Ricerc@Sapienza

Metamaterials have provided applications in spectral ranges covering radio frequencies and ultraviolet. However, most applications have been extrapolated to the visible or near-infrared after being developed at the GHz level. This is due to technological reasons since fabrication of microwave antennas is not as demanding as THz resonators or plasmonic nanostructures. Accordingly, this book has been divided into three parts. In the first part, fundamentals of metamaterials and metadevices are discussed, while describing recent advances in the field.

In this work, we focused on the investigation of UV-C radiation effects on novel nanomaterials structured with graphene nanoplatelets (GNPs) and DNA. Multifunctional nanocomposites were realized by combining the good electrical conductivity of GNPs with the biocompatibility and UV sensitivity of double-stranded DNA. GNP/DNA nanostructures were prepared by sonication-driven self-assembly in aqueous solution, and then dispersed into a PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)) matrix.

Solar radiation, generally referred to the electromagnetic radiation emitted by the Sun, constitutes one of the most critical risks for human exploration in space. Whereas on Earth such radiation is filtered for the shorter and highly hazardous wavelengths by the atmosphere and its ozone layer, in space solar radiation has profound and adverse effects on the structural and electronic components of spacecrafts, as well as on biological systems, if they are not properly shielded.

Graphene-based nanocomposites with multifunctional properties are used as sensing materials in various environments. The integration of the graphene sensing elements into the polymer matrix is not a trivial task, as the overall sensing properties of the material are highly affected by the amount and homogeneity of the filler dispersion. Here we investigate the fabrication process of functional nanocomposite films based on graphene-DNA hybrid complexes embedded in a flexible polydimethylsiloxane (PDMS) matrix.

In this work, nanocomposites containing assemblies of graphene nanoplatelets (GNP) and double-stranded DNA are investigated as UV-sensitive materials, as they show good electrical properties combined with the chemical sensitivity of DNA to UV radiation, particularly to the more energetic UV-C band. Nanocomposite films were prepared by drop-casting technique after embedding the graphene-DNA fillers in a flexible polydimethylsiloxane (PDMS) matrix using a suitable solvent.

Nanocomposite films with high electrical conductivity and UV sensitivity were prepared by integration of DNA-modified graphene nanoplatelets (GNPs) with a polymer matrix made of poly(3,4-ethylenedioxythio-phene):poly(styrenesulfonate) (PEDOT:PSS). The exceptional electrical properties and mechanical strength of graphene were used to enhance the PEDOT:PSS properties and stability, whereas DNA molecules are sensitive to UV and have an exfoliating effect on the GNPs in aqueous solution.

Candida albicans is the most common pathogenic fungus that is isolated in nosocomial infections in medically and immune-compromised patients. The ability of C. albicans to convert its form from yeast to hyphal morphology contributes to biofilm development that effectively shelters Candida against the action of antifungals molecules. In the last years, nanocomposites are the most promising solutions against drug-resistant microorganisms.

In this work, the fabrication and properties of ultraviolet-sensing films based on hybrid nanomaterials, containing graphene nanoplatelets (GNP) as signal transducer and DNA as UV-sensitive element, are investigated. The sensor components are prepared by sonication-driven non-covalent assembly and are embedded in a polymer matrix for enhanced adhesion on several types of space-grade materials and structures. We show that these nanomaterial sensing films can be used to monitor the effects of UV radiation exposure in real time.