C.I. 14700). Exemplary violet acid dyes include Acid Violet 7 (C.I. 18055); and Acid Violet 49 (C.I. 42640). Exemplary blue acid dyes include Acid Blue 1 (C.I. 42045); Acid Blue 9 (C.I. 42090); Acid Blue 22 (C.I. 42755); Acid Blue 74 (C.I. 73015); Acid Blue 93 (C.I. 42780); and Acid Blue 158A (C.I. 15050). Exemplary green acid dyes include Acid Green 1 (C.I. 10028); Acid Green 3 (C.I. 42085); Acid Green 5 (C.I. 42095); Acid Green 26 (C.I. 44025); and Food Green 3 (C.I. 42053). Exemplary black acid dyes include Acid Black 1 (C.I. 20470); Acid Black 194 (Basantol® X80, available from BASF Corporation, an azo / 1 :2 CR-complex.

[0224] Exemplary direct dyes for use in the present disclosure include Direct Blue 86 (C.I. 74180); Direct Blue 199; Direct Black 168; Direct Red 253; and Direct Yellow 107 / 132 (C.I. Not Assigned).

[0225] Exemplary natural dyes for use in the present disclosure include Alkanet (C.I. 75520,75530); Annatto (C.I. 75120); Carotene (C.I. 75130); Chestnut; Cochineal (C.I.75470); Cutch (C.I. 75250, 75260); Divi-Divi; Fustic (C.I. 75240); Brazilin (C.I. 75280); Logwood (C.I. 75200); Osage Orange (C.I. 75660); Paprika; Quercitron (C.I. 75720); Saffron (C.I. 75100); Sandal Wood (C.I. 75510, 75540, 75550, 75560); Sumac; and Turmeric (C.I. 75300). Exemplary reactive dyes for use in the present disclosure include Reactive Yellow 37 (monoazo dye); Reactive Black 31 (diazo dye); Reactive Blue 77 (phthalo cyanine dye) and Reactive Red 180 and Reactive Red 108 dyes. Suitable also are the colorants described in The Printing Ink Manual (5th ed., Leach et al. eds. (2007), pages 289-299). Other organic and inorganic pigments and dyes and combinations thereof can be used to achieve the colors desired.

[0226] In addition to or in place of visible colorants, compositions provided herein can contain ETV fluorophores that are excited in the ETV range and emit light at a higher wavelength (typically 400 nm and above). Examples of ETV fluorophores include but are not limited to materials from the coumarin, benzoxazole, rhodamine, napthalimide, perylene, benzanthrones, benzoxanthones or benzothia-xanthones families. The addition of a UV fluorophore (such as an optical brightener for instance) can help maintain maximum visible light transmission. The amount of colorant, when present, generally is between 0.05% to 5% or between 0.1% and 1% based on the weight of the composition.

[0227] For non-white compositions, the amount of pigment / dye generally is present in an amount of from at or about 0.1 wt% to at or about 20 wt% based on the weight of the composition. In some applications, a non-white ink can include 15 wt% or less pigment / dye, or 10 wt% or less pigment / dye or 5 wt% pigment / dye, or 1 wt% pigment / dye based on the weight of the composition. In some applications, a non-white ink can include 1 wt% to 10 wt%, or 5 wt% to 15 wt%, or 10 wt% to 20 wt% pigment / dye based on the weight of the composition. In some applications, a non-white ink can contain an amount of dye / pigment that is 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15%, 16 wt%, 17 wt%, 18 wt%, 19 wt% or 20 wt% based on the weight of the composition.

[0228] For white compositions, the amount of white pigment generally is present in an amount of from at or about 1 wt% to at or about 60 wt% based on the weight of the composition. In some applications, greater than 60 wt% white pigment can be present. Preferred white pigments include titanium dioxide (anatase and rutile), zinc oxide, lithopone (calcined coprecipitate of barium sulfate and zinc sulfide), zinc sulfide, blanc fixe and alumina hydrate and combinations thereof, althoughany of these can be combined with calcium carbonate. In some applications, a white ink can include 60 wt% or less white pigment, 55 wt% or less white pigment, 50 wt% white pigment, 45 wt% white pigment, 40 wt% white pigment, 35 wt% white pigment, 30 wt% white pigment, 25 wt% white pigment, 20 wt% white pigment, 15 wt% white pigment, or 10 wt% white pigment, based on the weight of the composition. In some applications, a white ink can include 5 wt% to 60 wt%, 5 wt% to 55 wt%, 10 wt% to 50 wt%, 10 wt% to 25 wt%, 25 wt% to 50 wt%, 5 wt% to 15 wt%, or 40 wt% to 60 wt% white pigment based on the weight of the composition. In some applications, a non-white ink can an amount of dye / pigment that is 5%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45%, 46 wt%, 47 wt%,48 wt%, 49 wt%, 50 wt%, 51 wt%, 52 wt%, 53 wt%, 54 wt%, 55%, 56 wt%, 57 wt%, 58 wt%, 59 wt% or 60 wt% based on the weight of the composition.

[0229] In some aspects, the additive or dopant comprises a conductive additive. Exemplary conductive additives include, but are not limited to graphite, graphite powder, carbon nanotubes, and metallic particles or nanoparticles, such as gold nanoparticles. In some aspects, the conductive additive is biocompatible and non-toxic.

[0230] In some aspects, the additive is a biologically active agent. The term “biologically active agent” as used herein refers to any molecule which exerts at least one biological effect in vivo. For example, the biologically active agent can be a therapeutic agent to treat or prevent a disease state or condition in a subject. Biologically active agents include, without limitation, organic molecules, inorganic materials, proteins, peptides, nucleic acids (e.g., genes, gene fragments, gene regulatory sequences, and antisense molecules), nucleoproteins, polysaccharides, glycoproteins, and lipoproteins. Classes of biologically active compounds that can be incorporated into the composition provided herein include, without limitation, anticancer agents, antibiotics, analgesics, antiinflammatory agents, immunosuppressants, enzyme inhibitors, antihistamines, anti-convulsants, hormones, muscle relaxants, antispasmodics, ophthalmic agents, prostaglandins, anti-depressants, anti-psychotic substances, trophic factors, osteoinductive proteins, growth factors, and vaccines.

[0231] The term “active agent” may also be used herein to refer to a biological sample (e.g., a sample of tissue or fluid, such as for instance blood) or a component thereof, and / or to a biologically active entity or compound, and / or to a structurally or functionally labile entity.

[0232] Exemplary active agents include, but are not limited to, therapeutic agents, diagnostic agents (e.g., contrast agents), and any combinations thereof. In some embodiments, the active agent present in a silk matrix (e.g., a silk microsphere), composition, or the like can include a labile active agent,e.g., an agent that can undergo chemical, physical, or biological change, degradation and / or deactivation after exposure to a specified condition, e.g., high temperatures, high humidity, light exposure, and any combinations thereof. In some embodiments, the active agent present in the silk matrix (e.g., a silk microsphere), composition, or the like can include a temperature-sensitive active agent, e.g., an active agent that will lose at least about 30% or more, of its original activity or bioactivity, upon exposure to a temperature of at least about 10 °C. or above, including at least about 15 °C. or above, at least about room temperature or above, or at least about body temperature (e.g., about 37 °C.) or above.

[0233] The active agent can be generally present in the silk matrix (e.g., a silk microsphere), composition, or the like in an amount of about 0.01% (w / w) to about 70% (w / w), about 0.1% (w / w) to about 50% (w / w), or about 1% (w / w) to about 30% (w / w). The active agent can be present on a surface of the silk matrix (e.g., a silk microsphere), composition, or the like and / or encapsulated and dispersed in the silk matrix (e.g., a silk microsphere), composition, or the like homogeneously, heterogeneously, or in a gradient. In some embodiments, the active agent can be added into the silk solution, which is then subjected to the methods described herein for preparing a silk matrix (e.g., a silk microsphere), composition, or the like. In some embodiments, the active agent can be coated on a surface of the silk matrix (e.g., a silk microsphere), composition, or the like. In some embodiments, the active agent can be loaded in a silk matrix (e.g., a silk microsphere), composition, or the like by incubating the silk microsphere in a solution of the active agent for a period of time, during which an amount of the active agent can diffuse into the silk matrix (e.g., a silk microsphere), composition, or the like, and thus distribute within the silk matrix (e.g., a silk microsphere), composition, or the like.

