Uso di idrotalciti in compositi a matrice PLA preparati nel fuso

Three-layered porous device in PCL/PEG blend for interface tissue engineering

Tissue interfaces, such as cartilage-to-bone, exhibit anisotropic structural properties, which gradually vary from one tissue to another. Consequently a regenerative scaffold designed for interface tissues should exhibit a gradient in composition, structure and mechanical features, mimicking those of the native zones. In particular, the architecture of pores plays a central role. Indeed, a biomedical implant should be designed with porosityand pore size gradients simulating the structure of the two interface tissues. One of the most common techniques to prepare porous scaffolds is the particulate leaching method, which involves the selective leaching of a mineral or organic compound as poro…

Efficacia di film polimerici a base di etilen-vinil-acetato e componenti di oli essenziali nei confronti del biofilm

An investigation of the compatibilization of blends of polyethylene and a semirigid liquid crystalline polymer

The mechanical properties of blends with liquid crystalline polymers are in general poor and lower than those expected on the basis of additivity rule because of the strong incompatibility between the flexible and rigid components. Compatibilization is then necessary to enhance the adhesion between the two phases and then to improve the final properties of these blends. The addition of maleic anhydride functionalized polymers could give rise to some compatibilization because of possible reactions between the maleic anhydride group and the end groups of the liquid crystalline polymers. These reactions do not seem to occur in blends of polyethylene and a semirigid liquid crystalline polymer. …

PCL/PEG based membranes for bacterial cells immobilization stimulate actinorhodin antibiotic production in S. coelicolor

The actinomycetes, Gram-positive filamentous bacteria, are the most prolific source of natural antibiotics. At industrial level, antibiotics from actinomycetes are usually produced at low levels by mean of fermentative processes in submerged cultivations, where one of the major factors negatively affecting bioproductivity is the phenomenon of a pellet-shaped biomass growth. The strategies based on cell-immobilization, which were already proven improving bacterial bioprocess productivity, could stimulate antibiotic production in actinomycetes.

Actinorhodin production intensification by nanofibrous membranes in Streptomyces coelicolor cultures

In this work, electrospun polycaprolactone (PCL) and polylactic acid (PLA) membranes, subjected or not to O2-plasma treatment, werwe used as support for cell-immobilization in S. coelicolor immobilized-cells created a compact biofilm on both kinds of membranes.

Enhancement of antibiotic productions by plasma modified PLA electrospun membranes in Streptomyces coelicolor immobilized-cell cultivations

This study, encouraging the use of PLA membranes for actinomycetes cultivations, could unveil functional insights associated with antibiotic production and S. coelicolor cellimmobilization

Improvement of actinorhodin production yield in Streptomyces coelicolor by immobilized-cell cultivations by using PCL- and PLA-based films

Actinomycetes are Gram-positive bacteria producing most of naturally occurring antibiotics (Donadio et al., 2010). At industrial level, antibiotics are produced by submerged fermentations where the actinomycete filamentous morphology negatively affects bioproductivity (van Dissel et al., 2014). Microporous membranes for bacterial cell-immobilization were already proven increasing bioproductivity in Streptomyces coelicolor, that is a model actinomycete producing the blue pigmented actinorhodin (ACT) antibiotic (Scaffaro et al., 2016). To develop an immobilized-cell bioreactor system, different kinds of polycaprolactone (PCL) and polylactic acid (PLA) films were produced by an electrospinning…

Caratterizzazione termomeccanica dell’acido polilattico e due suoi compositi

Questa memoria presenta i test sperimentali per la caratterizzazione termomeccanica del biopolimero acido polilattico e dei suoi compositi con farina di faggio o con nanorinforzo di montmorillonite modifcata, per uno studio di applicabilità nel settore automobilistico. Per la caratterizzazione meccanica e il confronto dei risultati vengono eseguiti prove di coppia e di trazione; i test dinamici vengono eseguiti per la caratterizzazione termomeccanica, determinando il modulo elastico e il fattore di perdita rispetto alla temperatura effettiva. This paper presents the experimental tests for the thermomechanical characterization of biopolymer polylactic acid, and its composites with beech flour…

