[Show abstract][Hide abstract] ABSTRACT: Nanoparticles, named cutinsomes , have been prepared from aleuritic (9,10,16-trihidroxipalmitic) acid and tomato fruit cutin monomers (a mixture of mainly 9(10),16-dihydroxypalmitic acid (85%, w/w) and 16-hydroxyhexadecanoic acid (7.5%, w/w)) with pectin in aqueous solution. The process of formation of the nanoparticles of aleuritic acid plus pectin has been monitored by UV-Vis spectrophotometry, while their chemical and morphological characterization was analyzed by ATR-FTIR, TEM, and non-contact AFM. The structure of these nanoparticles can be described as a lipid core with a pectin shell. Pectin facilitated the formation of nanoparticles, by inducing their aggregation in branched chains and favoring the condensation between lipid monomers. Also, pectin determined the self-assembly of cutinsomes on highly ordered pyrolytic graphite (HOPG) surfaces, causing their opening and forming interconnected structures. In the case of cutin monomers, the nanoparticles are fuse
PLoS ONE 04/2015; 10(4-4):e0124639. DOI:10.1371/journal.pone.0124639 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abstract Highly stretchable polyvinyl alcohol (PVA) films with a strain at break of around 700% were obtained from solutions in trifluoroacetic acid (TFA). Structural and chemical analysis by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (ATR-FTIR) showed that TFA is retained by PVA via hydrogen bonds between the carboxylic acid groups and the hydroxyl groups of the polymers causing a strong plasticizing effect. Additionally, composites of PVA with cellulose could be developed using TFA as common solvent. The morphological and mechanical properties of the polymer composites could be accurately tuned by modifying the relative concentrations of the two polymers. Data from water adsorption isotherms and wetting measurements indicated that the presence of trifluoromethyl groups in PVA render the composite films relatively hydrophobic.
Chemical Engineering Journal 04/2015; DOI:10.1016/j.cej.2015.04.092 · 4.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Solution-processed inorganic and organic materials have been pursued for more than a decade as low-threshold, high-gain lasing media, motivated in large part by their tunable optoelectronic properties and ease of synthesis and processing. Although both have demonstrated stimulated emission and lasing, they have not yet approached the continuous-wave pumping regime. Two-dimensional CdSe colloidal nanosheets combine the advantage of solution synthesis with the optoelectronic properties of epitaxial two-dimensional quantum wells. Here, we show that these colloidal quantum wells possess large exciton and biexciton binding energies of 132 meV and 30 meV, respectively, giving rise to stimulated emission from biexcitons at room temperature. Under femtosecond pulsed excitation, close-packed thin films yield an ultralow stimulated emission threshold of 6 μJ cm(-2), sufficient to achieve continuous-wave pumped stimulated emission, and lasing when these layers are embedded in surface-emitting microcavities.
[Show abstract][Hide abstract] ABSTRACT: Bioplastics with a wide range of mechanical properties were directly obtained from industrially processed edible vegetable and cereal wastes. As model systems, we present bioplastics synthesized from wastes of parsley and spinach stems, rice hulls, and cocoa pod husks by digesting in trifluoroacetic acid (TFA), casting, and evaporation. In this way, amorphous cellulose-based plastics are formed. Moreover, many other natural elements present in these plants are carried over into the bioplastics rendering them with many exceptional thermo-physical properties. Here, we show that, due to their broad compatibility with cellulose, amorphous cellulose can be naturally plasticized with these bioplastics by simply mixing during processing. Comparison of their mechanical properties with that of various petroleum based synthetic polymers indicates that these bioplastics have equivalent mechanical properties to the nondegrading ones. This opens up possibilities for replacing some of the nondegrading polymers with the present bioplastics obtained from agro-waste.
[Show abstract][Hide abstract] ABSTRACT: The cuticle is one of the most important plant barriers. It is an external and continuous lipid membrane that covers the surface of epidermal cells and whose main function is to prevent the massive loss of water. The spectroscopic characterization of the plant cuticle and its components (cutin, cutan, waxes, polysaccharides and phenolics) by infrared and Raman spectroscopies has provided significant advances in the knowledge of the functional groups present in the cuticular matrix and on their structural role, interaction and macromolecular arrangement. Additionally, these spectroscopies have been used in the study of cuticle interaction with exogenous molecules, degradation, distribution of components within the cuticle matrix, changes during growth and development and characterization of fossil plants.