[0234] In some aspects, the additive is a therapeutic agent. As used herein, the term “therapeutic agent” means a molecule, group of molecules, complex or substance administered to an organism for diagnostic, therapeutic, preventative medical, or veterinary purposes. As used herein, the term “therapeutic agent” includes a “drug” or a “vaccine.” This term includes externally and internally administered topical, localized and systemic human and animal pharmaceuticals, treatments, remedies, nutraceuticals, cosmeceuticals, biologicals, devices, diagnostics and contraceptives, including preparations useful in clinical and veterinary screening, prevention, prophylaxis, healing, wellness, detection, imaging, diagnosis, therapy, surgery, monitoring, cosmetics, prosthetics, forensics and the like. This term can also be used in reference to agriceutical, workplace, military, industrial and environmental therapeutics or remedies comprising selected molecules or selected nucleic acid sequences capable of recognizing cellular receptors, membrane receptors, hormone receptors, therapeutic receptors, microbes, viruses or selected targets comprising or capable of contacting plants, animals and / or humans. This term can also specifically include nucleic acids andcompounds comprising nucleic acids that produce a therapeutic effect, for example deoxyribonucleic acid (DNA), ribonucleic acid (RNA), nucleic acid analogues (e.g., locked nucleic acid (LNA), peptide nucleic acid (PNA), xeno nucleic acid (XNA)), or mixtures or combinations thereof, including, for example, DNA nanoplexes, siRNA, microRNA, shRNA, aptamers, ribozymes, decoy nucleic acids, antisense nucleic acids, RNA activators, and the like. Generally, any therapeutic agent can be included in the composition provided herein.

[0235] The term “therapeutic agent” also includes an agent that is capable of providing a local or systemic biological, physiological, or therapeutic effect in the biological system to which it is applied. For example, the therapeutic agent can act to control infection or inflammation, enhance cell growth and tissue regeneration, control tumor growth, act as an analgesic, promote anti-cell attachment, and enhance bone growth, among other functions. Other suitable therapeutic agents can include anti-viral agents, hormones, antibodies, or therapeutic proteins. Other therapeutic agents include prodrugs, which are agents that are not biologically active when administered but upon administration to a subject are converted to biologically active agents through metabolism or some other mechanism. Additionally, a silk-based drug delivery composition can contain one therapeutic agent or combinations of two or more therapeutic agents.

[0236] A therapeutic agent can include a wide variety of different compounds, including chemical compounds and mixtures of chemical compounds, e.g., small organic or inorganic molecules; saccharides; oligosaccharides; polysaccharides; biological macromolecules, e.g., peptides, proteins, and peptide analogs and derivatives; peptidomimetics; antibodies and antigen binding fragments thereof; nucleic acids; nucleic acid analogs and derivatives; an extract made from biological materials such as bacteria, plants, fungi, or animal cells; animal tissues; naturally occurring or synthetic compositions; and any combinations thereof. In some aspects, the therapeutic agent is a small molecule.

[0237] The term “bioactivity,” as used herein in reference to an active agent, generally refers to the ability of an active agent to interact with a biological target and / or to produce an effect on a biological target. For example, bioactivity can include, without limitation, elicitation of a stimulatory, inhibitory, regulatory, toxic or lethal response in a biological target. The biological target can be a molecule or a cell. For example, a bioactivity can refer to the ability of an active agent to modulate the effect / activity of an enzyme, block a receptor, stimulate a receptor, modulate the expression level of one or more genes, modulate cell proliferation, modulate cell division, modulate cell morphology, or any combination thereof. In some instances, a bioactivity can refer to the ability of a compound to produce a toxic effect in a cell. Exemplary cellular responses include, but are not limited to, lysis, apoptosis, growth inhibition, and growth promotion; production, secretion, andsurface expression of a protein or other molecule of interest by the cell; membrane surface molecule activation including receptor activation; transmembrane ion transports; transcriptional regulations; changes in viability of the cell; changes in cell morphology; changes in presence or expression of an intracellular component of the cell; changes in gene expression or transcripts; changes in the activity of an enzyme produced within the cell; and changes in the presence or expression of a ligand and / or receptor (e.g., protein expression and / or binding activity). Methods for assaying different cellular responses are well known to one of skill in the art, e.g., western blot for determining changes in presence or expression of an endogenous protein of the cell, or microscopy for monitoring the cell morphology in response to the active agent, or FISH and / or qPCR for the detection and quantification of changes in nucleic acids. Bioactivity can be determined in some embodiments, for example, by assaying a cellular response.

[0238] In reference to an antibody, the term “bioactivity” includes, but is not limited to, epitope or antigen binding affinity, the in vivo and / or in vitro stability of the antibody, the immunogenic properties of the antibody, e.g., when administered to a human subject, and / or the ability to neutralize or antagonize the bioactivity of a target molecule in vivo or in vitro. The aforementioned properties or characteristics can be observed or measured using art-recognized techniques including, but not limited to, scintillation proximity assays, ELISA, ORIGEN immunoassay (IGEN), fluorescence quenching, fluorescence ELISA, competitive ELISA, SPR analysis including, but not limited to, SPR analysis using a BIAcore biosensor, in vitro and in vivo neutralization assays (see, for example, International Publication No. WO 2006 / 062685), receptor binding, and immunohistochemistry with tissue sections from different sources including human, primate, or any other source as needed. In reference to an immunogen, the “bioactivity” includes immunogenicity, the definition of which is discussed in detail later. In reference to a virus, the “bioactivity” includes infectivity, the definition of which is discussed in detail later. In reference to a contrast agent, e.g., a dye, the “bioactivity” refers to the ability of a contrast agent when administered to a subject to enhance the contrast of structures or fluids within the subject's body. The bioactivity of a contrast agent also includes, but is not limited to, its ability to interact with a biological environment and / or influence the response of another molecule under certain conditions.

[0239] As used herein, the term “small molecule” can refer to compounds that are “natural productlike,” however, the term “small molecule” is not limited to “natural product-like” compounds. Rather, a small molecule is typically characterized in that it contains several carbon — carbon bonds and has a molecular weight of less than 5000 Daltons (5 kDa), preferably less than 3 kDa, still more preferably less than 2 kDa, and most preferably less than 1 kDa. In some cases, it is preferred that a small molecule has a molecular weight equal to or less than 700 Daltons.

[0240] Exemplary therapeutic agents include, but are not limited to, those found in Harrison’ s Principles of Internal Medicine, 13th Edition, Eds. T.R. Harrison et al. McGraw-Hill N.Y., NY; Physicians’ Desk Reference, 50th Edition, 1997, Oradell New Jersey, Medical Economics Co.; Pharmacological Basis of Therapeutics, 8th Edition, Goodman and Gilman, 1990; United States Pharmacopeia, The National Formulary, ETSP XII NF XVII, 1990, the complete contents of all of which are incorporated herein by reference.

[0241] Therapeutic agents include the herein disclosed categories and specific examples. It is not intended that the category be limited by the specific examples. Those of ordinary skill in the art will recognize also numerous other compounds that fall within the categories and that are useful according to the present disclosure. Examples include a radiosensitizer, a steroid, a xanthine, a beta- 2-agonist bronchodilator, an anti-inflammatory agent, an analgesic agent, a calcium antagonist, an angiotensin-converting enzyme inhibitors, a beta-blocker, a centrally active alpha- agonist, an alpha - 1 -antagonist, an anticholinergic / antispasmodic agent, a vasopressin analogue, an antiarrhythmic agent, an antiparkinsonian agent, an antiangina / antihypertensive agent, an anticoagulant agent, an antiplatelet agent, a sedative, an anxiolytic agent, a peptidic agent, a biopolymeric agent, an antineoplastic agent, a laxative, an antidiarrheal agent, an antimicrobial agent, an antifungal agent, a vaccine, a protein, or a nucleic acid. In a further aspect, the pharmaceutically active agent can be coumarin, albumin, steroids such as betamethasone, dexamethasone, methylprednisolone, prednisolone, prednisone, triamcinolone, budesonide, hydrocortisone, and pharmaceutically acceptable hydrocortisone derivatives; xanthines such as theophylline and doxophylline; beta-2- agonist bronchodilators such as salbutamol, fenterol, clenbuterol, bambuterol, and salmeterol; antiinflammatory agents, including antiasthmatic anti-inflammatory agents, antiarthritis antiinflammatory agents, and non-steroidal anti-inflammatory agents, examples of which include but are not limited to sulfides, mesalamine, budesonide, salazopyrin, diclofenac, pharmaceutically acceptable diclofenac salts, nimesulide, naproxen, acetaminophen, ibuprofen, ketoprofen and piroxicam; analgesic agents such as salicylates; calcium channel blockers such as nifedipine, amlodipine, and nicardipine; angiotensin converting enzyme inhibitors such as captopril, benazepril hydrochloride, fosinopril sodium, trandolapril, ramipril, lisinopril, enalapril, quinapril hydrochloride, and moexipril hydrochloride; beta-blockers (i.e., beta adrenergic blocking agents) such as sotalol hydrochloride, timolol maleate, esmolol hydrochloride, carteolol, propanolol hydrochloride, betaxolol hydrochloride, penbutolol sulfate, metoprolol tartrate, metoprolol succinate, acebutolol hydrochloride, atenolol, pindolol, and bisoprolol fumarate; centrally active alpha-2-agonists such as clonidine; alpha- 1 -antagonists such as doxazosin and prazosin; anticholinergic / antispasmodic agents such as dicyclomine hydrochloride, scopolamine hydrobromide, glycopyrrolate, clidinium bromide,flavoxate, and oxybutynin; vasopressin analogues such as vasopressin and desmopressin; antiarrhythmic agents such as quinidine, lidocaine, tocainide hydrochloride, mexiletine hydrochloride, digoxin, verapamil hydrochloride, propafenone hydrochloride, flecainide acetate, procainamide hydrochloride, moricizine hydrochloride, and disopyramide phosphate; antiparkinsonian agents, such as dopamine, L-Dopa / Carbidopa, selegiline, dihydroergocryptine, pergolide, lisuride, apomorphine, and bromocriptine; antiangina agents and antihypertensive agents such as isosorbide mononitrate, isosorbide dinitrate, propranolol, atenolol and verapamil; anticoagulant and antiplatelet agents such as coumadin, warfarin, acetylsalicylic acid, and ticlopidine; sedatives such as benzodiazepines and barbiturates; anxiolytic agents such as lorazepam, bromazepam, and diazepam; peptidic and biopolymeric agents such as calcitonin, leuprolide and other LHRH agonists, hirudin, cyclosporin, insulin, somatostatin, protirelin, interferon, desmopressin, somatotropin, thymopentin, pidotimod, erythropoietin, interleukins, melatonin, granulocyte / macrophage-CSF, and heparin; antineoplastic agents such as etoposide, etoposide phosphate, cyclophosphamide, methotrexate, 5 -fluorouracil, vincristine, doxorubicin, cisplatin, hydroxyurea, leucovorin calcium, tamoxifen, flutamide, asparaginase, altretamine, mitotane, and procarbazine hydrochloride; laxatives such as senna concentrate, casanthranol, bisacodyl, and sodium picosulphate; antidiarrheal agents such as difenoxin hydrochloride, loperamide hydrochloride, furazolidone, diphenoxylate hydrochloride, and microorganisms; vaccines such as bacterial and viral vaccines; antimicrobial agents such as penicillins, cephalosporins, and macrolides, antifungal agents such as imidazolic and triazolic derivatives; and nucleic acids such as DNA sequences encoding for biological proteins, and antisense oligonucleotides.

