Mariano Biasiucci

A Successful Chemical Strategy To Induce Oligothiophene Self-Assembly into Fibers with Tunable Shape and Function

Functional supramolecular architectures for bottom-up organic nano- and microtechnology are a high priority research topic. We discovered a new recognition algorithm, resulting from the combination of thioalkyl substituents and head-to-head regiochemistry of substitution, to induce the spontaneous self-assembly of sulfur overrich octathiophenes into supramolecular crystalline fibers combining high charge mobility and intense fluorescence. The fibers were grown on various types of surfaces either as superhelices or straight rods depending on molecular structure. Helical fibers directly grown on a field effect transistor displayed efficient charge mobility and intrinsic memory effect. Despite the fact that the oligomers did not have chirality centers, one type of hand-helicity was always predominant in helical fibers, due to the interplay of molecular atropisomerism and supramolecular helicity induced by terminal substituents. Finally, we found that the new sulfur overrich oligothiophenes can easily be prepared in high yields through ultrasound and microwave assistance in green conditions.

Effects of plasma treatments for improving extreme wettability behavior of cotton fabrics

A simple, environmentally benign and energy efficient process for fabricating single faced superhydrophilic/hydrophobic cotton fabrics by controlling surface texture and chemistry at the nano/microscale is reported here. Stable ultra-hydrophobic surfaces with advancing and receding water droplet contact angles in excess of 146° as well as extreme superhydrophilic surfaces are obtained. Hydrophobic water-repellent cotton fabrics were obtained following plasma treatment through diamond-like carbon (DLC) coating by plasma enhanced chemical vapour deposition. The influence of changing different precursor’s plasma pre-treatments such as H2, Ar or O2 on the properties of DLC coatings is also evaluated using atomic force microscopy, X-ray photoelectron spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, and analysed in terms of contact angle measurements. Because of the DLC coating, the coated fabric showed to endure its superhydrophobic character even after 12xa0months.

Bulk Heterojunction versus Diffused Bilayer: The Role of Device Geometry in Solution p-Doped Polymer-Based Solar Cells.

We exploit the effect of molecular p-type doping of P3HT in diffused bilayer (DB) polymer solar cells. In this alternative device geometry, the p-doping is accomplished in solution by blending the F4-TCNQ with P3HT. The p-doping both increases the film conductivity and reduces the potential barrier at the interface with the electrode. This results in an excellent power conversion efficiency of 4.02%, which is an improvement of ∼48% over the p-doped standard bulk heterojunction (BHJ) device. Combined VOC-light intensity dependence measurements and Kelvin probe force microscopy reveal that the DB device configuration is particularly advantageous, if compared to the conventional BHJ, because it enables optimization of the donor and acceptor layers independently to minimize the effect of trapping and to fully exploit the improved transport properties.

Dynamic Microscopy Study of Ultrafast Charge Transfer in a Hybrid P3HT/Hyperbranched CdSe Nanoparticle Blend for Photovoltaics.

We present a spectroscopic investigation on a new hyperbranched cadmium selenide nanocrystals (CdSe NC)/poly(3-hexylthiophene) (P3HT) blend, a potentially good active component in hybrid photovoltaics. Combined ultrafast transient absorption spectroscopy and morphological investigations by means of an ultrafast confocal microscope reveal a strong influence of the complex local structure on the photogenerated carrier dynamics. In particular, we map the electron-transfer process across the hybrid NC/polymer interface, and we reveal that charge separation occurs through a preferential pathway from the CdSe nanobranches to the P3HT chains. Efficient charge generation at the distributed heterojunction is also confirmed by scanning kelvin probe force microscopy measurements.

Bioinspired design of a photoresponsive superhydrophobic/oleophilic surface with underwater superoleophobic efficacy

Oil spills at sea are a severe global environmental issue. Smart materials with controllable wettability are of global challenging interest in oil–water related applications. Nature offers a versatile platform of remarkable hierarchical structures with a chemical component, which provides bioinspired solutions for solving many challenges. In this study, an approach to achieve robust superhydrophobic/oleophobic property on flexible polydimethylsiloxane (PDMS) surfaces which mimics the hierarchical morphology of the natural lotus leaf surface is shown. The structure is prepared by hydrothermal assembly of zinc oxide nanorods onto the microstructured surface, which results in an underwater superoleophobic surface with an oil contact angle up to 153° which can effectively prevent the surface from being polluted by oils. Our results are significant in terms of their importance to academic research and industrial applications and may lead to an innovative impact in the science field.

