Chitosan loaded with silver nanoparticles, CS-AgNPs, using thymus syriacus, wild mint, and rosemary essential oil extracts as reducing and capping agents

The present study describes the green method for the preparation of chitosan loaded with silver nanoparticles (CS-AgNPs) in the presence of 3 different extracted essential oils. The essential oils play dual roles as reductant and capping agents. The reducing power and DPPH (2,2-diphenyl-1-picrylhydrazyl) assay for the 3 essential oilsThymus syriacus (T), wild mint (M), and rosemary (R)have been reported. The preparation of CS-AgNPs was performed by 2 steps. The 3 previously extracted essential oils have been used as reducing and capping agent in the first step, while in the second step, silver nanoparticles were integrated in chitosan. The integration of AgNPs in the structure of chitosan was confirmed by ultraviolet-visible, Fourier transform infrared spectroscopy, scanning electron microscopy techniques, and energy dispersive X-ray. Surface plasmon resonance confirmed the formation of CS-AgNPs with maximum absorbance at lambda(max) between 405-410 and 410-430nm for colloidal and films of CS-AgNPs, respectively. The intensity of bands at 3408cm(-1) in the fourier transform infrared spectroscopy measurements was decreased substantially and shifted slightly to lower frequency (Delta upsilon = 43cm(-1)). Scanning electron microscopy shows a spherical morphology of AgNPs with size of 62nm for both colloidal and film samples, and energy dispersive X-ray analysis shows peaks confirming AgNPs formation.