Superconducting and other Innovative Materials and Devices Institute

Genova C., Dellepiane C., Carrega P., Sommariva S., Ferlazzo G., Pronzato P., Gangemi R., Filaci G., Coco S., Croce M.

In the last decade, the treatment of non-small cell lung cancer (NSCLC) has been revolutionized by the introduction of immune checkpoint inhibitors (ICI) directed against programmed death protein 1 (PD-1) and its ligand (PD-L1), or cytotoxic T lymphocyte antigen 4 (CTLA-4). In spite of these improvements, some patients do not achieve any benefit from ICI, and inevitably develop resistance to therapy over time. Tumor microenvironment (TME) might influence response to immunotherapy due to its prominent role in the multiple interactions between neoplastic cells and the immune system. Studies investigating lung cancer from the perspective of TME pointed out a complex scenario where tumor angiogenesis, soluble factors, immune suppressive/regulatory elements and cells composing TME itself participate to tumor growth. In this review, we point out the current state of knowledge involving the relationship between tumor cells and the components of TME in NSCLC as well as their interactions with immunotherapy providing an update on novel predictors of benefit from currently employed ICI or new therapeutic targets of investigational agents. In first place, increasing evidence suggests that TME might represent a promising biomarker of sensitivity to ICI, based on the presence of immune-modulating cells, such as Treg, myeloid derived suppressor cells, and tumor associated macrophages, which are known to induce an immunosuppressive environment, poorly responsive to ICI. Consequently, multiple clinical studies have been designed to influence TME towards a pro-immunogenic state and subsequently improve the activity of ICI. Currently, the mostly employed approach relies on the association of “classic” ICI targeting PD-1/PD-L1 and novel agents directed on molecules, such as LAG-3 and TIM-3. To date, some trials have already shown promising results, while a multitude of prospective studies are ongoing, and their results might significantly influence the future approach to cancer immunotherapy.

Babar Z.U., Della Ventura B., Velotta R., Iannotti V.

Two-dimensional materials have unique properties and their better functionality has created new paradigms in the field of sensing. Over the past decade, a new family of 2D materials known as MXenes has emerged as a promising material for numerous applications, including biosensing. Their metallic conductivity, rich surface chemistry, hydrophilicity, good biocompatibility, and high anchoring capacity for biomaterials make them an attractive candidate to detect a variety of analytes. Despite such notable properties, there are certain limitations associated with them. This review aims to present a detailed survey of MXene's synthesis; in particular, their superiority in the field of biosensing as compared to other 2D materials is addressed. Their low oxidative stability is still an open challenge, and recent investigations on MXene's oxidation are summarized. The hexagonal stacking network of MXenes acts as a distinctive matrix to load nanoparticles, and the embedded nanoparticles can bind an excess number of biomolecules (e.g., antibodies) thereby improving biosensor performance. We will also discuss the synthesis and corresponding performance of MXenes nanocomposites with noble metal nanoparticles and magnetic nanoparticles. Furthermore, Nb and Ti2C-based MXenes, and Ti3C2-MXene sandwich immunoassays are also reviewed in view of their importance. Different aspects and challenges associated with MXenes (from their synthesis to final applications) and the future perspectives described give new directions to fabricate novel biosensors.

Blundo E., Di Giorgio C., Pettinari G., Yildirim T., Felici M., Lu Y., Bobba F., Polimeni A.

The realization of ordered strain fields in 2D crystals is an intriguing perspective in many respects, including the instauration of novel transport regimes and enhanced device performances. However, the current straining techniques hardly allow to reach strains higher than ≈3% and in most cases there is no control over the strain distribution. In this work, a method is demonstrated to subject micrometric regions of atomically thin molybdenum disulfide (MoS2) to giant strains with the desired ordering. Selective hydrogen-irradiation of bulk flakes allows the creation of arrays of size/position-controlled monolayer domes containing pressurized hydrogen. However, the gas pressure is ruled by energy minimization, limiting the extent and geometry of the mechanical deformation of the 2D membrane. Here, a protocol is developed to create a mechanical constraint, that alters remarkably the morphology of the domes, otherwise subject to universal scaling laws, as demonstrated by atomic force microscopy. This enables the realization of unprecedented periodic configurations of large strain gradients—estimated by numerical simulations—with the highest strains being close to the rupture critical values (>10%). The creation of such high strains is confirmed by Raman experiments. The method proposed here represents an important step toward the strain engineering of 2D crystals.

