1a. Objectives (from AD-416):
Objective 1 - Develop chemistries and treatments that enable new cotton-based products for biomedical and specialty applications. Objective 2 - Develop enzyme-based technologies that enable new cotton-based products for decontamination applications. Objective 3 - Develop new finishing chemistries and innovative treatment processes that enable new cotton-based products with flame retardancy and moisture control. Objective 4 - Develop environmentally friendly cotton, dyeing and finishing processes based on the combination of sonication and enzymatic technologies.
1b. Approach (from AD-416):
The U.S. cotton industry continues to face supply and demand concerns. Since cotton is used in manufactured products, the industry has been challenged by the downsizing of manufacturing facilities that traditionally provide a major underpinning to domestic cotton consumption. Thus, with the goal of giving U.S. cotton utilization a competitive edge, research emphasis will be placed in cotton fiber science and product development where consumer and industrial needs are unmet and show promise. Some of the areas of consumer need for cotton products and process potential are: specialty nonwoven pads and wipes medical/hygiene, apparel/home furnishings, and enzymatic bio-processing. The targeted research in the areas of synthetic chemistry, enzymatic, bio-processing, flame retardant chemistry, and analytical cotton fiber science will be undertaken by the collaborative efforts of the Cotton Chemistry Utilization Unit to yield new cotton products. Collaboration and synergy with the research unit’s cotton nonwoven project in the areas of value-added cotton materials, enzymes, processing, and environmental sustainability make the likelihood of success high. Products that are envisioned to arise from this research include medical, hygiene, and hospital materials, broad spectrum anti-microbial and decontamination wipes, durable low-cost flame retardant apparel and home furnishings, and ultrasonic approaches for smooth finishing of cotton textiles. This proposed research also takes into account preserving the environment and economical cost. Research emphasis will be placed on developing approaches to enable a comprehensive understanding of the relation of structure to function on modified cotton for a broad range of potential uses.
3. Progress Report:
Agricultural Research Service (ARS) scientists at Southern Regional Research Center (SRRC), New Orleans, Louisiana, have developed new products, applications, and processes for expansion of domestic cotton in the areas of: 1) Flame Retardant Technology; 2) Nanotechnology; 3) Medical and Hygiene Products; 4) Bioprocessing; and 5) Biofuel Technology. Progress in these five areas of cotton research is as follows: 1) Flame Retardant Technology; a non-traditional approach to using fiber reactive small molecules as flame retardants that are also water soluble has proven highly effective. The water soluble compounds which are preferred by industry are bonded covalently to cellulose in the cotton fabric. In this regard cotton fabrics reacted with phosphinate-substituted cyanuryl chlorides and acyl-triazines have shown outstanding results in flame retardant testing while also withstanding many home launderings. 2) Cotton-Based Nanotechnology; a) the novel approach of multiple nano-layers (less than one micron thick each) applied as layer-by-layer 'nano-coatings' to cotton fabrics was shown to have excellent flame retardant properties, b) cotton cellulose nanocrystals were covalently linked to lysozyme (an enzyme that kills bacteria by breaking down the cell wall), and the resulting enzyme conjugate has the highest activity (1,500 U/mg cotton) yet reported in the literature for an immobilized enzyme. 3) Medical and Hygiene Products included: a) Increased thrombin production from blood-exposed, to charge modified cotton fibers having application to enhanced hemorrhage control properties in cotton dressings, c) Potent protease sequestrant wound dressings using citric acid crosslinking of cotton fibers have increased efficacy over the previous one making for a efficient low cost approach to treatment of chronic wounds, d) Using an expedient fiber surface analysis, new greige cotton/synthetic blend nonwovens were discovered based on fiber polarity and moisture uptake applicable to absorbent incontinence materials found in commercial incontinence products. 4) Bioprocessing: it has been demonstrated that enzyme treatments of cotton proceed up to twice as fast when carried out in a low level ultrasonic field. Optimal synergy between the enzyme and ultrasonic field occurs on a well defined cotton-liquid interface. Both cellulases and pectinases have been shown to be effective. Four new polygalacturonase enzymes were found to have ultrasound-enhanced bioscouring properties. 5) Biofuels: experiments utilizing switchgrass revealed the combination of ultrasound and enzymes resulted in an increase of 7.5% in reducing sugars compared to experiments using only enzymes. Through ammonium hydroxide, pretreated switchgrass, the combination of ultrasound and enzymes resulted in an increase of 9.3% in reducing sugars compared to experiments using just enzymes.
1. Flame retardant (FR) technology. The total synthesis of a water-soluble FR molecule is a FR cotton milestone since FR chemistry has involved compounds that were effective but were only soluble in organic solvents. The synthesis of a water-soluble FR compound attracted the attention of industrial stakeholders interested in FR cotton for use in a variety of cotton-based applications including firefighter apparel, institutional draperies, upholstery, carpet, transportation blankets, seat covers, children’s sleepwear, and bedding.
2. Cotton-based nanotechnology. By treating cotton fabrics with intumescent nano-coatings composed of phosphorous-nitrogen rich polymers with a layer-by-layer assembly, the cotton fabrics can be rendered anti-flammable. This novel approach to layer-by-layer nano-coatings on cotton was prominently highlighted in a Nature news story regarding its potential applications. A robust cotton cellulose nanocrystalline enzyme conjugate with record high activity demonstrates the potential use of immobilized enzymes on cotton cellulose nanocrystals as a route to improving the efficacy of industrial immobilized enzymes.
3. Medical and hygiene products. In the body's reaction to an open wound injury, the enzymes thrombin and elastase are released in the hemostatic and inflammatory stages. Modulation of the levels of these enzymes with charge modified cotton promises to improve healing in chronic and hemorrhaging wounds. The design of modern diapers and incontinence products relies on multiple layers of fabrics and materials which function to move and trap moisture effectively. Cotton fiber has scarcely been studied for these attributes. Electrokinetic analysis showed moisture uptake, swelling and polarity of nonwoven cotton blends were suitable for use in the top sheet and acquisition/distribution layers of incontinence products. A high volume incontinence industry has expressed active interest in absorbent cotton discovered.
4. Bioprocessing. Enzymes have been shown to be effective cotton textile treating systems to impart desizing, scouring, bleaching, de-fuzzing and denim abrasion effects while reducing energy, water and chemical consumption, but they work more slowly than their chemical-based counterparts. It was demonstrated that enzyme treatments of cotton proceeds up to twice as fast when carried out in a low level ultrasonic field through the mechanism of enhanced molecular movement.
5. Biofuels. The application of ultrasound in the bioconversion of switchgrass to biofuel-producing sugars was a significant accomplishment. The application of ultrasound significantly increased the amount of reducing sugars available for conversion to ethanol. Given the pressing need to improve and expand biofuel production and given the energy security needs in this country, this is a significant development.
Edwards, J.V., Prevost, N.T., Condon, B.D., French, A.D., Wu, Q. 2012. Immobilization of lysozyme-cellulose amide-linked conjugates on cellulose I and II cotton nanocrystalline preparations. Cellulose. 19(2):495-506.