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Polypyrrole nanowires (PPy-NWs) are synthesized by a novel templateless approach based on non-static solution-surface (NSSS) electropolymerization. The mechanism responsible for PPy-NW formation is the simultaneous oxidation of pyrrole and water, with concomitant formation of hydroxyl radicals and dioxygen nanobubbles. In particular, a localized PPy-NW deposition at the solution-air interface is enabled by solution-surface electropolymerization due to the surface excess of the monomer at the interface favored by the large surface tension of the solvent. In the proposed approach, solution-surface electropolymerization is performed in non-static conditions (NSSS), as the solution-air interface is shifted by flowing the electrolyte solution over the electrode surface. This allows a PPy-NW homogeneous deposition on whatever large area electrode to be rapidly achieved. Parameters influencing the morphology of PPy-NWs are studied, particularly focusing on flow rate, pH of the electrolyte solution, and electropolymerization time. The growth process of PPy-NWs is examined and the way of tuning their resulting morphology is discussed. Morphological investigation by scanning electron microscopy and chemical/electrochemical characterization of PPy-NWs by X-ray photoelectron spectroscopy and cyclic voltammetry, respectively, further support the proposed nanowire formation mechanism. Nanowires with diameter in the range of 40–300 nm are obtained, and the possibility of depositing differently sized nanowires with a predetermined spatial distribution on the same substrate is also demonstrated.

Aerosol particulate matter (PM) is a known risk factor for lung and liver cancer. In particular, PM under 1 μm in diameter (PM1) is very dangerous for health, affecting the respiratory system with several heavy outcomes and reaching other human districts like liver, where foreign substances are processed. Today PM1 is still difficult to be detected on-field with standard techniques and this paper reports a comparison between two sensing approaches for environmental particulate monitoring, which are suitable for miniaturization and integration into portable and low-cost devices. Specifically, transducers based on surface acoustic waves (SAW) and electrochemical impedance spectroscopy (EIS) were comparatively investigated as alternatives to more common but also expensive optical methods. Moreover, their performances were evaluated for the detection of nanoparticles of different dimensions (1 μm, 200 nm and 40 nm) to mimic different compositions of PM1 and reach a size scale which is an order of magnitude below present literature. Notably, both transduction methods were able to detect the presence of PM1 particulate. The SAW-based approach showed better performances in terms of sensitivity and detection of nanoscale particles, although the EIS strategy has a competitive sensitivity considering also its even lower cost.

The dielectric properties of YCTO bulk capacitors were investigated as a function of temperature from 25 degrees C to 150 degrees C and at microwave frequencies in comparison to a SiO2 bulk sample. The results confirm the high-k character of the YCTO ceramic, in addition to the low AC conductivity, namely epsilon' = 40.1 and sigma = 6 x 10(-8) S cm(-1) at 1 MHz, and show a weak frequency and temperature (25 degrees C-150 degrees C) dependence. A temperature coefficient value of -601 ppm degrees C-1 for the dielectric constant (TC epsilon') was estimated at 100 kHz. In the GHz regime, a comparison with bulk SiO2 confirms the higher YCTO dielectric permittivity. These results demonstrate high-k YCTO ceramic as a very promising material with high potentiality for electronic applications.

The increasing constraints in the miniaturization of modern electronic devices is driving the search for new high-k dielectric materials. Rare-earth transition metal oxides are very interesting because of the large values of dielectric constant observed in bulk samples. Here, we report on a comparison among the dielectric properties of yttrium copper titanate (YCTO) thin films and those of commonly used dielectrics such as SiO2 and MgO, grown in similar device structures. The YCTO permittivity was found to depend strongly on the oxygen pressure during deposition and can reach values even higher than those reported in bulk YCTO with good performances in terms of losses.