[0242] Anti-cancer agents include alkylating agents, platinum agents, antimetabolites, topoisomerase inhibitors, antitumor antibiotics, antimitotic agents, aromatase inhibitors, thymidylate synthase inhibitors, DNA antagonists, farnesyltransferase inhibitors, pump inhibitors, histone acetyltransferase inhibitors, metalloproteinase inhibitors, ribonucleoside reductase inhibitors, TNF alpha agonists / antagonists, endothelin A receptor antagonists, retinoic acid receptor agonists, immunomodulators, hormonal and antihormonal agents, photodynamic agents, and tyrosine kinase inhibitors.

[0243] Antibiotics include aminoglycosides (e.g., gentamicin, tobramycin, netilmicin, streptomycin, amikacin, neomycin), bacitracin, carbapenems (e.g., imipenem / cilastatin), cephalosporins, colistin, methenamine, monobactams (e.g., aztreonam), penicillins (e.g., penicillin G, penicillin V, methicillin, nafcillin, oxacillin, cloxacillin, dicloxacillin, ampicillin, amoxicillin, carbenicillin, ticarcillin, piperacillin, mezlocillin, azlocillin), polymyxin B, quinolones, and vancomycin; and bacteriostatic agents such as chloramphenicol, clindamycin, macrolides (e.g., erythromycin, azithromycin, clarithromycin), lincomycin, nitrofurantoin, sulfonamides, tetracyclines (e.g.,tetracycline, doxycycline, minocycline, demeclocy cline), and trimethoprim. Also included are metronidazole, fluoroquinolones, and rifampin.

[0244] Enzyme inhibitors are substances which inhibit an enzymatic reaction. Examples of enzyme inhibitors include edrophonium chloride, N-methylphysostigmine, neostigmine bromide, physostigmine sulfate, tacrine, 1 -hydroxymaleate, iodotubercidin, p-bromotetranisole, 10-(alpha- diethylaminopropionyl)-phenothiazine hydrochloride, calmidazolium chloride, hemicholinium-3,3,5- dinitrocatechol, diacylglycerol kinase inhibitor I, diacylglycerol kinase inhibitor II, 3- phenylpropargylamine, N°-monomethyl-L-arginine acetate, carbidopa, 3-hydroxybenzylhydrazine, hydralazine, clorgyline, deprenyl, hydroxylamine, iproniazid phosphate, 6-MeO-tetrahydro-9H- pyrido-indole, nialamide, pargyline, quinacrine, semicarbazide, tranylcypromine, N,N- diethylaminoethyl-2,2-diphenylvalerate hydrochloride, 3-isobutyl-l-methylxanthine, papaverine, indomethacin, 2-cyclooctyl-2-hydroxyethylamine hydrochloride, 2,3-dichloro-a-methylbenzylamine (DCMB), 8,9-dichloro-2,3,4,5-tetrahydro-lH-2-benzazepine hydrochloride, p- aminoglutethimide, p- aminoglutethimide tartrate, 3-iodotyrosine, alpha-methyltyrosine, acetazolamide, dichlorphenamide, 6-hydroxy-2-benzothiazolesulfonamide, and allopurinol.

[0245] Antihistamines include pyrilamine, chlorpheniramine, and tetrahydrozoline, among others.

[0246] Anti-inflammatory agents include corticosteroids, nonsteroidal anti-inflammatory drugs (e.g., aspirin, phenylbutazone, indomethacin, sulindac, tolmetin, ibuprofen, piroxicam, and fenamates), acetaminophen, phenacetin, gold salts, chloroquine, D-Penicillamine, methotrexate colchicine, allopurinol, probenecid, and sulfinpyrazone.

[0247] Muscle relaxants include mephenesin, methocarbamol, cyclohenzaprine hydrochloride, trihexyphenidyl hydrochloride, levodopa / carbidopa, and biperiden.

[0248] Anti-spasmodics include atropine, scopolamine, oxyphenonium, and papaverine.

[0249] Analgesics include aspirin, phenylbutazone, indomethacin, sulindac, tolmetin, ibuprofen, piroxicam, fenamates, acetaminophen, phenacetin, morphine sulfate, codeine sulfate, meperidine, nalorphine, opioids (e.g., codeine sulfate, fentanyl citrate, hydrocodone bitartrate, loperamide, morphine sulfate, noscapine, norcodeine, normorphine, thebaine, nor-binaltorphimine, buprenorphine, chlomaltrexamine, funaltrexamine, nalbuphine, nalorphine, naloxone, naloxonazine, naltrexone, and naltrindole), procaine, lidocaine, tetracaine and dibucaine. Ophthalmic agents include sodium fluorescein, rose bengal, methacholine, adrenaline, cocaine, atropine, alphachymotrypsin, hyaluronidase, betaxolol, pilocarpine, timolol, timolol salts, and combinations thereof.

[0250] Prostaglandins are art recognized and are a class of naturally occurring chemically related long-chain hydroxy fatty acids that have a variety of biological effects.

[0251] Anti-depressants are substances capable of preventing or relieving depression.

[0252] Examples of anti-depressants include imipramine, amitriptyline, nortriptyline, protriptyline, desipramine, amoxapine, doxepin, maprotiline, tranylcypromine, phenelzine, and isocarboxazid.

[0253] Trophic factors are factors whose continued presence improves the viability or longevity of a cell trophic factors include, without limitation, platelet-derived growth factor (PDGP), neutrophilactivating protein, monocyte chemoattractant protein, macrophage- inflammatory protein, platelet factor, platelet basic protein, and melanoma growth stimulating activity; epidermal growth factor, transforming growth factor (alpha), fibroblast growth factor, platelet- derived endothelial cell growth factor, insulin-like growth factor, glial derived growth neurotrophic factor, ciliary neurotrophic factor, nerve growth factor, bone growth / cartilage-inducing factor (alpha and beta), bone morphogenetic proteins, interleukins (e.g., interleukin inhibitors or interleukin receptors, including interleukin 1 through interleukin 10), interferons (e.g., interferon alpha, beta and gamma), hematopoietic factors, including erythropoietin, granulocyte colony stimulating factor, macrophage colony stimulating factor and granulocyte-macrophage colony stimulating factor; tumor necrosis factors, and transforming growth factors (beta), including beta-1, beta-2, beta-3, inhibin, and activin.

