Preparation and characterization of ZnO composite nanomaterials in chitosan oligosaccharide iodine solution

Composite nanomaterials of ZnO/chitosan oligosaccharide (ZnO/COS) and ZnO/chitosan oligosaccharide iodine (ZnO/CTS-I-2) were expected to have effective antimicrobial effects due to the synergistic effects of the components. In this work, we present a method to synthesize ZnO nanoparticles with size of 12.3-15.0 nm stabled in COS with low molecular weight (M-w) 3,321 g/mol and COS-I(2 )complex by precipitation of Zn2+ with NaOH at pH 9, and then ultrasonic treatment to form ZnO nanoparticles. The UV-Vis spectra of ZnO/COS and ZnO/COS-I-2 composite nanomaterials both appeared absorption peaks typical for surface plasmon resonances of ZnO nanoparticles in solution at 372 and 370 nm, respectively. X-ray diffraction (XRD) patterns confirmed the formation of ZnO/COS-I-2 with wurtzite crystal structure characterized in both materials. The FT-IR spectra of COS, COS-I-2, nano ZnO/COS, and nano ZnO/COS-I-2 were measured. The characteristic peaks for the bonding vibrations of -OH and -NH2 groups of ZnO/COS and ZnO/COS-I-2 shifted to a larger wavenumber than that of COS. The prepared ZnO/COS and ZnO/COS-I-2 nanocomposite materials may have potential for application as antibacterial agents used in medicine, food, and agricultural product preservation, control of harmful microorganisms on plants, and plant growth promotion.