In-situ deposition of Cu₂O micro-needles for biologically active textiles and their release properties

Highlights

• Formation of Cu₂O directly into viscose fabrics was carried out in two steps using quite simple technique.

• Micro-needles of Cu₂O with dimensions of 1.60 × 0.13 μm were obtained.

• Cu₂O – viscose fabrics exhibited 96.8–97.8% and 85.5–89.0% reduction viability in bacteria and fungi, respectively.

• Release was studied.

• Release profile of Cu^1+/2+ ions from fabrics was studied in water, physiological fluid and artificial sweat.

Abstract

Metal/metal oxide containing fibres are gradually increasing in textile industrialization recently, owing to their high potential for application as antimicrobial textiles. In this study, the reducing properties of cellulose were applied to synthesize cuprous oxide in-situ. The direct formation of Cu₂O on viscose fabrics was achieved via quite simple technique in two subsequent steps: alkalization and sorption. Cu contents in fabrics before and after rinsing ranged between 45.2–86.4 mmol/kg and 18.1–67.7 mmol/kg, respectively. Uniform micro-needles of Cu₂O were obtained with regular size and dimensions of 1.60 ± 0.20 μm in length and 0.13 ± 0.03 μm in width. Release of Cu^1+/2+ ions from selected samples was studied in water, physiological fluid and artificial sweat. Copper containing fabrics exhibited a percent of 96.8–97.8% and 85.5–89.0% for reduction in microbial viability, which was tested for S. aureus (as gram positive bacteria), E. coli (as gram-negative bacteria) and C. albicans and A. niger (as fungal species), respectively after 24 h contact time.

Introduction

According to United States environmental protection agency (USEPA), copper exhibits lower toxicity in comparison to many other heavy metals (IRIS, 2007). This makes copper preferable for use in different applications e.g. as disinfectant, water purifier, antifungal or antibacterial agent, algaecide and medicines (Block, 2001, Cooney, 1995, Gawande et al., 2016; Hubacher, Lara-Ricalde, Taylor, Guerra-Infante, & Guzmán-Rodríguez, 2001; Krajčiová, Melník, Havránek, Forgácsová, & Mikuš, 2014; Mallick et al., 2012; Reza, Ilmiawati, & Matsuoka, 2016). Nowadays the use of metal containing textiles is a progressively growing area due to their opportunities to be widely applicable in various purposes. Although in textile industrialization, silver has large-scaled applications (Angelova, Rangelova, Dineva, Georgieva, & Müller, 2014; Pivec et al., 2014; Pivec & Stana-Kleinschek, 2012; Wu et al., 2014), but the usage of copper and copper compounds in textiles is more preferable, due to various factors, such like: 1) A low sensitivity for human tissues and skin towards copper and copper containing fibres as reported in numerous literatures (Borkow and Gabbay, 2004, Hostynek and Maibach, 2004). 2) Detailed studies about the effects of Cu-containing intrauterine devices on women health, indicated that, low concentrations of copper could be expressed to be safe for humans (Bilian, 2002, Hubacher et al., 2001, Mallick et al., 2012). 3) Cu⁰ and copper ions exhibit antimicrobial properties (Borkow and Gabbay, 2004, Borkow and Gabbay, 2009). 4) Compared to Ag and Au which belong to the same subgroup in the periodic table, the cost of Cu is substantially lower (Iarikov, Demian, Rubin, Alexander, & Nambiar, 2012).

Therefore, different natural and synthetic fibres treated by copper and copper salts are reported to be applicable in various purposes (Cárdenas, Meléndrez, & Cancino, 2009; Cioffi et al., 2005, Gasana et al., 2006; Grace, Chand, & Bajpai, 2009; Guo, Jiang, Yuen, & Ng, 2012; Han, Kim, & Oh, 2001; Jia, Dong, Zhou, & Zhang, 2014; Lu, Liang, & Xue, 2012; Mary, Bajpai, & Chand, 2009; Schwarz et al., 2012; Shim et al., 2002; Wei, Yu, Wu, & Hong, 2008). Textiles for shielding of electromagnetic radiation have been prepared by plating of Cu on polyester fabrics through electroless deposition (Han et al., 2001, Lu et al., 2012). Similarly, electrolytic copper deposition was used for textile coloration (Guo et al., 2012). Electrically conductive textiles have been prepared by deposition of Cu (Gasana et al., 2006, Jia et al., 2014, Schwarz et al., 2012). The catalytic properties of Cu-nanoparticles and Cu-complexes also have been investigated on cellulose acetate (Shim et al., 2002). Medical textiles which exhibited antibacterial, antifungal and antiviral properties have been obtained via treatment with copper in its different forms (Cu, CuO, Cu₂O) (Abramov et al., 2009, Borkow and Gabbay, 2004, Cárdenas et al., 2009, Cioffi et al., 2005, Emam, Manian et al., 2014, Grace et al., 2009, Heliopoulos et al., 2013, Kramar et al., 2013, Mary et al., 2009, Turalija et al., 2015, Vainio et al., 2007, Wei et al., 2008).

