Showing papers by "Alice Scarpellini published in 2017"

Facile production of seaweed-based biomaterials with antioxidant and anti-inflammatory activities

Abstract: New seaweed-based biomaterials have been prepared using a simple method based on the selective dissolution in trifluoroacetic acid (TFA) of specific polymers and bioactive substances from red, green, and brown seaweeds. Depending on the seaweed's origin, the properties were found to be different, especially the mechanical ones. Furthermore, the samples were fully biodegradable in seawater in one month. Moreover, the antioxidant capacity of the biomaterials was highly increased respect to the pristine materials, demonstrating a selective extraction during the process of solubilization. Finally, biocompatibility and anti-inflammatory experiments demonstrated the non-toxicity of the biomaterials prepared from brown seaweed and a similar anti-inflammatory effect to commercial available drugs, confirming the potential application of the prepared biomaterials for the fabrication of biomedical devices.

Multilayer poly(3,4-ethylenedioxythiophene)-dexamethasone and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate-carbon nanotubes coatings on glassy carbon microelectrode arrays for controlled drug release

Abstract: The authors present an electrochemically controlled, drug releasing neural interface composed of a glassy carbon (GC) microelectrode array combined with a multilayer poly(3,4-ethylenedioxythiophene) (PEDOT) coating. The system integrates the high stability of the GC electrode substrate, ideal for electrical stimulation and electrochemical detection of neurotransmitters, with the on-demand drug-releasing capabilities of PEDOT-dexamethasone compound, through a mechanically stable interlayer of PEDOT-polystyrene sulfonate (PSS)-carbon nanotubes (CNT). The authors demonstrate that such interlayer improves both the mechanical and electrochemical properties of the neural interface, when compared with a single PEDOT-dexamethasone coating. Moreover, the multilayer coating is able to withstand 10 × 106 biphasic pulses and delamination test with negligible change to the impedance spectra. Cross-section scanning electron microscopy images support that the PEDOT-PSS-CNT interlayer significantly improves the adhesion between the GC substrate and PEDOT-dexamethasone coating, showing no discontinuities between the three well-interconnected layers. Furthermore, the multilayer coating has superior electrochemical properties, in terms of impedance and charge transfer capabilities as compared to a single layer of either PEDOT coating or the GC substrate alone. The authors verified the drug releasing capabilities of the PEDOT-dexamethasone layer when integrated into the multilayer interface through repeated stimulation protocols in vitro, and found a pharmacologically relevant release of dexamethasone.

Preparation, Characterization, and Preliminary In Vitro Testing of Nanoceria-Loaded Liposomes.

Abstract: Cerium oxide nanoparticles (nanoceria), well known for their pro- and antioxidant features, have been recently proposed for the treatment of several pathologies, including cancer and neurodegenerative diseases. However, interaction between nanoceria and biological molecules such as proteins and lipids, short blood circulation time, and the need of a targeted delivery to desired sites are some aspects that require strong attention for further progresses in the clinical application of these nanoparticles. The aim of this work is the encapsulation of nanoceria into a liposomal formulation in order to improve their therapeutic potentialities. After the preparation through a reverse-phase evaporation method, size, Z-potential, morphology, and loading efficiency of nanoceria-loaded liposomes were investigated. Finally, preliminary in vitro studies were performed to test cell uptake efficiency and preserved antioxidant activity. Nanoceria-loaded liposomes showed a good colloidal stability, an excellent biocompatibility, and strong antioxidant properties due to the unaltered activity of the entrapped nanoceria. With these results, the possibility of exploiting liposomes as carriers for cerium oxide nanoparticles is demonstrated here for the first time, thus opening exciting new opportunities for in vivo applications.

Facile synthesis of Ge–MWCNT nanocomposite electrodes for high capacity lithium ion batteries

Abstract: Germanium (Ge) nanocrystals combined with multiwalled carbon nanotube (Ge–MWCNT) composites were synthesized via a solvothermal approach and characterized through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and scanning and transmission electron microscopy (SEM and TEM). The electrochemical behaviour during lithium insertion and de-insertion was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge measurements. The as prepared Ge–MWCNT nanocomposite exhibits improved cycling performance with higher capacity retention than pristine Ge. The Ge–MWCNTs exhibit a discharge capacity of ∼1160 mA h g−1 after 60 cycles at a current rate of 0.1C. Furthermore, they showed an excellent rate performance at a current rate of 5C (where 1C is 1600 mA g−1) by delivering a specific capacity of ∼406 mA h g−1 over 400 charge–discharge cycles.