Di Giorgio C., Blundo E., Pettinari G., Felici M., Bobba F., Polimeni A.

2D materials, such as graphene, hexagonal boron nitride (hBN), and transition-metal dichalcogenides (TMDs), are intrinsically flexible, can withstand very large strains (>10% lattice deformations), and their optoelectronic properties display a clear and distinctive response to an applied stress. As such, they are uniquely positioned both for the investigation of the effects of mechanical deformations on solid-state systems and for the exploitation of these effects in innovative devices. For example, 2D materials can be easily employed to transduce nanometric mechanical deformations into, e.g., clearly detectable electrical signals, thus enabling the fabrication of high-performance sensors; just as easily, however, external stresses can be used as a “knob” to dynamically control the properties of 2D materials, thereby leading to the realization of strain-tuneable, fully reconfigurable devices. Here, the main methods are reviewed to induce and characterize, at the nm level, mechanical deformations in 2D materials. After presenting the latest results concerning the mechanical, elastic, and adhesive properties of these unique systems, one of their most promising applications is briefly discussed: the realization of nano-electromechanical systems based on vibrating 2D membranes, potentially capable of operating at high frequencies (>100 MHz) and over a large dynamic range.

Wang H., Gopal P., Picozzi S., Curtarolo S., Buongiorno Nardelli M., Sławińska J.

AbstractFerroelectric Rashba semiconductors (FERSCs) have recently emerged as a promising class of spintronics materials. The peculiar coupling between spin and polar degrees of freedom responsible for several exceptional properties, including ferroelectric switching of Rashba spin texture, suggests that the electron’s spin could be controlled by using only electric fields. In this regard, recent experimental studies revealing charge-to-spin interconversion phenomena in two prototypical FERSCs, GeTe and SnTe, appear extremely relevant. Here, by employing density functional theory calculations, we investigate spin Hall effect (SHE) in these materials and show that it can be large either in ferroelectric or paraelectric structure. We further explore the compatibility between doping required for the practical realization of SHE in semiconductors and polar distortions which determine Rashba-related phenomena in FERSCs, but which could be suppressed by free charge carriers. Based on the analysis of the lone pairs which drive ferroelectricity in these materials, we have found that the polar displacements in GeTe can be sustained up to a critical hole concentration of over ~1021/cm3, while the tiny distortions in SnTe vanish at a minimal level of doping. Finally, we have estimated spin Hall angles for doped structures and demonstrated that the spin Hall effect could be indeed achieved in a polar phase. We believe that the confirmation of spin Hall effect, Rashba spin textures and ferroelectricity coexisting in one material will be helpful for design of novel all-in-one spintronics devices operating without magnetic fields.

De Feo G., Di Domenico A., Ferrara C., Abate S., Sesti Osseo L.

Waste cooking oil (WCO) can be a useful secondary raw material, if properly managed. On the contrary, uncontrolled disposal generates negative environmental impacts as well as economic loss. Therefore, improving WCO recovery rate, with the cooperation of citizens and effective collection programs, is fundamental. The aim of the study was to investigate the reason for the low recovery of WCO in those areas suffering serious waste management problems such as the Campania region in Southern Italy. For this purpose, the case of a WCO collection program adopted in Angri, a town of around 34,000 people with a high population density, was studied. In 2015, the collection program was managed by a social cooperative, while, in 2016, after the change of the local government, the collection of WCO was entrusted to a private company. In 2015, the households’ participation in the collection program was surveyed through a structured questionnaire. The results revealed that the collection of WCO was practiced by 53% of the respondents. Among those not collecting WCO, 76% of the sample wrongly disposed of WCO in their home (kitchen or toilet). Misinformation was the main reason why they did not adhere to the collection program. Therefore, it was suggested to support information and environmental education campaigns to promote environmental awareness of citizens. Unfortunately, the change of management, together with serious problems in the collection of municipal waste in the whole region, due to the continuous closures of the mechanical and biological plants, produced a sharp decline in the collection from 7730 kg in 2015 to an average of 3800 kg for the period 2016–2019, with a loss of more than 15,000 kg of WCO wrongly disposed with consequent environmental and economic damage. Therefore, information and awareness campaigns are important but the form of entrusting the collection service is equally important, especially in areas with long-standing waste management problems.

Durante O., Di Giorgio C., Granata V., Neilson J., Fittipaldi R., Vecchione A., Carapella G., Chiadini F., DeSalvo R., Dinelli F., Fiumara V., Pierro V., Pinto I.M., Principe M., Bobba F.

