The ability to control the placement of individual molecules promises to enable a wide range of applications and is a key challenge in nanoscience and nanotechnology. Many biological interactions, in particular, are sensitive to the precise geometric arrangement of proteins. We have developed a technique which combines molecular-scale nanolithography with site-selective biochemistry to create biomimetic arrays of individual protein binding sites. The binding sites can be arranged in heterogeneous patterns of virtually any possible geometry with a nearly unlimited number of degrees of freedom. We have used these arrays to explore how the geometric organization of the extracellular matrix (ECM) binding ligand RGD (Arg-Gly-Asp) affects cell adhesion and spreading. Systematic variation of spacing, density and cluster size of individual integrin binding sites was used to elicit different cell behavior. Cell spreading assays on arrays of different geometric arrangements revealed a dramatic increase in spreading efficiency when at least 4 liganded sites were spaced within 60 nm or less, with no dependence on global density. This points to the existence of a minimal matrix adhesion unit for fibronectin defined in space and stoichiometry. Developing an understanding of the ECM geometries that activate specific cellular functional complexes is a critical step toward controlling cell behavior. Potential practical applications range from new therapeutic treatments to the rational design of tissue scaffolds that can optimize healing without scarring. More broadly, spatial control at the single-molecule level can elucidate factors controlling individual molecular interactions and can enable synthesis of new systems based on molecular-scale architectures. Among the candidates for future generation lithography technologies is nanoimprint lithography (NIL), 10,11 which is a high throughput patterning technique in which a pattern is formed in a thin polymer film that has been cast on a substrate by molding it to a relief image in a rigid template (mask). The pattern is then transferred from the polymer by a variety of thin film deposition and/or etching techniques. There is no theoretical limitation to the resolution of the features imprinted by NIL; 12 the practical limit is determined by the size of the features on the NIL template, which is typically patterned by electron beam lithography. We have recently developed a process based on NIL and self-aligned pattern transfer which reduces the imprinted feature size and is capable of creating metallic structures below 5 nm. 13 We have also developed a facile surface chemistry which allows us to functionalize these structures with a broad array of biomolecular species with a high degree of selectivity. 14 Using these techniques, we have fabricated biomimetic surfaces upon which we can control the precise placement of individual biomolecules. We report here how these surfaces can be used to study the role of geometric organization of extracellular matrix (ECM) binding ligand...

This review highlights the potential of Kelvin probe force microscopy (KPFM) beyond imaging to simultaneously study structural and electronic properties of functional surfaces and interfaces. This is of paramount importance since it is well established that a solid surface possesses different properties than the bulk material. The versatility of the technique allows one to carry out investigations in a non‐invasive way for different environmental conditions and sample types with resolutions of a few nanometers and some millivolts. KPFM can be used to acquire a wide knowledge of the overall electronic and electrical behavior of a sample surface. Moreover, by KPFM it is possible to study complex electronic phenomena in supramolecular engineered systems and devices. The combination of such a methodology with external stimuli, e.g., light irradiation, opens new doors to the exploration of processes occurring in nature or in artificial complex architectures. Therefore, KPFM is an extremely powerful technique that permits the unraveling of electronic (dynamic) properties of materials, enabling the optimization of the design and performance of new devices based on organic‐semiconductor nanoarchitectures.

The ability of amyloid-␤ peptide (A␤) to disrupt membrane integrity and cellular homeostasis is believed to be central to Alzheimer's disease pathology. A␤ is reported to have various impacts on the lipid bilayer, but a clearer picture of A␤ influence on membranes is required. Here, we use atomic force and transmission electron microscopies to image the impact of different isolated A␤ assembly types on lipid bilayers. We show that only oligomeric A␤ can profoundly disrupt the bilayer, visualized as widespread lipid extraction and subsequent deposition, which can be likened to an effect expected from the action of a detergent. We further show that A␤ oligomers cause widespread curvature and discontinuities within lipid vesicle membranes. In contrast,thisdetergent-likeeffectwasnotobservedforA␤monomers and fibers, although A␤ fibers did laterally associate and embed into the upper leaflet of the bilayer. The marked impact of A␤ oligomers on membrane integrity identified here reveals a mechanism by which these oligomers may be cytotoxic.

The development of new flexible and stretchable sensors addresses the demands of upcoming application fields like internet-of-things, soft robotics, and health/structure monitoring. However, finding a reliable and robust power source to operate these devices, particularly in off-the-grid, maintenance-free applications, still poses a great challenge. The exploitation of ubiquitous temperature gradients, as the source of energy, can become a practical solution, since the recent discovery of the outstanding thermoelectric properties of a conductive polymer, poly(3,4-ethylenedioxythiophene)poly(styrenesulfonate) (PEDOT:PSS). Unfortunately the use of PEDOT:PSS is currently constrained by its brittleness and limited processability. Herein, PEDOT:PSS is blended with a commercial elastomeric polyurethane (Lycra), to obtain tough and processable self-standing films. A remarkable strainat-break of ≈700% is achieved for blends with 90 wt% Lycra, after ethylene glycol treatment, without affecting the Seebeck voltage. For the first time the viability of these novel blends as stretchable self-powered sensors is demonstrated.

Molecular dyads based on polycyclic electron donor (D) and electron acceptor (A) units represent suitable building blocks for forming highly ordered, solution‐processable, nanosegregated D‐A domains for potential use in (opto)electronic applications. A new dyad, based on alkyl substituted hexa‐peri‐hexabenzocoronene (HBC) and perylene monoimide (PMI) separated by an ethinylene linker, is shown to have a high tendency to self‐assemble into ordered supramolecular arrangements at multiple length scales: macroscopic extruded filaments display long‐range crystalline order, nanofiber networks are produced by simple spin‐coating, and monolayers with a lamellar packing are formed by physisorption at the solution‐HOPG interface. Moreover, highly uniform mesoscopic ribbons bearing atomically flat facets and steps with single‐molecule heights self‐assemble upon solvent‐vapor annealing. Electrical measurements of HBC‐PMI films and mesoscopic ribbons in a transistor configuration exhibit ambipolar transport with well balanced p‐ and n‐type mobilities. Owing to the increased level of order at the supramolecular level, devices based on ribbons show mobility increases of more than one order of magnitude.