Au Nanoparticles Decorated Graphene-Based Hybrid Nanocomposite for As(III) Electroanalytical Detection

Electrochemical sensors integrating hybrid nanostructured platforms are a promising alternative to conventional detection techniques for addressing highly relevant challenges of heavy metal determination in the environment. Hybrid nanocomposites based on graphene derivatives and inorganic nanoparticles (NPs) are ideal candidates as active materials for detecting heavy metals, as they merge the relevant physico-chemical properties of both the components, finally leading to a rapid and sensitive current response. In this work, a hybrid nanocomposite formed of reduced graphene oxide (RGO) sheets, surface functionalized by π-π interactions with 1-pyrene carboxylic acid (PCA), and decorated in situ by Au NPs, was synthesized by using a colloidal route. The hybrid nanocomposite was characterized by cyclic voltammetry and electrochemical impedance spectroscopy with respect to the corresponding single components, both bare and deposited as a layer-by-layer junction onto the electrode. The results demonstrated the high electrochemical activity of the hybrid nanocomposite with respect to the single components, highlighting the crucial role of the nanostructured surface morphology of the electrode and the PCA coupling agent at the NPs-RGO interphase in enhancing the nanocomposite electroactivity. Finally, the Au NP-decorated PCA-RGO sheets were tested by anodic stripping voltammetry of As(III) ion—a particularly relevant analyte among heavy metal ions—in order to assess the sensing ability of the nanocomposite material with respect to its single components. The nanocomposite has been found to present a sensitivity higher than that characterizing the bare components, with LODs complying with the directives established by the U.S. EPA and in line with those reported for state-of-the-art electrochemical sensors based on other Au-graphene nanocomposites

Theoretical insights on electron donor-acceptor interactions involving carbon dioxide

Electron donor-acceptor (EDA) interactions are widely involved in chemistry and their understanding is essential to design new technological applications in a variety of fields ranging from material sciences and chemical engineering to medicine. In this work, we study EDA complexes of carbon dioxide with ketones using several ab initio and Density Functional Theory methods. Energy contributions to the interaction energy have been analyzed in detail using both variational and perturbational treatments. Dispersion energy has been shown to play a key role in explaining the high stability of a non-conventional structure, which can roughly be described by a cooperative EDA interaction

Freestanding piezoelectric rings for high efficiency energy harvesting at low frequency

Energy harvesting at low frequency is a challenge for microelectromechanical systems. In this work we present a piezoelectric vibration energy harvester based on freestanding molybdenum (Mo) and aluminum nitride (AlN) ring-microelectromechanical-system (RMEMS) resonators. The freestanding ring layout has high energy efficiency due to the additional torsional modes which are absent in planar cantilevers systems. The realized RMEMS prototypes show very low resonance frequencies without adding proof masses, providing the record high power density of 30.20 μW mm−3 at 64 Hz with an acceleration of 2g. The power density refers to the volume of the vibrating RMEMS layout

Electrochemical Characterization and Electroanalytical Aplications of RGO_AuNPs Hybrids

A novel synthetic route for the synthesis of gold nanoparticles (AuNPs) modified graphene electrodes has been developed: Reduced Graphene Oxide (RGO) sheets are functionalized with pyrene linkers acting as growing sites for gold nanoparticles (AuNPs) of different dimensions (approximatively 5, 10 and 20 nm). The Au surface is functionalized with oleylamine or 3,4-dimethylbenzenethiol as capping agents. The hybrid material is deposited onto Carbon Screen Printed Electrodes (C-SPEs) for a deep physico-chemical and electrochemical characterization, using Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements. The role played by every single hybrid counterpart has been investigated, showing a synergistic effect, which is responsible of the enhancement of the system properties. The charge transfer from gold nanoparticles to graphene, assisted and stimulated by the pyrene linker, seems to be the key point to understand the peculiarities of this innovative material. The as prepared RGO-AuNPs hybrids have been used in the electroanalytical detection of both inorganic and organic species (arsenic, H2O2, dopamine), showing promising results in terms of sensitivities and detection limits. In particular, regarding the detection of the neurotransmitter dopamine by means of Differential Pulse Voltammetry in Phosphate Buffer Solution, a LOD of (3.3 \ub1 0.2) ppb has been reached, comparable with other electroanalytical results in the literature and in accordance with the benchmark for this molecule [1]. For arsenic detection, the hybrid devices show increased performances in comparison with bare gold or gold NPs, also allowing speciation between arsenic (III) and (V), appropriately adjusting the experimental conditions. In the case of H2O2, the hybrid devices display high electrocatalytic activity and fast electron-transfer kinetics, representing an ideal platform for developing oxidoreductase-based electrochemical biosensors as well as for detecting H2O2 in real samples. [1] J.A. Ribeiro, P.M.V. Fernandes, C.M. Pereira, F. Silva, Talanta 160 (2016) 653-679

