The Effect of Vitamin D3 and Silver Nanoparticles on HaCaT Cell Viability

Vitamin D3, known to regulate bone homeostasis, has recently been shown to have many pleiotropic effects in different tissues and organs due to the presence of its receptor in a wide range of cells. Our previous study demonstrated that vitamin D3 was able to increase the wound healing respect to the control sample, 24 h after cutting, without however leading to a complete repair. The aim of the study was to combine vitamin D3 with silver nanoparticles to possibly enable a faster reparative effect. The results showed that this association was capable of inducing a complete wound healing only after 18 h. Moreover, a treatment of vitamin D3 + silver nanoparticles yielded a small percentage of keratinocytes vimentin-positive, suggesting the possibility that the treatment was responsible for epithelial to mesenchymal transition of the cells, facilitating wound healing repair. Since vitamin D3 acts via sphingolipid metabolism, we studied the expression of gene encoding for the metabolic enzymes and protein level. We found an increase in neutral sphingomyelinase without involvement of neutral ceramidase or sphingosine kinase2. In support, an increase in ceramide level was identified by Ultrafast Liquid Chromatography–Tandem Mass Spectrometry, suggesting a possible involvement of ceramides in wound healing process.     

Melting and crystallization behavior of poly(tetrafluoroethylene) by temperature modulated calorimetry

Temperature-modulated differential scanning calorimetry (TMDSC) in the quasi-isothermal mode is applied to investigate melting and crystallization of poly(tetrafluoroethylene) (PTFE) obtained from aqueous dispersion, both melt-crystallized and native (as-polymerized). The differences, shown in the past between the melting behavior of melt-crystallized and native PTFE, have been confirmed and further evidenced through this technique. A large reversing heat capacity is present in the melting and crystallization regions. As proposed by many authors, the presence of the reversing heat capacity can be related to surface melting and crystallization. It can occur on the growth and/or fold surfaces and it has been shown that it is larger for those macromolecules having higher chain mobility that allows rearrangements on the crystal surface. In the present case, the large observed reversing heat capacity can be related to the very high sliding ability of PTFE chains in the pseudohexagonal phase, which is much larger than that of most semicrystalline polymers. Due to the crystal-crystal transition at 30 °C, which can be described as a fusion in the longitudinal direction, melting of PTFE can be considered intermediate between the irreversible melting of macromolecules and the completely reversible isotropization of liquid crystalline polymers.     

Graft copolymers of lignin with electron poor alkenes

The synthesis of copolymers between lignin and electron poor alkenes is described. Lignin from steam‐exploded pine, from steam‐exploded straw, and organosolv were used as starting materials. Beforehand, lignins were fully characterized by using elemental analysis, ultraviolet spectroscopy, gel permeation chromatography (GPC), Fourier transform infrared (FTIR), and both¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. The synthesis of copolymers was performed using a previously described procedure utilizing calcium chloride and hydrogen peroxide as reagents. FTIR of copolymers showed absorptions due to the presence of both lignin and the electron withdrawing group on the alkene. GPC analysis showed the presence of fractions with high molecular weights: the M_z of lignin from pine was 3729 while the copolymer with methyl acrylate showed M_z = 383790. Differential calorimetry showed the presence of glass transitions in the range of ?9 to 4.5°C due to the presence of grafted polyalkene chains. When acrylonitrile was used as starting material DSC analysis of the product showed a glass transition at 119°C, which can be attributed to grafted polyacrylonitrile chain. Lignin from steam explosion could be a good raw material in the preparation of graft copolymers. Furthermore, lignin from pine gave better results than that from straw. Finally, lignin from steam explosion gave better results than organosolv lignin. These results can be explained on the basis of the structural properties of used lignins. Both UV and ¹³C NMR spectra showed that lignin from pine contained a consistent amount of double bonds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1163–1171, 2003     

X-Ray Photoelectron Spectroscopy characterization of electrosynthesized poly(3-thiophene acetic acid) and its application in Molecularly Imprinted Polymers for atrazine

X-Ray Photoelectron Spectroscopy (XPS) was used to extensively investigate the chemical structure of electrosynthesized poly(3-thiophene acetic acid). The observation of the integrity of carboxylic functionalities upon polymerization, along with the strong affinity between monomer and the herbicide atrazine (At) evidenced by Nuclear Magnetic Resonance, prompted the exploitation of the application of the electrosynthesized polymer in the preparation of a Molecularly Imprinted Polymer (MIP) for At. Experimental conditions for film electrosynthesis in the presence of template (At) were selected. XPS spectroscopy was used also for the characterization of the imprinted film, evidencing the entrapment of the template in polymer matrix and the removal of most template upon washing. Moreover, XPS results about the use of a cross-linking agent (3,3-bithiophene) for prospective improvement of MIP structural integrity are illustrated.     