Biopolymeric bilayer films for packaging applications prepared by co-extrusion film blowing

The requirements for reducing packaging waste drove academic efforts to search compostable bio-sourced polymeric materials. Multilayer systems can represent a suitable strategy to obtain the required properties and to improve biopolymer performance. Thus, the aim of the current work is the preparation by co-extrusion film blowing of a bio-based bilayer film with the purpose to overcome the drawbacks of the individual components.

Graphene oxide and Fumed silica graphene oxide nanocomposites modification by thermal treatments

In the present study we investigate post synthesis thermal treatments up to 400 °C of graphene oxide (GrO) prepared from commercial graphite and of GrO–silica nanocomposites prepared by a solution of commercial Fumed silica nanoparticles (average diameter 7 nm or 40 nm) and the GrO. The thermal treatments were carried out in air, vacuum or He atmosphere to highlight tunable changes. Two GrO batches with small differences in the D (~1350 cm–1) and G (~1580 cm–1) Raman bands have been employed to evaluate effects depending on preparation. Thermal effects have been monitored through the Raman spectroscopy focusing on D, G and 2D (2500–3500 cm–1) bands spectral ranges. The experiments evidenced…

Effect of Streptomyces coelicolor M145 cell immobilization on actinorhodin production

Non previsto

Image processing techniques for the analysis of the micro-architecture of three-dimensional porous scaffolds

Plasma Functionalization of Multiwalled Carbon Nanotubes and Their Use in the Preparation of Nylon 6-Based Nanohybrids

The possibility to obtain carbon nanotubes (CNT)/polyamide 6 composites with excellent mechanical properties in a simple, industrially scalable way is investigated. Commercial CNTs are treated by plasma while changing some key parameters (exposure time, plasma power, type of gas) in order to optimize the process and to achieve a sufficient degree of functionalization. The treated samples are characterized by Fourier transform infrared spectroscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The most interesting samples are selected to be used as reinforcing fillers, in different concentrations, in a polyamide 6 matrix. The mechanical tests show a dramatic increase of both tens…

IMPROVED PRODUCTION OF THE ANTIBIOTIC ACTINORHODIN IN STREPTOMYCES COELICOLOR IMMOBILIZED-MYCELIAL CELL CULTIVATIONS

Objectives i) Evaluation of ACT production in Streptomyces coelicolor M145 mycelial cells immobilized on polycaprolactone (PCL) and polylactic acid (PLA) nanofiber membranes, modified or not by an O2- plasma treatment. ii) Identification of gene products associated with the improvement of ACT production.

The small protein TrpM modulates morpho-physiological differentiation in Streptomyces coelicolor

TrpM, a small protein of 63 amino acids, is encoded by a gene of the trpCMBA locus involved in tryptophan biosynthesis in the model actinomycete Streptomyces coelicolor. Indeed, the trpM knock-out mutant strain is characterized by a delayed growth on minimal medium, smaller aerial hyphae, and reduction of both spore and antibiotic actinorhodin production in comparison with the wild-type strain. These observations are in agreement with proteomic analyses which highlighted a role for TrpM in controlling i) tryptophan production through precursor availability and, thus ii) bacterial growth and morpho-physiological differentiation. To further elucidate the role of TrpM, a S. coelicolor trpM kno…

Polimeri antibatterici contenenti carvacrolo come approccio innovativo per il controllo del biofilm

Progettazione efficiente di Biocompositi Rinforzati con fibre di Agave

La crescente sensibilità nei riguardi dell'inquinamento ambientale e le nuove disposizioni legislative in materia di protezione dell'ambiente, hanno portato negli ultimi anni ad una crescente attenzione verso i cosiddetti biocompositi, cioè verso materiali compositi ecocompatibili e/o rinnovabili, ottenuti da biopolimeri rinforzati da fibre naturali come lino, kenaf, agave ecc. Il presente lavoro intende dare un contributo alla comprensione del comportamento meccanico ed alla efficiente progettazione di performanti biocompositi, ottenuti attraverso una oculata scelta di matrici termoindurenti e termoplastiche, rinforzate con fibre di agave. Dopo avere indagato sulle peculiari proprietà dell…