Slott-Agape Project

SLOTT-AGAPE (Systematic Lensing Observation at Toppo Telescope - Andromeda Gravitational Amplification Pixel Lensing Experiment) is a new collaboration project among international partners from England, France, Germany, Italy and Switzerland that intends to perform microlensing observation by using M31 as target. The MACHOs search is made thanks to the pixel lensing technique.Comment: 4 pages, 2 figures, proceeding of XLIII Congresso della Societa' Astronomica Italiana, Napoli, 4-8 Maggio, 199

TiO2 Nanocrystals Decorated CVD Graphene for Electroanalytical Sensing

In this work, the manufacturing and characterization of an optically transparent and UV-light photoactive anode, formed of monolayer graphene grown by chemical vapor deposition (CVD) and decorated with a close packed multilayered nanostructured layout of colloidal TiO2 nanocrystals (NCs), are reported. The hybrid material has been prepared by a facile solution-based procedure, which relays on soaking the CVD graphene in a solution of 1-pyrene butyric acid (PBA) surface coated TiO2 NCs, achieved upon implementation of a capping exchange process for displacing the pristine organic ligand deriving from the colloidal synthesis. Pyrene undergoes \u3c0-\u3c0 stacking interactions, anchoring the NCs to the platform with retention of the NC geometry and composition. The NCs immobilize onto the graphene platform with preservation of its aromatic structure and the resulting hybrid has been found optically transparent in the visible spectral range. (Photo)electrochemical investigation shows that the composite material has a promising sensitivity for selectively detecting dopamine and norepinephrine and, concomitantly, exhibits a (photo)electric activity higher than that of bare graphene. Thus, the achieved hybrid material results interesting for the manufacturing of photo-active components to integrate in photo-renewable sensor elements along with photodetectors and solar cells

Functional Hybrids of Multilayer CVD Graphene and Colloidal Anatase Nanocrystals

UV-light photoactive hybrids based on CVD graphene (from 1 to 5 layers) decorated with TiO2 nanocrystals (NC) surface functionalized with 1-pyrene butyric acid (PBA), were prepared by a simple solution-based procedure. PBA functionalization was obtained by a capping exchange procedure onto pre-synthesized organic-capped NCs [1]. An in-depth physico-chemical characterization demonstrated the successful immobilization of the colloidal NCs on the graphene multilayers, which preserves or even enhances the graphene intrinsic structural properties: the electrical conductivity is higher than that measured for bare graphene, due to a p-doping effect, related to a hole transfer from the nano-objects to graphene, mediated by the short aromatic ligand acting as a charge channel. The hybrids properties are strongly dependent on the number of layers of CVD graphene. The use of two redox probes [inner-sphere, surface sensitive (K4Fe(CN)6) and outer-sphere, surface insensitive (Ru(NH3)6Cl3)], in a CV and EIS study, allowed to understand these features, showing a strong difference between the mono-, the bi- and the other multi-layers, in terms of different diffusional mechanism and redox active sites [2]. Moreover, the stacked layers of the pyrene-coated TiO2 NCs are found to increase the electroactivity, the capacitive behavior, as well as the photo-electrical response of graphene, concomitantly maintaining its high charge mobility. The photoelectrical conversion of the hybrid is enhanced of 50% with respect to the bare graphene, with a long recombination lifetime of the photogenerated electron-hole pairs. For all the above reasons, the photoactive composite has a great potential as an optically transparent component for manufacturing photoanodes to be integrated in solar cells or photodetectors and in FETs or (photo)electrochemical sensors, also exploiting the possibility of photorenovating the sensor surface [3]. [1] C. Ingrosso et al., ACS Appl. Mater. & Interfaces 7 (2015) 4151-4159. [2] D.A. Brownson, D.K. Kampouris, C.E. Banks, Chem. Soc. Rev. 41 (2012) 6944-6976. [3] V. Pifferi et al., Anal. Bioanal. Chem. 408(26) (2016), 7339-7349

Toxicity after moderately hypofractionated versus conventionally fractionated prostate radiotherapy: A systematic review and meta-analysis of the current literature

Background: Moderately hypofractionated radiotherapy (RT) currently represents the standard RT approach for all prostate cancer (PCa) risk categories. We performed a systematic review and meta-analysis of available literature, focusing on acute and late genitourinary (GU) and gastrointestinal (GI) adverse events (AEs) of moderate hypofractionation for localized PCa. Materials and methods: Literature search was performed and two independent reviewers selected the records according to the following Population (P) Intervention (I) Comparator (C) and Outcomes (O) (PICO) question: “In patients affected by localized PCa (P), moderately hypofractionated RT (defined as a treatment schedule providing a single dose per fraction of 3–4.5 Gy) (I) can be considered equivalent to conventionally fractionated RT (C) in terms of G > 2 GI and GU acute and late adverse events (O)?”. Bias assessment was performed using Cochrane Cochrane Collaboration's Tool for Assessing Risk of Bias. Results: Thirteen records were identified and a meta-analysis was performed. Risk of acute GI and GU > 2 adverse events in the moderately hypofractionated arm was increased by 9.8 % (95 %CI 4.8 %–14.7 %; I2 = 57 %) and 1.5 % (95 % CI -1.5 %-4.4 %; I2 = 0%), respectively. Discussion: Overall, majority of trials included in our meta-analysis suggested that moderately hypofractionated RT is equivalent, in terms of GI and GU adverse events, to conventional fractionation. Pooled analysis showed a trend to increased GI toxicity after hypofractionated treatment, but this might be related to dose escalation rather than hypofractionation