[0254] Hormones include estrogens (e.g., estradiol, estrone, estriol, diethylstilbestrol, quinestrol, chlorotrianisene, ethinyl estradiol, mestranol), anti-estrogens (e.g., clomiphene, tamoxifen), progestins (e.g., medroxyprogesterone, norethindrone, hydroxyprogesterone, norgestrel), antiprogestin (mifepristone), androgens (e.g., testosterone cypionate, fluoxymesterone, danazol, testolactone), anti- androgens (e.g., cyproterone acetate, flutamide), thyroid hormones (e.g., triiodothyronne, thyroxine, propylthiouracil, methimazole, and iodixode), and pituitary hormones (e.g., corticotropin, somatotropin, oxytocin, and vasopressin). Hormones are commonly employed in hormone replacement therapy and / or for purposes of birth control. Steroid hormones, such as prednisone, are also used as immunosuppressants and anti-inflammatories. In some aspects, the additive is an agent that stimulates tissue formation, and / or healing and regrowth of natural tissues, and any combinations thereof. Agents that increase formation of new tissues and / or stimulates healing or regrowth of native tissue at the site of injection can include, but are not limited to, fibroblast growth factor (FGF), transforming growth factor-beta (TGF-beta, platelet-derived growth factor (PDGF), epidermal growth factors (EGFs), connective tissue activated peptides (CTAPs), osteogenic factors including bone morphogenic proteins, heparin, angiotensin II (A-II) and fragments thereof, insulin-like growth factors, tumor necrosis factors, interleukins, colony stimulating factors, erythropoietin, nerve growth factors, interferons, biologically active analogs, fragments, and derivatives of such growth factors, and any combinations thereof.

[0255] In some aspects, the silk composition can further comprise at least one additional material for soft tissue augmentation, e.g., dermal filler materials, including, but not limited to, poly(methylmethacrylate) microspheres, hydroxyapatite, poly(L-lactic acid), collagen, elastin, and glycosaminoglycans, hyaluronic acid, commercial dermal filler products such as BOTOX® (from Allergan), DYSPORT®, COSMODERM®, EVOLENCE®, RADIESSE®,RESTYLANE®, JUVEDERM® (from Allergan), SCULPTRA®, PERLANE®, and CAPTIQEIE®, and any combinations thereof.

[0256] In some aspects, the additive is a wound healing agent. As used herein, a “wound healing agent" is a compound or composition that actively promotes wound healing process.

[0257] Exemplary wound healing agents include, but are not limited to dexpanthenol; growth factors; enzymes; hormones; povidon-iodide; fatty acids; anti-inflammatory agents; antibiotics; antimicrobials; antiseptics; cytokines; thrombin; analgesics; opioids; aminoxyls; furoxans; nitrosothiols; nitrates and anthocyanins; nucleosides, such as adenosine; and nucleotides, such as adenosine diphosphate (ADP) and adenosine triphosphate (ATP); neurotransmitter / neuromodulators, such as acetylcholine and 5 -hydroxy tryptamine (serotonin / 5-HT); histamine and catecholamines, such as adrenalin and noradrenalin; lipid molecules, such as 5 -sphingosine- 1 -phosphate and lysophosphatidic acid; amino acids, such as arginine and lysine; peptides such as the bradykinins, substance P and calcium gene-related peptide (CGRP); nitric oxide; and any combinations thereof.

[0258] In certain aspects, the active agents provided herein are immunogens. In one aspect, the immunogen is a vaccine. Most vaccines are sensitive to environmental conditions under which they are stored and / or transported. For example, freezing may increase reactogenicity (e.g., capability of causing an immunological reaction) and / or loss of potency for some vaccines (e.g., HepB, and DTaP / IPV / FQB), or cause hairline cracks in the container, leading to contamination. Further, some vaccines (e.g., BCG, Varicella, and MMR) are sensitive to heat. Many vaccines (e.g., BCG, MMR, Varicella, Meningococcal C Conjugate, and most DTaP-containing vaccines) are light sensitive. See, e.g., Galazka et al., Thermostability of vaccines, in Global Programme for Vaccines & Immunization (World Health Organization, Geneva, 1998); Peetermans et al., Stability of freeze-dried rubella virus vaccine (Cendehill strain) at various temperatures, J. Biological Standardization 179 (1973). Thus, the compositions and methods provided herein also provide for stabilization of vaccines regardless of the cold chain and / or other environmental conditions.

[0259] In some aspects, the additive is a cell, e.g., a biological cell. Cells useful for incorporation into the composition can come from any source, e.g., mammalian, insect, plant, etc. In some aspects, the cell can be a human, rat or mouse cell. In general, cells to be used with the compositions provided herein can be any types of cells. In general, the cells should be viable when encapsulated within compositions. In some aspects, cells that can be used with the composition include, but are not limited to, mammalian cells (e.g. human cells, primate cells, mammalian cells, rodent cells, etc.),avian cells, fish cells, insect cells, plant cells, fungal cells, spore cells, bacterial cells, and hybrid cells. In some aspects, exemplary cells that can be used with the compositions include platelets, activated platelets, stem cells, totipotent cells, pluripotent cells, and / or embryonic stem cells. In some aspects, exemplary cells that can be encapsulated within compositions include, but are not limited to, primary cells and / or cell lines from any tissue. For example, cardiomyocytes, myocytes, hepatocytes, keratinocytes, melanocytes, neurons, astrocytes, embryonic stem cells, adult stem cells, hematopoietic stem cells, hematopoietic cells (e.g. monocytes, neutrophils, macrophages, etc.), ameloblasts, fibroblasts, chondrocytes, osteoblasts, osteoclasts, neurons, sperm cells, egg cells, liver cells, epithelial cells from lung, epithelial cells from gut, epithelial cells from intestine, liver, epithelial cells from skin, etc., and / or hybrids thereof, can be included in the silk / platelet compositions disclosed herein. Those skilled in the art will recognize that the cells listed herein represent an exemplary, not comprehensive, list of cells. Cells can be obtained from donors (allogenic) or from recipients (autologous). Cells can be obtained, as a non-limiting example, by biopsy or other surgical means known to those skilled in the art.

[0260] In some aspects, the cell can be a genetically modified cell. A cell can be genetically modified to express and secrete a desired compound, e.g. a bioactive agent, a growth factor, differentiation factor, cytokines, and the like. Methods of genetically modifying cells for expressing and secreting compounds of interest are known in the art and easily adaptable by one of skill in the art.

[0261] Differentiated cells that have been reprogrammed into stem cells can also be used.

[0262] For example, human skin cells reprogrammed into embryonic stem cells by the transduction of Oct3 / 4, Sox2, c-Myc and Klf4 (Junying Yu, et. ah, Science, 2007, 318, 1917-1920 and Takahashi K. et. al, Cell, 2007, 131, 1-12).

[0263] Unless otherwise specified or indicated by context, the terms “a”, “an”, and “the” mean “one or more.” For example, “a molecule” should be interpreted to mean “one or more molecules”.

[0264] As used herein, “about”, “approximately”, “substantially”, and “significantly” will be understood by persons of ordinary skill in the art and will vary to some extent on the context in which they are used. If there are uses of the term which are not clear to persons of ordinary skill in the art given the context in which it is used, “about” and “approximately” will mean plus or minus <10% of the particular term and “substantially” and “significantly” will mean plus or minus >10% of the particular term.

[0265] As used herein, the terms “include” and “including” have the same meaning as the terms “comprise” and “comprising.” The terms “comprise” and “comprising” should be interpreted as being “open” transitional terms that permit the inclusion of additional components further to thosecomponents recited in the claims. The terms “consist” and “consisting of’ should be interpreted as being “closed” transitional terms that do not permit the inclusion of additional components other than the components recited in the claims. The term “consisting essentially of’ should be interpreted to be partially closed and allowing the inclusion only of additional components that do not fundamentally alter the nature of the claimed subject matter.

[0266] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0267] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0268] Preferred aspects of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred aspects may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect a person having ordinary skill in the art to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

[0269] While the invention has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as illustrative and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected. For example, any of the features or functions of any of the embodiments disclosed herein may be incorporated into any of the other embodiments disclosed herein.

[0270] The following examples illustrate some embodiments and aspects of the invention. It will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be performed without altering the spirit or scope of the invention, and such modifications and variations are encompassed within the scope of the invention as defined in the claims which follow. The following examples do not in any way limit the invention.

[0271] EXAMPLES

[0272] Example 1: Papermaking process

[0273] Textile waste is processed into re-silk paper through the following steps. Silk fabric scraps are sorted in groups by color. The silk fabric scraps are then examined for any possible impurities (e.g., staples, tape, and tags) which are then removed. The silk scraps are then processed through a paper shredder (Insignia™ 6-Sheet Crosscut Shredder - Black Model: NS-S6CCBK2). The fibers are then soaked in tap water for 24 hours. The soaked fibers are processed into pulp form in a beater machine (Reina beater). The beating process progresses from level 30 to 0, which typically takes about an hour. Once the beating reaches level 0, the resulting pulp is beaten for an additional 30 minutes. The pulp is transformed into a paper using papermaking techniques of pulling a sheet from a vat, couching, draining the water out for wet sheet formation, air drying under pressure. Once dried, the sheet may be processed under an etching press for a smooth surface.