Fabrication of flexible all-inorganic nanocrystal solar cells by room-temperature processing

We demonstrate the fabrication of all-inorganic heterostructured n–p junction devices made of colloidal PbS quantum dots (QDs) and TiO2 nanorods (NRs). The entire device fabrication procedure relies on room-temperature processing, which is compatible with flexible plastic substrates and low-cost production. Through Kelvin Probe Force Microscopy and femtosecond pump and probe spectroscopy we decipher the electron transfer process occurring at the interface between the colloidal PbS QDs and TiO2 anatase NRs. Overall we demonstrate a high power conversion efficiency of ∼3.6% on glass and ∼1.8% on flexible substrates, which is among the highest reported for entirely inorganic-nanocrystal based solar cells on plastic supports.

Nonenzymatic Ligation of an RNA Oligonucleotide Analyzed by Atomic Force Microscopy

The products of ligation reaction of a 24 nucleotides long PolyA RNA adsorbed on mica were observed by atomic force microscopy. The occurrence of oligonucleotides at different degrees of polymerization has been quantitatively studied before and after ligation reaction. The microscopy images at the nanoscale show that nonenzymatic ligation of pristine RNA monomers results in the formation of supramolecular aggregates, with prevalence of dimers and tetramers. Analytical conditions were defined allowing the identification, the quantitative evaluation, and their distribution after ligation reaction, also providing an estimate of the degree of hydration of the objects. Such investigation is of particular biological relevance and provides the simplest yet model system for direct investigation of RNA reactions by advanced microscopy.

Physiological formation of fluorescent and conductive protein microfibers in live fibroblasts upon spontaneous uptake of biocompatible fluorophores.

We have recently reported initial results concerning an original approach to introduce additional properties into fibrillar proteins produced by live fibroblasts and extruded into the ECM. The key to such an approach was biocompatible, fluorescent and semiconducting synthetic molecules which penetrated spontaneously the cells and were progressively encompassed via non-bonding interactions during the self-assembly process of the proteins, without altering cell viability and reproducibility. In this paper we demonstrate that the intracellular secretion of fluorescent microfibers can be generalized to living primary and immortalized human/mouse fibroblasts. By means of real-time single-cell confocal microscopy we show that the fluorescent microfibers, most of which display helical morphology, are generated by intracellular coding of the synthetic molecules. We also describe co-localization experiments on the fluorescent microfibers isolated from the cell milieu demonstrating that they are mainly made of type-I collagen. Finally, we report experimental data indicating that the embedded synthetic molecules cause the proteins not only to be fluorescent but also capable of electrical conductivity.

Therapeutic PCL scaffold for reparation of resected osteosarcoma defect

Osteosarcomas are highly malignant tumors, which develop rapid growth and local infiltration, inducing metastases that spread primarily in the lung. Treatment of these tumors is mainly based on pre- and post-operative chemotherapy and surgery of the primary tumor. Surgical resection though, generates bone defects. Reparation of these weaknesses presents formidable challenges to orthopedic surgery. Medicine regenerative grafts that act as both tumor therapy with constant local drug delivery and tissue regeneration may provide a new prospect to address this need. These implants can provide sustained drug release at the cancer area, decreasing systemic second effects such as inflammation, and a filling of the resected tissues with regenerative biomaterials. In this study microporous poly-ε-caprolactone (PCL) scaffolds have been developed for sustained local release of anti-inflammatory drug dexamethasone (DXM), used as drug model, in cancer medicine regenerative field. The microporous PCL matrix of the scaffolds supported the attachment, proliferation and osteogenic differentiation of osteoblast-like cells, while the polyelectrolyte multilayers, anchored to the inner pore surfaces, sustained locally DXM release. These microporous scaffolds demonstrate the ability to deliver DXM as a localized tumor therapy and to promote proliferation and differentiation of osteoblast-like cells in vitro.

Unconventional tailorable patterning by solvent-assisted surface-tension-driven lithography

Unconventional nanopatterning methods are emerging as powerful tools for the development of controlled shapes and ordered morphology of nanostructured materials with novel properties and tailorable functions. Here, we report a simple yet straightforward and efficient approach for patterning through unconventional dewetting that involves surface tension driven process. Using this innovative approach, we have successfully demonstrated to be able to prepare surface micro-patterns over large areas deposited through Eu(3+):TiO2 nanoparticles providing rational control over the local nucleation of nanoparticles. Remarkably, these features could be addressed by polar or apolar solvents, suggesting potential applications in bottom-up nanodevices. This paper represents the first such attempt to create an inorganic materials non-lithographic template for the directed deposition of Eu(3+):TiO2 or related metal oxides. The technique, which is driven by the unique chemical properties and geometrical layout of the underlying patterned micrometer-sized templates, enables the construction of micro- and nano-structuration of dispersed inorganic functional materials suitable for electrooptical and photonic applications.