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In this paper it is reported the preparation of a food packaging based on isotactic polypropylene (PP) coated with layered double hydroxide (LDH) hosting sorbate as active molecule. The active nano-hybrid (LDH-sorbate) was dispersed into a food grade resin and used as coating. The release of the sorbate anchored to the LDH was compared to the release of the molecule free dispersed into the food grade resin and resulted much slower. It was evaluated the efficiency of the active packaging to inhibit Salmonella enterica subsp. arizonae, Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Campylobacter jejuni, and the global migration using two food simulant (i.e. poly (2,6-diphenyl-p-phenylene oxide) and vegetable oil). Experimental data, in compliance with the migration limits of the European Union regulation, demonstrated the suitability of the prepared material for food contact. White bread was packed into the active PP film and untreated PP, as control. Organoleptic characteristics, moisture analysis, peroxide evolution and mold count showed that the bread packaged in the active film retained its starting characteristics up to 12 days of storage at ambient temperature.

Resin-based composites are widely used as dental restorative materials due to their excellent properties. They must have high modulus, high hardness, and be chemically inert while minimizing moisture uptake. To fulfill these higher standard prerequisites and properties, continuous improvements in each of their components are required. This study develops novel composites with multiple biofunctions. Light-cured Bis-GMA/TEGDMA dental resin (RK)/layered double hydroxide intercalated with fluoride ions (LDH-F)/calcium bentonite (Bt) hybrid composites were prepared. The loading ratio of LDH-F to Bt was varied, ranging from 2.5/2.5 to 10/10 parts per hundred RK and structural, mechanical, and biological properties were studied. The incorporation of even small mass fractions (e.g., 2.5 wt % of LDH-F and 2.5 wt % of Bt) in RK dental resin significantly improved the mechanical properties of the pristine resin. The synthetized materials showed antibacterial and antibiofilm effects against three bacterial strains isolated from healthy volunteers&rsquo, saliva (Streptococcus spp., Bacteroides fragilis, and Staphylococcus epidermidis) without affecting its ability to induce dental pulp stem cells differentiation into odontoblast-like cells. The capability to balance between the antibiofilm activity and dental pulp stem cells differentiation in addition with improved mechanical properties make these materials a promising strategy in preventive and restorative dentistry.

The paper reports the formulation of an active packaging based on PET coated with a Layered Double Hydroxide (LDH) hosting 2-acetoxybenzoic anion (salicylate) as antimicrobial molecule. The release of the molecule anchored to the LDH, compared to the molecule free dispersed into the coating, appeared much slower. Permeability of carbon dioxide and oxygen through the packaging at different temperatures was evaluated, as well as the capability of the active material to inhibit Pseudomonas, Listeria and Lactobacillus. Table grape was stored in thermal stress conditions (i.e. 10 °C) into the active packaging and the total mesophilic aerobic count and yeasts and moulds population was evaluated up to 14 days of storage. The experimental results were used for a theoretical prediction of shelf life of the packed grapes and compared with the same fruit packed into untreated material. Global and specific migration of salicylic acid from the active packaging demonstrated, in compliance with the migration limits of the EU regulation, the suitability of the considered material for food contact.

Layered double hydroxide (LDH) nanofillers were considered as hosts of p-hydroxybenzoate as an antimicrobial molecule for active coating. A food grade resin with LDH-p-hydroxybenzoate and two different types of food grade zeolites was used to prepare active coatings for Polyethylene terephthalate (PET) trays. The release kinetics of the active molecule were followed using UV spectrophotometry and the experimental results were analyzed with the Gallagher&ndash, Corrigan model. The thermal properties of the coating mixtures and the PET coating were analyzed and found to be dependent on the coating&rsquo, s composition. On the basis of CO2 transmission rate and off-odors tests, the best coating composition was selected. Global migration in ethanol (10% v/v), acetic acid (3% w/v), and vegetable oil, and specific migration of p-hydroxybenzoic acid revealed the suitability of the material for food contact. Antimicrobial tests on the packaging demonstrated a good inhibition against Salmonella spp. and Campylobacter jejuni. Red meat was packed into the selected active materials and results were compared to uncoated PET packaging. Color tests (browning of the meat) and analysis of Enterobacteriaceae spp. and total viable count evolution up to 10 days of storage demonstrated the capability of the considered active packaging in prolonging the shelf life of red meat.

