Mechanical properties and antibacterial activities of novel nanobiocomposite films of chitosan and starch

New nanocomposite films (thickness 0.13 mm-0.2 mm) of chitosan, starch, glycerin, cyclophosphamide and Fe3O4 nanoparticles were prepared containing five various amounts of Fe3O4 NPs (2-10%). The water uptakes of films were measured at 25 degrees C in three acidic, neutral and alkaline media. The greatest swellings were observed in the acidic pH but the least water uptakes were found in the alkaline medium. Moreover, addition of the magnetic NPs to the films led to enormous decrease in the swellings in the acidic medium but small variations were occurred in the neutral and alkaline media. The VSM analysis revealed the saturated magnetizations equal to 70.41 and similar to 0.5-1.5 emu/g for the Fe3O4 NPs and nanocomposite films 1-5, respectively. The tensile strength analysis illustrated that addition of starch and glycerin to the chitosan considerably enhanced the elongation at breaks while decreased the tensile strengths. Addition of 2% Fe3O4 NPs increased the elongation but adding further Fe3O4 NPs to the films (4 -10% NPs) decreased the elongation. The highest Young's modulus was found for the CS and among nanocomposites 1-5, the film 5 containing 10% Fe3O4 NPs indicated the greatest modulus. The in vitro antibacterial activities against the Gram-positive Staphylococcus aureus and the Gram-negative Escherichia coli bacteria exhibited greater antibacterial effects against Gram-positive bacterium. In addition, nanocomposite films containing higher percents of Fe3O4 NPs displayed greater antibacterial effects. (C) 2014 Elsevier Ltd. All rights reserved.