*3.7. Hydrophilicity of Cotton Fabrics*

Hydrophilicity of cotton fabrics has been assessed by the amount of absorbed water. Hydrophilicity of untreated cotton fabric and cotton fabrics treated with ACR and [Cu2(ACR)(NO3)2] complex has been determined to be 112%, 95% and 86%, respectively. The results clearly indicated that the compounds induce an increase in hydrophobicity when applied to cotton fabric may be due to an increase in the number of hydrophobic groups on the surface of the treated cotton fabric. More effective hydrophobicity has been achieved with the cotton fabric treated with [Cu2(ACR)(NO3)2], if compared to that of ACR treated fabric, which effect can be explained by the enhanced lipophilicity of the [Cu2(ACR)(NO3)2] complex.

### *3.8. SEM Analysis*

*Pseudomonas aeruginosa* is an excellent biofilm producer, and it has been selected to investigate the efficacy of the cotton fabrics treated with the ACR and [Cu2(ACR)(NO3)2] in preventing the adhesion and biofilm formation [38]. In Figure 6 are presented SEM micrographs of untreated cotton fabrics and cotton fabrics treated with ACR and its [Cu2(ACR)(NO3)2] complex after 24 h of incubation. From the SEM images, it is clearly seen that a formation of P. aeruginosa biofilm on the untreated cotton fabric (Figure 6B). In this case, many bacterial cells are adhered to the cotton surface and embedded into extracellular bio matrix. On the other hand, a significant reduction of biofilm formation and bacterial the adhesion has been observed on the surface of the cotton fabric treated with ACR (Figure 6D). Only single bacterial cells are attached to the cotton surface of the cotton fabric treated with the complex [Cu2(ACR)(NO3)2] (Figure 6C). Thus, the deposition of ACR and [Cu2(ACR)(NO3)2] complex on the

cotton fabric prevents the formation and proliferation of a bacterial biofilm, allowing the production of antibacterial cotton fabric.

**Figure 6.** Scanning Electron Microscopy (SEM) micrograph of cotton fabrics tested against *P. aeruginosa* at magnification X 5000: (**A**) Cotton textile before treatments; (**B**) biofilm on untreated cotton textile; (**C**) absence of biofilm on cotton textile treated with [Cu2(ACR)(NO3)2]; (**D**) reduced biofilm formation on cotton textile treated with ACR.
