Improving the performance of chitosan in the synthesis and stabilization of gold nanoparticles

•An improvement of the chitosan performance in synthesis of gold NPs is reported.•Nanoparticles were obtained by reaction of grafted chitosan with AuCl4-ions.•The modification of chitosan considerably affects its reactivity with AuCl4-ions.•Gold NPs were characterised by UV–Vis spectroscopy, DLS and TEM.

This work used chitosan polysaccharide and its graft copolymers with ε-caprolactone and N-vinyl-2-pyrrolidone chains to synthesise and stabilise gold nanoparticles. The nanoparticle synthesis was performed directly by reaction of polymers with potassium tetrachloroaurate in an aqueous medium and it was demonstrated that the polymers can act as reducing and stabilizing agents. The modification of chitosan considerably affects the copolymer performance during the gold nanoparticle synthesis. Different synthetic parameters, such as the reaction time, temperature, concentration and polymer and metallic salt feed ratio, were assessed. The gold nanoparticles were characterised via UV–Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM), and zeta potential. In general, using grafted chitosan improves the synthetic performance of gold nanoparticles over unmodified chitosan, which is reflected in the amount, size distribution and suspension stability of the obtained nanoparticles. These results are promising due to the potential technological applications of chitosan derivatives.

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