A novel antimicrobial packaging system, as active coating on a commercial Poly(ethylene terephthalate) (PET) film, was formulated and tested in vitro against the spoilage bacteria of Mozzarella cheese. It is based on layered double hydroxide (LDHs) intercalated with salicylate and carbonate anions dispersed in a solvent-based heat seal. The population of spoilage microorganisms (total coliforms, Pseudomonas, fungi), along with the functional microbiota of Mozzarella cheese (lactic acid bacteria) was characterized. Microbial shelf life was evaluated at 18 °C, to simulate thermal abuse. Experimental results show an increase in the microbial shelf life of the packaged Mozzarella cheese of about 20 days, confirming that the investigated active coating may exert an inhibitory effect on the microorganisms responsible for spoilage phenomena, without affecting the functional microbiota of the product.

Fluoride-releasing restorative dental materials can be beneficial to remineralize dentin and help prevent secondary caries. However, the effects of fluoride release from dental materials on the activity of dental pulp stem cells are not known. Here we investigate whether different fluoride release kinetics from dental resins supplemented with modified hydrotalcite (RK-F10) or fluoride-glass filler (RK-FG10) could influence the behavior of a human dental pulp stem cell subpopulation (STRO-1+ cells) known for its ability to differentiate toward an odontoblast-like phenotype. The 2 resins, characterized by similar physicochemical properties and fluoride content, exhibited different long-term fluoride release kinetics. Our data demonstrate that long-term exposure of STRO-1+ cells to a continuous release of a low amount of fluoride by RK-F10 increases their migratory response to transforming growth factor β1 (TGF-β1) and stromal cell–derived factor 1 (SDF-1), both important promoters of pulp stem cell recruitment. Moreover, the expression patterns of dentin sialoprotein ( dspp), dentin matrix protein 1 ( dmp1), osteocalcin ( ocn), and matrix extracellular phosphoglycoprotein ( mepe) indicate a complete odontoblast-like cell differentiation only when STRO-1+ cells were cultured on RK-F10. On the contrary, RK-FG10, characterized by an initial fluoride release burst and reduced lifetime of the delivery, did not elicit any significant effect on both STRO-1+ cell migration and differentiation. Taken together, our results highlight the importance of taking into account fluoride release kinetics in addition to fluoride concentration when designing new fluoride-restorative materials.

This work describes a successful attempt toward the development of composite materials based on nanofilled epoxy resins for the realization of structural aeronautic components providing efficient lightning strike protection. The epoxy matrix is prepared by mixing a tetrafunctional epoxy precursor with a reactive diluent which allows the moisture content to be reduced and facilitates the nanofiller dispersion step. The reactive diluent also proves to be beneficial for improving the curing degree of nanofilled epoxy mixtures. It increases the mobility of reactive groups resulting in a higher cure degree than the epoxy precursor alone. This effect is particularly advantageous for nanofilled resins where higher temperature treatments are needed, compared to the unfilled resin, to reach the same cure degree. As nanofiller, different carbon nanostructured fiber-shaped fillers are embedded in the epoxy matrix with the aim of improving the electrical properties of the resin. The results highlight a strong influence of the nanofiller nature on the electrical properties especially in terms of electrical percolation threshold (EPT) and electrical conductivity beyond the EPT. Among the analyzed nanofillers, the highest electrical conductivity is obtained by using multiwalled carbon nanotubes (MWCNTs) and heat-treated carbon nanofibers (CNFs). The achieved results are analyzed by considering the nanofiller morphological parameters and characteristics with respect to the impact on their dispersion effectiveness.

