Maria Grazia Volpe

Compatibilized poly(ε-caprolactone)/poly(L-lactide) blends for biomedical uses

A binary poly(L-lactide)/poly(e-caprolactone) (PLLA/PCL) (70/30 w/w) blend and a ternary PLLA/PCL/PLLA-PCL-PLLA blend of the same composition which contains 4 wt.-% of a triblock PLLA-PCL-PLLA copolyester as compatibilizing agent were prepared by melt mixing at 200°C. Investigation of the thermal and mechanical properties of the blends and scanning electron microscopy of their fracture surfaces showed in the case of the ternary blend a better state of dispersion of PCL in the PLLA matrix and an improved toughness.

Preparation and characterisation of composites based on biodegradable polymers for “in vivo” application

Abstract Poly( l -lactic) acid (PLLA), polycaprolactone (PCL), three different copolymers based on poly( l -lactic) acid and polyglycolic acid (PLLA-co-PGA), and their composites with hydroxyapatite obtained from bovine bone (ossein), were tested in order to have information on the thermal, morphological, mechanical and biochemical properties in view of their use as biocompatible/biodegradable materials. Ossein, which is essentially a biological hydroxyapatite, was found to improve the modulus and increase the hydrophilicity of the polymeric substrate. In addition, the size of the ossein particles was found to be critical for the improvement of mechanical properties. Finally, preliminary results on the in vitro biocompatibility of selected blends carried out by using primary cultures of human osteoblasts showed that the presence of hydroxyapatite stimulates a more positive cellular response.

Unsaturated polyester resins from glycolysed waste polyethyleneterephthalate: synthesis and comparison of properties and performance with virgin resin

Recycling of polyethyleneterephthalate (PET) bottles for soft drinks is accomplished by depolymerization through glycolysis. Obtained intermediates are reacted with mixtures of saturated and unsaturated acids to obtain unsaturated polyesters (UP) suitable for use as a matrix for fibre-reinforced thermosetting composites. The influence of chemical structure of glycols on the chemo-rheological behaviour of resins, has been verified. By using di-ethylene glycol, the behaviour of the resulting UP closely resembles that of UP obtained from virgin monomers. Moreover, composite sheets containing UP developed in the present research, show enhanced toughness if compared with the analogous composite made of virgin UP resin.

Inhibitory effect of pomegranate (Punica granatum L.) polyphenol extracts on the bacterial growth and survival of clinical isolates of pathogenic Staphylococcus aureus and Escherichia coli

In the present study major polyphenols of pomegranate arils and peel by-products were extracted in 50% (v/v) aqueous ethanol, characterized and used in microbiological assays in order to test antimicrobial activity against clinically isolated human pathogenic microorganisms. Total concentration of polyphenols and in vitro antioxidant properties were determined by the Folin-Ciocalteu and DPPH methods, respectively. The most abundant bioactive molecules, including anthocyanins, catechins, tannins, gallic and ellagic acids were identified by RP-HPLC-DAD, also coupled to off-line matrix assisted laser desorption/ionization (MALDI-TOF) mass spectrometry (MS). The inhibitory spectrum of extracts against test microorganisms was assessed by the agar well-diffusion method. Data herein indicated that both pomegranate aril and peel extracts have an effective antimicrobial activity, as evidenced by the inhibitory effect on the bacterial growth of two important human pathogens, including Staphylococcus aureus and Escherichia coli, which are often involved in foodborne illness.

Reactive blending methodologies for biopol

Multicomponent polymeric systems containing Biopol as one of the phases are described as obtained according to two different procedures : radical polymerization of an acrylic polymer in the presence of Biopol, and melt-mixing of Biopol with polycaprolactone in the presence of peroxide. The decomposition of peroxide causes, in both cases, the formation of intergrafted species responsible for interfacial activity and compatibilization. The results of chemical, chemical-physical, morphological and mechanical tests, confirming the occurrence of such interactions, are reported.

Potential Anti-Inflammatory Effects of the Hydrophilic Fraction of Pomegranate (Punica granatum L.) Seed Oil on Breast Cancer Cell Lines

In this work, we characterized conjugated linolenic acids (e.g., punicic acid) as the major components of the hydrophilic fraction (80% aqueous methanol extract) from pomegranate (Punica granatum L.) seed oil (PSO) and evaluated their anti-inflammatory potential on some human colon (HT29 and HCT116), liver (HepG2 and Huh7), breast (MCF-7 and MDA-MB-231) and prostate (DU145) cancer lines. Our results demonstrated that punicic acid and its congeners induce a significant decrease of cell viability for two breast cell lines with a related increase of the cell cycle G0/G1 phase respect to untreated cells. Moreover, the evaluation of a great panel of cytokines expressed by MCF-7 and MDA-MB-231 cells showed that the levels of VEGF and nine pro-inflammatory cytokines (IL-2, IL-6, IL-12, IL-17, IP-10, MIP-1α, MIP-1β, MCP-1 and TNF-α) decreased in a dose dependent way with increasing amounts of the hydrophilic extracts of PSO, supporting the evidence of an anti-inflammatory effect. Taken together, the data herein suggest a potential synergistic cytotoxic, anti-inflammatory and anti-oxidant role of the polar compounds from PSO.

