Thermoplastic nanocomposite materials with potential bactericide properties were prepared and their surface properties and adhesion to Streptococcus mutans, S. mutans, were characterized. Solution blow spinning was successfully used to prepare films with a fiber-like structure on the surface of nanocomposites based on Polyvinylidene fluoride, PVDF, filled with well dispersed TiO 2 nanoparticles. PVDF/TiO 2 nanocomposites were prepared varying the nanoparticles content (0 %, 1 %, 2 %, 5 % and 10 % by weight). In order to understand the influence of the presence of TiO 2 nanoparticles and the final surface properties on the adhesion of S. mutans to the materials, a deep characterization was carried out focusing on the morphology, roughness, surface free energy from contact angle measurements and cell adhesion by single cell force spectroscopy. It was observed that the uniform dispersion of the nanofiller arose from nanoparticles embedded in the polymer when fibers were created during the blow spinning process. TiO 2 content influenced the topography of the films probably due to a direct effect on the solvent evaporation rate. Although this factor greatly conditioned the roughness of the samples and therefore the surface free energy, S. mutant adhesion on the substrates under study was concluded to be more dependent on the specific interactions with the surface polar groups of the material.

The world of cosmetics is now aiming at biobased materials which are skin-compatible and can be used to generate more sustainable beauty masks with enhanced bioactivity. This work presents, in this line of interest, the combination of two innovative technologies, namely electrospinning and dry powder impregnation, to generate biobased skin soluble electrospun pullulan carriers dry impregnated with chitin nanofibrils-nanolignin-glycyrrethinic acid (CLA) complexes, as effective biobased and skin compatible beauty masks. The scalability of the pullulan electrospun carrier and bioactive complexes impregnation were optimized and the morphology evaluated. Subsequently, skin compatibility and mask effectiveness were investigated in vitro and in vivo. The results showed that cell viability was optimal for both impregnated and neat pullulan fibers. Additionally, the CLA impregnated pullulan fibers were able to upregulate the endogenous antimicrobial molecule HBD-2. Preliminary studies in vivo indicated that the beauty mask containing the CLA complexes significantly decreased area, length and depth of forehead and crow’s feet wrinkles, and significantly increased moisturizing levels in the skin. The developed beauty mask was also seen to increase skin firmness, while it did not show skin irritation after the test. The work demonstrates that the combination of these two technologies may open new alternatives to more sustainable bioactive cosmetic products for the skin.

Solution blow spinning, SBS, a quite novel processing method, was used to obtain poly (ethylene-co-vinyl acetate), EVA, films with controlled surface properties. The influence of the surface characteristics of EVA films on the adhesion of DH5α Escherichia coli was studied. In particular, the initial concentration of the EVA solution to be blow spun was varied in order to get different surface topographies. Considering the potential use of EVA based materials in applications such as food packaging or scaffolds for tissue engineering all factors affecting proliferation of microorganisms on their surfaces should be studied and understood. Structural, morphological and surface characterizations based on the use of infrared spectroscopy, FTIR, scanning electron microscopy, SEM, and contact angle measurements were performed to ascertain the main factor influencing the E. coli adhesion on the EVA films. Roughness data were determined at different scales from 3D surfaces obtained using a stereoscopic reconstruction of SEM images. It was concluded that, depending on the conditions of the SBS process, only variations of topography were found on the EVA films, being therefore the unique cause of different adhesion capacity of E. coli cells. A correlation between roughness and the number of attached E. coli cells showed that the higher the roughness at microscale level the higher the biofilm development, demonstrating that, apart from specific interactions at nanoscale surface, heterogeneity at microscale can greatly modify the antibacterial action.

Nowadays, there is growing increase of plastics use in the world of food industry and medicine. In this context there is a need of, apart from conventional properties of plastics, minimizing growth of harmful microorganisms. In this article new polymer based materials are prepared, characterized and evaluated against their antibacterial action. New materials based on poly(ethylene-co-vinyl acetate) are prepared by solution blow spinning, SBS. Mats of nanocomposites constituted by micrometric fibers are obtained with compositions ranging from 0% to 6% by weight of Cu nanoparticles, CuNp. In order to understand the effect of the CuNp on the E. coli cell adhesion and biofilm formation, morphology, structure, thermal and surface properties of the nanocomposites are studied by several techniques. SBS allows preparing the nanocomposites with quite uniform dispersion of CuNp within the polymer. Neither the presence of CuNp nor the SBS process induce changes in the structure and in the thermo-degradation of EVA40. The presence of CuNp exerts antibacterial effect against the DH5α E. coli. There is a direct action of the CuNp on the extracellular polymeric substances and on the bacterial metabolism. CuNp also affect HaCaT cells growing, delaying the process at higher amounts of Cu but keeping their viability.

Solution blow spinning, SBS, was used to prepare fibrous films of thermoplastic nanocomposites with potential antibacterial properties based on polysulfone, PSF, filled with well dispersed TiO 2 nanoparticles. The PSF/TiO 2 nanocomposites were produced with different nanoparticles content up to 10% by weight. A wide characterization was carried out focusing on the morphology at the nanoscale, roughness, contact angles, and surface free energy. Cell adhesion was studied by inspection by scanning electron microscopy (SEM). A uniform dispersion of the nanofiller was achieved, with the nanoparticles evenly embedded in the polymer along the fibers when they were created during the blow spinning process. TiO 2 content influenced the topography of the films, most likely due to a direct effect on the solvent evaporation rate. The results obtained pointed out that an increase of the surface hydrophobicity as a result of the increased roughness induced by the presence of TiO 2 nanoparticles was the main contribution to the reduction of DH5a Escherichia coli cells adhesion.