Polymer blends of steam-explosion lignin and poly(ε-caprolactone) by high-energy ball milling

Lignin powder, obtained from an abundant and low-cost source, straw, through a low-environmental-impact process, steam explosion, was used for the preparation of blends with a biodegradable polyester, poly(ε-caprolactone) (PCL), with an innovative technique, high-energy ball milling. Lignin strongly stabilized PCL against UV radiation. The modulus of the blends increased with the addition of lignin; nevertheless, the elongation at breaking decreased. Through thermal characterization (differential scanning calorimetry and dynamic mechanical analysis), lignin and PCL were found to be immiscible. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of hyaluronic acid on bacterial and fungal species,including clinically relevant opportunistic pathogens

Hyaluronic acid (HA) has several clinical applications (aesthetic surgery, dermatology, orthopaedics and ophtalmology). Following recent evidence, suggesting antimicrobial and antiviral properties for HA, we investigated its effects on 15 ATCC strains, representative of clinically relevant bacterial and fungal species. The in vitro system employed allowed to assess optical density of broth cultures as a measure of microbial load in a time-dependent manner. The results showed that different microbial species and, sometimes, different strains belonging to the same species, are differently affected by HA. In particular, staphylococci, enterococci, Streptococcus mutans, two Escherichia coli strains, Pseudomonas aeruginosa, Candida glabrata and C. parapsilosis displayed a HA dose-dependent growth inhibition; no HA effects were detected in E. coli ATCC 13768 and C. albicans; S. sanguinis was favoured by the highest HA dose. Therefore, the influence of HA on bacteria and fungi warrants further studies aimed at better establishing its relevance in clinical applications.     

Ag nanoparticles capped by a nontoxic polymer: Electrochemical and spectroscopic characterization of a novel nanomaterial for glucose detection

Modified electrodes with metal or metal oxides nanoparticles are particularly appealing to improve sensor performances and fabricate miniaturized devices, as required also in glucose detection. A Pt electrode modified by drop casting of a novel nanostructured film based on silver nanoparticles (Ag-NPs) capped in a commercial nontoxic polyvinyl alcohol (PVA) matrix is proposed here as a valid alternative to classical glucose (bio)sensors. The extensive electrochemical and spectroscopic characterization by X-ray Photoelectron Spectroscopy (XPS) of this advanced nanomaterial is presented to study its response to glucose and to investigate the chemical nature of deposited Ag.     

Influence of thermo-vacuum treatment on thermal degradation of various wood species

Solid wood has a certain amount of resistance to fire exposure. Recently, there is also great interest in characterization of the thermal behaviour of treated wood due to increasing demand of such products within the perspective of sustainability of environment. The objective of this study was to evaluate and predict the thermal decomposition process of samples from different wood species, Norway spruce (Picea abies Karst.), common ash (Fraxinus excelsior L.) and Turkey oak (Quercus cerris L.), so that such data can be used for enhanced design of wood products for more effective and better utilization in different applications. Spruce and ash samples were treated at a temperature of 190 °C for 2 h while Turkey oak specimens were steamed at a temperature of 110 °C for 24 h before they were thermally treated at a temperature of 160 °C for 3 h. A thermo-gravimetric analysis of the samples highlighted intraspecific differences in mass loss and the stage of thermal degradation between treated and untreated specimens. The degradation of the wood was characterized by twofold reaction stages, with an exception of Norway spruce samples, which exhibited a one-stage reaction. In addition, thermal treatments affected chemical composition of wood. The obtained results will be helpful in determining the applicability of these materials according to their thermal degradation properties.