1a. Objectives (from AD-416):
Develop commercially viable processes based on chemical or enzymatic crosslinking that increase the market value of wool. 1A: Develop systems for functional modification of wool. 1B: Develop keratin modification systems. Develop extraction and derivatization processes for the production of commercially viable products from keratin. 2A: Extract and characterize keratin from wool. 2B: Form structural keratin materials for product development.
1b. Approach (from AD-416):
1A. Crosslinking and self-crosslinking systems can be used to modify wool. - Wool fabric of fine-gauge jersey knit suitable for military underwear will be processed by the ARS Process to confer anionic charge for subsequent reactivity with quaternary amine compounds to add antimicrobial resistance. This approach can be used to attach other compounds containing quaternary amino groups. It will also be used to improve physical/mechanical properties. 1B. Keratin can be self-crosslinked, crosslinked to wool, and crosslinked to agents for delivery to wool through TG-mediation. - How to retain or increase the strength of wool in processing will be addressed by applying KP with and without TG to a fine-gauge jersey fabric of fine yarn size required by Military specifications for ARS washable wool. The extracted keratins of domestic wool from fine to coarse will be applied to the fabrics. Their adhesion and permeation characteristics will be examined. The effects of these applications on strength, shrinkage and physical/mechanical properties will be determined. Making these applications to the fabric will enable the determination of how the various KP molecular weight fractions impact fiber strength and this will have implications for yarn processing before the fabric is knitted or woven. 2A. Oxidation, reduction, and enzyme systems can be used to isolate keratin with the chemical and structural integrity of wool. - Alkaline oxidation and reduction methods will be used to hydrolyze wool to convert keratin amides and disulfides to the corresponding acids. Smaller peptide and protein fragments from hydrolysis of wool will be composed of Type II keratin intermediate filament and keratin with microfibrillar structure. MALDI-TOF/TOF spectrophotometry will be used to identify these IFPs. Keratin functionality and end-use will be determined by the hydrolysis conditions used to break or restore disulfide likages. KP sites of reactivity such as amide, carboxyl, sulfoxide, sulfide, and thiosulfide will be identified. Solubilized wool fiber with will exhibit various transformed morphologies such as lyophilized powders. The isolated keratin materials will be characterized by molecular mass and functional group content to determine their unique characteristics as feedstock materials for developing novel products and applications. Hydrolysis systems will be designed to recover pure keratin in the form of IFPs as constituent microfibrillar and matrix proteins. The conditions of hydrolysis will range from mild to severe as governed by pH, exposure time, and temperature. One method will involve alkaline oxidation hydrolysis at pH 12 to 13. 2B. Keratin from wool can be tailored into adaptable forms which can be modified to meet the needs of bio-based commercial markets to replace petroleum-derived products. The physical forms and behaviors of these products will be controlled by the conditions of wool hydrolysis, keratin recovery from hydrolysis, and subsequent modification (s) of the extracted keratin.
3. Progress Report:
Keratin-from-wool is repositioning wool in niche markets for personal care. 1a. ARS Processing of wool continues sustained interest through co-investigations and invited presentations: Mori Consultant Eng, Japan; publication "Expanding the utility of ARS process bleaching," publication Textile Res. J 81(7),2011,1818-1828; American Sheep Industry (ASI) / National Lamb Feeders Association Convention, Scottsdale, AZ,: Wool and Keratin from Wool for Bio-based, Value-added Products, 2012. 1b. Enzyme-assisted crosslinking by transamidation was further investigated and extended to investigate the binding of keratin to keratin, keratin to wool, and keratin-associated nanoparticles to wool. This technology was incorporated into keratin product development. 2a. Keratin hydrolysates and powders were transformed into products of different forms and all exhibited ability to absorb and desorb high levels of moisture for exceptional uptake and delivery of active agents. These materials were thermally responsive and exhibited unique mechanical, rheological, and textural properties and were characterized for functionality and potential reactivity by various analytical and instrumental methods, physical and chemical analysis. 2b. Keratin films, gels, sponges, mats, microfibers were evaluated as products and adducts to meet targeted end-uses. From the patent issued as SN 13/106, 942, "Methods to Produce Keratin Elastomer," an Invention Disclosure is pending application under the title, "Keratin from Wool to Strengthen Hair" (Patent Application is being prepared). A presentation at the ACS meeting in San Diego, entitled, "Keratin Sponge/hydrogel: Interpenetrating Biopolymer Network for Riboflavin Delivery," reported novel keratin sponge materials as a delivery agent. Various novel forms of keratin were produced as pliable keratin skin and edible keratin pasta by investigations on modifying keratin hydrolysate products with nonsynthetic additives which are commonly used in “green” formulations for personal care. Keratin manuscripts were submitted to report as a platform for active agent delivery as "Keratin Sponge as Absorbent, Excipient Biomaterial Part II. Active Agent Delivery."
1. Wool and keratin modification systems. ARS process for wool can provide bleaching and shrinkproofing to other fiber types: cotton, rayon, and nylon and that the process can be used under modified conditions to form a new sheer fabric similar to organdy and voile which are typically made of cotton. ARS research established that wool can be modified by directly applying unassisted keratin hydrolysate solution or keratin powder in solution to wool fiber and fabric. Further modification of wool for specific end-use was accomplished by systems involving the crosslinking wool with keratin materials through enzyme-mediated transamidation chemistry. ARS researchers at Wyndmoor, Pennsylvania also established that this enzyme reaction can be used to carry agents to wool to improve properties such as strength. It was shown that this process, the enzyme-mediated crosslinking of wool, can be used to attach active agents to wool, to keratin hydrolysates, and to powders for delivery to other solid keratinous substrates. Nanoparticle wool as a platform for derivatized keratin delivery was proven by the documentation of the molecular association of the complex of tethered keratin to nanoparticle silver and the adhesion of this complex to wool. Proof of concept of the ability of keratin to form a complex with nanoparticle silver was shown by micrographs documenting the adhesion of nanoparticle silver to keratin in a head-to-tail configuration.
2. Isolation of keratin from wool, formation and structural characterization for product commercialization. Keratin from wool was isolated by ARS researchers at Wyndmoor, Pennsylvania by a wide variety of extraction methods which proved nondestructive to chemical composition. Many physical forms of keratin were isolated with different micro- and macrostructural integrity. They were characterized for chemical, physical, thermal, rheological differences to determine their suitability for various specific enduses as stand-alone products and as platforms for agent delivery for the pharmaceutical, biomedical, cosmetic, and personal care industries. In response to requests for proposals, four proposals were submitted for review to these global industries through NineSigma.