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In this paper, the great sensitivity and selectivity to NO2 detection at low temperature down to ppb level of zinc oxide (ZnO) thick-film sensors are reported. Sensor performances of ZnO films prepared by screen-printing technique were evaluated comparing two different ZnO nano-powders in wurtzite crystal structure. Powders were synthesized by hydrothermal route (HT-ZnO) and by auto-combustion sol–gel synthesis (AC-ZnO). After proper characterization of the nano-powders, the thick-film sensors were fabricated by screen-printing technique onto α-alumina substrates equipped with Pt interdigitated electrodes, followed by a thermal treatment. The sensor response was studied in the range 50–250 °C. Best results were reached at 150 °C, with sensor response R (Zg/Z0)—defined as the ratio between impedance under NO2 (Zg) and impedance under dry air (Z0)—equal to 42.92 for HT-ZnO and to 23.18 for AC-ZnO under 0.5 ppm of NO2 in dry conditions. Finally, response and recovery time were measured, and selectivity of the sensors was determined by exposing the film toward O3, CO2, CH4, N2O and humidity at the best working temperature. Both sensors showed great sensitivity for NO2 detection, supporting the exploitation of these sensors as NO2 detectors at ppb level.

Highlights The present review highlights the importance of remotely activated nanoparticles for anticancer purposes.For each physical input, we present its possible active synergy with several nanomaterials.We report examples and the mechanism of action when clarified.Clinical trials involving remotely triggered nanoparticles are discussed., Cancer has nowadays become one of the leading causes of death worldwide. Conventional anticancer approaches are associated with different limitations. Therefore, innovative methodologies are being investigated, and several researchers propose the use of remotely activated nanoparticles to trigger cancer cell death. The idea is to conjugate two different components, i.e., an external physical input and nanoparticles. Both are given in a harmless dose that once combined together act synergistically to therapeutically treat the cell or tissue of interest, thus also limiting the negative outcomes for the surrounding tissues. Tuning both the properties of the nanomaterial and the involved triggering stimulus, it is possible furthermore to achieve not only a therapeutic effect, but also a powerful platform for imaging at the same time, obtaining a nano-theranostic application. In the present review, we highlight the role of nanoparticles as therapeutic or theranostic tools, thus excluding the cases where a molecular drug is activated. We thus present many examples where the highly cytotoxic power only derives from the active interaction between different physical inputs and nanoparticles. We perform a special focus on mechanical waves responding nanoparticles, in which remotely activated nanoparticles directly become therapeutic agents without the need of the administration of chemotherapeutics or sonosensitizing drugs.

This paper deals with the preparation and characterization of nanocomposite (NC) materials, comparing different technologies for sample fabrication, in view of their possible application as piezoelectric sensors. Those NCs consist on BaTiO3 nanoparticles embedded into a polyvinylidene fluoride matrix, where both the ceramic and the polymeric phases could exhibit ferroelectricity. In particular, we compare the properties of samples prepared through three different methods, i.e., solvent casting, enabling a fast realization, spin-coating, which allows to realize thin flexible films particularly interesting for large area sensors, and hot embossing, which is exploited to modify the residual porosity in the thick films. The influence of the fabrication techniques on the physical and chemical properties is investigated. Different electrode materials have been tested and compared, ranging from sputtered Pt to an engineered thermally evaporated Ti/Au bilayer. Leakage current, polarization, displacement curves, and piezoelectric coefficient d 33 are evaluated by small signal indirect measurements, comparing the properties of different materials and understanding how processing technologies influence the sensor performances by acting on the functional materials.

In this work, the coating of 3-D foam-like glass-ceramic scaffolds with a bioactive mesoporous glass (MBG) was investigated. The starting scaffolds, based on a non-commercial silicate glass, were fabricated by the polymer sponge replica technique followed by sintering; then, electrophoretic deposition (EPD) was applied to deposit a MBG layer on the scaffold struts. EPD was also compared with other techniques (dipping and direct in situ gelation) and it was shown to lead to the most promising results. The scaffold pore structure was maintained after the MBG coating by EPD, as assessed by SEM and micro-CT. In vitro bioactivity of the scaffolds was assessed by immersion in simulated body fluid and subsequent evaluation of hydroxyapatite (HA) formation. The deposition of a MBG coating can be a smart strategy to impart bioactive properties to the scaffold, allowing the formation of nano-structured HA agglomerates within 48 h from immersion, which does not occur on uncoated scaffold surfaces. The mechanical properties of the scaffold do not vary after the EPD (compressive strength ~19 MPa, fracture energy ~1.2 × 10(6) J m(-3)) and suggest the suitability of the prepared highly bioactive constructs as bone tissue engineering implants for load-bearing applications.