Among all transition metal oxides, titanium dioxide (TiO2) is one of the most intensively investigated materials due to its large range of applications, both in the amorphous and crystalline forms. We have produced amorphous TiO2 thin films by means of room temperature ion-plasma assisted e-beam deposition, and we have heat-treated the samples to study the onset of crystallization. Herein, we have detailed the earliest stage and the evolution of crystallization, as a function of both the annealing temperature, in the range 250–1000 °C, and the TiO2 thickness, varying between 5 and 200 nm. We have explored the structural and morphological properties of the as grown and heat-treated samples with Atomic Force Microscopy, Scanning Electron Microscopy, X-ray Diffractometry, and Raman spectroscopy. We have observed an increasing crystallization onset temperature as the film thickness is reduced, as well as remarkable differences in the crystallization evolution, depending on the film thickness. Moreover, we have shown a strong cross-talking among the complementary techniques used displaying that also surface imaging can provide distinctive information on material crystallization. Finally, we have also explored the phonon lifetime as a function of the TiO2 thickness and annealing temperature, both ultimately affecting the degree of crystallinity.

Nivas J.J., Amoruso S.

Extensive research work has been carried out on the generation and application of laser-induced periodic surface structures (LIPSS). LIPSS with a sub-wavelength period generated by femtosecond laser irradiation, generally indicated as ripples, have been extensively investigated. Instead, the other ordered surface structures characterized by a supra-wavelength period, indicated as grooves, have been much less studied. Grooves typically form at larger irradiance levels or for higher number of laser pulses. Here, we report a comprehensive overview of recent investigations on the supra-wavelength grooves formed on crystalline silicon irradiated by femtosecond laser pulses. The authors’ recent experimental work is mainly addressed giving an explicit picture of the grooves generation process, namely illustrating the influence of the various experimental parameters, including, e.g., polarization, wavelength, fluence and repetition rate of the laser beam as well as number of laser pulses hitting the surface of the material. The effect of irradiation of a static or moving target and of the environmental conditions (e.g., vacuum or air ambient) will also be discussed. Finally, possible mechanisms envisaged to explain grooves formation and still open issues are briefly discussed.

Di Lorenzo T., Di Cicco M., Di Censo D., Galante A., Boscaro F., Messana G., Paola Galassi D.M.

A growing concern for contamination due to pharmaceutical compounds in groundwater is expanding globally. The β-blocker propranolol is a β-adrenoceptors antagonist commonly detected in European groundwater bodies. The effect of propranolol on stygobiotic species (obligate groundwater dweller species) is compelling in the framework of environmental risk assessment (ERA) of groundwater ecosystems. In fact, in Europe, ERA procedures for pharmaceuticals in groundwater are based on data obtained with surrogate surface water species. The use of surrogates has aroused some concern in the scientific arena since the first ERA guideline for groundwater was issued. We performed an ecotoxicological and a behavioural experiment with the stygobiotic crustacean species Diacyclops belgicus (Copepopda) to estimate a realistic value of the Predicted No Effect Concentration (PNEC) of propranolol for groundwater ecosystems and we compared this value with the PNEC estimated based on EU ERA procedures. The results of this study showed that i) presently, propranolol does not pose a risk to groundwater bodies in Europe at the concentrations shown in this study and ii) the PNEC of propranolol estimated through the EU ERA procedures is very conservative and allows to adequately protect these delicate ecosystems and their dwelling fauna. The methodological approach and the results of this study represent a first contribution to the improvement of ERA of groundwater ecosystems.

Iemmo L., Urban F., Giubileo F., Passacantando M., Di Bartolomeo A.

We report a facile approach based on piezoelectric-driven nanotips inside a scanning electron microscope to contact and electrically characterize ultrathin MoS2 (molybdenum disulfide) flakes on a SiO2/Si (silicon dioxide/silicon) substrate. We apply such a method to analyze the electric transport and field emission properties of chemical vapor deposition-synthesized monolayer MoS2, used as the channel of back-gate field effect transistors. We study the effects of the gate-voltage range and sweeping time on the channel current and on its hysteretic behavior. We observe that the conduction of the MoS2 channel is affected by trap states. Moreover, we report a gate-controlled field emission current from the edge part of the MoS2 flake, evidencing a field enhancement factor of approximately 200 and a turn-on field of approximately   40   V / μ m at a cathode–anode separation distance of 900   nm .