Synergistic Applications of Graphene-Based Materials and Deep Eutectic Solvents in Sustainable Sensing: A Comprehensive Review.

The recently explored synergistic combination of graphene-based materials and deep eutectic solvents (DESs) is opening novel and effective avenues for developing sensing devices with optimized features. In more detail, remarkable potential in terms of simplicity, sustainability, and cost-effectiveness of this combination have been demonstrated for sensors, resulting in the creation of hybrid devices with enhanced signal-to-noise ratios, linearities, and selectivity. Therefore, this review aims to provide a comprehensive overview of the currently available scientific literature discussing investigations and applications of sensors that integrate graphene-based materials and deep eutectic solvents, with an outlook for the most promising developments of this approach.

Directional Growth of cm-Long PLGA Nanofibers by a Simple and Fast Wet-Processing Method.

The development of aligned nanofibers as useful scaffolds for tissue engineering is an actively sought-for research objective. Here, we propose a novel improvement of an existing self-assembly-based nanofabrication technique (ASB-SANS). This improvement, which we termed Directional ASB-SANS, allows one to produce cm2-large domains of highly aligned poly(lactic-co-glycolic acid) (PLGA) nanofibers in a rapid, inexpensive, and easy way. The so-grown aligned PLGA nanofibers exhibited remarkable adhesion to different substrates (glass, polyimide, and Si/SiOx), even when immersed in PBS solution and kept at physiological temperature (37 °C) for up to two weeks. Finally, the Directional ASB-SANS technique allowed us to grow PLGA fibers also on highly heterogeneous substrates such as polyimide-based, gold-coated flexible electrodes. These results suggest the viability of Directional ASB-SANS method for realizing biocompatible/bioresorbable, nanostructured coatings, potentially suitable for neural interface systems.

Rationalization and optimization of waste management and treatment in modern cruise ships.

Here we report over possible optimizations onboard cruise ships in the management of glass, paper and cellulosic waste, ranging from simple rationalization of the materials' use (for glass and paper) to the recovery of some of the energy embedded in paper and other cellulosic waste. This latter option is investigated considering two possibilities: i) the recovery of thermal energy from incinerator's flue gas by means of an absorption plant, ii) the production of syngas to be directly fed to the ship engines. For each option, we calculated the achievable benefits in terms of reduced fuel consumption, avoided CO2 emissions and cost savings (evaluated on the basis of the avoided fuel consumption). Finally, on the basis of the previously calculated benefits, we defined three different scenarios, each including the rationalization of glass and paper waste management, topped by different combinations of thermal energy recovery/syngas production. We then evaluated these scenarios in terms of environmental and economic benefits. This analysis showed that even trivial approaches, as a simple rationalization of paper consumption, can allow consistent advantages over existing waste management policies; moreover, syngas generators for treating cellulosic waste emerged as very effective tools for lowering the environmental impact of modern cruise ships. Joining these two strategies allows notable savings in terms of fuel, CO2 emissions and ship operational costs, and could represent a path for sizably reducing the environmental footprint of cruise ships.

Control of polymorphism in thiophene derivatives by sublimation-aided nanostructuring.

Here we applied a novel concept of "sublimation-aided nanostructuring" to control the polymorphism of a model material. The process exploits fractional precipitation as a tool for crystallisation in confinement using a templating agent that sublimes away from the system at the end of the process.

Combined wet lithography and fractional precipitation as a tool for fabrication of spatially controlled nanostructures of poly(3-hexylthiophene) ordered aggregates.

Herein, we propose an easy and practical method for the fabrication of highly ordered supramolecular structures. The proposed approach combines fractional precipitation and wet lithography, to obtain a spatially-defined pattern of submicrometric structures with a high molecular order of poly(3-hexylthiophene). The process is demonstrated by XRD, confocal and time-resolved spectroscopy and by the performance of an effective field effect transistor.

Nanostructured P3HT as a Promising SensingElement for Real-Time, Dynamic Detection ofGaseous Acetone.

The dynamic response of gas sensors based on poly(3-hexylthiophene) (P3HT) nanofibers(NFs) to gaseous acetone was assessed using a setup based on flow-injection analysis, aimed atemulating actual breath exhalation. The setup was validated by using a commercially available sensor.The P3HT NFs sensors tested in dynamic flow conditions showed satisfactory reproducibility down toabout 3.5 ppm acetone concentration, a linear response over a clinically relevant concentration range(3.5-35 ppm), excellent baseline recovery and reversibility upon repeated exposures to the analyte,short pulse rise and fall times (less than 1 s and about 2 s, respectively) and low power consumption(few nW), with no relevant response to water. Comparable responses' decay times under eithernitrogen or dry air suggest that the mechanisms at work is mainly attributable to specific analytesemiconductingpolymer interactions. These results open the way to the use of P3HT NFs-basedsensing elements for the realization of portable, real-time electronic noses for on-the-fly exhaledbreath analysis.

