The infrared spectroscopy of chitosan films doped with silver and gold nanoparticles

Abstract This work presents the dependences of the absorption intensity of the acid-soluble chitosan biopolymer films in the infrared (IR) region of the spectrum on the concentrations of silver and gold nanoparticles (NPs) of different morphologies. The interaction mechanisms in the vibrational spectra overlapping area of the silver NPs and chitosan molecules (2500–3500 cm −1 ) were observed. The influence of the metal NPs on the dipole moments of the OH-, NH 3 + - and CH-chitosan molecule group oscillations was established. This interaction leads to a linear increase of the IR absorption intensity with an increase of the silver nanoparticle concentration, synthesized by the citrate and borohydride methods. The presence of silver and gold ablative NPs in the chitosan films demonstrates the IR absorption intensity exponential decrease with the metal NPs’ concentrations.