[Show abstract][Hide abstract] ABSTRACT: The assessment of the risks exerted by nanoparticles is a key challenge for academic, industrial, and regulatory communities worldwide. Experimental evidence points towards significant toxicity for a range of nanoparticles both in vitro and in vivo. Worldwide efforts aim at uncovering the underlying mechanisms for this toxicity. Here, we show that the intracellular ion release elicited by the acidic conditions of the lysosomal cellular compartment - where particles are abundantly internalized - is responsible for the cascading events associated with nanoparticles-induced intracellular toxicity. We call this mechanism a lysosome-enhanced Trojan horse effect since, in the case of nanoparticles, the protective cellular machinery designed to degrade foreign objects is actually responsible for their toxicity. To test our hypothesis, we compare toxicity for similar gold particles whose main difference is in the internalization pathways. We show that particles known to pass directly though cell membranes be
[Show abstract][Hide abstract] ABSTRACT: Technologies able to handle microvolumes of liquids, like microfluidics and liquid marbles, are attractive for applications that include miniaturized biological and chemical reactors, sensors, microactuators, and drug delivery systems. Inspired from natural fibrous envelopes, here we present an innovative approach for liquid encapsulation and manipulation by using electrospun nanofibers. We demonstrated the realization of not-wetting soft solids consisting of a liquid core wrapped in a hydrophobic fibrillar cloak of a fluoroacrylic copolymer and cellulose acetate. By properly controlling the wetting and mechanical properties of the fibers, we created final architectures with tunable mechanical robustness that were stable on a wide range of substrate (from paper to glass) and floated on liquid surfaces. Remarkably, the realized fiber-coated drops endured vortex mixing in a continuous oil phase at high stirring speed without bursting or water losses, favouring mixing processes inside the entrapped liquid volume. Moreover, the produced cloak can be easily functionalized by incorporating functional particles, active molecules or drugs inside the nanofibers.
[Show abstract][Hide abstract] ABSTRACT: We have studied in vitro toxicity of iron oxide nanoparticles (NPs) coated with a thin silica shell (Fe3O4/SiO2 NPs) on A549 and HeLa cells. We compared bare and surface passivated Fe3O4/SiO2 NPs to evaluate the effects of the coating on the particle stability and toxicity. NPs cytotoxicity was investigated by cell viability, membrane integrity, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) assays, and their genotoxicity by comet assay. Our results show that NPs surface passivation reduces the oxidative stress and alteration of iron homeostasis and, consequently, the overall toxicity, despite bare and passivated NPs show similar cell internalization efficiency. We found that the higher toxicity of bare NPs is due to their stronger in-situ degradation, with larger intracellular release of iron ions, as compared to surface passivated NPs. Our results indicate that surface engineering of Fe3O4/SiO2 NPs plays a key role in improving particles stability in biological environments reducing both cytotoxic and genotoxic effects.
PLoS ONE 01/2014; 9(1):e85835. DOI:10.1371/journal.pone.0085835 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Plasmonic resonators have generated much interest in recent years due to their ability to localize optical energy into thin continuous metallic regions. We present the integration of such resonators into flexible polydimethylsiloxane-gold nanocomposite materials that couple light efficiently, in order to prepare a totally optical layout for tactile sensors, able to detect low applied pressure forces. The development of plasmonic nanostructured resonators of thin gold layers onto polydimethylsiloxane is achieved using light texturing. In particular, this technique creates uniform patterns of gold nanoparticles forming quasi continuous gold thin layers behaving as plasmonic resonators. The excitation of the resonators and the detection of the signal after the application of the pressure are done through optical fibers avoiding electrical connections or circuits embedded into the elastomer. The proposed totally optical tactile sensor is easily processable and ideal for upscaling oriented towards humanoid robotics and biocompatible elastomeric human interface skin prostheses.
[Show abstract][Hide abstract] ABSTRACT: In recent years, education in nanotechnology has evolved to reflect the
new skill set required to perform multidisciplinary research. As the
field further develops, it will need to evolve again.
[Show abstract][Hide abstract] ABSTRACT: In this work, we propose a quantitative assessment of nanoparticles toxicity in vivo. We show a quantitative ranking of several types of nanoparticles (AuNPs, AgNPs, cadmium-based QDs, cadmium-free QDs, and iron oxide NPs, with different coating and/or surface chemistries), providing a categorization of their toxicity outcomes. This strategy may offer an innovative high-throughput screening tool of nanomaterials, of potential and broad interest to the nanoscience community.