In the present study, a composite material consisting of polypyrrole nanowires (PPyNWs) and platinum nanoparticles (PtNPs) has been developed by an all-electrochemical approach and proved to be highly effective for electrochemical determination of dopamine (DA). PPyNWs are electropolymerized by a template-free method, and PtNPs are subsequently electrodeposited by cyclic voltammetry. Chemical characterization by X-ray photoelectron spectroscopy showed the effective PtNP immobilization on polymer nanowires discriminating at the same time Pt species deposited and revealing the occurrence of polypyrrole-PtNP interaction. The morphology of the composite material was characterized using scanning electron microscopy that showed spherical Pt nanoparticles well distributed within PPy-NW network. DA detection was performed by differential pulse voltammetry technique obtaining satisfactory performances in terms of linear range (1-77 ?M), sensitivity, reproducibility (RSD 2.7%), and detection limit (0.6 ?M). The electrocatalytic role of PtNPs in DA electroxidation process is clearly demonstrated by the comparison with PPyNWs only. Moreover, no significant response is observed in the presence of common interference as ascorbic acid and uric acid, which may coexist with DA in biological fluids, demonstrating a good selectivity toward DA. Moreover, DA was detected in human serum samples spiked obtaining a satisfactory recovery of 94%. A synergistic effect involving both PtNPs and PPyNWs is invoked for explaining the observed electrocatalytic activity.

Herein we present a straightforward approach for the use of polydopamine (PDA) in adsorption of heavy metals from aqueous solutions. This is achieved by fabricating a healthy and environmentally friendly polydimethylsiloxane (PDMS) foam with a mussel inspired PDA layer deposited on the surface. Critical adsorption parameters (pH, temperature and PDA thickness) are optimized by the application of experimental design methodology. Adsorption kinetics and isotherms are studied in detail evidencing a good fitting with Langmuir isotherm and pseudo-second-order kinetics thus suggesting the occurrence of a chemical sorption process with monolayer nature between metals and PDMS/PDA foam. Intraparticle diffusion model evidences good accessibility and high affinity of binding sites on PDA surface. Once adsorbed, metals are reduced to a lower toxic form and can be then removed by a mild acidic treatment thus being easily collected and stocked.

Sustainable growth, environmental preservation, and improvement of life quality are strategic fields of worldwide interest and cornerstones of international policies. Humanity health and prosperity are closely related to our present choices on sustainable development. The main sources of pollution concern industry, including mining, chemical companies, and refineries, wastewater treatment; and consumers themselves. In order to guide and evaluate the effects of environmental policies, diffuse monitoring campaigns and detailed (big) data analyses are needed. In this respect, the development and availability of innovative sensor platforms for field analysis and remote sensing are of crucial relevance. In this review, we provide an overview of the area, analyzing the major needs, available technologies, novel approaches, and perspectives. Among environmental pollutants that threaten the biosphere, we focus on inorganic and organic contaminants, which affect air and water quality. We describe the technologies for their assessment in the environment and then draw some conclusions and mention future perspectives opened by the integration of sensing technologies with robotics and the Internet of Things. Without the ambition to be exhaustive in such a rapidly growing field, this review is intended as a support for researchers and stakeholders looking for current, state-of-the-art, and key enabling technologies for environmental monitoring.

Energy efficient, low-cost, user-friendly, and green methods for the removal of toxic phenolic compounds from aqueous solution are necessary for waste treatment in industrial applications. Herein we present an interesting approach for the utilization of oxidized carbon nanotubes (CNTs) in the removal of phenolic compounds from aqueous solution. Dried pristine CNTs were stably incorporated in a solid porous support of polydimethylsiloxane (PDMS) facilitating the handling during both oxidation process of the nanomaterial and uptake of phenolic compounds, and enabling their safe disposal, avoiding expensive post-treatment processes. The adsorption studies indicated that the materials can efficiently remove phenolic compounds from water with different affinities towards different phenolic compounds. Furthermore, the adsorption kinetics and isotherms were studied in detail. The experimental data of adsorption fitted well with Langmuir and Freundlich isotherms, and pseudo-second-order kinetics, and the results indicated that the adsorption process was controlled by a two-step intraparticle diffusion model. The incorporation of CNTs in polymeric matrices did not affect their functionality in phenol uptake. The material was also successfully used for the removal of phenolic compounds from agricultural waste, suggesting its possible application in the treatment of wastewater. Moreover, the surface of the material could be regenerated, decreasing treatment costs.

