Pulsed laser deposition of a dense and uniform Au nanoparticles layer for surface plasmon enhanced efficiency hybrid solar cells

n/

Magneto-Optical properties of noble-metal nanostructures: functional nanomaterials for bio sensing

Metallic nanostructures supporting Localized Surface Plasmon Resonances (LSPR) are characterized by their unique ability to control and manipulate light at the nanoscale. Noble metal nanostructures, such as gold nanostructures, are demonstrating to exhibit magneto-optic activity in the presence of modulated magnetic field of low intensity in transversal configuration (T-MOKE). Validation of experimental findings was achieved by numerical simulations based on Finite Element Method (FEM) techniques. The developed numerical models allowed studying the combination of the T-MOKE effect with the localized surface plasmon resonance of metal nanoparticles. Numerical optical and magneto-optical spectra provided a deep insight on the physical aspects behind the magneto-optical activity of metal nanostructures strictly related to direction of oscillations electrical dipoles generated in resonance conditions. Additionally the MO signal was characterized as a transducing signal for refractive index sensing in liquid conditions. The outcome is an increase in the limit of detection of magneto optical transducer with respect to traditional plasmonic sensors. A new strategy for magneto-plasmonic sensing based on the use of glass supported -Au nanostructures based on their MO properties has put forward.The authors want to acknowledge G. Montagna and E. Melissano for technical support and the financial support from Italian MIUR through FIRB project RBFR10OAI0 Nanoplasmag. A. G.-M. acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (Contract No.MAT2014-58860-P), and the Comunidad de Madrid (Contract No. S2013/MIT-2740).Peer reviewe

Modulating Thermal Properties of Polymers through Crystal Engineering

Crystal engineering has exclusively focused on the development of advanced materials based on small organic molecules. We now demonstrate how the cocrystallization of a polymer yields a material with significantly enhanced thermal stability but equivalent mechanical flexibility. Isomorphous replacement of one of the cocrystal components enables the formation of solid solutions with melting points that can be readily fine-tuned over a usefully wide temperature range. The results of this study credibly extend the scope of crystal engineering and cocrystallization from small molecules to polymers

Tailoring of silica-based nanoporous pod by spermidine multi-activity

Ubiquitous in nature, polyamines (PAs) are a class of low-molecular aliphatic amines critically involved in cell growth, survival and differentiation. The polycation behavior is validated as a successful strategy in delivery systems to enhance oligonucleotide loading and cellular uptake. In this study, the chemical features and the functional roles of the PA spermidine are synergistically exploited in the synthesis and bioactive functionalization of SiO2-based structures. Inspired by biosilicification, the role of spermidine is assessed both as catalyst and template in a biomimetic one-pot synthesis of dense silica-based particles (SPs) and as a competitive agent in an interfacial reassembly strategy, to empty out SPs and generate spermidine-decorated hollow silica nanoporous pods (spd-SNPs). Spermidine bioactivity is then employed for targeting tumor cell over-expressed polyamine transport system (PTS) and for effective delivery of functional miRNA into melanoma cells. Spermidine decoration promotes spd-SNP cell internalization mediated by PTS and along with hollow structure enhances oligonucleotide loading. Accordingly, the functional delivery of the tumor suppressor miR-34a 3p resulted in intracellular accumulation of histone-complexed DNA fragments associated with apoptosis. Overall, the results highlight the potential of spd-SNP as a multi-agent anticancer therapy

Modulating Thermal Properties of Polymers through Crystal Engineering

Crystal engineering has exclusively focused on the development of advanced materials based on small organic molecules. We now demonstrate how the cocrystallization of a polymer yields a material with significantly enhanced thermal stability but equivalent mechanical flexibility. Isomorphous replacement of one of the cocrystal components enables the formation of solid solutions with melting points that can be readily fine-tuned over a usefully wide temperature range. The results of this study credibly extend the scope of crystal engineering and cocrystallization from small molecules to polymers

Study of structural properties of mesoscopic systems at nanoscale

Dottorato di ricerca in fisica. 12. ciclo. Coordinatore Marco BoitiConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Novel insight into the physics of short-range ordered nanoholes: Newly defined lattice model and transmittance response related to lattice parameters and ordering evolution

