Laboratorio NEST

Every time a chemical reaction occurs, an energy exchange between reactants and environment exists, which is defined as the enthalpy of the reaction. In the last decades, research has resulted in an increasing number of devices at the micro-or nano-scale. Sensors, catalyzers, and energy storage systems are more and more developed as nano-devices which represent the building blocks for commercial "macroscopic" objects. A general method for the direct evaluation of the energy balance of such systems is not available at present. Calorimetry is a powerful tool to investigate energy exchange, but it usually needs macroscopic sample quantities. Here we report on the development of an original experimental setup able to detect temperature variations as low as 10 mK in a sample of ∼ 10 ng using a thermometer device having physical dimensions of 5 × 5 mm 2. The technique has been utilized to measure the enthalpy release during the adsorption process of H2 on a titanium decorated monolayer graphene. The sensitivity of these thermometers is high enough to detect a hydrogen uptake of ∼ 10 −10 moles, corresponding to ∼ 0.2 ng, with an enthalpy release of about 23 µJ. The experimental setup allows, in perspective, the scalability to even smaller sizes.

Organic functionalization of graphene nanosheets and rGO via 1,3-dipolar cycloaddition of azomethine ylide is shown to be a significant step towards a controlled synthesis of graphene-based advanced nanoscale devices with engineered functionalities.

Chemical, mechanical, thermal and/or electronic properties of bulk or lowdimensional materials can be engineered by introducing structural defects to form novel functionalities. When using particles irradiation, these defects can be spatially arranged to create complex structures, like sensing circuits, where the spatial resolution of the defective areas plays a fundamental role. Here, we show that structural defects can be patterned by low-energy electrons in monolayer graphene sheets with spatial resolution strongly defined by the surface of the supporting substrate. Indeed, two-dimensional micro-Raman mapping revealed that the surroundings of irradiated areas contain unintentional defects of the graphene lattice, whose density depends on the methods exploited to clean the supporting surface. By combining Monte Carlo simulations with the analysis of the graphene Raman modes, we attributed these structural modifications mainly to the action of back-scattered electrons and back-scat...

Spatially-resolved organic functionalization of monolayer graphene is successfully achieved by combining lowenergy electron beam irradiation with 1,3-dipolar cycloaddition of azomethine ylide. Indeed, the modification of the graphene honeycomb lattice obtained via electron beam irradiation yields to a local increase of the graphene chemical reactivity. As a consequence, thanks to the high-spatially resolved generation of structural defects (∼ 100 nm), chemical reactivity patterning has been designed over the graphene surface in a well-controlled way. Atomic force microscopy and Raman spectroscopy allow to investigate the two-dimensional spatial distribution of the structural defects and the new features that arise from the 1,3-dipolar cycloaddition, confirming the spatial selectivity of the graphene functionalization achieved via defect engineering. The Raman signature of the functionalized graphene is investigated both experimentally and via ab initio molecular dynamics simulations, computing the power spectrum. Furthermore, the organic functionalization is shown to be reversible thanks to the desorption of the azomethine ylide induced by focused laser irradiation. The selective and reversible functionalization of high quality graphene using 1,3-dipolar cycloaddition is a significant step towards the controlled synthesis of graphene-based complex structures and devices at the nanoscale.

Chemical, mechanical, thermal and/or electronic properties of bulk or lowdimensional materials can be engineered by introducing structural defects to form novel functionalities. When using particles irradiation, these defects can be spatially arranged to create complex structures, like sensing circuits, where

Spatially-resolved organic functionalization of monolayer graphene is successfully achieved by combining lowenergy electron beam irradiation with 1,3-dipolar cycloaddition of azomethine ylide. Indeed, the modification of the graphene honeycomb lattice obtained via electron beam irradiation yields to a local increase of the graphene chemical reactivity. As a consequence, thanks to the high-spatially resolved generation of structural defects (∼ 100 nm), chemical reactivity patterning has been designed over the graphene surface in a well-controlled way. Atomic force microscopy and Raman spectroscopy allow to investigate the two-dimensional spatial distribution of the structural defects and the new features that arise from the 1,3-dipolar cycloaddition, confirming the spatial selectivity of the graphene functionalization achieved via defect engineering. The Raman signature of the functionalized graphene is investigated both experimentally and via ab initio molecular dynamics simulations, computing the power spectrum. Furthermore, the organic functionalization is shown to be reversible thanks to the desorption of the azomethine ylide induced by focused laser irradiation. The selective and reversible functionalization of high quality graphene using 1,3-dipolar cycloaddition is a significant step towards the controlled synthesis of graphene-based complex structures and devices at the nanoscale.