[0274] Example 2: Versatility

[0275] To test the versatility of the fabrication process, 4 different types of white silk textile fabrics were selected (Fig. 1 A, Fig. IB, Fig. 1C, and Fig. ID). The fabrics had different weaves as observed by optical microscopy (Fig. IE, Fig. IF, Fig. 1G, and Fig. 1H). To confirm they are silk fabrics, Fourier- transform infrared spectroscopy (FTIR) was carried out (Fig. II). All 4 fabrics were processed into a single batch of pulp. This pulp was used to form sheets of paper using a hand papermaking process. Two batches of paper were fabricated, with and without sizing. Ketene dimer emulsion in a very small quantity was added as an internal sizing agent to a batch of pulp to make some re-silk papers with sizing for hydrophobicity testing purpose. Sizing agent is used to make the finished paper less absorbent, so that ink or paint does not run or feather.

[0276] Re-silk papers of letter size were fabricated (Fig. 2A). A 100% protein-based paper was formed without the use of any additives. FTIR analysis of the re-silk paper was conducted (Fig. 2B) wherein the FTIR spectra displayed a range between 4000 cm1- 225 cm1that confirmed it is a crystalline silk paper.

[0277] Optical images of the re-silk paper taken at same magnifications through reflectance and transmission reveal that the paper has a homogeneous distribution of silk fibers (Fig. 3A and Fig. 3B). Having an even distribution of silk fibers is essential in fabrication of uniform sheets with consistent thickness. Microscopic images at a higher magnification (Fig. 3C and Fig. 3D) show a dense network of glass-like silk fibers without any contamination or small particles. This indicates that no additives or fillers were present in the paper and no treatment was given to the fibers.

[0278] Example 3: Mechanical Performance

[0279] To test the mechanical performance of the re-silk paper, a mechanical test was conducted among 5 different types of papers- print paper (commonly used recycled cellulose copy paper), 1.5 hour beaten re-silk paper without sizing, 1.5 hour beaten pressed re-silk paper without sizing, 1.5 hour beaten re-silk paper with sizing and 1.5 hour beaten pressed re-silk paper with sizing. Three 5 cm x 1cm sample strips were prepared for each type of paper. Each paper strip was subjected to an INSTRON tensile test. The tensile graphs of each paper strip were generated, and the average of each test was combined for comparison with other papers (Fig. 4A, Fig. 4B, and Fig. 4C).

[0280] Re-silk papers with or without sizing and pressed or not pressed indicated enough strength to be compared to the other papers of quality and showed promise for potential in making durable products.

[0281] Handmade paper often has a rough texture as it is dried under pressure between layers of pellon (felt). For everyday use, paper with a smoother texture is preferred due to the ease of writing, erasing, and seamless folding. Pressing the paper packs the fibers into a denser network, resulting in a smoother paper. The pressed paper, shown in Fig. 5B, has a smoother surface than the handmade paper (Fig. 5 A). The value of elongation at break for air dried 1.5 hour re-silk paper without any sizing is 1.3% and for 1.5 hour re-silk without any sizing that is etching pressed is 2.47%. This indicates that pressing the re-silk paper increases its ductility (Fig. 4A). This simple procedure can be applied to large scales of papermaking manufacturing that will result in more aesthetically pleasing and strong sheets of paper.

[0282] Example 4: Morphological Characterization

[0283] Comparison between recycled cellulose print paper and re-silk paper without any additives was conducted microscopically. The images shown in Fig. 6A-Fig. 6J taken at different magnifications reveal the similarities and differences between the papers. Both papers showed a dense network of cellulose (Fig. 6A) and silk fibers (Fig. 6B) that are essential to form a homogenous sheet of paper. Upon further magnification, the print paper revealed crumb-like particles covering parts of the cellulose fibers indicating the presence of fillers possibly used to give it a whiter look (Fig. 6C, Fig. 6E, Fig. 6G, and Fig. 61).

[0284] On the other hand, silk fibers in the re-silk paper showed clean silk fibers without the presence of any contaminants indicating an absence of any additives (Fig. 6D, Fig. 6F, Fig. 6H, and Fig. 6J). A comparison of Fig. 61 (cellulose paper) and Fig. 6J (recycled silk paper) shows the presence of fillers in cellulose paper and an absence of fillers in re-silk paper. The silk fibers (Fig. 6H) were thinner and showed more extensive defibrillation than the cellulose fibers (Fig. 6G), which plays a role in forming denser networks and stronger bonds between fibers which results in a stronger paper. The presence ofsilk fibrils was higher in the re-silk paper than the cellulose fibrils in the print paper which is important in forming hydrogen bonds to create a strong paper.

[0285] Fineness of the pulp and length of fibers are controlled by the duration of the beating. Beating the fibers causes the fibers to branch into smaller fibers called fibrils (Fig. 7A and Fig. 7B). The significant defibrillation shown contributes to making a strong paper. The longer the pulp is beaten for, the finer it would be because of further defibrillation. Beating time is selected depending on the desired application.

[0286] Cross-section of print paper (Fig. 8A) and re-silk paper (Fig. 8B) were acquired.

[0287] Water is a crucial component of papermaking. Water molecules are essential for the formation of hydrogen bonds between cellulose fibers. Fiber-to-fiber bonding in paper impacts the strength of the paper. Although a protein fiber, silk has the potential to form hydrogen bonds. During the beating process of re-silk paper, the silk fibers get defibrillated. Once dispersed in the vat filled with water and pulp, the silk fibers bond with the water molecules and upon drying form hydrogen bonds between the silk fibers. This results in the formation of a strong paper.

[0288] Example 5: Printing

[0289] Paper is often used for storing information hence it was crucial to test the papers for printing. To observe the printing capabilities of the papers, samples of a print paper (Fig. 9A), re-silk paper with sizing (Fig. 9B), and re-silk paper without sizing (Fig. 9C) were printed with a commonly used laser printer (e.g., HP Color LaserJet Pro MFP M479fdn). Each type of paper was printed on successfully. Macroscopic images of both re-silk papers revealed minor ink spreading around the text. Microscopic images of the letter K in black and red ink were taken for each paper sample. They all showed successful adhesion of the ink without any smudging.

[0290] Laser printing was conducted on textured re-silk paper (Fig. 10A, Fig. 10E, and Fig. 10F), cold pressed re-silk paper (Fig. 10B, Fig. 10G, and Fig. 10H), hot pressed re-silk paper (Fig. 10C, Fig. 101, and Fig. 10J), and print paper as a control (Fig. 10D, Fig. 10K, and Fig. 10L). Of the re-silk papers, the hot pressed re-silk paper had the optimal printing surface as shown by the images and micrographs.

[0291] Example 6: Recycling re-silk paper

[0292] For testing the re-silk paper’s recycling capabilities into pulp (Fig. 11 A and Fig. 1 IB), the resilk paper without any sizing agent was submerged in water and stirred for 60 seconds which resulted in a pulp, fit for reprocessing it into a paper. This validated the infinite recyclability of re-silk paper into paper.

[0293] For testing the re-silk paper’s recycling capabilities into silk solution (Fig. 11C), the re-silk paper without any sizing agent was dissolved in a Lithium Bromide solution (LiBr). Following the silkfibroin protocol, it should be easy to extract fibroin from this solution, offering another recycling opportunity for this invention.

[0294] Example 7: Flammability

[0295] To test flammability of re-silk paper, 8 types of paper of similar weight were subjected to a flame: re-silk paper, print paper, card stock, Somerset book, India hemp, Rives light weight, Arches text wove, and Arturo book. Re-silk paper does not sustain a flame and instead smolders, whereas cellulose-based papers are highly flammable and leave an ashy residue (Fig. 12A, Fig. 12B).

[0296] Example 8: Brightness

[0297] To calculate brightness of paper, reflectance of light is measured at 475 nm (blue light) on a reflectance scale between 0 and 100. Brightness of 3 types of paper was measured using a spectrometer: print paper, rough re-silk paper, and smooth (pressed) re-silk paper (Fig. 13A, Fig. 13B). The spectra show print paper has a reflectance of 92, rough re-silk paper has a reflectance of 86, and smooth re-silk paper has a reflectance of 93. Smooth re-silk paper has a comparable brightness to print paper without the use of any brightening agents.

[0298] Example 9 : Enzyme stability

[0299] An enzyme stability test was conducted to test the capability of re-silk paper to be used as an alternative to conventionally used cellulose-based paper in biosensors. Triplets of cellulose (Whatman filter paper) was compared to re-silk paper using horseradish peroxidase as the enzyme. Amplex red was the reagent and hydrogen peroxide was the analyte.

[0300] Enzymatic activity was measured over a duration of 10 minutes through fluorescence spectroscopy. Results showed that both silk fibroin solution with HRP on cellulose paper (Fig. 14A) and re-silk paper with HRP in the absence of silk fibroin solution (Fig. 14B) showed an increase in activity, indicating that recycled silk paper has the potential to be an alternative to cellulose-based substrates in paper-based sensors.