This paper presents unforeseen conceptualization, methods and results on the physics of short-range ordered (SRO) gold nanohole (NH) distributions, fabricated by a recent protocol developed by the authors. The straightforward extension to SRO-NHs of the existing knowledge about periodic NH arrays is confuted and an alternative interpretative picture is proposed and discussed based on three main advancements. First, it is set up a so-called short-range lattice (SR-Lat) method to rigorously and fully characterize the coverage-dependent short-range ordering through the determination of local coordination and periodicity length (aSR) of the NH arrangement. Second, it is demonstrated the failure of the common assumption that the average center-to-center distance of nearest neighbor colloids/nanoholes (dNN) is the characteristic length-scale of SRO-NHs and aSR is set as the proper periodicity parameter. Third, a predictive relationship is formulated between the wavelength of the propagating plasmon modes and aSR that highlights inherent differences with respect to periodic NHs. The presented results lay rigorous foundation for studying systems with correlated diosrdering in general and for making predictions useful not only in design and applications of SRO-NHs, but also on the surface physics in the photonics and sensing fields

Block Copolymer and Cellulose Templated Mesoporous TiO₂-SiO₂ Nanocomposite as Superior Photocatalyst

A dual soft-templating method was developed to produce highly crystalline and mesoporous TiO2-SiO2 nanocomposites. Pluronic F127 as the structure-directing agent and pure cellulose as the surface area modifier were used as the templating media. While Pluronic F127 served as the sacrificing media for generating a mesoporous structure in an acidic pH, cellulose templating helped to increase the specific surface area without affecting the mesoporosity of the TiO2-SiO2 nanostructures. Calcination at elevated temperature removed all the organics and formed pure inorganic TiO2-SiO2 composites as revealed by TGA and FTIR analyses. An optimum amount of SiO2 insertion in the TiO2 matrix increased the thermal stability of the crystalline anatase phase. BET surface area measurement along with low angle XRD revealed the formation of a mesoporous structure in the composites. The photocatalytic activity was evaluated by the degradation of Rhodamine B, Methylene Blue, and 4-Nitrophenol as the model pollutants under solar light irradiation, where the superior photo-degradation activity of Pluronic F127/cellulose templated TiO2-SiO2 was observed compared to pure Pluronic templated composite and commercial Evonik P25 TiO2. The higher photocatalytic activity was achieved due to the higher thermal stability of the nanocrystalline anatase phase, the mesoporosity, and the higher specific surface area

Accurate assessment of the oxygen reduction electrocatalytic activity of Mn/polypyrrole nanocomposites based on rotating disk electrode (RDE) measurements, complemented with multi-technique structural characterizations

This paper reports on the quantitative assessment of the oxygen reduction reaction (ORR) electrocatalytic activity of electrodeposited Mn/polypyrrole (PPy) nanocomposites for alkaline aqueous solutions, based on the Rotating Disk Electrode (RDE) method and accompanied by structural characterizations relevant to the establishment of structure-function relationships. The characterization of Mn/PPy films is addressed to the following: (i) morphology, as assessed by Field-Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscope (AFM); (ii) local electrical conductivity, as measured by Scanning Probe Microscopy (SPM); and (iii) molecular structure, accessed by Raman Spectroscopy; these data provide the background against which the electrocatalytic activity can be rationalised. For comparison, the properties of Mn/PPy are gauged against those of graphite, PPy, and polycrystalline-Pt (poly-Pt). Due to the literature lack of accepted protocols for precise catalytic activity measurement at poly-Pt electrode in alkaline solution using the RDE methodology, we have also worked on the obtainment of an intralaboratory benchmark by evidencing some of the time-consuming parameters which drastically affect the reliability and repeatability of the measurement

Integration Methods of Cyclodextrins on Gold and Carbon Electrodes for Electrochemical Sensors

Cyclodextrins (CDs) are oligosaccharides composed of six (α), seven (β) or eight (γ) glucose units. Their inner hydrophobic cavity and hydrophilic external surface enable the formation of the “host-guest inclusion complex” with different organic or inorganic molecules showing high molecular selectivity. For these characteristics, CDs have many potential applications in electrochemical sensing. To enable CDs immobilization on the electrode surfaces, different chemical modifications are needed depending of the electrode material, while nanomaterials have been exploited to enhance the sensing signal. The CDs binding onto gold nanoparticles or carbon nanotubes, as an electron-transfer mediator to the electrode surface, is a typical example of it, while also graphene is largely used. The aim of the present review is to give an overview of CDs properties and their applications to electrochemical sensors for medical diagnostics. Different kinds for the functionalization of CDs onto electrode surfaces will be reviewed as well as their performance in presence of nanomaterials. Finally, CDs-based devices for sensing biomedical molecules of biomedical interest will be briefly presented and discussed