Preparation of sulfur nanoparticle-incorporated antimicrobial chitosan films

Three different types of sulfur nanoparticles (SNP) were prepared and used to prepare functional chitosan/SNP composite films. The composite films were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The optical, mechanical, water vapor barrier (WVP), thermal stability, and antibacterial properties of the composite films were also analyzed. The SEM analysis showed that the SNP were dispersed evenly in the chitosan film. Incorporation of SNP enhanced the hydrophobicity, mechanical strength, and water vapor barrier property as well as antimicrobial activity of the chitosan film depending on the type of SNP. Among the SNP composite films, SNP capped with chitosan (SNP3) composite film exhibited the strongest antimicrobial activity against food-borne pathogenic Gram-negative (Escherichia coli) and Gram-positive (Listeria monocytogenes) bacteria with complete sterilization within 6 h and 12 h, respectively. The chitosan/SNP composite films have high potential to be used as antimicrobial food packaging films or wound dressings in biomedical applications.