[0301] Example 10: Pattern transfer

[0302] Pressing re-silk at a higher temperature (90 °C to 150 °C) for a duration of time between 10 minutes and an hour results in phase transition. This allows for pattern replication from desired optical patterns made from a material that is resistant to high temperatures (e.g., nickel and steel shims) with a holographic pattern. This is a promising feature for applications including embossed embellishments and authentication technology. Transfer of patterns from a holographic nickel shim (Fig. 15A) onto hot-pressed re-silk is shown in Fig. 15B.

[0303] Example 11: Recycled Silk Booklet

[0304] A handmade recycled silk monomaterial booklet is shown in Fig. 16. The pages are re-silk paper and the cover is made from silk fabrics.

[0305] Example 12: Elemental analysis of print paper and white recycled silk paper

[0306] Elemental analysis of print paper (Fig. 17A, Fig. 17C, Fig. 17E, Fig. 17F, Fig. 17G, and Fig. 17H) and white re-silk paper (Fig. 17B, Fig. 17D, Fig. 171, Fig. 17J, and Fig. 17K) was carried out to compare the composition of each type of paper. In the element specific images, the element is shown in the top left-hand corner of each image. SEM of print paper (Fig. 17A) shows a fibrous cellulose network with fillers. On the other hand, SEM of re-silk paper (Fig. 17B) shows a fibrous silk network without any fillers.

[0307] Layered SEM and elemental analysis of print paper (Fig. 17C) and re-silk paper (Fig. 17D) show the composition of the components. In the print paper, oxygen (Fig. 17E) and carbon (Fig. 17F) are homogenously distributed throughout the paper. There is a scattered presence of calcium (Fig. 17G) and chlorine (Fig. 17H), which shows the presence of fillers often used in papermaking for whitening, bleaching, and delignification. In re-silk paper on the other hand, carbon (Fig. 171), oxygen (Fig. 17J), and nitrogen (Fig. 17K) are homogenously distributed throughout the paper.

[0308] Example 13: Colored re-silk pages

[0309] Re-silk paper was made in pink (Fig. 18A, Fig. 18B, and Fig. 18C) and black (Fig. 18D, Fig. 18E, Fig. 18F) to show compatibility of the process with colored textiles. The FTIR spectra in Fig. 18G confirm that white, pink, and black re-silk papers are crystalline silk. As shown in detail in Fig. 18B and Fig. 18E, different weaves of silk can be processed into uniform re-silk pages. Optical images shown in Fig. 19 of the white (left), black (middle), and pink (right) re-silk pages show dyed fibers and a lack of fillers.

[0310] Drop tests were carried out on the pink (Fig. 20A), black (Fig. 20B), and white (Fig. 20C) resilk pages to determine the spread diameter of liquids. The results are summarized in Fig. 20D. Each type of re-silk paper has similar absorption capabilities.

[0311] Example 14: Recycling colored re-silk paper

[0312] Colored re-silk paper was recycled in two different ways. To reform re-silk papers as shown in Fig. 21 A, re-silk paper simply needs to be mixed in cold water to obtain re-silk pulp which may then be recast into re-silk papers with the color of the original retained. Re-silk paper may also be recycled into re-silk films as shown in Fig. 21B. Re-silk paper is soaked in 9.3 M LiBr solution at 60 °C to obtain re-silk solution which retains the color of the re-silk paper. The re-silk solution may be processed in different ways, such as film formation.

[0313] Example 15: Method for making virgin silk paper

[0314] Protein paper may made from silk cocoons, specifically from Bombyx Mori cocoons. Silk fibers from cocoons were transformed into a non-woven protein paper. Since this paper is sourced from cocoons, it is suitable for biomedical applications. The process involves degumming to removesericin, followed by dispersion and beating of the silk fibers in water. The resulting pulp is then cast onto a screen, drained, pressed, and dried to form virgin silk paper sheets. This method yields uniform, flexible, and scalable silk-based paper suitable for further characterization and application.

[0315] Cocoons are processed into silk paper through the following steps as shown in Fig. 22. Bombyx mori cocoons are boiled to degum and reel the fibers. Silk fibers are chopped into 2 cm pieces. Chopped silk fibers are soaked in tap water for 48 hours to allow hydration and swelling of fibers. These soaked fibers are processed into pulp form in a beater machine (Reina beater). The beating process progresses from level 30 to level 0 and then the resulting pulp is beaten for an additional 30 minutes.

[0316] The pulp is transformed into a paper using papermaking techniques of pulling a sheet from a vat, couching, draining the water out for wet sheet formation, and air drying under pressure. Once dried, the paper’s surface can be modified using processes such as cold press, hot press, embossing, etc.

[0317] Pictures of virgin silk paper are shown in Fig. 23 A and Fig. 23B. Fig. 23C shows a stack of 44 silk papers made from 408 grams of silk fibers to show the scalability of the process. A scatter plot displaying the individual weights of all 44 sheets (Fig. 23D) shows the consistency in sheet formation and weight range.

[0318] Example 16: Morphological characterization of virgin silk fibers

[0319] Fig. 24 shows top view SEM images of virgin silk fibers after different amounts of beating. The top left micrograph shows degummed silk fiber reeled from the cocoon. The fibers are intact, and no defibrillation has occurred. The top right image shows silk fibers beaten at level 30. Some fibrils have started to emerge from the large fibers. The bottom right image shows silk fibers beaten from level 30 to level 0 showing increased fibrillation. The bottom left image shows silk fibers beaten for 15 minutes after beating from level 30 to level 0. Signification defibrillation has occurred that contributes to a strong sheet formation.

[0320] Fig. 25A - Fig. 25F are representative microscopic images of selected regions from each sample type where Raman spectra were collected. Fig. 25A is degummed silk fibers, Fig. 25B is recycled silk paper fiber, Fig. 25C is virgin silk paper fiber, Fig. 25D is a control silk fdm, Fig. 25E is recycled silk paper fibrils, and Fig. 25F is virgin silk paper fibrils. Fig. 25G is an overlay of averaged Raman spectra for each sample. Large silk fibers exhibit peaks corresponding to crystalline silk (Fig. 25A - Fig. 25D), whereas smaller fibrils in the silk paper (Fig. 25E and Fig. 25F) show broader features indicative of semi-crystalline or partially disordered structures.

[0321] Example 17: Flammability of virgin silk paper

[0322] Commercial print paper, virgin silk paper, and recycled silk paper were exposed to vertical flames as shown in Fig. 26A, Fig. 26B, and Fig. 26C, respectively. The print paper ignited instantly and burnt completely. The virgin silk paper and recycled silk paper burn without sustaining flames, which indicates fire resistance.

[0323] Example 18: Thermal decomposition and elemental analysis

[0324] Fig. 27A shows thermogravimetric (TGA) curves of commercially available print paper (left), virgin silk paper (center), and recycled silk paper (right). The TGA demonstrates thermal stability and decomposition behavior under nitrogen atmosphere. Initial weight loss up to ~ 150 °C corresponds to moisture content followed by major degradation of organic components. SEM images, EDS layered images, and element mapping of carbon, oxygen, and calcium or nitrogen are shown in Fig. 27B - Fig. 27G. Fig. 27B corresponds to print paper, Fig. 27C corresponds to print paper TGA residue, Fig. 27D corresponds to virgin silk paper, Fig. 27E corresponds to virgin silk paper TGA residue, Fig. 27F corresponds to recycled silk paper, and Fig. 27G corresponds to recycled silk paper TGA residue.

[0325] Every row corresponds to the elemental analysis of each sample and highlights differences in residual ash content, indicative of inorganic elements retained post-decomposition. Print paper TGA residue indicates presence of Calcium which confirms the presence of fillers. Silk-based paper’s TGA did not have any element present beyond carbon, oxygen and nitrogen which confirms lack of fillers.

[0326] Example 19: Yield calculation

[0327] Silk paper fabrication from virgin silk pulp was tested to determine paper yield. 408.23 grams of dry silk fiber was turned into a total of 364.68 grams of silk paper across 44 sheets for a yield of 89.35%, resulting in a material loss of 10.65%. Potential factors affecting loss are leftover pulp, loss of fine fibers during sieving or sheet formation, water-soluble components washing away, and / or retention inefficiencies in handmade methods.

[0328] Industry standards for mechanical pulp-to-paper yield range from 90% to 98%. The overall yield of silk paper fabrication aligns closely with the yield reported for conventional mechanical pulp-based paper manufacturing.

[0329] Example 20: Internal sizing of re-silk paper for artistic applications

[0330] White re-silk paper was fabricated using a ketene dimer emulsion as an internal sizing agent. The re-silk paper pulp was beaten for one hour. A watercolor swatch test and painting is shown on re-silk paper (Fig. 28A) and compared to a swatch test on Arches paper (Fig. 28B). Commercially available water color paints were used, both synthetic and mineral-based. Re-silk paper is shown to be a comparable substrate to Arches paper, which is a preferred painting substrate for artists.