Amoxicillin (AMOX) was intercalated in layered double hydroxide (LDH) nanoparticles by coprecipitation. LDH intercalated with AMOX (LDH/AMOX) was successfully encapsulated at different concentrations into poly(?-caprolactone) (PCL) by the electrospinning technique. Mats of non-woven PCL fibers loaded with LDH/AMOX were obtained and characterized in terms of morphology and in vitro release. The fibrous structure of a pristine PCL sample was composed of individual, uniform, and randomly oriented fibers with an average diameter ranging around 0.8. ?m. The addition of LDH/AMOX at different concentrations caused a slight increase of the average diameter and the presence of rare beads possibly due to clusters of the nano-hybrid on the surface of the microfibers.The release curves present a sustained release behavior, although an initial rapid drug release was found. The initial high-rate drug release period was followed by a second step in which the release is slow, extending for long time. The comparison of the release curves showed that the release of AMOX protected into the clay is slower than the release of the drug alone. © 2012 Elsevier B.V.

Microwave-assisted solvent-free modification of pectin was successfully accomplished, consisting in the esterification of several fatty acids by pectin alcoholic functions. The reaction was performed by simply mixing the reagents with a catalytic amount of the inorganic base (potassium carbonate) and irradiating the obtained mixture with microwaves for a short time (3-6 min). The replacement of the traditional heating with a microwave source allowed the development of a new synthetic protocol which provided increased yield of the final products, since it eliminates the small amount of degraded polysaccharide produced during traditional oil bath heating. The desired esters were fully characterized by FT-IR spectroscopy and thermogravimetric analysis.

Syndiotactic polystyrene (sPS) samples were quenched at low temperature (0 degrees C) in the presence of Multi-Walled Carbon Nanotubes (MWCNT) at different concentrations. The influence of carbon nanotubes on the structure and physical properties of sPS composites was investigated by SEM, X-ray diffractograms, DSC (Differential Scanning Calorimetry), and Dynamic Mechanical Analysis (DMA). A good dispersion of the carbon nanotubes in the sPS matrix was found, at least for the low MWCNT concentration, whereas opposite effects were noticed on T-g and elastic modulus, depending on concentration. The pristine sPS sample was almost amorphous at 0 degrees C, whereas in the filled samples the crystallinity increased on increasing the MWCNT concentration, indicating a strong nucleation effect of the nanotubes. Interestingly, in spite of the low temperature, the beta crystallinity was induced and this crystalline form increases on increasing the carbon nanotube concentration, being dominant (68% of the total crystallinity) already at 3 wt% of MWCNT concentration.

Mg-Al Hydrotalcite-like clay (LDH) intercalated with diclofenac anions (HTlc-DIC) was introduced into poly(-caprolactone) (PCL) in different concentrations by the electrospinning technique, and mats of nonwoven fibers were obtained and compared to the pristine pure electrospun PCL. The fibers, characterized by X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry, show an exfoliated clay structure up to 3 wt%, a good thermal stability of the diclofenac molecules and a crystallinity of PCL comparable to the pure polymer. The scanning electron microscopy revealed electrospun PCL and PCL composite fibers diameters ranging between 500 nm to 3.0 m and a generally uniform thickness along the fibers. As the results suggested the in vitro drug release from the composite fibers is remarkably slower than the release from the corresponding control spun solutions of PCL and diclofenac sodium salt. Thus, HTlc-DIC/PCL fibrous membranes can be used as an antinflammatory scaffold for tissue engineering.

