(256c) Antibacterial Electrospun Mats Based on Poly(D,L-Lactide) Nanofibers and Zinc Oxide Nanoparticles

PLA nanocomposites with antibacterial properties are of high potential interest as food packaging biomaterials. The investigations carried out in this study include the rheological properties of solutions used for electrospinning the nanofibrous mats as well as, the morphological and antibacterial evaluation of the mats based on poly(D,L-Lactide) nanofibers loaded with  different zinc oxide  nanoparticles. A detailed rheological analysis of the solutions used for electrospinning was carried out in order to understand the achieved morphology and structure of nanofibers. The effect of ZnO nanoparticles was investigated for various PLA solutions and solvents. The polymer solutions were prepared at various loading level of ZnO: 0.4, 0.8, 1, 3 and 5 wt % to the weight of  the polymer. Two solvent systems were used : trifluoroethanol and a mixture of dichloromethane/ trifluoroethanol (50:50 v/v). The PLA solutions with low loading level of ZnO nanoparticles showed higher viscosity (η) than the neat PLA. They also showed a maximum value of η at 3 wt % content. Solutions containing more than 3 wt % ZnO exhibited a notable decrease in viscosity, which could be probably due to the PLA degradation. The morphological-characterization of the electrospun nanofibers was performed using scanning electron microscopy (SEM). The SEM images showed a network of smooth randomly oriented PLA nanofibers. ZnO  agglomeration was observed on the surface of the nanofibers. The antimicrobial efficiency of these nanocomposite fibers against E. coli (DH5 α) as Gram-negative bacteria and  Staphylococcus aureus as Gram-positive bacteria was evaluated using the dynamic method. The antibacterial results showed that the addition of zinc oxide nanoparticles reduced slightly bacteria growth  on PLA/ZnO nanofibers.