Soot nucleation is one of the most complex and debated steps of the soot formation process in combustion. In this work, we used scanning tunneling microscopy (STM) and spectroscopy (STS) to probe morphological and electronic properties of incipient soot particles formed right behind the flame front of a lightly sooting laminar premixed flame of ethylene and air. Particles were thermophoretically sampled on an atomically flat gold film on a mica substrate. Highresolution STM images of incipient soot particles were obtained for the first time showing the morphology of sub-5 nm incipient soot particles. High-resolution single-particle spectroscopic properties were measured confirming the semiconductor behavior of incipient soot particles with an electronic band gap ranging from 1.5 to 2 eV, consistent with earlier optical and spectroscopic observations.

Organic functionalization of graphene is successfully performed via 1,3-dipolar cycloaddition of azomethine ylide in the liquid phase. The comparison between 1-methyl-2-pyrrolidinone and N,Ndimethylformamide as dispersant solvents, and between sonication and homogenization as dispersion techniques, proves N,N-dimethylformamide and homogenization as the most effective choice. The functionalization of graphene nanosheets and reduced graphene oxide is confirmed using different techniques. Among them, energy-dispersive X-ray spectroscopy allows to map the pyrrolidine ring of the azomethine ylide on the surface of functionalized graphene, while micro-Raman spectroscopy detects new features arising from the functionalization, which are described in agreement with the power spectrum obtained from ab initio molecular dynamics simulation. Moreover, X-ray photoemission spectroscopy of functionalized graphene allows the quantitative elemental analysis and the estimation of the surface coverage, showing a higher degree of functionalization for reduced graphene oxide. This more reactive behavior originates from the localization of partial charges on its surface due to the presence of oxygen defects, as shown by the simulation of the electrostatic features. Functionalization of graphene using 1,3-dipolar cycloaddition is shown to be a significant step towards the controlled synthesis of graphene-based complex structures and devices at the nanoscale.

Surface chemical and biochemical functionalization is a fundamental process that is widely applied in many fields to add new functions, features, or capabilities to a material's surface. Here, we demonstrate that surface acoustic waves (SAWs) can enhance the chemical functionalization of gold films. This is shown by using an integrated biochip composed by a microfluidic channel coupled to a surface plasmon resonance (SPR) readout system and by monitoring the adhesion of biotin-thiol on the gold SPR areas in different conditions. In the case of SAW-induced streaming, the functionalization efficiency is improved ≈ 5 times with respect to the case without SAWs. The technology here proposed can be easily applied to a wide variety of biological systems (e.g., proteins, nucleic acids) and devices (e.g., sensors, devices for cell cultures).

