Detection and quantification of intracellular structures is fundamental in biomedical sciences. New emerging inspection tools based on holographic microscopy and quantitative phase imaging can give answers to such critical demands. Holographic tomography (HT) systems are the best candidates for this challenge. Recently, HT has been demonstrated working in flow-cytometry (FC) modality. Results show that the novel HTFC tool is capable to furnish 3D visualization and quantifications of the different intracellular particles. In particular, here we report that exogenous nanographene oxide particles as well as endogenous lipid droplets can be detected, measured, and visualized in each flowing cell by label-free HTFC. This method opens the way for accurate and high-throughput measurements at the 3D single-cell level for different applications such as diagnosis of diseases, development of drug delivery applications, and examination of cell functionalities. Experiments and processing methods will be described, and several examples will be discussed.

Nowadays, the use of multi-functional mortars has increased significantly, with interesting applications in the sustainable construction. In the environment, the cement-based materials are subjected to leaching, so the assessment of potential adverse effects upon aquatic ecosystem is necessary. This study focuses on the evaluation of the ecotoxicological threat and of a new type of cement-based mortar (CPM-D) and its raw materials leachates. A screening risk assessment were performed by Hazard Quotient methods. The ecotoxicological effects were investigated by a test battery with bacteria, crustacean, and algae. Two different procedures, Toxicity test Battery Index (TBI) and Toxicity Classification System (TCS), to obtain a single value for toxicity rank were used. Raw materials showed the highest metal mobility and in particular, for Cu, Cd and V potential hazard was evidenced. Leachate toxicity assessment evidenced the highest effects linked to cement and glass while the mortar showed the lowest ecotoxicological risk. TBI procedure allows a finer classification of effect linked to materials with respect to TCS which is based on worst case approach. A safe by design approach taking into account the potential and the effective hazard of the raw materials and of their combinations could allow to achieve sustainable formulations for building materials.

The influence of soft segment (SS) content on the properties of novel polyurethane networks (PUNs), prepared by a two-step polymerization in a solvent mixture, was investigated in this work. Hyperbranched polyester of the third pseudo generation (BH-30) was used as a crosslinker, and together with isophorone diisocyanate (IPDI) was applied to build hard segments (HS) in PUNs. On the other hand, SS of the prepared PUNs are based on polycaprolactone (PCL). The content of SS in PUNs varied from 10 to 50 wt%. The structural, thermal and mechanical properties, swelling behavior, as well as morphology of PUNs, were explored by various experimental methods. Performed investigations have shown that the use of BH-30 led to the emergence of relatively high crosslinking density and good mechanical properties, and that all features of PUNs significantly depend on the SS content. Higher PCL content caused presence of certain crystallinity, better thermal stability, more pronounced microphase separated morphology, but also lower degree of hydrogen bonding, crosslinking density and storage modulus of the prepared PUNs. The obtained results have shown that the properties of PUNs can be easily varied and customized to different practical needs.

Intelligent composite materials and devices are attracting a great interest owing to their potential impact on various future life applications. To meet the growing demand for multifunctional materials, the development and validation of visible sensing behavior is highly desirable, but the development of a single multifunctional wearable sensing material still remains a challenge to be achieved. To reach this goal, here we present a wearable intelligent fabric with piezoresistivity and mechanoluminescence ability based on a layer-structured graphene-based conductive cotton fabric and SrAlO:Eu, Dy/polyurethane foamed coating. The presence of the foamed coating structure endows the flexible composite fabric with a controllable positive/negative piezoresistivity (gauge factor from -2.5 to 17) and a bright mechanoluminescence ability that can be used in the darkness without additional batteries. Three-dimensional chromaticity diagrams have also been developed as advanced tools to quantitatively assess the luminescence, whose lightness, during the bending cycles, is highly repeatable with value in the range from ~25 to ~55. The multifunctional layered composite sensor provides multiple output signals which can be accurately recognized and assigned to independent triggering events, opening up new opportunities in advanced wearable devices based on commercial fabrics.

This paper provides a bio-based polyurethane foam (PUR) solution, following a cradle-to-factory approach. The design of bio-based rigid PURs, reinforced with sustainable fillers have gained remarkable attention in "green" construction sector. Their marked performances make them a viable solution for synthetic counterparts' replacement. In this work, functionalized hemp fibers and silica powders were selected as reactive fillers, imparting multifunctional properties to the designed PURs. Hemp fibers underwent ultramilling, phenolation and/or nano-transformation to obtain four different filler types, i.e. nano- and micro-sized hemp particles, and functionalized hemp nano and micro-size couples. Silica nanoparticles were extracted from rice husk and functionalized with phytic acid. The composite PURs were prepared by adding 6 % wt of filler to cardanol/vegetable-based polyol solutions. The effect of the filler's chemistry on the properties of the foams was investigated. A Life Cycle Assessment of the filler production stages was performed to assess their eco-profile impact.

