Title : Enhanced durability of antimicrobial activity in cotton textiles by L-Cysteine-Capped Copper Nanoparticles through laundering cycles
Abstract:
In this study, L-cysteine-capped copper nanoparticles (Cys-CuNPs) were successfully linked into a cotton textile, being attached in a covalent way to the cotton fibers via esterification. The CuNPs were adhered to the fiber surface through coordination bonds with the thiol groups from the L-cys, and its antimicrobial activity was tested in several laundering cycles.
Materials and methods: The characterization of the Cys-CuNP was accomplished by UV−visible (UV−Vis), Z-potential and X-ray diffraction (XRD). After the attachment of the Cys-CuNPs to the raw cotton, the textile surface was characterized by variable pressure scanning electron microscopy (VP-SEM), and Fourier transform infrared spectroscopy (FT-IR). The antibacterial activity of the cotton textile functionalized with the Cys-CuNPs was tested through 100 laundering cycles using lauryl sulphate and distilled water. Every ten laundering cycles the antibacterial activity of the textile was performed by disk diffusion analysis.
Results: The UV−Vis analysis showed the presence of CuNPs in the Cys-CuNPs solution, showing the SPR for the CuNPs among 580–620 nm. In addition, they exhibited a Z-potential among -17 and -10 mV, with the presence of elemental and oxide Cu shown by the XRD analysis. The VP-SEM images from the cotton fabrics covered in Cys-CuNPs showed the presence of spherical CuNPs on their surface. Furthermore, FT-IR analysis exhibited peaks associated with the presence of L-cysteine (SH-) and carboxylic acid arising from the esterification reaction among the cellulose from cotton and the carboxylic acid in the L-Cys molecules. Finally, the cotton textile exhibited antibacterial activity against Escherichia coli, Staphylococcus aureus and Candida albicans and its antimicrobial activity and durability was up 80 laundering cycles.
Conclusions: This study demonstrates the ability of Cys-CuNPs to bind in a covalent way to the cellulose from cotton fabric, showing an antimicrobial activity.