White Electroluminescence from a Microcontact‐Printing‐Deposited CdSe/ZnS Colloidal Quantum‐Dot Monolayer

We developed a dry, simple, and low-cost technique for deposition of colloidal semiconductor nanocrystals on organic-material layers. This technique allows the deposition of a homogeneous thin layer (about 10 nm) of mixed CdSe/ZnS red, green, and blue QDs. The independent processing of QD and organic material permits the fabrication of hybrid white multilayer-structure LEDs without any restrictions in the choice of organic material

Improved Photovoltaic Performance of Heterostructured Tetrapod-Shaped CdSe/CdTe Nanocrystals Using C60 Interlayer

[*] Prof. G. Gigli, Dr. Y. Q. Li, R. Mastria, A. Fiore, Dr. C. Nobile, Dr. L. X. Yin, Dr. M. Biasiucci, Dr. G. Cheng, Prof. R. Cingolani, Dr. L. Manna National Nanotechnology Lab of CNR-INFM (NNL) University of Salento Via Arnesano, 73100 Lecce (Italy) E-mail: [email protected] Dr. M. Biasiucci, Prof. A. M. Cucolo Physical Department ''E. R. Caianiello'' University of Salerno Via S. Allende, 84081 Baronissi (SA) (Italy

Molecular-Level Switching of Polymer/Nanocrystal Non-Covalent Interactions and Application in Hybrid Solar Cells

Hy brid composites obtained upon blending conjugated polymers and colloidal inorganic semiconductor nanocrystals are regarded as attractive photo-active materials for optoelectronic applications. Here we demonstrate that tailoring nanocrystal surface chemistry permits to exert control on non-covalent bonding and electronic interactions between organic and inorganic components. The pendant moieties of organic ligands at the nanocrystal surface do not merely confer colloidal stability while hindering charge separation and transport, but drastically impact morphology of hybrid composites during formation from blend solutions. The relevance of our approach to photovoltaic applications is demonstrated for composites based on poly(3-hexylthiophene) and Pbs nanocrystals, considered as inadequate before the submission of this manuscript, which enable the fabrication of hybrid solar cells displaying a power conversion efficiency that reaches 3 %. Upon (quasi)steady-state and time-resolved analisys of the photo-induced processes in the nanocomposites and their organic and inorganic components, we ascertained that electron transfer occurs at the hybrid interface yielding long-lived separated charge carriers, whereas interfacial hole transfer appears slow. Here we provide a reliable alternative aiming at gaining control over macroscopic optoelectronic properties of polymer/nanocrystal composites by acting at the molecular-level via ligands' pendant moieties, thus opening new possibilities towards efficient solution-processed hybrid solar cells

Synthesis and Photovoltaic Properties of Regioregular Head-to-Head Substituted Thiophene Hexadecamers

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White Electroluminescence from a Microcontact-Printing-Deposited CdSe/ZnS Colloidal Quantum-Dot Monolayer

We developed a dry, simple, and low-cost technique for deposition of colloidal semiconductor nanocrystals on organic-material layers. This technique allows the deposition of a homogeneous thin layer (about 10 nm) of mixed CdSe/ZnS red, green, and blue QDs. The independent processing of QD and organic material permits the fabrication of hybrid white multilayer-structure LEDs without any restrictions in the choice of organic material

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 <i>V</i>_OC–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

Therapeutic PCL scaffold for reparation of resected osteosarcoma defect

Abstract 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

Cell self-patterning on uniform PDMS-surfaces with controlled mechanical cues

The exploitation of cell-instructive scaffolds with uniform physical/chemical surfaces and controlled stiffness will be greatly useful in tissue engineering applications to resemble the extracellular matrix (ECM) or topographical appearance of native tissues. We herein describe a versatile and straightforward method to assemble a polydimethylsiloxane (PDMS)-composite structure in which a uniformly laminin-coated membrane is placed on top of a micropatterned substrate that applies a stiffness gradient. This 'double-sheet' structure provides soft or stiff microdomains that guide the self-patterning of different cell types [e. g. chronic myeloid leukemia (KU812), cervix carcinoma (HeLa), NIH 3T3 and BJ], thereby stimulating their cytoskeletal remodeling. More interestingly, we used these uniform PDMS surfaces with patterned rigidity for obtaining co-cultures of tumor blood cells (KU812) and adherent fibroblasts (NIH 3T3) with spatially-controlled distribution. Thus, beyond single-cell stiffening and mechanosensing, these surfaces should also be used as simple and feasible co-culture systems for mimicking and dissecting the bidirectional interactions between blood cells and specific stromal elements of their in vivo microenvironment

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 oligonudeotides 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