The optical properties of polymethylmethacrylate polymer dispersed liquid crystals

Abstract The effect of the addition of polymer liquid crystals as dispersed molecules to polymethylmethacrylate (PMMA) on the optical properties in the UV-visible and near infrared regions is investigated. From transmission, absorption and reflection spectra the absorption coefficient α(ω) and refractive index (n) at angular frequency of radiation (ω) have been calculated at room temperature. The values of the optical band gap (Eopt) have been obtained from the direct allowed transitions in k-space. The width of the tails of localized states in the band gap (ΔE) was evaluated from Urbach edges. Both the parameters (Eopt) and (ΔE) vary with the mixing ratio of dispersed liquid crystals.

Rubber modification of polybutyleneterephthalate by reactive blending concurrently with polymerization reaction

Abstract Rubber modification of polybutyleneterephthalate (PBT) was accomplished by the addition of suitable functionalized ethylene-propylene copolymers (EPR) concurrently with the high temperature polycondensation of 1,4-butanediol and dimethylterephthalate. Ester and alcohol modified rubbers were tested in the polymerization process, and it was found that the type and amount of grafted groups can play a fundamental role because they determine mode and state of dispersion of the elastomeric phase inside the plastic matrix. An attempt was made to correlate the results obtained to the influence of the different kinds of grafted pendant groups on the polymerization equilibria of PBT.

Evaluation of Selenite Effects on Selenoproteins and Cytokinome in Human Hepatoma Cell Lines

The need to explore new alternative therapeutic strategies and chemoprevention methods for hepatocellular carcinoma is growing significantly. Selenium is a trace element that plays a critical role in physiological processes, and is used in cancer chemoprevention. The aim of this work was to test in vitro the effect of sodium selenite on the human hepatoma cell lines, HepG2 and Huh7, to assess its effect on the expression of GPX1, SELK and SELENBP1 and also to evaluate its action on inflammation determinants such as cytokines. Our results show that: (i) the increase observed for the GPX1 and SELK expression is correlated with an increase in the sodium selenite concentration, also evidencing an inverse association between the levels of these two proteins and SELENBP1; (ii) the selenium concentrations evaluated in protein extracts increase in proportional way with the selenite concentrations used in the treatment, suggesting that other selenoproteins can also be modulated and should be evaluated in further studies, and (iii) some cytokines, VEGF and three pro-inflammatory cytokines, i.e., IL-6, IL-8, and IL-17, decreased with an increasing selenite concentration. Finally, interactomic studies show that GPX1 and SELK, and the four pro-inflammatory cytokines are functionally correlated evidencing a putative anti-inflammatory role for the selenite.

Extraction and characterization of vegetable oils from cherry seed by different extraction processes

The aim of this work was to compare the content and composition of oil from cherry seeds using supercritical fluid extraction (SFE) using carbon dioxide as solvent, and Soxhlet extraction using diethyl ether. The compositions of free fatty acids and phytosterols, achieved with two extraction methods, were analyzed. Gas chromatographic analysis of unsaponifiables cherry seed oil samples, obtained with SFE and Soxhlet extraction, permitted to identify in particular two sterols, the s-sitosterol and campesterol. Brassicasterol or stigmasterol were not present in the extracts. The percentages of monitored components changed in function of extraction used procedure, allowing to assert that, with SFE, higher yield of phytosterols was provided. Preliminary data showed that there were significant differences also in the fatty acid composition of cherry seed oil obtained with the two extraction procedures (by means supercritical carbon dioxide or solvent). With the Soxhlet extraction, 48.6% of saturated fatty acids, 17.74% of unsaturated acids, 32.75% of polyunsaturated are obtained. On the contrary, with SFE decreased the percentage of saturated fatty acids (38.43%) in favor of larger amounts of unsaturated (19.93%) and polyunsaturated (36.04%). The supercritical fluid extraction procedure proved so effective in getting an oil of superior quality, without the possibility of degradation phenomena due to the solvent or heat. In both extraction procedures the cherry seed oil contained high percentages of arachidic acid (C20:0) and linoleic acid (C18:2, ?-6). An interesting result was also the presence of nervonic acid in remarkable amount, in all examined samples. Nervonic acid is a long-chain monounsaturated fatty acid (C24:1, ?-9), of marine origin, precursor of the neuronal cell membrane glycolipids, with a key role in the modulation of ion channels and membrane receptors, and therefore widely used as a neurotrophic factor in food supplements and nutraceuticals.