Controlled self-organization of polymer nanopatterns over large areas.

Self-assembly methods allow to obtain ordered patterns on surfaces with exquisite precision, but often lack in effectiveness over large areas. Here we report on the realization of hierarchically ordered polymethylmethacrylate (PMMA) nanofibres and nanodots over large areas from solution via a fast, easy and low-cost method named ASB-SANS, based on a ternary solution that is cast on the substrate. Simple changes to the ternary solution composition allow to control the transition from nanofibres to nanodots, via a wide range of intermediate topologies. The ternary solution includes the material to be patterned, a liquid solvent and a solid substance able to sublimate. The analysis of the fibres/dots width and inter-pattern distance variations with respect to the ratio between the solution components suggests that the macromolecular chains mobility in the solidified sublimating substance follows Zimm-like models (mobility of macromolecules in diluted liquid solutions). A qualitative explanation of the self-assembly phenomena originating the observed nanopatterns is given. Finally, ASB-SANS-generated PMMA nanodots arrays have been used as lithographic masks for a silicon substrate and submitted to Inductively Coupled Plasma-Reactive Ion Etching (ICP-RIE). As a result, nanopillars with remarkably high aspect ratios have been achieved over areas as large as several millimeters square, highlighting an interesting potential of ASB-SANS in practical applications like photon trapping in photovoltaic cells, surface-enhanced sensors, plasmonics.

Easy fabrication of aligned PLLA nanofibers-based 2D scaffolds suitable for cell contact guidance studies.

An easy, low-cost and fast wet processing-based method named ASB-SANS (Auxiliary Solvent-Based Sublimation-Aided NanoStructuring) has been used to fabricate poly(l-lactic acid) (PLLA) highly ordered and hierarchically organized 2D fibrillar patterns, with fiber widths between 40 and 500 nm and lengths exceeding tens of microns. A clear contact guidance effect of these nanofibrillar scaffolds with respect to HeLa and NIH-3T3 cells growth has been observed, on top of an overall good viability. For NIH-3T3 pronounced elongation of the cells was observed, as well as a remarkable ability of the patterns to guide the extension of pseudopodia. Moreover, SEM imaging revealed filopodia stemming from both sides of the pseudopodia and aligned with the secondary PLLA nanofibrous structures created by the ASB-SANS procedure. These results validate ASB-SANS as a technique capable to provide biocompatible 2D nanofibrillar patterns suitable for studying phenomena of contact guidance (and, more in general, the behavior of cells onto nanofibrous scaffolds), at very low costs and in an extremely easy way, accessible to virtually any laboratory.

Toward Low-Voltage and Bendable X-Ray Direct Detectors Based on Organic Semiconducting Single Crystals.

Organic materials have been mainly proposed as ionizing radiation detectors in the indirect conversion approach. The first thin and bendable X-ray direct detectors are realized (directly converting X-photons into an electric signal) based on organic semiconducting single crystals that possess enhanced sensitivity, low operating voltage (≈5 V), and a minimum detectable dose rate of 50 µGy s(-1) .

A home-made system for IPCE measurement of standard and dye-sensitized solar cells.

A home-made system for incident photon-to-electron conversion efficiency (IPCE) characterization, based on a double-beam UV-Vis spectrophotometer, has been set up. In addition to its low cost (compared to the commercially available apparatuses), the double-beam configuration gives the advantage to measure, autonomously and with no need for supplementary equipment, the lamp power in real time, compensating possible variations of the spectral emission intensity and quality, thus reducing measurement times. To manage the optical and electronic components of the system, a custom software has been developed. Validations carried out on a common silicon-based photodiode and on a dye-sensitized solar cell confirm the possibility to adopt this system for determining the IPCE of solar cells, including dye-sensitized ones.

Organic semiconducting single crystals as solid-state sensors for ionizing radiation.

So far, organic semiconductors have been mainly proposed as detectors for ionizing radiation in the indirect conversion approach, i.e. as scintillators, which convert ionizing radiation into visible photons, or as photodiodes, which detect visible photons coming from a scintillator and convert them into an electrical signal. The direct conversion of ionizing radiation into an electrical signal within the same device is a more effective process than indirect conversion, since it improves the signal-to-noise ratio and it reduces the device response time. We report here the use of Organic Semiconducting Single Crystals (OSSCs) as intrinsic direct ionizing radiation detectors, thanks to their stability, good transport properties and large interaction volume. Ionizing radiation X-ray detectors, based on low-cost solution-grown OSSCs, are here shown to operate at room temperature, providing a stable linear response with increasing dose rate in the ambient atmosphere and in high radiation environments.

Organic semiconducting single crystals as next generation of low-cost, room-temperature electrical X-ray detectors.

Direct, solid-state X-ray detectors based on organic single crystals are shown to operate at room temperature, in air, and at voltages as low as a few volts, delivering a stable and reproducible linear response to increasing X-ray dose rates, with notable radiation hardness and resistance to aging. All-organic and optically transparent devices are reported.