substrate, owing to the sound-velocity mismatch between substrate and fl uid, SAWs will radiate acoustic energy into the fl uid. This will induce a pressure wave and drive a steady-state fl ow known as acoustic streaming, the basis for the gamut of possible SAW microfl uidic operations. At the same time, however, the viscous dissipation of the acoustic energy into the fl uid can generate a heating effect. [ 31 ] This heating effect is a much-discussed issue in SAW-driven microfl uidics and questions surrounding the problem of fl uid heating are continually arising. How much will the dissipation of the acoustic wave into a droplet raise its temperature? Will any temperature rise be enough to negatively affect biological samples or even evaporation rates? This is especially of concern in the case of free-droplets where a systematic study of fl uid-heating effects would be desirable over the typical SAW-microfl uidic operational frequency and power ranges. At the same time, it is interesting to understand to which extent any microfl uidic heating effects can actually be positively exploited to enhance biological or chemical reactions in lab-on-a-chip devices when desired. To date, only few studies investigated SAW thermal effect in microfl uidics. The fi rst reported characterization of SAWdriven liquid heating effects was carried out by Kondoh et al. in 2005 and further expanded upon in 2009. [ 31-33 ] In these experiments, the authors demonstrated that the primary source of fl uid heating is, in fact, the radiated acoustic wave, with temperature changes being strongly dependent on input power and fl uid viscosity. It was not clear, however, if droplet heating was isolated from heating effects occurring at the interdigital transducer (IDT). The latter can signifi cantly heat up the substrate-and through it the droplet on its surface-if not properly controlled. In 2006, Beyssen et al. reported similar results using comparable experimental conditions, further quantifying the effect of fl uid viscosity on temperature changes and uniformity. [ 34 ] In 2009, Kulkarni et al. showed the possibility to use this heating mechanism as an energy source for synthetic chemistry in digital microfl uidic systems. [ 35 ] More recently, Roux-Marchand et al. further investigated the temperature uniformity within viscous glycerol droplets and found decreased uniformity at high SAW powers but did not discuss absolute temperature changes. [ 36 ] As a recent application of acoustic microdroplet heating, Reboud et al. demonstrated polymerase chain reactions (PCRs) in an oil-covered droplet. [ 37 ]

This work was supported by the PAR FAS 2007-2013 "GLIOMICS" of "Regione Toscana". Proteomics/genomics/metabolomics for the biomarkers identification and the development of an ultrasensitive sensing platform to be used with peripheral fluids for glioblastoma multiforme cancer.

Polyphenols are a family of compounds present in grapes, musts, and wines. Their dosage is associated with the grape ripening, correct must fermentation, and final wine properties. Owing to their anti-inflammatory properties, they are also relevant for health applications. To date, such compounds are detected mainly via standard chemical analysis, which is costly for constant monitoring and requires a specialized laboratory. Cheap and portable sensors would be desirable to reduce costs and speed up measurements. This paper illustrates the development of strategies for sensor surface chemical functionalization for polyphenol detection. We perform measurements by using a commercial quartz crystal microbalance with dissipation monitoring apparatus. Chemical functionalizations are based on proteins (bovine serum albumin and gelatin type A) or customized peptides derived from istatine-5 and murine salivary protein-5. Commercial oenological additives containing pure gallic tannins or proa...

A scalable surface-acoustic-wave- (SAW-) based cantilevered device for portable bio-chemical sensing applications is presented. Even in the current, proof-of-principle implementation this architecture is shown to outperform commercial quartz–crystal microbalances in terms of sensitivity. Adhesion of analytes on a functionalized surface of the cantilever shifts the resonant frequency of a SAW-generating transducer due to the stress-induced variation of the speed of surface acoustic modes. We discuss the relevance of this approach for diagnostics applications based on miniaturized devices.

Fast and controllable surface acoustic wave (SAW) driven digital microfluidic temperature changes are demonstrated. Within typical operating conditions, the direct acoustic heating effect is shown to lead to a maximum temperature increase of about 10 °C in microliter water droplets. The importance of decou- pling droplets from other on-chip heating sources is demonstrated. Acoustic- heating-driven temperature changes reach a highly stable steady-state value in ≈3 s, which is an order of magnitude faster than previously published. This rise time can even be reduced to ≈150 ms by suitably tailoring the applied SAW-power excitation profile. Moreover, this fast heating mechanism can lead to significantly higher temperature changes (over 40 °C) with higher viscosity fluids and can be of much interest for on-chip control of biological and/or chemical reactions.

Infertility has become a highly-spread disease but the efficiency of standard in vitro fertilization (IVF) cycles is only 30%, and their cost is very high. Recently, strategies based on microfluidics and dynamic in vitro systems have been proposed to improve the throughput of successful assisted hatchings. Here, these novel methods are presented and categorized in three main groups: microdroplet dynamic biore-actors, microchannel based cultures and microcontainers. In contraposition to the conventional static cultures, these devices introduce a dynamic microenvironment in order to mimic the physiological dynamic stimulations that are crucial for embryo development. The critical parameters-such as embryo density, medium flow rate, shear stress and microvibration frequency-are discussed and critically compared among the different systems, highlighting their strengths, drawbacks and potential impact on IVF.