The resistive behavior of multi-walled carbon nanotube (MWCNT)/epoxy resins, tested under mechanical cycles and different levels of applied strain, was investigated for specimens loaded in axial tension. The surface normalized resistivity is linear with the strain for volume fraction of MWCNTs between 2.96 × 10−4 and 2.97 × 10−3 (0.05 and 0.5% wt/wt). For values lower than 0.05% wt/wt, close to the electrical percolation threshold (EPT) a non-linear behavior was observed. The strain sensitivity, in the range between 0.67 and 4.45, may be specifically modified by controlling the nanotube loading, in fact the sensor sensitivity decreases with increasing the carbon nanotubes amount. Microscale damages resulted directly related to the resistance changes and hence easily detectable in a non-destructive way by means of electrical measurements. In the fatigue tests, the damage is expressed through the presence of a residual resistivity, which increases with the amount of plastic strain accumulated in the matrix.

New self-assembled nano-particles were developed by chemical conjugation of natural fatty acids to the backbone of hyaluronan (HA). The chemical structure and the self-association behavior of them were studied by FT-IR, NMR, fluorescence and dynamic light scattering. The HA derivatives form stable spherical shape aggregates, as assessed by transmission electron microscopy. This journal is

Polyethylene (PE) from postuse automotive fuel tanks is considered a valuable material for mechanical recycling, and we assessed its properties, paying particular attention to transport properties and processability. The characterization included the study of the sorption-desorption isotherms, the rheological analysis of the molten materials and their processability. In particular, we obtained, sorption-desorption isotherms using a model molecule (n-heptane) to simulate contact with the fuel. The measurements were carried out on films of PE blend for tanks and separately on the components of the blend. Rotational rheometry was carried out on scraps from used tanks and on virgin material for comparison. We performed some extrusion tests to evaluate the possibility of mechanical recycling of the postuse materials. In particular, we examined the melt-fracture incoming conditions by making use of a twinscrew extruder with a round die. Stress-strain measurements were carried out on films of virgin and used material, obtained with a press on a laboratory scale to evaluate the change of the mechanical properties of a manufacture obtained by reprocessing a polymer aged in contact with a mixture of liquids.

Blends of poly(lactic acid) (PLA) and poly(épsilon-caprolactone) (PCL), loaded with different amounts of Amoxicillin antibiotic (AMOX) were electrospun to investigate their release properties and obtain a controlled and tuneable release. The processing parameters for electrospinning were set up and reliable membranes were obtained. Morphology and thermal behaviour were found dependent on the component ratio as well as on the incorporated drug amount. A very different release kinetics of the two pristine polymers, very rapid for PCL and very slow for PLA, reflected in intermediate release time. However comparing the release amount with that predicted by the mixture rule a preferential incorporation of AMOX into PLA can be inferred.

Low density polyethylene (LDPE) and either isotactic polypropilene (IPP) or a copolymer of isotactic polypropilene with 3% of ethylene (CPP) were blended, and analyzed with X-rays, differential thermal calorimetry, dynamic mechanical analysis, and transport properties of dichloromethane vapour at different activities. The results show that polyethylene and polypropylene crystallize in different domains in the usual crystalline forms (orthorhombic and monoclinic respectively). Also the amorphous phases are not miscible; moreover in the blend LDPE-IPP, in which PE crystallize less, the transport of the vapours occurs mainly through polyethylene, whereas the opposite is true in the blend LDPE-CPP, in which polypropylene crystallizes less. The sorption properties are in agreement with the additivity of sorption of the two amorphous phases.

