Synergistic Effect of Halloysite and Cellulose Nanocrystals on the Functional Properties of PVA Based Nanocomposites

Poly­(vinyl alcohol) (PVA) based nanocomposites filled with different amounts of halloysites (HNTs) and/or cellulose nanocrystals (CNC) were produced and characterized in terms of mechanical and barrier properties, thermal stability, and transparency. A significant increase in tensile strength by more than 70% and an unexpected improvement in elongation at break were observed for all the PVA nanocomposites when compared to the pristine PVA. Moreover, the presence of both CNC and HNTs at the highest loadings of 5 and 3 wt %, respectively, improved the thermal stability of the PVA matrix and reduced its water vapor permeability (WVP) by more than 42%. All the developed PVA nanocomposites maintained their transparency due to the good and homogeneous dispersion of both the nanofillers in the PVA matrix. Results highlight the synergistic effect of HNT and CNC on the barrier and mechanical properties of PVA, mainly due to the establishment of specific interactions between the OH groups of HNT and CNC particles

Metal Nanoparticles Embedded in Cellulose Nanocrystal Based Films: Material Properties and Post-use Analysis

The dispersion of nanoparticles having different size-, shape-, and composition-dependent properties is an exciting approach to design and synthesize multifunctional materials and devices. This work shows a detailed investigation of the preparation and properties of free-standing nanocomposite films based on cellulose nanocrystals (CNC) loaded with three different types of metal nanoparticles. CNC-based nanocomposites having zinc oxide (ZnO), titanium dioxide (TiO₂), and silver oxide (Ag₂O) have been obtained through evaporation-induced self-assembly (EISA) in acqueous solution. Morphological and optical characteristics, chemical properties, wettability, and antimicrobial assays of the produced films were conducted. Furthermore, disintegrability in composting condition of CNC based nanocomposites was here investigated for the first time. The morphological observations revealed the formation of a chiral nematic structure with uniformly distributed nanoparticles. The bionanocomposite films based on the metal nanoparticles had effective antimicrobial activity, killing both <i>Escherichia coli RB</i> (<i>E. coli</i> RB) and <i>Staphylococcus aureus 8325–4</i> (<i>S. aureus</i> 8325–4). The simplicity method of film preparation, the large quantity of cellulose in the world, and the free-standing nature of the nanocomposite films offer highly advantageous characteristics that can for the new development of multifunctional materials

Tuning Multi/Pluri-Potent Stem Cell Fate by Electrospun Poly(l-lactic acid)-Calcium-Deficient Hydroxyapatite Nanocomposite Mats

In this study, we investigated whether multipotent (human-bone-marrow-derived mesenchymal stem cells [hBM-MSCs]) and pluripotent stem cells (murine-induced pluripotent stem cells [iPSCs] and murine embryonic stem cells [ESCs]) respond to nanocomposite fibrous mats of poly­(l-lactic acid) (PLLA) loaded with 1 or 8 wt % of calcium-deficient nanohydroxyapatite (d-HAp). Remarkably, the dispersion of different amounts of d-HAp to PLLA produced a set of materials (PLLA/d-HAp) with similar architectures and tunable mechanical properties. After 3 weeks of culture in the absence of soluble osteogenic factors, we observed the expression of osteogenic markers, including the deposition of bone matrix proteins, in multi/pluripotent cells only grown on PLLA/d-HAp nanocomposites, whereas the osteogenic differentiation was absent on stem-cell-neat PLLA cultures. Interestingly, this phenomenon was confined only in hBM-MSCs, murine iPSCs, and ESCs grown on direct contact with the PLLA/d-HAp mats. Altogether, these results indicate that the osteogenic differentiation effect of these electrospun PLLA/d-HAp nanocomposites was independent of the stem cell type and highlight the direct interaction of stem cell-polymeric nanocomposite and the mechanical properties acquired by the PLLA/d-HAp nanocomposites as key steps for the differentiation process