Preparation and characterization of ZnOcomposite nanomaterials in chitosan oligosaccharide iodine solution

Composite nanomaterials of ZnO/chitosan oligosaccharide (ZnO/COS) and ZnO/chitosan oligosaccharide iodine (ZnO/CTS‐I2) 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 (Mw) 3,321 g/mol and COS‐I2complex 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‐I2composite 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‐I2with wurtzite crystal structure characterized in both materials. The FT‐IR spectra of COS, COS‐I2, nano ZnO/COS, and nano ZnO/COS‐I2were measured. The characteristic peaks for the bonding vibrations of –OH and –NH2groups of ZnO/COS and ZnO/COS‐I2shifted to a larger wavenumber than that of COS. The prepared ZnO/COS and ZnO/COS‐I2nanocomposite 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.