The Impact of Graft CD3 Cell/Regulatory T Cell Ratio on Acute Graft-versus-Host Disease and Post-Transplantation Outcome: A Prospective Multicenter Study of Patients with Acute Leukemia Undergoing Allogeneic Peripheral Blood Stem Cell Transplantation

Although it is well known that tumor site- or bone marrow-infiltrating regulatory T cells (Tregs) might be correlated with worse outcomes in solid tumors and acute leukemias by promoting immune surveillance escape, their contribution to the immediate post-allogeneic transplantation phase by peripheral blood (PB) allografts remains unclear. Moreover, the Treg content in stem cells harvested from PB has been suggested to be correlated with acute graft versus-host-disease (aGVHD) and immunologic recovery after allogeneic PB stem cell transplantation (allo-PBSCT). This study aimed to investigate the impact of the graft content of Tregs, as graft CD3+/Tregs ratio (gCD3/TregsR), on acute GVHD and post-allo-PBSCT outcomes. We prospectively enrolled 94 consecutive patients at 9 Italian centers of the Gruppo Italiano Trapianto di Midollo Osseo (GITMO) with acute myelogenous (n = 71; 75%) or lymphoblastic (n = 23; 25%) leukemia in complete remission who underwent matched related donor (n = 35; 37%) or unrelated donor (n = 59; 63%) allo-PBSCT. The median graft CD3+ cell, Treg, and gCD3/TregsR values were 196 × 106/kg body weight (range, 17 to 666 × 106/kg), 3 × 106/kg (range, 0.1 to 35 × 106/kg), and 71 (range, 1 to 1883), respectively. The discriminatory power of the gCD3/TregsR value to predict grade ≥II aGVHD was assessed by estimating the area under the receiver operating characteristic (ROC) curve (AUC). Any grade and grade ≥II aGVHD occurred in 24 (26%) and 17 (18%) allo-PBSCT recipients, respectively. By ROC analysis, AUC (0.74; 95% confidence interval [CI], 0.608 to 0.866; P =.002) identified 70 as the optimal gCD3/TregsR cutoff value predicting the appearance of grade ≥II aGVHD with 76% sensitivity and 71% specificity. Patients were subdivided into a high (ROC curve value ≥70) gCD3/TregsR group (HR; n = 48) and a low (ROC curve value <70) gCD3/TregsR group (LR; n = 46). The incidence of grade II-IV aGVHD was lower in the LR group compared with the HR group (9% [4 of 46] versus 27% [13 of 48]) in both univariate analysis (odds ratio [OR], 4.8; 95% CI, 1.44 to 16.17; P =.015) and multivariate analysis (OR, 5.0; 95% CI, 1.34 to 18.93; P =.017), whereas no differences were documented taking into account aGVHD of any grade. The overall survival, disease-free survival, nonrelapse mortality, and relapse rates at 2 and 3 years were 61% and 54%, 62% and 55%, 15% and 23%, and 27% and 30%, respectively. Of note, gCD3/TregsR did not significantly correlate with relapse (P =.135). Taken together, our data from this prospective multicenter study confirm the value of Tregs in preventing aGVHD while maintaining the graft-versus-leukemia effect. © 2021 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc

Enhanced photoactivity and conductivity in transparent TiO2 nanocrystals/graphene hybrid anodes

An optically transparent and UV-light active anode, characterized by high (photo) conductivity, charge mobility and exciton lifetime, based on graphene, grown by CVD, decorated with colloidal TiO2 nanocrystals (NCs), has been fabricated, by a direct and facile solution-based procedure. TiO2 NCs anchor onto graphene by means of p-p stacking interactions occurring between the pyrene-1-butyric acid (PBA) surface coating ligand and the 2-D platform and assemble in a highly interconnected multilayered layout, by means of interligand pi-pi forces, retaining composition and geometry, along with the graphene structure. Remarkably, the PBA-coated TiO2 NCs on the graphene increase its electrical conductivity, electroactivity, and capacitive behavior, as well as photoelectrical response under UV-light, resulting in a 50% enhanced photoelectroactivity and a long exciton recombination lifetime. The photoanodes can be integrated into solar cells as optically transparent electrodes, in photodetectors, FETs and (bio)sensors