Antimicrobial Biocomposites Fiber‐Welded with Lignocellulose Containing Silver Nanoparticles

Abstract

Biopolymer materials that use silver to imbue antimicrobial properties are finding broad application in areas such as packaging, textiles, and building materials. Conventional methods to incorporate silver can damage the supporting biopolymer matrix and/or result in large‐sized silver nanoparticles (Ag NPs) with poor antimicrobial efficacy. To mitigate these concerns, in this study, uniformly distributed, small (≈5–10 nm) Ag NPs are grown into a well‐preserved lignocellulose powder matrix by using a gas‐phase reducing agent at low temperature. The Ag NP‐ lignocellulose powders are fully characterized and their antimicrobial performance is investigated by inactivating planktonic bacteria and inhibiting biofilms. The most potent antimicrobial product, L_10Ag, achieves more than 4‐log reduction in planktonic bacterial viability within 3 h and a biofilm inhibition rate of 97.9%. Furthermore, the Ag NP impregnated powders are post‐processed through natural fiber welding (NFW), an emergent, innovative, ionic liquid (IL)‐based method that can be used to engineer biopolymer materials into new functional biocomposites. NFW transforms the powders into higher‐order structures, imparting anti‐microbial capacity without degrading the material properties of the biopolymer support.

Mesoporous Natural Fiber Welded Cellulose Containing Silver Nanoparticles as a Recyclable Heterogeneous Catalyst

“…[ 27 ] However, the TOF values for the 1.0–10 wt% AgNP‐NFW catalysts are inversely proportional to AgNP loading. If we assume that the AgNP sizes observed by SEM are uniform throughout the composite (as has been observed in our previous studies on Pd‐ and Ag‐based NPs prepared via IW in cellulosic materials [ 18,19 ] ), this trend could be due to physical differences in the mesoporous catalyst support. In a recent study, Aiello et al.…”

“…We hypothesized this mesoporous matrix would be ideal for housing AgNP prepared via IW because prior studies using IW in untreated, low surface area cellulose delivered ≈9 nm diameter AgNPs. [ 18 ] In the current study, the IW process required isopropanol (IPA, to preserve the mesoporosity) and ethylenediamine (EN, to solubilize the AgCH 3 CO 2 ); as a result, AgNPs that appear nominally spherical with diameters of ≈27 ± 5 nm were observed ( Figure and Figure S1, Supporting Information). This semi‐quantitative size distribution of AgNP at the surface was determined by measuring the size of particles observed in the highest resolution SEM images.…”

“…Upon drying in air, the Ag‐laden NFW cellulose composite was subjected to low temperature tube furnace reduction (N 2 at 120 °C for 2 h, then H 2 at 120 °C for 2 h), which the previous study has demonstrated will convert the Ag + to AgNP. [ 18 ] Each AgNP catalyst was subsequently rinsed with water for 24 h to remove residual EN, then they were resubjected to the “gamut rinse” and dried in air (60 °C for 24 h). By this method, catalysts containing 0.01, 0.1, 1.0, 5.0, and 10 wt% Ag in mesoporous cellulose were prepared.…”

“…Since 2016, natural fiber welding (NFW) has emerged as a promising method for engineering cellulose-based nanoparticle catalyst supports. [17][18][19] In NFW, biopolymer fibers are partially dissolved and mobilized upon exposure to controlled amounts of an ionic liquid (IL) (e.g., 1-ethyl-3-methylimidazolium acetate (EMImAc)), then reorganized into welded fibers upon IL removal. NFW is environmental friendly and sustainable and can often improve the mechanical properties of the welded fiber product.…”

Toward a Green Chemistry Approach for the Functionalization of Melamine Foams with Silver Nanoparticles

“…In yellow is highlighted the two characteristic peaks corresponding to the 3d core level of Ag, Ag 3d 3/2 and Ag 3d 5/2 , at binding energy 374 eV and 368 eV, respectively. [ 16,57 ]…”