Objectives The aim of this work was the preparation of a new fluoride-releasing dental material characterized by a release of fluoride relatively constant over time without any initial toxic burst effect. This type of delivery is obtained by a matrix controlled elution and elicits the beneficial effect of a low amount of fluoride on human dental pulp stem cells (hDPSCs) towards mature phenotype. Methods The modified hydrotalcite intercalated with fluoride ions (LDH-F), used as filler, was prepared via ion exchange procedure and characterized by X-ray diffraction and FT-IR spectroscopy. The LDH-F inorganic particles (0.7, 5, 10, 20 wt.%) were mixed with a photo-activated Bis-GMA/TEGDMA (45/55 wt/wt) matrix and novel visible-light cured composites were prepared. The dynamic thermo-mechanical properties were determined by dynamic mechanical analyzer. The release of fluoride ions in physiological solution was determined using a ionometer. Total DNA content was measured by a PicoGreen dsDNA quantification kit to assess the proliferation rate of hDPSCs. Alkaline phosphatase activity (ALP) was measured in presence of fluoride resins. Results Incorporation of even small mass fractions ( e.g. 0.7 and 5 wt.%) of the fluoride LDH in Bis-GMA/TEGDMA dental resin significantly improved the mechanical properties of the pristine resin, in particular at 37 °C. The observed reinforcement increases on increasing the filler concentration. The release of fluoride ions resulted very slow, lasting months. ALP activity gradually increased for 28 days in hDPSCs cell grown, demonstrating that low concentrations of fluoride contributed to the cell differentiation. Conclusions The prepared composites containing different amount of hydrotalcite filler showed improved mechanical properties, slow fluoride release and promoted hDPSCs cell proliferation and cell differentiation.

Purpose The purpose of this work was to achieve detailed biomaterials characterization of a drug delivery system for local cancer treatment based on electrospun titanocene trichloride-loaded resorbable polycaprolactone (PCL) fibers. Methods The PCL fibers were characterized for their structural, morphologic and physical properties. The drug release kinetics of the titanocene complex was investigated at different concentrations, to obtain a set of correlations between structure and tuneable release. After exposing cancer cells directly onto the surface of PCL fibers, the anti-proliferative effects of titanocene-loaded PCL were assessed by: (i) counting viable cells via live/dead staining methods, and (ii) analyzing cell apoptosis. Results and Conclusions Titanocene concentration influenced fiber diameters reduced for PCL filled with titanocene. X-ray analysis suggested that the titanocene, encapsulated into the PCL fibers, is not allowed to crystallize and exists as amorphous aggregates into the fibers. The titanocene release curves presented two stages unrelated to PCL degradation: an initial burst release followed by a release linear with time, extending for a very long time. All of the titanocene-loaded fibers revealed sustained drug release properties suggesting their potential clinical applicability for the treatment of local cancer diseases.

Transport properties of dichloromethane were analysed in high- and low-density polyethylene films, obtained with different thermal treatments, in order to correlate sorption and diffusion with the crystallinity of the samples. The crystalline fraction of all the analysed samples was evaluated from density and X-ray data; it ranged from 40%–85%. From the X-ray diffractograms the reciprocal of the width at half-height for the strongest reflection was derived for all the samples; it was considered as an order parameter. It was found that the sorption depends only on the fraction of amorphous phase; in fact, the specific sorption, normalized for the crystallinity of the sample, is constant for all the samples. However, the zero concentration diffusion coefficient,D 0, varies with the sample crystallinity, but there is no simple correlation between these two parameters; rather a transition seems to separate two ranges in which the diffusion coefficient decreases with the crystallinity. At variance, a linear decrease of the diffusion parameter with the order parameter, derived from the X-ray diffractograms, was found in the whole range of crystallinity.

A study concerning the characterization of a multiphase nanocomposite systems based on epoxy matrix, loaded with a 1% of hydrotalcite clay and a range of MWCNT is presented. The electromagnetic properties are measured over a very ample range of frequency (from dc to 12GHz). The use of the clay may determine a low aggregation of the MWCNT in the resin thus improving the EM performances of the nanocomposites.

Newpolymeric composite materials containing a nanohybrid to be used for the controlled release of an antibiotic molecule, chloramphenicol succinate, have been formulated, prepared and characterised. The nanohybrid consists of a layered double hydroxide of Mg–Al hydrotalcitetype, in which the nitrate anions present in the host galleries were replaced with chloramphenicol succinate anions (CFS−) by a simple ion-exchange reaction. Different amounts of the hybrid material were incorporated in polycaprolactone and processed as films of 0.15mm thickness. The composite materials were analysed by X-ray diffractometry and thermogravimetry and their mechanical properties were determined. They showed properties even better than those of the pristine polymer. The release process of the antibiotic molecules was found to be very interesting and promising for tuneable drug delivery. It consists of two stages: an initial stage of a very rapid burst, in which a small fraction of drug is released; and a second stage that is much slower, extending for a longer and longer time. This behaviour is profoundly different and much slower than that of a sample in which the antibiotic molecule is directly incorporated into the polymeric matrix. The parameters influencing drug release have been individuated and discussed.