Modification of textiles with copper can be carried out through two main routes; deposition for Cu particles (oxides/metallic) (Abramov et al., 2009; Barua, Das, Aidew, Buragohain, & Karak, 2013; Emam, Manian et al., 2014, Heliopoulos et al., 2013; Kotelnikova, Vainio, Pirkkalainen, & Serimaa, 2007; Perelshtein et al., 2009, Turalija et al., 2015, Vainio et al., 2007) and sorption of Cu ions (Chen et al., 2009; Emam, Manian, Široká, & Bechtold, 2012; Huang, Ou, Boving, Tyson, & Xing, 2009). Due to limitations in maximum copper content available by sorption of Cu ions (Emam et al., 2012), the application of Cu particles based on oxide/metallic form in textiles is described to be promising for textile functionalization and thus scientific interest increased recently (Abramov et al., 2009, Emam, Manian et al., 2014, Heliopoulos et al., 2013, Turalija et al., 2015). Modification of cellulosic materials with cuprous oxide already has been studied extensively (Abramov et al., 2009, Barua et al., 2013, Borkow and Gabbay, 2004, Emam, Manian et al., 2014, Jia et al., 2014, Kotelnikova et al., 2007, Perelshtein et al., 2009, Turalija et al., 2015, Vainio et al., 2007). Cuprous oxide may be deposited on cellulose through in-situ and ex-situ methods. In the ex-situ method (indirect method), Cu(I)oxide is prepared in a first step and then loaded on the cellulose substrate (Abramov et al., 2009, Turalija et al., 2015). However, in case of in-situ method (direct methods) the Cu ions at first are inserted into the cellulose polymer matrix. In a second step the reduction to form the insoluble Cu(I)oxide is initiated (Emam, Manian et al., 2014, Kotelnikova et al., 2007, Vainio et al., 2007). Copper uploading could be controlled easily in case of the ex-situ technique. However, incorporation of metal/metal oxides using in-situ technique has been reported to be advantageous with lower chemical consumption and producing textiles with good fastness properties (Emam, Mowafi, Mashaly, & Rehan, 2014; Emam, Saleh et al., 2015, Emam, Saleh et al., 2016). Additionally, in case of in-situ techniques the use of cross-linkers to bind the particulate material is not required (Tang et al., 2013, Tang et al., 2012). As a result, methods which form the active cuprous oxide in-situ by use of external reducing agents/chemicals are of high interest as basis for a clean production technique.

Under appropriate conditions cellulose exhibits reducing properties due to the presence of hydroxyl and aldehyde groups (Emam and El-Bisi, 2014, Emam, Mowafi et al., 2014, Emam, Saleh et al., 2015; Emam et al., 2016). This behaviour has been utilised to prepare colloidal silver nanoparticles and for in-situ incorporation of nanosilver into cellulosic fibers/fabrics (Emam and El-Bisi, 2014, Emam, Mowafi et al., 2014, Emam, Saleh et al., 2015; Emam et al., 2016), carboxymethyl cellulose, starch, alginate, pectin, acacia and xanthan, also have been used to synthesis nano-sized Ag⁰/Au⁰ particles from Ag¹⁺/Au³⁺ ions solution (Ahmed, Abdel-Mohsen, & Emam, 2016; Ahmed & Emam, 2016; Ahmed, Zahran, & Emam, 2016; El-Rafie, Ahmed, & Zahran, 2014; Emam & Ahmed, 2016; Emam, El-Rafie, Ahmed, & Zahran, 2015; Emam & Zahran, 2015; Hebeish, El-Rafie, Abdel-Mohdy, Abdel-Halim, & Emam, 2010; Zahran et al., 2014a, Zahran et al., 2014b). Similarly carbohydrates serve as active agents to reduced Cu²⁺ ions to Cu¹⁺ to form Cu₂O (Emam, Manian et al., 2014; Ródio, Pereira, Tavares, & da Costa Ferreira, 1999; Turalija et al., 2015). This reduction process was promoted by elevated temperature and presence of alkali (El-Rafie et al., 2014, Emam and El-Bisi, 2014, Emam, Manian et al., 2014, Emam, Mowafi et al., 2014, Emam, Saleh et al., 2015; Emam et al., 2016; Emam and Zahran, 2015, Ródio et al., 1999, Turalija et al., 2015, Zahran et al., 2014a, Zahran et al., 2014b).

The present study focuses on direct deposition of Cu₂O on viscose fabrics using a quite simple technique in two subsequent steps which are alkalisation and sorption. Alkalization has been used for enhancing the reducing power of cellulose, to achieve in-situ incorporation of cuprous oxide (Cu₂O) into viscose fabrics. To incorporate Cu₂O into viscose fabrics, viscose fabrics were treated with a defined amount of alkali followed by impregnation in CuSO₄ solution of different concentration. Carboxylic group content was determined using the methylene blue sorption and copper content on Cu-fabrics was measured using atomic absorption spectroscopy (AAS). Colorimetric data and mechanical properties were recorded for the treated fabrics as function of conditions applied in preparation. Treated fabrics were characterized using scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD) and attenuated total reflection–fourier transformation infrared spectroscopy (ATR-FTIR). Release properties of Cu²⁺ ions from treated fabrics were studied in different liquid media such as water, physiological model fluid and artificial sweat. Biological activities of Cu-containing fabrics were tested quantitatively using the shaking flask test method with bacterial strains of Escherichia coli and Staphylococcus aureus and fungal species of Candida albicans and Aspergillus niger.