Submitted to: Nanoscale Advances
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2022
Publication Date: 12/6/2022
Citation: Nam, S., Hillyer, M.B., He, Z., Chang, S., Edwards, J.V. 2022. Self-induced transformation of raw cotton to a nanostructured primary cell wall for a renewable antimicrobial surface. Nanoscale Advances. 4(24):5404-5416. https://doi.org/10.1039/D2NA00665K.
Interpretive Summary: This study offers one of the most sustainable and affordable ways to practice nanotechnology in producing permanent antimicrobial textile products. The current nanotechnology used in the textile industry involves complex and high-cost synthesis of silver nanoparticles (Ag NPs), and the resulting Ag NP-treated textile products, suffer from a lack of durability. We introduced a new idea that raw cotton fiber can simply synthesize Ag NPs to itself (450 mg/kg) without the aid of any reducing and stabilizing agents. Unlike scoured and bleached cotton that is typically used in the fabrication of textiles, raw cotton contains noncellulosic constituents in the primary cell wall, which acted as reducing agents. TEM images of the cross-section of the fiber confirmed the inorganic-organic hybrid sub-structure with about 200 nm thickness, in which many Ag NPs (ca. 28 nm in diameter) were uniformly formed. Some of Ag NPs diffused into the secondary cell wall. The Ag NPs synthesized underneath the fiber surface were physically trapped and chemically bound, exhibiting superior washing durability. About 74% of the total Ag in the raw cotton fabric remained after 50 laundering cycles. The Ag NP synthesis by raw cotton fiber is economical and eco-friendly, as it not only eliminates the use of a reducing agent, a stabilizing agent, and a binder but also saves large amounts of water, energy, and chemicals that are used in the scouring and bleaching processes. Blending Ag NP-raw cotton fibers into the fabrication of textile products will equip them with the antimicrobial surface, which renews wash after wash.
Technical Abstract: In this study, raw cotton is shown to undergo self-induced transformation to a nanostructured primary cell wall. This process affords a metal nanoparticle-mediated antimicrobial surface that is regenerable through multiple washings. Raw cotton, without being scoured and bleached, contains noncellulosic constituents in the primary cell wall including pectin, sugars, and hemicellulose. These types of noncellulosic components of the primary cell wall provide definitive active binding sites for the in situ synthesis of silver nanoparticles (Ag NPs) having a diameter of ca. 28 nm. Facile heating in an aqueous solution of silver nitrate activated raw cotton to manufacture Ag NPs yielding up to 450 mg/kg. The efficiency of raw cotton’s synthesis was demonstrated by comparing the results with scoured and bleached cotton and monitoring the evolution pattern of the nanoparticle synthesis with surface plasmon resonance. Transmission electron microscopic images of raw cotton fiber cross-sections confirmed the formation of an inorganic-organic hybrid layer with a thickness of 200 nm. The Ag NPs embedded in the primary cell wall are effectively immobilized, exhibiting resistance to leaching as judged by continuous launderings. Determination of the total Ag remaining in raw cotton after 50 laundering cycles was found to be 74%. The raw cotton’s Ag NP synthesis offers a durable and sustainable method for producing reliable cotton-based Ag NP-functionalized fabrics and fiber-based prototypes and affords a promising economical alternative to the facile production of antimicrobial textile products.