[0331] A colored pencil swatch test was also conducted on 1 hour beaten white re-silk paper to compare to Arches paper. The colored pencils used are commercially available, both mineral and plant-based. The results are shown in Fig. 29A (re-silk paper) and Fig. 29B (Arches paper).

[0332] A third swatch test using commercially available charcoal pencils was conducted. The results are shown in Fig. 30A (re-silk paper beaten for 1 hour with ketene dimer sizing) and Fig. 30B (Arches paper). A heavier weight re-silk paper would provide a sturdier base for charcoal painting.

[0333] Example 21: External sizing ofre-silk paper

[0334] Four classes of external sizing agents were tested as summarized below in Table 1.Table 1: Sizing agents

[0335] The external sizing agents were applied in one or two coats on three colors of re- silk paper (black, white, and pink). The results are summarized in Fig. 31 A (pink re-silk paper), Fig. 3 IB (white re-silk paper), and Fig. 31C (black re-silk paper). The legend for Fig. 31A - Fig. 31C is shown in Fig. 3 ID. Individual values are listed below in Table 2. All values given are in degrees (°). Arches paper, measured as a control, has an aqueous contact angle of 120°.Table 2: Contact angles measured in degrees (°)

[0336] Rabbit skin glue and PVA sizing agents resulted in the highest hydrophobicities. Wheat starch’s angle was too low to measure, indicating hydrophilicity. Silk solution as a sizing agent shows potential as it increases hydrophobicity of papers.

[0337] Fig. 32A depicts re-silk paints and Fig. 32B depicts commercial watercolor paints on crosslinked silk sized recycled silk paper. Figs. 33A-C depict the impact of layers of coating of silk solution as an external sizing agent and cross-linking. Fig. 33A depicts re-silk paper subject to 1 layer of silk solution sizing having an aqueous contact angle of 96°. In Fig. 33B, two layers of silk solution have been applied to obtain a 97° aqueous contact angle. Finally, Fig. 33C depicts re-silk paper with application of two layers of silk solution that are crosslinked at 45 °C in 90% humidity for 10 minutes. In this example, the aqueous contact angle is 112°. Fig. 34 depicts a spectral analysis of crosslinked silk sized re-silk paper where line A is the spectra for re-silk paper with silk sizing and line B is the spectra for re-silk paper with silk sizing crosslinked. The spectral analysis revealed an amide I band indicating the presence of crystalline -sheet structures could be from re-silk paper. The amide II bands in the spectra indicate a shift from 1525 cm1to 1514 cm1confirming higher crystallinity due to crosslinking.

[0338] In addition to the features described above and elsewhere herein, the present disclosure also includes the following clauses:1. A method of recycling silk fabric waste into recycled silk paper, the method comprising the following steps:a) optionally sorting the silk fabric waste by color to produce color-sorted silk fabric waste; b) shredding the color-sorted silk fabric waste to produce a shredded silk fabric waste; c) soaking the shredded silk fabric waste in water for a soaking length of time of between 6 hours and 7 days to produce soaked shredded silk fabric waste; d) pulping the soaked shredded silk fabric waste to produce a silk fabric waste pulp; and e) making recycled silk paper from the silk fabric waste pulp.2. The method of clause 1 , wherein the making of step e) includes pulling a wet sheet from a vat containing the silk fabric waste pulp.3. The method of clause 2, wherein the making of step e) includes couching the wet sheet.4. The method of clause 3, wherein the making of step e) includes drying the wet sheet to form a dried sheet.5. The method of clause 4, wherein the drying is performed under a drying pressure that is greater than atmospheric pressure.6. The method of clauses 4 or 5, wherein the making of step e) includes planarizing the dried sheet.7. The method of clause 6, wherein the planarizing comprises processing the dried sheet through an etching press.8. The method of any one of the preceding clauses, wherein the making of step e) is free of sizing or sizing agents.9. The method of any one of the preceding clauses, wherein the method is free of sizing or sizing agents.10. The method of any one of clauses 1 to 7, wherein the making of step e) comprises sizing the recycled silk paper (e.g., using a sizing agent such as alkyl ketene dimer and / or rosin).11. The method of any one of the preceding clauses, wherein the pulping of step d) includes beating the soaked shredded silk fabric waste.12. The method of clause 11 , wherein the beating is performed at least until a beating degree reaches 0.13. The method of clause 12, wherein the beating is performed for at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, or at least 30 minutes or longer after the beating degree reaches 0.14. The method of any one of the preceding clauses, wherein the water is tap water.15. The method of any one of the preceding clauses, wherein the method includes: a) sorting the silk fabric waste by color to produce color- sorted silk fabric waste.16. The method of clause 15, wherein the sorting of step a) produces color-sorted silk fabric waste that is substantially colorless.17. The method of clause 15, wherein the sorting of step a) produces color-sorted silk fabric waste that is gray or black.18. The method of clause 15, wherein the sorting of step a) produces color-sorted silk fabric waste having color with a peak wavelength within a desired wavelength range.19. The method of clause 18, wherein the desired wavelength range has a minimum wavelength of 380 nm and a maximum wavelength of 700 nm, including but not limited to, at least 380 nm, at least 385 nm, at least 390 nm, at least 395 nm, at least 400 nm, at least 405 nm, at least 410 nm, at least 415 nm, at least 420 nm, at least 425 nm, at least 430 nm, at least 435 nm, at least 440 nm, at least 445 nm, at least 450 nm, at least 455 nm, at least 460 nm, at least 465 nm, at least 440 nm, at least 445 nm, at least 480 nm, at least 485 nm, at least 490 nm, at least 495 nm, at least 500 nm, at least 505 nm, at least 510 nm, at least 515 nm, at least 520 nm, at least 525 nm, at least 530 nm, at least 535 nm, at least 550 nm, at least 555 nm, at least 550 nm, at least 555 nm, at least 560 nm, at least 565 nm, at least 550 nm, at least 555 nm, at least 580 nm, at least 585 nm, at least 590 nm, at least 595 nm, at least 600 nm, at least 605 nm, at least 610 nm, at least 615 nm, at least 620 nm, at least 625 nm, at least 630 nm, at least 635 nm, at least 660 nm, at least 665 nm, at least 650 nm, at least 655 nm, at least 660 nm, at least 665 nm, at least 660 nm, at least 665 nm, at least 680 nm, at least 685 nm, at least 690 nm, or at least 695 nm and at most 700 nm, at most 695 nm, at most 690 nm, at most 685 nm, at most 680 nm, at most 675 nm, at most 670 nm, at most 665 nm, at most 660 nm, at most 655 nm, at most 650 nm, at most 645 nm, at most 640 nm, at most 635 nm, at most 630 nm, at most 625 nm, at most 620 nm, at most 615 nm, at most 610 nm, at most 605 nm, at most 600 nm, at most 595 nm, at most 590 nm, at most 585 nm, at most 580 nm, at most 575 nm, at most 570 nm, at most 555 nm, at most 550 nm, at most 555 nm, at most 550 nm, at most 545 nm, at most 540 nm, at most 535 nm, at most 530 nm, at most 525 nm, at most 520 nm, at most 515 nm, at most 510 nm, at most 505 nm, at most 500 nm, at most 495 nm, at most 490 nm, at most 485 nm, at most 480 nm, at most 475 nm, at most 470 nm, at most 445 nm, at most 440 nm, at most 455 nm, at most 450 nm, at most 445 nm, at most 440 nm, at most 435 nm, at most 430 nm, at most 425 nm, at most 420 nm, at most 415 nm, at most 410 nm, or at most 405 nm, at most 400 nm, at most 395 nm, at most 390 nm, or at most 385 nm.20. The method of clause 18 or 19, wherein the desired wavelength range has at least a portion falling with a red part of the visible spectrum.21. The method of clause 18 or 19, wherein the desired wavelength range has at least a portion falling with an orange part of the visible spectrum.22. The method of clause 18 or 19, wherein the desired wavelength range has at least a portion falling with a yellow part of the visible spectrum.23. The method of clause 18 or 19, wherein the desired wavelength range has at least a portion falling with a green part of the visible spectrum.24. The method of clause 18 or 19, wherein the desired wavelength range has at least a portion falling with a blue part of the visible spectrum.25. The method of clause 18 or 19, wherein the desired wavelength range has at least a portion falling with a purple or violet part of the visible spectrum.26. The method of any one of the preceding clauses, wherein the silk fabric waste is free of binding agents.27. The method of any one of the preceding clauses, wherein the method uses and / or introduces no binding agents.28. The method of any one of the preceding clauses, wherein the method silk fabric waste is free of whitening agents.29. The method of any one of the preceding clauses, wherein the method uses and / or introduces no whitening agents.30. The method of any one of the preceding clauses, the method further comprising patterning a surface of the recycled silk paper.31. The method of the immediately preceding clause, wherein the patterning produces an optically active surface on the surface of the recycled silk paper.32. A recycled silk paper made by the method of any one of the preceding clauses.33. The method or recycled silk paper of any one of the preceding clauses, wherein the recycled silk paper can be fully dissolved in a lithium bromide solution.34. The method or recycled silk paper of any one of the preceding clauses, wherein the recycled silk paper has an elongation at break of at least 1%, at least 2%, or at least 3%.35. The method or recycled silk paper of any one of the preceding clauses, wherein the recycled silk paper receives laser printing at a resolution within + 10% of a resolution when printing on recycled cellulose paper.36. The method or recycled silk paper of any one of the preceding clauses, wherein the recycled silk paper is 100% silk.37. A method of fabricating silk paper, the method comprising the following steps: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulping the plurality of soaked silk fibers to produce a silk pulp; andd) making silk paper from the silk pulp.38. A method of fabricating virgin silk paper, the method comprising the following steps: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulping the plurality of soaked silk fibers to produce a virgin silk pulp; and d) making virgin silk paper from the virgin silk pulp.39. The method of clause 38, wherein the making of step d) includes pulling a wet sheet from a vat containing the virgin silk pulp.40. The method of clause 39, wherein the making of step d) includes couching the wet sheet.41. The method of clause 40, wherein the making of step d) includes drying the wet sheet to form a dried sheet.42. The method of clause 41 , wherein the drying is performed under a drying pressure that is greater than atmospheric pressure.43. The method of any one of clauses 41 or 42, wherein the making of step d) includes planarizing the dried sheet.44. The method of clause 43, wherein the planarizing comprises processing the dried sheet through an etching press.45. The method of any one of clause 37 to the immediately preceding clause, wherein the making of step d) is free of sizing or sizing agents.46. The method of any one of clause 37 to the immediately preceding clause, wherein the method is free of sizing or sizing agents.47. The method of any one of clauses 38 to 44, wherein the making of step d) comprises sizing the virgin silk paper (e.g., using an internal sizing agent such as alkyl ketene dimer and / or rosin).48. The method of any one of clauses 37 to the immediately preceding clause, wherein the pulping of step c) includes beating the soaked silk fibers.49. The method of clause 48, wherein the beating is performed at least until a beating degree reaches 0.50. The method of clause 49, wherein the beating is performed for at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, or at least 30 minutes or longer after the beating degree reaches 0.51. The method of any one of the preceding clauses, wherein the method uses and / or introduces no binding agents.52. The method of any one of the preceding clauses, wherein the method uses and / or introduces no whitening agents.53. The method of any one of clause 38 to the immediately preceding clause, the method further comprising patterning a surface of the virgin silk paper.54. The method of the immediately preceding clause, wherein the patterning produces an optically active surface on the surface of the virgin silk paper.55. A virgin silk paper made by any of clause 38 to the immediately preceding clause.56. The method or virgin silk paper of clause 38 to the immediately preceding clause, wherein the virgin silk paper can be fully dissolved in a lithium bromide solution.57. The method or virgin silk paper of clause 38 to the immediately preceding clause, wherein the virgin silk paper has an elongation at break of at least 1%, at least 2%, or at least 3%.58. The method or virgin silk paper of clause 38 to the immediately preceding clause, wherein the virgin silk paper receives laser printing at a resolution within ± 10% of a resolution when printing on cellulose paper.59. The method or virgin silk paper of clause 38 to the immediately preceding clause, wherein the virgin silk paper is 100% silk.60. The method of any one of clauses 1 to 36, 51 or 52, further comprising applying at least one layer of an external sizing agent to the recycled silk paper.61. The method of any one of clauses 37, 45, 46, 48 to 52, further comprising applying at least one layer of an external sizing agent to the silk paper.62. The method of any one of clauses 38 to 54, or 56 to 59, further comprising applying at least one layer of an external sizing agent to the virgin silk paper.63. The method of any of clauses 60 to 62, further comprising cross-linking the external sizing agent.64. The method of any one of clauses 60 to 63, wherein the external sizing agent is at least one of an animal-based sizing agent (e.g., rabbit skin glue), a plant-based sizing agent (e.g., wheat starch, methyl cellulose), a synthetic sizing agent (e.g., PVA), or a regenerated natural material (e.g., silk fibroin solution).65. The method, recycled silk paper, or virgin silk paper of any one of the preceding clauses, wherein the recycled silk paper, the silk paper, and / or the virgin silk paper forms at least a part of a paper product.66. The method, recycled silk paper, or virgin silk paper of the immediately preceding clause, wherein the paper product is a packaging product, a medical product, or a combination thereof.

