Carbohydrate Polymers 110 (2014) 148–155 Contents lists available at ScienceDirect Carbohydrate Polymers j ourna l ho me pa g e: www.elsevier.com/locate/carbpol Production of antibacterial colored viscose fibers using in situ prepared spherical Ag nanoparticles Hossam E. Emam ∗ , Salwa Mowafi, Hamada M. Mashaly, Mohamed Rehan Textile Research Division, National Research Centre, Dokki, Cairo 12622, Egypt a r t i c l e i n f o Article history: Received 16 February 2014 Received in revised form 4 March 2014 Accepted 20 March 2014 Available online 3 April 2014 Keywords: Viscose In situ AgNPs Coloration Antibacterial fibers a b s t r a c t In situ incorporation technique was used for coloration and acquiring excellent antibacterial proper- ties for viscose fibers by silver nanoparticles (AgNPs). AgNPs were prepared in situ and incorporated in viscose matrix directly without using any other reducing and stabilizing agents. The main objective of this research was to successfully employ the reducing and stabilizing features of cellulose to produce nanosilver–viscose composites. Coloration of fibers after in situ AgNPs incorporation is related to surface plasmon resonance of silver. Colorimetric data were recorded as a function of washings to characterize the final colored fibers. Fastness properties and silver release were all measured to study the washable and wear off properties. Depending on the silver concentration, yellowish colored fibers with differ- ent shades were produced. Good fastness properties were obtained after 20 washings without using any crosslinker or binder. The colored fibers had excellent antibacterial activities against Escherichia coli, even after 20 washings. © 2014 Elsevier Ltd. All rights reserved. 1. Introduction Nanoparticles of noble metals showed specific colors accord- ing to their surface plasmon resonance (SPR) absorption. Hence the examination of surface Plasmon resonance is taking a part of a huge research area, to investigate the properties on the nano- meter scale (El-Sayed, 2001; Eustis, 2006; Eustis & El-Sayed, 2006). Numerous characteristics of nanometals, including their optical, electronic, catalytic, chemical and physical properties had shown to be related to size and shape of the precursor nanoparticles. The shape and crystallographic structure are the two major fac- tors affecting on the SPR bands, the catalytic properties and surface activities of nanoparticles (Dick, McFarland, Haynes, & Van, 2002). On the other hand, the size of metal nanoparticles influences their optical properties (Qiaoling & Yahong, 2012). The reducing and stabilizing agents used in the preparation process of nanomaterials play an important role in control- ling both of size and shape of the resultant nanomaterials, and in turn, affects on the color of the net produced nanosilver colloidal solution. Kotelnikova et al. reported that, using of dif- ferent reducing agents affects on the color of AgNPs incorporated cellulose. Using cellulose itself or sodium borohydride as reduc- tant gave metallic silver with yellow color. By using ammonia ∗ Corresponding author. Tel.: +20 1008002487. E-mail address: hossamelemam@yahoo.com (H.E. Emam). or glycerol as reducers the red–brown color of Ag 0 was pro- duced, while the grey color appeared when hydrogen potassium phosphate or hydroquinone were used (Kotelnikova, Demidov, Wegener, Windeisen, & Kotelnikov, 2003; Kotelnikova, Stoll, et al., 2003). Silver nanoparticles (AgNPs) colloidal solution was prepared with different colors including yellow, red, green, blue and grey (Abdel-Mohsen, Abdel-Rahman et al., 2014; Bois et al., 2009; Gopinath et al., 2012; Harekrishna et al., 2009; Hebeish et al., 2010 Emam et al., 2013; Salprima et al., 2013) depending on their shape. In acidic medium, the preparation of silver nanopar- ticles by utilizing cellulose as reducing agent produced grey color (Emam et al., 2013). The yellowish color is corresponding to the spherical AgNPs which was easily produced by using carbohydrate materials as reducing agents (Abdel-Mohsen, Abdel-Rahman et al., 2014; Harekrishna et al., 2009; Hebeish et al., 2010). The triangular silver nanoplates and silver nanoprism have been obtained by sev- eral researchers with blue color, showing three absorbance beaks at 350, 450–500 and at 700–800 nm (Bin et al., 2011; Deivaraj, Lala, & Lee, 2005; Guoli, Wentao, Kai, & Zhanfang, 2011; Huiying et al., 2008; Jia et al., 2013; Sadhan, Priyanka, Santanu, Gobinda, & Ajay, 2012). Also, the silver nanodisc colloidal solution exhibited three absorbance beaks at 350, 400 nm and the maximum beak at 500–650 nm. These three beaks are contributing to the red color (Deivaraj et al., 2005; Sadhan et al., 2012). However, silver nanorods or nanoplates colloids had a greenish color (Deivaraj et al., 2005; Sadhan et al., 2012). http://dx.doi.org/10.1016/j.carbpol.2014.03.082 0144-8617/© 2014 Elsevier Ltd. All rights reserved.