New polymeric composite materials containing a nanohybrid to be used for the controlled release of an antibiotic molecule, chloramphenicol succinate, have been formulated, prepared and characterised. The nanohybrid consists of a layered double hydroxide of Mg-Al hydrotalcite-type, in which the nitrate anions present in the host galleries were replaced with chloramphenicol succinate anions (CFS(-)) by a simple ion-exchange reaction. Different amounts of the hybrid material were incorporated in polycaprolactone and processed as films of 0.15mm thickness. The composite materials were analysed by X-ray diffractometry and thermogravimetry and their mechanical properties were determined. They showed properties even better than those of the pristine polymer. The release process of the antibiotic molecules was found to be very interesting and promising for tuneable drug delivery. It consists of two stages: an initial stage of a very rapid burst, in which a small fraction of drug is released; and a second stage that is much slower, extending for a longer and longer time. This behaviour is profoundly different and much slower than that of a sample in which the antibiotic molecule is directly incorporated into the polymeric matrix. The parameters influencing drug release have been individuated and discussed.

A black colorant alternative to carbon black, for Polyethylene tanks, which avoids the hysteresis of solvent and allows a more friendly recycling process, was studied. Sorption-desorption isotherms where obtained using a model molecule (n-heptane), in order to simulate the contact with the fuel. The material pigmented with the alternative black colorant was put in contact with liquid fuel for six months: after desorption the rheological behaviour was analyzed at 240°C. Films were obtained after contact with fuel, and submitted to dynamic mechanical analysis. The experimental data were compared with the ones obtained from the material utilized by FIAT Company (Italy) for fuel tanks (carbon black pigmented), both virgin and used ones.

2011 - 2012, The technical parameters for electrospinning solutions of biodegradable polymers poly(ε-caprolactone), poly(lactic acid) and their composites with active molecules were defined and set up. A trial-and-error approach has been employed by varying solution properties and processing parameters to obtain uniform defect-free fibers. Amoxicillin drug was intercalated in layered double hydroxide nanoparticles by coprecipitation and then the modified nanohybrid was successfully encapsulated at different concentrations into poly(ε-caprolactone) matrix by the electrospinning technique. Non-woven fibrous mats were fabricated and characterized in terms of morphology, in vitro release and antibacterial properties. Blends of poly(lactic acid) and poly(ε-caprolactone), loaded with different amounts of amoxicillin were electrospun to investigate the release behaviour and obtain a controlled and tuneable release. Morphology and thermal behaviour were found dependent on the component ratio as well as on the incorporated drug amount. [edited by author], XI n.s.

2010 - 2011 The objective of this PhD project regards the formulation, preparation and characterization of polymeric materials in which lamellar inorganic solids containing potentially active molecules are dispersed. In particular the present work was aimed at the preparation and characterization of "Active Food Packaging Materials" using inorganic fillers modified with active molecules (antimicrobials, antioxidants) dispersed in polymeric matrices for the realization of: 1) Materials with improved barrier properties to gases and vapors 2) Systems for controlled release of active molecules, act to protect and extend the shelf life of food products. Two techniques of dispersion of active inorganic fillers in polymer matrices have been used, generating: 1) polymeric nanocomposites 2) coatings of polymeric surfaces. A screening of different polymers, from biodegradable and thermoplastic to natural, was done to compare the effect of the fillers and of the dispersion technique on the properties mentioned above.[edited by author] X n.s.