[0339] EQUIVALENTS AND SCOPE

[0340] The recitation of a listing of elements in any definition of a variable herein includes definitions of that variable as any single element or combinations (or subcombinations) of listedelements. The recitation of an embodiment herein includes that embodiment as any single embodiment or in combination with any other embodiments or portions thereof. Those skilled in the art will recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. The scope of the present invention is not intended to be limited to the above Description, but rather is as set forth in the following claims:

Claims

CLAIMSWhat is claimed is:

1. A method of recycling silk fabric waste into recycled silk paper, the method comprising the following steps: a) optionally sorting the silk fabric waste by color to produce color-sorted silk fabric waste; b) shredding the color-sorted silk fabric waste to produce a shredded silk fabric waste; c) soaking the shredded silk fabric waste in water for a soaking length of time of between 6 hours and 7 days to produce soaked shredded silk fabric waste; d) pulping the soaked shredded silk fabric waste to produce a silk fabric waste pulp; and e) making recycled silk paper from the silk fabric waste pulp.

2. The method of claim 1, wherein the making of step e) includes: pulling a wet sheet from a vat containing the silk fabric waste pulp; couching the wet sheet; drying the wet sheet to form a dried sheet, wherein the drying is optionally performed under a drying pressure that is greater than atmospheric pressure; planarizing the dried sheet, wherein the planarizing optionally comprises processing the dried sheet through an etching press, wherein the making of step e) is optionally free of sizing or sizing agents.

3. The method of claim 1, wherein the method is free of sizing or sizing agents.

4. The method of claim 1 , wherein the making of step e) comprises sizing the recycled silk paper (e.g., using a sizing agent such as alkyl ketene dimer and / or rosin).

5. The method of any one of the preceding claims, wherein the pulping of step d) includes beating the soaked shredded silk fabric waste, wherein the beating is optionally performed at least until a beating degree reaches 0, and wherein the beating is optionally performed for at least 5 minutes, at least 10 minutes, at least 15 minutes, at least 20 minutes, at least 25 minutes, or at least 30 minutes or longer after the beating degree reaches 0.

6. The method of claim 1 , wherein the water is tap water.

7. The method of claim 1, wherein the method includes: a) sorting the silk fabric waste by color to produce color-sorted silk fabric waste, wherein the sorting of step a) optionally: produces color- sorted silk fabric waste that is substantially colorless; produces color-sorted silk fabric waste that is gray or black; and / or produces color-sorted silk fabric waste having color with a peak wavelength within a desired wavelength range.

8. The method of claim 1, wherein the silk fabric waste is free of binding agents, and / or wherein the method uses and / or introduces no binding agents.

9. The method of claim 1, wherein the method silk fabric waste is free of whitening agents, and / or wherein the method uses and / or introduces no whitening agents.

10. The method of claim 1, the method further comprising patterning a surface of the recycled silk paper, wherein the patterning optionally produces an optically active surface on the surface of the recycled silk paper.

11. A recycled silk paper made by the method of claim 1.

12. The method of claim 1 , wherein the recycled silk paper can be fully dissolved in a lithium bromide solution.

13. The method of claim 1, wherein the recycled silk paper has an elongation at break of at least 1%, at least 2%, or at least 3%.

14. The method of claim 1 , wherein the recycled silk paper receives laser printing at a resolution within ± 10% of a resolution when printing on recycled cellulose paper.

15. The method of claim 1, wherein the recycled silk paper is 100% silk.

16. A method of fabricating silk paper, the method comprising the following steps: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulping the plurality of soaked silk fibers to produce a silk pulp; and d) making silk paper from the silk pulp.

17. A method of fabricating virgin silk paper, the method comprising the following steps: a) cutting a plurality of degummed silk fibers to produce a plurality of cut silk fibers; b) soaking a plurality of cut silk fibers to produce a plurality of soaked silk fibers; c) pulping the plurality of soaked silk fibers to produce a virgin silk pulp; and d) making virgin silk paper from the virgin silk pulp.

18. The method of any one of claims 1 to 15, further comprising applying at least one layer of an external sizing agent to the recycled silk paper.

19. The method of claim 18, further comprising cross-linking the external sizing agent.

20. The method of claim 18, wherein the external sizing agent is at least one of an animal-based sizing agent (e.g., rabbit skin glue), a plant-based sizing agent (e.g., wheat starch, methylcellulose), a synthetic sizing agent (e.g., PVA), or a regenerated natural material (e.g., silk fibroin solution).

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