Sonochemical Deposition of Silver Nanoparticles on Wool Fibers Liraz Hadad, 1 Nina Perkas, 1 Yosef Gofer, 1 Jose Calderon-Moreno, 2 Anil Ghule, 3 Aharon Gedanken 1 1 Department of Chemistry and Kanbar Laboratory for Nanomaterials, Center for Advanced Materials and Nanotechnology, Bar-Ilan University, Ramat-Gan 52900, Israel 2 Applied Physics Department, Universitat Politecnica de Catalunya, Avenida Canal Olimpic, Castelldefels, 08860 Barcelona, Spain 3 Department of Chemistry, National Tsing Hua University, 2 Kuang Fu Road, Hsin Chu, Taiwan Received 5 July 2006; accepted 30 October 2006 DOI 10.1002/app.25813 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: Silver nanoparticles were deposited on the surface of natural wool with the aid of powered ultra- sound. The average particle size was 5–10 nm, but larger aggregates of 50–100 nm were also observed. The sono- chemical irradiation of a slurry containing wool fibers, sil- ver nitrate, and ammonia in an aqueous medium for 120 min under an argon atmosphere yielded a silver–wool nano- composite. By varying the gas and reaction conditions, we could achieve control over the deposition of the metallic silver particles on the surface of the wool fibers. The resulting silver-deposited wool samples were characterized with X-ray diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, high-re- solution scanning electron microscopy, electron-dispersive X-ray analysis, Brunauer, Emmett, and Teller physical adsorption method, X-ray photoelectron spectroscopy, and Raman and diffused reflection optical spectroscopy. The results showed that the strong adhesion of the sil- ver to the wool was a result of the adsorption and interac- tion of silver with sulfur moieties related to the cysteine group. Ó 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1732–1737, 2007 Key words: fibers; irradiation; metal-polymer complexes; nanocomposites; nanolayers; nanoparticles; proteins INTRODUCTION The growing interest in textile materials with antimi- crobial properties has stimulated an extensive search for new technologies for the modification of wool fibers and the production of safety yarns. 1–3 Different types of antimicrobial treatments have been studied for the protection of wool products from damage caused by pathogenic microorganisms. Among these treatments, there is the coating of wool with resin- bonded copper-8-quinolinolate, chlorinated phenol and its derivatives, sodium dichloroisocyanurate, qua- ternary ammonium compounds, metal ions, and or- ganic tin compounds in finishing processes. 4–6 A novel biotemplate redox technique has been employed for the deposition of silver nanoclusters on another type of natural fiber—silk fibroin fiber. 7 Wool fibers as proteins consist of polar groups of amino acid residues able to bind other charged or- ganic and inorganic molecules. The cationic amine salts can interact with anionic acidic groups in acid dyes to form ionic pairs, thus coloring the wool fibers. Similarly, the carboxylic acid groups existing in wool proteins are also interactive with many other cationic compounds. For instance, metal ions such as Ag þ and Cu 2þ can be absorbed into the wool fibers. 7,8 It has been demonstrated that the treatment of wool with metal nanoparticles may induce useful changes in nat- ural fibers such as antistatic properties, electrical con- ductivity, and antimicrobial activity. 9,10 The principal requirements for metal–fiber nano- composites are small dimensions, regular shapes, and uniform size distributions of the silver nanoparticles. Sonochemical irradiation has been proven to be an effective method for the synthesis of nanophase mate- rials and for the deposition and insertion of nanopar- ticles onto and into mesoporous and ceramic supports as well as polymers. The efficiency of sonochemistry comes from the explosive collapse of the bubbles forming in the liquid as a result of sonochemical irra- diation. The hot-spot mechanism explains that the effect of very high temperatures obtained upon the collapse of the bubbles, following by very high cooling rates, leads to the creation of nanostructure prod- ucts. 11,12 The advantage of this method, which has been demonstrated, is the achievement of a very ho- mogeneous coating with a narrow particle size distri- bution. 13,14 In previous publications, we have reported the preparation of amorphous silver about 20 nm in Correspondence to: A. Gedanken (gedanken@mail.biu.ac.il). Journal of Applied Polymer Science, Vol. 104, 1732–1737 (2007) V V C 2007 Wiley Periodicals, Inc.