Statistical study of the influence of CNTs purification and plasma functionalization on the properties of Polycarbonate-CNTs nanocomposites

This work reports a statistical study on the relationship between the chemical-physical properties of CNTs, which vary by changing the conditions of purification and plasma treatment, and the macroscopic properties of PC-based nanocomposites. CNTs are synthesized and then purified in two different ways and used as fillers for the preparation of PC/CNTs nanocomposites. In some cases, oxygen plasma treatment is carried out to improve their affinity to the matrix. The CNTs are characterized by TGA, ICP/OES and FT-Raman spectroscopy, titration and morphological analysis. Mechanical, dynamic-mechanical, electrical and morphological tests are used for characterizing PC/CNTs nanocomposites.

Biopolymeric porous structure for selective oil sorption and activity intensification of oil-degrading bacteria

Oil pollution is one of the environmental concerns that are currently becoming a major issue in the petroleum industry. Among the different methods for environmental cleaning, the use of sorbents to recover the spilled oils is becoming more and more attractive because of their peculiar advantages such as reusability and recoverability of the oil. In this context, bioremediation is often considered a promising and cost-effective technology that could help a more sustainable recovery of contaminated water by using oil-degrading microorganisms. In this work, it is proposed a PCL-based biodegradable and floatable oil removal sponge, able to immobilize and increase biodegradation ability of hydr…

PLA/PCL nanofibrous blends via multi-jet electrospinning: processing-morphology-property relationships

Electrospinning permits to prepare ultrafine fibers with micro to nano-meter range diameters. Multi-jet approaches can be used to fabricate blend nanofibrous mats composed by two or more polymers presenting different properties such as degradation rate, mechanical properties and so on. In this study, a series of PLA/PCL blend nanofiber mats were prepared by dual-jet electrospinning. The relative weight ratio of PLA and PCL in blend was controlled by changing the flow ratio of the two syringe pumps containing the polymer solutions.

Silica as a green exfoliant agent for graphene oxidepolymer nanocomposites prepared in the melt

For the first time, solid-state exfoliant agents were used to hinder the re-aggregation of graphene oxide (GO) during melt processing with polyamide 6 (PA6). This technique drastically reduces the time and difficulty related to solvent (removal, disposal, etc.), and avoids water consumption, since in this case 150 mL of water under mild operative conditions are enough to prepare the amount of GOS necessary for the realization of almost 100 grams of PA6- GOS nanocomposites with outstanding ultimate properties.

Reprocessing of PLA based nanocomposites: Effect of nanofiller

Several studies investigated the effect of the reprocessing on the properties of PLA. However, recycling of PLA-based nanocomposites was not been investigated in depth so far. PLA is susceptible to thermo-degradation during melt processing operations. For this purpose, the study of thermo-mechanical degradative phenomena associated to its re-processing is of great concern in order to assess the possibility of recycling PLA-based nanocomposites. This work aims to evaluate the effect of reprocessing on morphology and properties of PLA reinforced with different nanofillers, i.e. hydrotalcites (HT) and graphene nanoplatelets (GnPs), pointing out on the role of the nanofiller.

Thermomechanical Characterization of Polylactic Acid and Composites

This paper presents the experimental tests for the thermomechanical characterization of biopolymer polylactic acid, and its composites with beech flour or with nanoreiforcement of modified montmorillonite, in order to evaluate any applicability in the automotive sector. Tests of torque and traction are executed for the mechanical characterization and the results comparison; dynamical tests are executed for the thermomechanical characterization, determining the elastic modulus and loss factor versus the actual temperature.