Currently, the scientific community has spent a lot of effort in developing "green" and environmentally friendly processes and products, due the contemporary problems connected to pollution and climate change. Cellulose nanocrystals (CNCs) are at the forefront of current research due to their multifunctional characteristics of biocompatibility, high mechanical properties, specific surface area, tunable surface chemistry and renewability. However, despite these many advantages, their inherent hydrophilicity poses a substantial challenge for the application of CNCs as a reinforcing filler in polymers, as it complicates their dispersion in hydrophobic polymeric matrices, such as polyurethane foams, often resulting in aggregate structures that compromise their properties. The manipulation and fine-tuning of the interfacial properties of CNCs is a crucial step to exploit their full potential in the development of new materials. In this respect, starting from an aqueous dispersion of CNCs, two different strategies were used to properly functionalize fillers: (i) freeze drying, solubilization in DMA/LiCl media and subsequent grafting with bio-based polyols; (ii) solvent exchange and subsequent grafting with bio-based polyols. The influence of the two functionalization methods on the chemical and thermal properties of CNCs was examined. In both cases, the role of the two bio-based polyols on filler functionalization was elucidated. Afterwards, the functionalized CNCs were used at 5 wt% to produce bio-based composite polyurethane foams and their effect on the morphological, thermal and mechanical properties was examined. It was found that CNCs modified through freeze drying, solubilization and bio-polyols grafting exhibited remarkably higher thermal stability (i.e., degradation stages > 100 °C) with respect to the unmodified freeze dried-CNCs. In addition, the use of the two grafting bio-polyols influenced the functionalization process, corresponding to different amount of grafted-silane-polyol and leading to different chemico-physical characteristics of the obtained CNCs. This was translated to higher thermal stability as well as improved functional and mechanical performances of the produced bio-based composite PUR foams with respect of the unmodified CNCs-composite ones (the best case attained compressive strength values three times more). Solvent exchange route slightly improved the thermal stability of the obtained CNCs; however; the so-obtained CNCs could not be properly dispersed within the polyurethane matrix, due to filler aggregation.

"Compact and lightweight" graphene-based mortars were produced and their piezo-resistive behavior was analyzed. Such property is exploitable in the production of functional building materials, which could work as stress-strain sensors. First, graphene-isopropyl alcohol dispersion was synthesized through Liquid Phase Exfoliation and the few layered structure was evidenced via Raman spectroscopy. Afterward, "compact and lightweight" mortars-graphene based composites were produced by using, respectively, cement and cement/diatomite as matrix, the previously mentioned graphene dispersion and a suitable amount of water. The morphological, structural, thermal and electro-mechanical properties of the obtained materials were analyzed. The mix-design here discussed can pave the way for a new kind of eco-friendly, multi-applicative, multi-responsive building material.

Nano graphene-based materials offer interesting physicochemical and biological properties for biotechnological applications due to their small size, large surface area and ability to interact with cells/tissues. Among carbon-based nanomaterials, graphene oxide is one of the most used in biological field. There is an increasing interest in shedding light on the interaction mechanisms of nanographene oxide (nGO) with cells. In fact, the effects on human health of GO, and its toxicological profile, are still largely unknown. Here we show that, by minimizing the oxidation degree of GO, its toxicity is significantly reduced in NIH 3T3 cells. Moreover, we show that mild oxidation of graphene nanoplatelets produces nGO particles, which are massively internalized into the cell cytoplasm. MTT(3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay was performed to analyze cell viability. Transmission electron microscopy (TEM) analysis was performed to evaluate nGO internalization mechanism into the cytoplasm under different oxidation degree and concentrations. For the first time, we evaluated quantitatively, the cell volume variation after nGO internalization in live fibroblasts through a label-free digital holography (DH) imaging technique and in quasi-real-time modality, thus avoiding the time-consuming and detrimental procedures usually employed by electron-based microscopy. In conclusion, here we have demonstrated that DH can be a viable tool to visualize and display 3D distributions of nano graphene oxide (nGO) uptake by fibroblast cells. DH opens the route for high-throughput investigation at single cell level for understanding how in different conditions nanoparticles aggregates distribute inside the cells.