Journal of Nanoparticle Research 09/2013; 15(9). DOI:10.1007/s11051-013-1936-3 · 2.18 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We demonstrate the generation of natural polymeric structures of complex shapes and controlled composition, starting from the collision of aqueous drops of alginate with the surface of a calcium ion-based liquid. We prove that by tuning the impact velocity of the alginate drops on the target surface one can control the floating state of the drops inducing the formation of mushroom-like structures, upon alginate gelation. Besides the geometric peculiarity, the presented approach allows us to provide dual functionality to the polymeric objects, attaching different kinds of functional molecules onto their surface areas, which are immersed or not in the liquid, making such architectures attractive for the development of a novel class of bionanocomposites.
[Show abstract][Hide abstract] ABSTRACT: Fatigue resistance of the photochromic diarylethene molecules 1,2-bis[2-methylbenzo[b]thyophen-3-yl]-3,3,4,4,5,5-hexafluoro-1-cyclopentene embedded in three different acrylic polymers is studied upon multiple coloration–decoloration cycles. The resistance to photofatigue is found to be different in the three polymeric materials when one-photon excitation was used for the reversible photoconversion experiment. In particular, the photochromic molecules lose their photoisomerization ability faster if they are embedded in poly(methyl methacrylate) (PMMA) with respect to poly(ethyl methacrylate-co-methyl acrylate) (PEMMA) and poly(ethyl methacrylate) (PEMA). We propose several explanations based on the physico-chemical properties of the matrix and of the photochromic molecules. In the case of two-photon excitation, which is necessary for 3D optical writing, the fatigue resistance is found to be poorer than in the one-photon case. The accelerated photodegradation can be assigned to the non-linear nature of interaction between the polymeric composite material and light.
Materials Science and Engineering B 06/2013; 178(10):730–735. DOI:10.1016/j.mseb.2013.03.009 · 2.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this article, we propose a new class of optical pressure sensors suitable for robot tactile sensing. These sensors are based on a tapered optical fiber (where optical signals travel) embedded onto a polydimethylsiloxane (PDMS)- gold nanocomposite material (GNM). By applying different pressure forces to the PDMS-based nanocomposite, we measure in real time the change of optical transmittivity due to the coupling between the GNM and tapered fiber region. The intensity reduction of the transmitted light intensity is correlated with the magnitude of the pressure force.
[Show abstract][Hide abstract] ABSTRACT: Point mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) gene are being increasingly recognized as important diagnostic and prognostic markers in cancer. In this work, we describe a rapid and low-cost method for the naked-eye detection of cancer-related point mutations in KRAS, based on gold nanoparticles. This simple colorimetric assay is sensitive (limit of detection in the low picomolar range), instrument-free, and employs non-stringent room temperature conditions, thanks to a combination of DNA-conjugated gold nanoparticles, a probe design which exploits cooperative hybridization for increased binding affinity, and signal enhancement on the surface of magnetic beads. Additionally, the scheme is suitable for point-of-care applications, as it combines naked-eye detection, small sample volumes, and isothermal (PCR-free) amplification.
[Show abstract][Hide abstract] ABSTRACT: Local heating can be produced by iron oxide nanoparticles (IONPs) when exposed to an alternating magnetic field (AMF). To measure the temperature profile at the nanoparticle surface with a subnanometer resolution, here we present a molecular temperature probe based on the thermal decomposition of a thermo-sensitive molecule, namely, azobis[N-(2-carboxyethyl)-2-methylpropionamidine]. Fluoresceineamine (FA) was bound to the azo molecule at the IONP surface functionalized with poly(ethylene glycol) (PEG) spacers of different molecular weights. Significant local heating, with a temperature increase up to 45 °C, was found at distances below 0.5 nm from the surface of the nanoparticle, which decays exponentially with increasing distance. Furthermore, the temperature increase was found to scale linearly with the applied field at all distances. We implemented these findings in an AMF-triggered drug release system in which doxorubicin was covalently linked at different distances from the IONP surface bearing the same thermo-labile azo molecule. We demonstrated the AMF triggered distance-dependent release of the drug in a cytotoxicity assay on KB cancer cells.
[Show abstract][Hide abstract] ABSTRACT: The understanding of the interactions between biological systems and nanoengineered devices is crucial in several research fields, including tissue engineering, biomechanics, synthetic biology and biomedical devices. This review discusses the current knowledge of the interactions between bacteria and abiotic nanostructured substrates. First, the effects of randomly organized nanoscale topography on bacterial adhesion and persistence are described. Second, the interactions between microorganisms and highly organized/ordered micro- and nano-patterns are discussed. Finally, we survey the most promising approaches for the fabrication of silver polymeric nanocomposites, which have important applications as antimicrobial materials. The advantages, drawbacks and limitations of such nanotechnologies are critically discussed in view of potential future applications.