Valentina Arima

Electronic rectification in protein devices

We show that the electron-transfer protein azurin can be used to fabricate biomolecular rectifiers exploiting its native redox properties, chemisorption capability and electrostatic features. The devices consist of a protein layer interconnecting nanoscale electrodes fabricated by electron beam lithography. They exhibit a rectification ratio as large as 500 at 10 V, and operate at room temperature and in air.

Hybrid molecular electronic devices based on modified deoxyguanosines

A new type of organic semiconductor, based on self-assembled modified DNA nucleosides (deoxyguanosine lipophilic derivative), is employed to fabricate hybrid molecular devices. Two different modifications of the guanosine are synthesized in order to change the oxidation potential of the active molecular system. The influence of the solvent on the self-assembly process and on the carrier transport is investigated by atomic force microscopy and electrical measurements, respectively. Our results demonstrate that upon appropriate engineering of the molecule and choice of the solvent, self-organization of molecules in ordered structures is achieved, resulting in high conductivity and electronic rectification in solid-state, planar molecular devices. The transport properties depend strongly on the molecular structure and on the arrangement of the molecules into the hybrid devices, thus opening the route to molecular transport engineering in hybrid molecular electronics.

Radiochemistry on chip

We have developed an integrated microfluidic platform for producing 2-[(18)F]-fluoro-2-deoxy-D-glucose ((18)F-FDG) in continuous flow from a single bolus of radioactive isotope solution, with constant product yields achieved throughout the operation that were comparable to those reported for commercially available vessel-based synthesisers (40-80%). The system would allow researchers to obtain radiopharmaceuticals in a dose-on-demand setting within a few minutes. The flexible architecture of the platform, based on a modular design, can potentially be applied to the synthesis of other radiotracers that require a two-step synthetic approach, and may be adaptable to more complex synthetic routes by implementing additional modules. It can therefore be employed for standard synthesis protocols as well as for research and development of new radiopharmaceuticals.

Quartz crystal microbalance with dissipation (QCM-D) as tool to exploit antigen–antibody interactions in pancreatic ductal adenocarcinomadetection

Novel synthetic peptides represent smart molecules for antigen-antibody interactions in several bioanalytics applications, from purification to serum screening. Their immobilization onto a solid phase is considered a key point for sensitivity increasing. In this view, we exploited Quartz Crystal Microbalance with simultaneous frequency and dissipation monitoring (QCM-D) with a double aim, specifically, as investigative tool for spacers monolayer assembling and its functional evaluation, as well as high sensitive method for specific immunosorbent assays. The method was applied to pancreatic ductal adenocarcinoma (PDAC) detection by studying the interactions between synthetic phosphorylated and un-phosphorylated α-enolase peptides with sera of healthy and PDAC patients. The synthetic peptides were immobilized on the gold surface of the QCM-D sensor via a self-assembled alkanethiol monolayer. The presented experimental results can be applied to the development of surfaces less sensitive to non-specific interactions with the final target to suggest specific protocols for detecting PDAC markers with un-labeled biosensors.

Catalytic Self‐Propulsion of Supramolecular Capsules Powered by Polyoxometalate Cargos

Multicompartment, spherical microcontainers were engineered through a layer-by-layer polyelectrolyte deposition around a fluorescent core while integrating a ruthenium polyoxometalate (Ru4POM), as molecular motor, vis-à-vis its oxygenic, propeller effect, fuelled upon H2O2 decomposition. The resulting chemomechanical system, with average speeds of up to 25 μm s(-1), is amenable for integration into a microfluidic set-up for mixing and displacement of liquids, whereby the propulsion force and the resulting velocity regime can be modulated upon H2O2-controlled addition.

Random laser emission from a paper-based device

Random laser emission is obtained from a fluidic paper-based device realized by conventional soft-lithography techniques on common, flexible, renewable and biocompatible commercial paper. The device is realized exclusively on paper by creating microfluidic porous channels on the cellulose fibres, in which a laser dye (Rhodamine B) can flow by capillarity. The modulation of the random lasing characteristics, in terms of threshold and spectral position, can be tailored by acting on the confinement induced by the lithographic process as well as on the shape and functionalization at the interface of the emitting regions.

Nitrogen supported solvent evaporation using continuous-flow microfluidics

In this work we demonstrate a continuously operating microfluidic device for solvent removal and exchange for chemical syntheses by means of a supporting gas. The glass device consists of three sections: (i) three merging microchannels to create an annular gas–liquid stream; (ii) a serpentine channel with a heater underneath to allow efficient evaporation of the volatile solvent; (iii) a section with side capillaries to separate the liquid from the gas phase. We demonstrate the performance of the device for the removal of acetonitrile from an acetonitrile–water mixture. We achieved efficient removal of acetonitrile within a few seconds for flow rates of 20–30 μL min−1 and a nitrogen pressure of 1.2 bar. In three steps, acetonitrile was reduced from 50 wt% in the feed solution to 1 wt% in the final solution. We believe that the device can be easily applied to other solvent mixtures.

Rectification in Supramolecular Zinc Porphyrin/Fulleropyrrolidine Dyads Self‐Organized on Gold(111)

Self-assembled donor/acceptor dyads are of current interest as they are biomimetic to the natural photosynthetic conversion system. Herein, we present an ultrahigh-vacuum scanning tunneling microscopy and scanning tunneling spectroscopy (UHV-STM/STS) study of ex situ self-assembled supramolecular dyads consisting of fulleropyrrolidines (PyC(2)C(60)) axially ligated to zinc(II) tetraphenylporphyrin (ZnTPP), self organized on a 4-aminothiophenol (4-ATP) self-assembled monolayer on gold(111). These dyads show both bias-polarity-dependent apparent height in STM images and highly rectifying behavior in tunneling spectroscopy. First-principles density functional theory calculations clarify the conformational and electronic properties of the 4-ATP/ZnTPP/PyC(2)C(60) system. Interestingly, we find easier tunneling for electrons moving from the acceptor side of the dyads to the donor side, in the inverse-rectifying sense with respect to previously reported molecular rectifiers. Such behavior cannot be explained as an elastic resonant tunneling process, but it can by using a model based on the Aviram-Ratner mechanism.

A Protein‐Based Three Terminal Electronic Device

Abstract: Because of their natural functional characteristics, involving inter‐ and intramolecular electron transfer, metalloproteins are good candidates for biomolecular nanoelectronics. In particular, blue copper proteins, such as azurin, can bind gold via a disulfide site present on its surface and they have a natural electron transfer activity that can be exploited for the realization of molecular switches whose conduction state can be controlled by tuning their redox state through an external voltage source. We report on the implementation of a prototype of protein transistor operating in air and in the solid state, based on this class of proteins. The three terminal devices exhibit various functions depending on the relative source‐drain and gate‐drain voltages bias, opening a way to the implementation of a new generation of logic architectures.

SFM study of the surface of halogen-bonded hybrid co-crystals containing long-chain perfluorocarbons

Different scanning force microscopy (SFM) techniques were employed to investigate the structure and composition of the fundamental crystal faces of prototype halogen-bonded co-crystals of long-chain perfluorocarbons. These crystals were found to show surfaces with well-defined ledges formed by intersecting crystal planes having different chemical compositions with the perfluorocarbons (PFCs) covering the largest area of the crystal as a reminiscence of the strong segregation observed in the bulk crystal structure.