The present study is focused on the development and characterization of innovative cementitious-based composite sensors. In particular, multifunctional cement mortars with enhanced piezoresistive properties are realized by exploiting the concept of confinement of Multiwall Carbon Nanotubes (MWCNTs) and reduced Graphene Oxide (rGO) in a three-dimensional percolated network through the use of a natural-rubber latex aqueous dispersion. The manufactured cement-based composites were characterized by means of Inelastic Neutron Scattering to assess the hydration reactions and the interactions between natural rubber and the hydrated-cement phases and by Scanning Electron Microscopy and X-Ray diffraction to evaluate the morphological and mineralogical structure, respectively. Piezo-resistive properties to assess electro-mechanical behavior in strain condition are also measured. The results show that the presence of natural rubber latex allows to obtain a three-dimensional rGO/MWCNTs segregate structure which catalyzes the formation of hydrated phases of the cement and increases the piezo-resistive sensitivity of mortar composites, representing a reliable approach in developing innovative mortar-based piezoresistive strain sensors.

Cellulose Nanocrystals, CNC, opportunely functionalized are proposed as reactive fillers in bio-based flexible polyurethane foams to improve, mainly, their mechanical properties. To overcome the cellulose hydrophilicity, CNC was functionalized on its surface by linking covalently a suitable biobased polyol to obtain a grafted-CNC. The polyols grafted with CNC will react with the isocyanate in the preparation of the polyurethane foams. An attractive way to introduce functionalities on cellulose surfaces in aqueous media is silane chemistry by using functional trialkoxy silanes, X-Si (OR)3 . Here, we report the synthesis of CNC-grafted-biopolyol to be used as a successful reactive filler in bio-based polyurethane foams, PUFs. The alkyl silanes were used as efficient coupling agents for the grafting of CNC and bio-polyols. Four strategies to obtain CNC-grafted-polyol were fine-tuned to use CNC as an active filler in PUFs. The effective grafting of the bio polyol on CNC was evaluated by FTIR analysis, and the amount of grafted polyol by thermogravimetric analysis. Finally, the morphological, thermal and mechanical properties and hydrophobicity of filled PUFs were thoughtfully assessed as well as the structure of the foams and, in particular, of the edges and walls of the cell foams by means of the Gibson-Ashby model. Improved thermal stability and mechanical properties of PU foams containing CNC-functionalized-polyol are observed. The morphology of the PU foams is also influenced by the functionalization of the CNC.

Graphene family materials (GFM) have large perspectives for drug delivery applications but their internalization in live cells is under investigation in a wide variety of studies in order to assess the best conditions for efficient cellular uptake. Here we show that mild oxidation of graphene nanoplatelets produces nano-graphene oxide (nGO) particles which are massively internalized into the cell cytoplasm. This remarkable uptake of nGO in NIH-3T3 cells has never been observed before. We performed vitality tests for demonstrating the biocompatibility of the material and analyzed the internalization mechanism under different oxidation degrees and concentrations. Moreover, we evaluated quantitatively, for the first time, the cell volume variation after nGO internalization in live cells through a label-free digital holographic imaging technique and in quasi real-time modality, thus avoiding the time consuming and detrimental procedures usually employed by electron-based microscopy. The results demonstrate that nGO formulations with a tailored balance between exposed surface and content of functional groups are very promising in drug delivery applications.

TIPOLOGIA: dimostrazione/laboratorio DESCRIZIONE: In accordo con la filosofia dell'economia circolare, con questa attività si vuole mostrare al pubblico come sia possibile dare nuova vita ad alcuni scarti alimentari trasformandoli in bioplastiche ad alto valore aggiunto per applicazioni di consumo in diversi settori. ATTIVITA' PREVISTE: Verrà mostrato al pubblico uno schema del processo di produzione di chitina/ chitosano, a partire da gusci di crostacei, e di alginato, a partire da alghe brune. Successivamente il pubblico sarà coinvolto in attività di laboratorio nelle quali chitosano e alginato saranno impiegati per la creazione di capsule e cerotti per uso farmaceutico e film rinforzati per applicazioni agricole.

Liquid-crystalline elastomer (LCE) nanocomposites exhibiting shape memory properties were prepared by dispersing a chemically modified graphene oxide (GO) in a smectic, lightly crosslinked epoxy resin obtained by curing p-bis(2,3-epoxypropoxy)-?-methylstilbene (DOMS) with sebacic acid (SA). Chemical grafting of DOMS monomer on GO particle surface improved interfacial adhesion between the epoxy matrix and the filler. The obtained nanocomposite films were characterized in their phase behavior, morphological and thermal properties. Furthermore, their shape memory properties were analyzed through two-way thermomechanical cycling tests. The combination of the LCE liquid crystallinity and the efficient dispersion of functionalized GO resulted in toughened, highly oriented systems endowed with enhanced shape memory response. Incorporation of 0.15 wt.% GO resulted in a significant increase of spontaneous elongation and reduced actuation temperature during cycling thermomechanical tensile testing, demonstrating the potential of these systems as shape memory materials for sensors and actuators.

