## 2 Materials and Methods
### Methods  
#### 2.2.1 Magnetron Sputtering  
The knitted PETE samples were modified using a DC magnetron sputtering system produced by P.P.H. Jolex s. c. (Czestochowa, Poland), schematically presented in Figure 2.  
The apparatus was developed for the Lukasiewicz Research Network--Textile Research Institute in Lodz, Poland--for the purpose of the project Envirotex--PO IG no. 01.03.01-00-006/08 co-financed from the funds of European Regional Development Fund within the framework of the Operational Programme Innovative Economy 2007-2013. It allows the semi-continuous deposition of metallic coatings on different fabrics (up to 60 cm wide).  
The deposition of coatings was carried out in the atmosphere of argon, the distance between a copper target and the sputtering substrate was equal to 15 cm, the applied powers varied from 350 to 1000 W. The established optimal sputtering conditions were: the power discharge--700 W; the time of deposition--10 min; the resulting power density--0.72 W/cm\({}^{2}\) and the working pressure \(2.0\times 10^{-3}\) mbar. The applied parameters were chosen on the basis of the previous research concerning the deposition of copper on the Polylactide (PLA) nonwoven fabrics. A preliminary study was performed for the purpose of another publication, which has been recently published [111]. In order to choose the appropriate deposition parameters, the authors varied the sputtering power of the magnetron target from 350 up to 1000 W. At the same time, the sputtering time was changed from 10 to 30 min. The upper limit of the applied power was set as a result of our previous experiments showing  
Figure 1: The structures of polymer components of polyethylene terephthalalate-elastane (PETE). (**a**) Polyethylene Terephthalalate (PET) (k, m, n, z-the degree of polymerization). (**b**) Elastane (EA) (ABA polyether–polyturea–polytether block copolymer; R= linear, cyclic or aromatic diamine chain exchanger; m = 29; z = 6) according to [PERSON] et al. [110].  
Figure 2: The schematic diagram of applied DC magnetron sputtering system.  
that higher values of power have destructive effect on the PLA substrate. The preliminary analysis of antimicrobial activity was carried out for the obtained samples. The results exhibited no antibacterial and antifungal effect for the sputtering power lower than 700 W. Taking into consideration the possible cytotoxicity of copper, the authors decided to choose the minimal sputtering power for which the antimicrobial activity was observed for further research. This allows us to minimize the content of copper and thus, minimizes the risk of cytotoxicity. In order to enable the comparison of results obtained for different materials, the authors decided to apply the same deposition parameters for the PETE substrate as for the PLA substrate. Since for the PLA nonwovens the observed antibacterial activity did not vary substantially between the samples subjected to 10 and 30 min of copper deposition, the authors decided to choose the lower deposition time in order to further limit the Cu content. Therefore, the final deposition parameters applied in this work were established at 700 W and 10 min for each side of the substrate.  
In order to vary the copper content in the PETE-Cu\({}^{(0)}\), composites two different deposition variants were applied, namely: 10 min single-sided deposition of copper on PETE (sample name: PETE-Cu\({}^{(0)}\)-1) and 20 min two-sided deposition of PETE (10 min for the upper and 10 min for the lower side of the sputtering fabric; sample name: PETE-Cu\({}^{(0)}\)-2; PETE-Cu\({}^{(0)}\)-2.1 and PETE-Cu\({}^{(0)}\)-2.2).