Colloidal lithography is an innovative fabrication technique employing spherical, nanoscale crystals as a lithographic mask for the low cost realization of nanoscale patterning. The features of the resulting nanostructures are related to the particle size, deposition conditions and interactions involved. In this work, we studied the absorption of polystyrene spheres onto a substrate and discuss the effect of particle–substrate and particle–particle interactions on their organization. Depending on the nature and the strength of the interactions acting in the colloidal film formation, two different strategies were developed in order to control the number of particles on the surface and the interparticle distance, namely changing the salt concentration and absorption time in the particle solution. These approaches enabled the realization of large area (≈cm2) patterning of nanoscale holes (nanoholes) and nanoscale disks (nanodisks) of different sizes and materials.

Functional, flexible, and integrated lab-on-chips, based on elastic membranes, are capable of fine response to external stimuli, so to pave the way for many applications as multiplexed sensors for a wide range of chemical, physical and biomedical processes. Here, we report on the use of elastic thin membranes (TMs), integrated with a reaction chamber, to fabricate a membrane-based pressure sensor (MePS) for reaction monitoring. In particular, the TM becomes the key-element in the design of a highly sensitive MePS capable to monitor gaseous species production in dynamic and temporally fast processes with high resolution and reproducibility. Indeed, we demonstrate the use of a functional MePS integrating a 2 pm thick polydimethylsiloxane TM by monitoring the dioxygen evolution resulting from catalytic hydrogen peroxide dismutation. The operation of the membrane, explained using a diffusion-dominated model, is demonstrated on two similar catalytic systems with catalase-like activity, assembled into polyelectrolyte multilayers capsules. The MePS, tested in a range between 2 and 50 Pa, allows detecting a dioxygen variation of the mu mol L-1 s(-1) order. Due to their structural features, flexibility of integration, and biocompatibility, the MePSs are amenable of future development within advanced lab-on-chips.

Mixed iron-manganese oxide nanoparticles, synthesized by a simple procedure, were used to remove nickel ion from aqueous solutions. Nanostructures, prepared by using different weight percents of manganese, were characterized by transmission electron microscopy, selected area diffraction, X-ray diffraction, Raman spectroscopy, and vibrating sample magnetometry. Adsorption/desorption isotherm curves demonstrated that manganese inclusions enhance the specific surface area three times and the pores volume ten times. This feature was crucial to decontaminate both aqueous samples and food extracts from nickel ion. Efficient removal of Ni2+ was highlighted by the well-known dimethylglyoxime test and by ICP-MS analysis and the possibility of regenerating the nanostructure was obtained by a washing treatment in disodium ethylenediaminetetraacetate solution.

The surface of a detector grade CVD polycrystalline diamond sample (5 × 5 × 0.05 mm3) was irradiated by an ArF excimer laser (? = 193 nm, ? = 20 ns) to produce graphitic conductive layers. In particular, two sets of four parallel graphitic strip-like contacts, with 1 mm pitch, were created along the whole sample on the top and on the rear surfaces of the sample respectively. The two series of stripes lie normally to each other. Such a grid allows to obtain a segmented all-carbon device capable of giving bi-dimensional information on particle detection processes in nuclear applications. Afterwards, an extensive characterization of the samples was performed: SEM and micro-Raman investigations to study the morphological and structural evolution of the irradiated areas, EDS measurements to individuate any absorption phenomena from environment associated to laser treatment, and nanoindentation mapping to understand how the hard-soft transformation occurred depending on the locally transferred energy. Finally, current-voltage analyses were carried out checking the ohmic behavior of the diamond-graphite contact. By comparing the results of the different characterization analyses, a strong periodicity of the modified surface properties was found, confirming the reliability and reproducibility of the laser-induced graphitization process. The results demonstrate that the laser-writing technique is a good and fast solution to produce graphitic contacts on diamond surface and therefore represents a promising way to fabricate segmented all-carbon devices. © 2016 Elsevier B.V.

In this work, we demonstrate the excitation of surface acoustic waves (SAW) harmonics up to GHz regime in photolitographed devices fabricated on gallium arsenide (GaAs) by acting on the IDT metallization ratio among the finger width and pitch. Specifically, we observed up to the 13th harmonic, which corresponds to a frequency of about 1.7 GHz. Moreover, we employed time-resolved spectroscopy for isolating the shape of the SAW bandpass-filter response (for each harmonic) eliminating the interference between acoustic and electromagnetic waves. Notably, the extracted SAW spectra are characterized by a bandwidth which remains constant for the different harmonic modes, unlike the case of traditional SAW filters (having a 0.5 metallization ratio) where the pass band Delta f = f(0)/n(p) np increases with the working frequency. These results are relevant for applications where high frequencies and multiple harmonics excitation are desirable, or where quantitative measurements of the direct SAW signal are required.