Shape memory nanocomposites were prepared and characterized. The polymer matrix consisted in an epoxy-based liquid crystalline elastomer (LCE). Multi-walled carbon nanotubes (MWCNT) and graphite nanoplatelets (GNP) were selected as fillers. The influence of different contents of nanofillers on mechanical, thermal and shape memory properties was evaluated. In order to disperse and homogeneously distribute the nanofillers within the polymer matrix an in-depth evaluation of the optimal conditions to synthesize the materials was carried out. These conditions had a substantial influence on the final distribution of the nanofillers within the epoxy-based matrix, which was analyzed from a macroscopic and microscopic point of view.

In this paper, epoxy-based shape-memory liquid crystalline lightly cross-linked networks (LCN) are synthesized and characterized with a view to the future development of two-way autonomous shape-memory actuators by coupling the LCN with an external epoxy-matrix. Carboxylic acids of different aliphatic chain lengths are used as curing agents for a rigid-rod epoxy-based mesogen. Thermal and liquid-crystalline (LC) properties of the LCN are investigated, through calorimetric and X-ray diffraction analysis on unstretched and stretched samples. Structural and thermomechanical properties are studied by means of tensile and dynamic-mechanical analyses and the shape-memory capabilities are analyzed in terms of actuation strain and stress under partially- and fully constrained thermomechanical procedures. The results possibility to obtain LCN with isotropization temperatures above 100 degrees C, controlled degree of liquid crystallinity, and high actuation stress and strain by simply varying the aliphatic chain length of the curing agent. Moreover, by properly adjusting the programming conditions (stress level), it is possible to optimize and stabilize the actuation performance. In addition, the effects of the liquid-crystalline domains on the network relaxation and their degree of orientation after programming at the different stress levels have been discussed. Overall, proper design of chain length and stress level allows strain actuation to be modulated from low, similar to 60%, to high, similar to 160% strain levels. The results evidence the possibility of finely tuning LCN with controlled and stable actuation protocols by balancing the aliphatic chain length and programming conditions.

This investigation presents a new approach to obtain free-standing thermally-triggered "two-way" shape-memory actuators by realizing multilayer structures constituted by glassy thermoset (GT) films anchored to a previously programmed liquid-crystalline network (LCN) film. The GT is obtained via dual-curing of off-stoichiometric "thiol-epoxy" mixtures, thus enabling the development of complex actuator configurations thanks to the easy processing in the intermediate stage, and a compact and resistant design due to the strong adhesion between the layers obtained upon the final curing stage of the GT. A model based on the classical multilayered beam theory to predict the maximum deflection of a "beam-like" design is proposed and its reliability is verified by experimental investigation of actuators with different configurations and LCN stretching levels. The results show the capability of these actuators to bend and unbend under various consecutive heating-cooling procedures in a controlled way. The maximum deflection can be modulated through the configuration and the LCN stretching level, showing an excellent fitting with the model predictions. The model is able to predict high actuation levels (angles of curvature approximate to 180 degrees) and the bidirectional shape-memory behavior of the device as a function of the thickness, configuration of the layers, and the LCN stretching level. This approach enables the design of free-standing two-way actuators covering a range of bending actuation from 27 to 98% of the theoretical maximum deflection.

abstract

Thermally induced shape-memory polymers are materials based on exploiting one or more phase transitions, such as glass, melting, or clearing transition, to trigger a shape-memory effect. Among shape-memory polymers, liquid crystalline elastomers are considered as very interesting candidates, thanks to the synergistic effect of the ordered liquid crystalline phase and the polymeric network on their programming and recovering behavior. Here, the synthesis of new shape-memory smectic epoxy-based elastomers incorporating multiwalled carbon nanotubes is reported. The realized materials show two types of shape-memory behavior that can be selectively actuated by choosing the appropriate thermal recovery conditions. The surface modification of the nanotubes enables a dramatic enhancement of the actuation extent at low nanofiller content. Moreover, the stress threshold required to trigger the reversible thermomechanical actuation is significantly decreased. The effect of nanotubes on thermomechanical properties of the materials is elucidated and correlated to the microstructure and phase behavior of the host system. Results demonstrate that the incorporation of multiwalled carbon nanotubes amplifies the soft-elastic response of the liquid crystalline phase to external stimuli. Tunable thermomechanical properties of these systems make them potentially suitable for a variety of applications ranging to robotics, sensing and actuation, and artificial muscles.