Copolymerization of Norbornene and Norbornadiene Using a cis-Selective Bimetallic W-Based Catalytic System.

Abstract: The bimetallic cluster Na[W2(μ-Cl)3Cl4(THF)2]·(THF)3 ({W2}, {W 3 W}6+, a′2e′4), which features a triple metal-metal bond, is a highly efficient room-temperature initiator for ring opening metathesis polymerization (ROMP) of norbornene (NBE) and norbornadiene (NBD), providing high-cis polymers. In this work, {W2} was used for the copolymerization of the aforementioned monomers, yielding statistical poly(norbornene)/poly(norbornadiene) PNBE/PNBD copolymers of high molecular weight and high-cis content. The composition of the polymer chain was estimated by 13C CPMAS NMR data and it was found that the ratio of PNBE/PNBD segments in the polymer chain was relative to the monomer molar ratio in the reaction mixture. The thermal properties of all copolymers were similar, resembled the properties of PNBD homopolymer and indicated a high degree of cross-linking. The morphology of all materials in this study was smooth and non-porous; copolymers with higher PNBE content featured a corrugated morphology. Glass transition temperatures were lower for the copolymers than for the homopolymers, providing a strong indication that those materials featured a branched-shaped structure. This conclusion was further supported by viscosity measurements of copolymers solutions in THF. The molecular structure of those materials can be controlled, potentially leading to well-defined star polymers via the “core-first” synthesis method. Therefore, {W2} is not only a cost-efficient, practical, highly active, and cis-stereoselective ROMP-initiator, but it can also be used for the synthesis of more complex macromolecular structures.

Tailoring of size, emission and surface chemistry of germanium nanoparticles via liquid-phase picosecond laser ablation

Abstract: Germanium nanoparticles (Ge-NPs) have been studied as optical probes, and label-free and therapeutic agents for biomedical applications over the past few years. However, little progress in their synthesis has been made due to limited emission tunability and poor water stability of Ge-NPs. In this work, Ge-NPs suspensions with different emission colors, blue (≈450 nm), green (≈510 nm) and red (≈650 nm), were prepared at room temperature via 60 ps pulsed laser ablation of the Ge target in liquid. The emission color of the Ge-NPs is tuned by adjusting the laser wavelengths (λ = 355 nm, λ = 532 nm and λ = 1064 nm), and is explained in terms of an in situ ablation/photo-fragmentation process. Results also showed that laser wavelengths control the average size of Ge-NPs (from ≈3 to 18 nm). The effects of variables such as laser wavelengths, dispersing medium and aging time were studied. Optical (PL, FTIR, Raman) and structural (XRD, TEM, electron diffraction) investigations show that Ge-NPs prepared in organic media are more resistant to oxidation, resulting from the passivation of the Ge-NP surface, i.e., the Ge–C bond at a frequency of ≈700 cm−1. We found out that the laser wavelengths act on the surface passivation degree, showing a higher Ge–C/Ge–O ratio at 532 nm laser wavelength.

One-Pot Hybrid SnO2 /Poly(methyl methacrylate) Nanocomposite Formation through Pulsed Laser Irradiation.

Abstract: The localized in situ formation of tin dioxide (SnO2 ) nanoparticles embedded in poly(methyl methacrylate) (PMMA) films is presented. This is achieved by the photoinduced conversion of the tin acetate precursor included in polymeric films, through controlled UV or visible pulsed laser irradiation at λ=355 and 532 nm, respectively. The evolution of the formation of nanoparticles is followed by UV/Vis spectroscopy and shows that their growth is affected in different ways by the laser pulses at the two applied wavelengths. This, in combination with electron microscopy analysis, reveals that, depending on the irradiation wavelength, the size of the nanoparticles in the final nanocomposites differs. This difference is attributed to distinct mechanistic pathways that lead to the synthesis of small nanoparticles (from 1.5 to 4.5 nm) at λ=355 nm, whereas bigger ones (from 5 to 16 nm) are formed at λ=532 nm. At the same time, structural studies with both X-ray and electron diffraction measurements demonstrate the crystallinity of SnO2 nanoparticles in both cases, whereas XPS analysis confirms the light-induced oxidation of tin acetate into SnO2 . Taken all together, it is demonstrated that the pulsed laser irradiation at λ=355 and 532 nm leads to the formation of SnO2 nanoparticles with defined features highly dispersed in PMMA solid matrices.