Authors aimed to provide a magnetic responsiveness to bone-mimicking nano-hydroxyapatite (n-HA). For this purpose, dextran-grafted iron oxide nanoarchitectures (DM) were synthesized by a green-friendly and scalable alkaline co-precipitation method at room temperature and used to functionalize n-HA crystals. Different amounts of DM hybrid structures were added into the nanocomposites (DM/n-HA 1:1, 2:1 and 3:1weight ratio) which were investigated through extensive physicochemical (XRD, ICP, TGA and Zeta-potential), microstructural (TEM and DLS), magnetic (VSM) and biological analyses (MTT proliferation assay). X-ray diffraction patterns have confirmed the n-HA formation in the presence of DM as a co-reagent. Furthermore, the addition of DM during the synthesis does not affect the primary crystallite domains of DM/n-HA nanocomposites. DM/n-HAs have shown a rising of the magnetic moment values by increasing DM content up to 2:1 ratio. However, the magnetic moment value recorded in the DM/n-HA 3:1 do not further increase showing a saturation behaviour. The cytocompatibility of the DM/n-HA was evaluated with respect to the MG63 osteoblast-like cell line. Proliferation assays revealed that viability, carried out in the absence of external magnetic field, was not affected by the amount of DM employed. Interestingly, assays also suggested that the DM/n-HA nanocomposites exhibit a possible shielding effect with respect to the anti-proliferative activity induced by the DM particles alone.

Lower genital tract infections caused by both sexually and not-sexually transmitted pathogens in women are a key public health priority worldwide, especially in developing countries. Since standard analyses are time-consuming, appropriate therapeutic intervention is often neglected or delayed. Lab-on-chips and biosensors open new perspectives and offer innovative tools to simplify the diagnosis by medical staff, especially in countries with inadequate resources. Here we report a biosensing platform based on Electrochemical Impedance Spectroscopy (EIS) that allows multiplexed detection of Candida albicans, Streptococcus agalactiae and Chlamydia trachomatis with a single biochip, enabling a quick screening thanks to the presence of different immobilized antibodies, each specific for one of the different target pathogens.

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and lethal cancers in Europe and the United States. It has a very low 5 years-survival rate and its diagnosis is often late and imprecise due to the lack of specificity of currently used markers for PDAC. As previously demonstrated PDAC patients’ sera may contain autoantibodies towards phosphorylated a-enolase (ENOA), which in combination with other standard markers can increase specificity in diagnosis of PDAC. In this context we realized a microfluidic platform with integrated EIS biosensors. We achieved a specific antibodies detection by immobilizing onto electrodes peptides corresponding to a portion of ENOA. Phosphorylation of peptides was found to influence the recognition of antibodies in PDAC patients’ sera detected by the developed biochip thus validating the EIS technique as a strong tool for quick, cost-saving and label-free analysis of serum samples. Biochip results are in agreement with those from traditional techniques, such as ELISA and western blot, but measurements are much more sensitive and specific, increasing the possibility of PDAC diagnosis. In addition this approach is faster and more reproducible compared to traditional techniques making the developed biochips ideal for a quick, cost-saving and label-free analysis of serum samples.

Nearly amorphous high-k yttrium copper titanate thin films deposited by laser ablation were investigated in both metal-oxide-semiconductor (MOS) and metal-insulator-metal (MIM) junctions in order to assess the potentialities of this material as a gate oxide. The trend of dielectric parameters with film deposition shows a wide tunability for the dielectric constant and AC conductivity, with a remarkably high dielectric constant value of up to 95 for the thick films and conductivity as low as 6 x 10(-10) S cm(-1) for the thin films deposited at high oxygen pressure. The AC conductivity analysis points out a decrease in the conductivity, indicating the formation of a blocking interface layer, probably due to partial oxidation of the thin films during cool-down in an oxygen atmosphere. Topography and surface potential characterizations highlight differences in the thin film microstructure as a function of the deposition conditions; these differences seem to affect their electrical properties.