Rosaria Rinaldi

Enhanced fluorescence by metal nanospheres on metal substrates.

We investigate the metal enhanced fluorescence by silver nanospheres on a thin silver substrate. Experimental measurements for core/shell colloidal nanocrystals embedded in a polymer matrix show a fluorescence enhancement factor of about 9. We apply the discrete dipole approximation method to describe the local-field enhancement factor (LFEF). We find that the observed fluorescence enhancement is related to the broad LFEF profile induced by the substrate.

Nanotechnology approaches to self-organized bio-molecular devices

Abstract In this paper we briefly describe new strategies to exploit self-assembled solid-state biomolecular materials as active elements of electronic devices. Two basically different approaches are proposed: a top-down approach, where biomolecular semiconductors consisting of DNA basis are self-organized and interconnected by planar metallic nanopatterns, and a bottom-up approach, where single or ordered matalloproteins are immobilized in a nanocircuit realizing a hybrid covalently bound biologic–inorganic system. The transport characteristics of different devices such as diodes, photodetectors and metal–semiconductor–metal structures will be described.

Retention of nativelike conformation by proteins embedded in high external electric fields.

In this Communication, we show that proteins embedded in high external electric fields are capable of retaining a nativelike fold pattern. We have tested the metalloprotein azurin, immobilized onto SiO2 substrates in air with proper electrode configuration, by applying static fields up to 10(6)-10(7) Vm. The effects on the conformational properties of protein molecules have been determined by means of intrinsic fluorescence measurements. Experimental results indicate that no significant field-induced conformational alteration occurs. Such results are also discussed and supported by theoretical predictions of the inner protein fields.

Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer‐Scale Spatial Resolution

A fundamental issue in biomedical and environmental sciences is the development of sensitive and robust sensors able to probe the analyte of interest, under physiological and pathological conditions or in environmental samples, and with very high spatial resolution. In this work, novel hybrid organic fibers that can effectively report the analyte concentration within the local microenvironment are reported. The nanostructured and flexible wires are prepared by embedding fluorescent pH sensors based on seminaphtho‐rhodafluor‐1‐dextran conjugate. By adjusting capsule/polymer ratio and spinning conditions, the diameter of the fibers and the alignment of the reporting capsules are both tuned. The hybrid wires display excellent stability, high sensitivity, as well as reversible response, and their operation relies on effective diffusional kinetic coupling of the sensing regions and the embedding polymer matrix. These devices are believed to be a powerful new sensing platform for clinical diagnostics, bioassays and environmental monitoring.

Sub-micron lithography on proteins by room temperature transfer molding

Nanopatterning of proteins is important for many bio-diagnostic applications. We report on 200-nm scale patterning of thin films of proteins, by a specifically designed soft lithographic technique. This employs an elastomeric replica of a master, whose patterned side is firstly spin-coated by the protein and then turned upside down on a glass substrate. The patterned protein film is completely transferred to the substrate, exploiting the hydrophobic character of the elastomer. The process completely preserves the properties of biological matter, as it operates at room temperature and it does not require any bio-destructive solvent.

Metalloprotein-based field-effect transistor: a prototype

A key challenge in nanoelectronics is the use of a bottom-up approach to fabricate nanodevices from molecular building blocks. Here, a field-effect transistor based on the metallo-protein Azurin is demonstrated. Azurin is attractive because of its natural redox properties (provided by the Cu redox site) and self-assembly capability (which allows the chemisorption on suitable surfaces). Our prototype structure consists of two planar nanoelectrodes connected by a protein self-assembled monolayer and a back electrode as gate. The transfer characteristic exhibits a pronounced resonance and transport is explained in terms of equilibrium between the two possible oxidation states of the copper site.

Nanofibers: Ratiometric Organic Fibers for Localized and Reversible Ion Sensing with Micrometer‐Scale Spatial Resolution (Small 48/2015)

On page 6417, L. L. del Mercato, D. Pisignano, and co-workers report a new type of 3D nanostructured pH-sensing organic fiber with embedded ratiometric fluorescent capsules. Upon proton-induced switching, the fibers undergo optical changes that are recorded by fluorescence detectors and correlated to the analyte concentration. The developed electrospinning fabrication approach is facile and versatile and enables the creation of sensitive and highly robust pH-sensing 3D scaffolds for environmental monitoring and biomedical applications, including tissue engineering and wound healing.