RESUMO

Gold nanoparticles (AuNPs), chemically synthesized by citrate reduction, were for the first time immobilized onto chitosan-treated soybean knitted fabric via exhaustion method. AuNPs were successfully produced in the form of highly spherical, moderated polydisperse, stable structures. Their average size was estimated at ≈35 nm. Successful immobilization of chitosan and AuNPs were confirmed by alterations in the fabric's spectrophotometric reflectance spectrum and by detection of nitrogen and gold, non-conjugated C=O stretching vibrations of carbonyl functional groups and residual N-acetyl groups characteristic bands by X-ray photoelectron spectroscopy (XPS) and Fourier-Transform Infrared Spectroscopy (FTIR) analysis. XPS analysis confirms the strong binding of AuNPs on the chitosan matrix. The fabrics' thermal stability increased with the introduction of both chitosan and AuNPs. Coated fabrics revealed an ultraviolet protection factor (UPF) of +50, which established their effectiveness in ultraviolet (UV) radiation shielding. They were also found to resist up to 5 washing cycles with low loss of immobilized AuNPs. Compared with AuNPs or chitosan alone, the combined functionalized coating on soy fabrics demonstrated an improved antimicrobial effect by reducing Staphylococcus aureus adhesion (99.94%) and Escherichia coli (96.26%). Overall, the engineered fabrics were confirmed as multifunctional, displaying attractive optical properties, UV-light protection and important antimicrobial features, that increase their interest for potential biomedical applications.