|LUM, JUNE - Us Army Natick Center|
|RICHARDS, MOLLY - Us Army Natick Center|
|ZHANG, QINGBO - Brown University|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2020
Publication Date: 4/14/2020
Citation: Nam, S., Hillyer, M.B., Condon, B.D., Lum, J.S., Richards, M.N., Zhang, Q. 2020. Silver nanoparticle-infused cotton fiber: durability and aqueous release of silver in laundry water. Journal of Agricultural and Food Chemistry. 68:13231-13240. https://doi.org/10.1021/acs.jafc.9b07531.
Interpretive Summary: Silver nanoparticles find wide use in household and industrial products including textiles for their antimicrobial efficacy. To impart the wash durability of the nanoparticle, the nanoparticles are typically coated onto textiles with some binders. However, the currently available surface-treated commercial and laboratory-prepared textile products have shown significant leach of silver nanoparticles into laundry water. This study showed that the in situ internal formation of silver nanoparticles within cotton fiber is an effective and reliable way to improve wash durability. Cotton fibers were infused with about 0.3 wt% of silver nanoparticles (12 nm) in the entire volume of the fiber and underwent consecutive simulated launderings up to 50 cycles in water and a detergent solution. Colorimetric, spectroscopic, and elemental analyses on the silver nanoparticle-infused cotton consistently showed the two-step silver release from externally and internally formed nanoparticles during the initial and extended washings, respectively. The external nanoparticles on the fiber surface linearly released silver, most of which are ionic silver in water, showing better particle-leach resistance than surface-treated silver nanoparticles in commercial and laboratory-prepared textiles in the literature. The plateau-like silver releases in water and a detergent solution as increasing the laundering cycle were attributed to the immobilization of the internal nanoparticles within the fiber. A majority of the internal nanoparticles—92% and 87%—were estimated to remain in cotton after 50 laundering cycles in water and a detergent solution, respectively. Considering that most textile manufacturing processes involve washing, the final products that the consumer will experience in household use would have mainly internal nanoparticles, resulting in the retention of antimicrobial activity during their long term use.
Technical Abstract: Although application of silver nanoparticles to antibacterial items of commerce is well established, there have been increasing concerns on their leach, particularly into laundry water from textile products. However, a recently developed process wherein silver nanoparticles are synthesized in situ within the cotton fiber itself promises their wash fastness. In this study, the silver release behavior of the silver nanoparticle-infused cotton fiber during consecutive launderings in water and a detergent solution. Approximately 3,000 mg/kg of silver nanoparticles with 12 nm in diameter were uniformly produced in the entire volume of cotton fiber. A combination of colorimetric, spectroscopic, and elemental analyses showed 1) a non-linear silver release behavior: a rapid release from externally formed nanoparticles on the fiber surface during the initial washing and a plateau-like release from internally formed nanoparticles during the extended washing and 2) superior particle-leach resistance as compared with those in commercial and laboratory-prepared textiles in the literature. The results indicate that the internal nanoparticles were immobilized inside cotton fiber for leach-proof textile products. About 92% and 87% of the internal nanoparticles were retained in cotton after 50 simulated home laundering cycles in water and a detergent solution, respectively.