In this thesis, nanocomposite films based on polymer composition of chitosan (CT), tragacanth (TG) and silica (SiO 2 ) nanoparticles () were prepared with the aid of ultrasonication through casting method and investigated by various techniques. According to the results of field emission scanning electron microscopy (FE-SEM), among three different amounts of SiO 2 nanoparticles that were applied to the polymeric matrix (2, 5 and 8 wt.% respect to the CT-TG blend weight) weight of 5 wt% provided a more smooth surface for the nanocomposite films and this weight ratio was considered to be optimal. Then, to modify the surface of the SiO 2 and also to induce antibacterial property, silver (Ag) were prepared through a green method using Rosemary extract as a reducing agent for silver nitrate salt. Then, the composite of SiO 2 and Ag (SiO 2 @Ag) were prepared in three different weight ratios (1:0.3, 1:0.5 and 1:1) and then 5 wt% of SiO 2 @Ag respect to the weight of CT-TG blend was incorporated into the polymeric matrix. Nanocomposite films were prepared by ultrasonication and solution casting method. Various analyzes such as fourier transform infrared spectroscopy (FT-IR), FE-SEM, X-ray diffraction, transmission electron microscopy (TEM), and X-ray energy dissociation-Elemental Mapping (EDX-EM) were used to the characterization of the films. The nanocomposite films containing SiO 2 and SiO 2 @Ag were immersed in the simulated body fluid solution in order to the formation of hydroxyapatite and the pH changes of the solution were studied during 28 days. Subsequently, by various techniques such as FT-IR, FE-SEM and EDX-EM the changes on the surface of the films were invetstigated. The TEM images showed uniform dispersion of SiO 2 and SiO 2 @Ag in the CT-TG blend. By examining the contact angle of the water droplets with the surface of the nanocomposite films, it was found that the presence of SiO 2 in the CT-TG blend, the hydrophilicity of the nanocomposite films compared to the pure polymer blend was increased. Also, the presence of SiO 2 @Ag caused the highest hydrophilicity in nanocomposite films. In the study of antibacterial activity of SiO 2 @Ag nanocomposite films against two species of Escherichia coli and Staphylococcus aureus as known Gram-negative and Gram-positive bacteria, respectively. It was found that the higher content of Ag within the matrix caused more antibacterial activity. Inhibition zone diameters were observed in millimeters in the presence of two drops of deionized water as well as two drops of 1% v/v aqueous solution of acetic acid and the highest aqueous growth area was observed for CT-TG/SiO 2 @Ag (1/1) film.