Golden and Silver–Golden Chitosan Hydrogels and Fabrics Modified with Golden Chitosan Hydrogels

Golden and silver–golden chitosan hydrogels and hydrogel-modified textiles of potential biomedical applications are investigated in this work. The hydrogels are formed by reactions of chitosan with HAuCl4·xH2O. For above the critical concentration of chitosan (c*), chitosan–Au hydrogels were prepared. For chitosan concentrations lower than c*, chitosan–Au nano- and microgels were formed. To characterise chitosan–Au structures, sol–gel analysis, UV–Vis spectrophotometry and dynamic light scattering were performed. Au concentration in the hydrogels was determined by the flame atomic absorption spectrophotometry. Colloidal chitosan–Au solutions were used for the modification of fabrics. The Au content in the modified fabrics was quantified by inductively coupled plasma mass spectrometry technique. Scanning electron microscopy with energy dispersion X-ray spectrometer was used to analyse the samples. Reflectance spectrophotometry was applied to examine the colour of the fabrics. The formation of chitosan–Au–Ag hydrogels by the competitive reaction of Au and Ag ions with the chitosan macromolecules is reported.