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The ability to self‐assemble DNA nanodevices with programmed structural dynamics that can sense and respond to the local environment can enable transformative applications in fields including mechanobiology and nanomedicine. The responsive function of biomolecules is often driven by alterations in conformational distributions mediated by highly sensitive interactions with the local environment. In this review, the current state‐of‐the‐art in constructing complex DNA geometries with dynamic and mechanical properties to enable a molecular scale force measurement is first summarized. Next, an overview of engineering modular DNA devices that interact with cell surfaces is highlighted detailing examples of mechanosensitive proteins and the force‐induced dynamic molecular interaction on the downstream biochemical signaling. Finally, the challenges and an outlook on this promising class of DNA devices acting as nanomachines to operate at a low piconewton range suitable for a majority of biological effects or as hybrid materials to achieve higher tension exertion required for other biological investigations, are discussed. [ABSTRACT FROM AUTHOR]

Pneumocystis jirovecii pneumonia is a difficult invasive infection to diagnose. Apart from microscopy of respiratory specimens, two diagnostic tests are increasingly used including real-time quantitative PCR (qPCR) of respiratory specimens, mainly in bronchoalveolar lavage fluids (BAL), and serum β-1,3-D-glucan (BDG). It is still unclear how these two biomarkers can be used and interpreted in various patient populations. Here we analyzed retrospectively and multicentrically the correlation between BAL qPCR and serum BDG in various patient population, including mainly non-HIV patients. It appeared that a good correlation can be obtained in HIV patients and solid organ transplant recipients but no correlation can be observed in patients with hematologic malignancies, solid cancer, and systemic diseases. This observation reinforces recent data suggesting that BDG is not the best marker of PCP in non-HIV patients, with potential false positives due to other IFI or bacterial infections and false-negatives due to low fungal load and low BDG release. [ABSTRACT FROM AUTHOR]

We investigate the mechanism of self-assembly of fattyacids (FA)and methyl oleate on an Al oxy-hydroxide surface with a view to decipheringthe role and nature of interfacial processes (adsorption, chemicalbinding, molecular organization, etc.). For this purpose, we focuson parameters related to intrinsic properties of molecules, namelythe level of unsaturation and the nature of the head group (carboxylicacid or ester). After the FA adsorption, the presence of coordinativebonded carboxylate species on the Al oxy-hydroxide surface is demonstratedby means of PM-IRRAS analysis. We observe that contact of methyl oleatewith the surface leads to its chemical transformation through a saponificationreaction. As a consequence, it binds to the surface in a manner similarto that for fatty acids. Through an innovative mode of atomic forcemicroscopy (AFM), the organization of the adsorbed molecules is demonstrated.Our results reveal the existence of highly ordered nanostructuresguided by the FA self-assembly. The size of these nanostructures wasdetermined with accuracy, suggesting that it exceeds one FA monolayer.By contrast, no organization was observed with methyl oleate. [ABSTRACT FROM AUTHOR]

Highlights from the article: Keywords: atomic force microscopy; collagen adsorption; nanoparticles; network; self-assembly The approach explores the network analysis method to provide quantitative description of the dewetting patterns of collagen layers from AFM images and show how nanoparticles impact collagen behavior at the interface. Atomic force microscopy, collagen adsorption, nanoparticles, network, self-assembly.

The adsorption behavior of collagen on solid surfaces is a process that determines the role of this protein to mediate cell–material interaction. Herein, the mechanism of self‐assembly and organization of collagen on a model substrate is investigated in the presence of TiO2 nanoparticles. In solution, results show that nanoparticles do not alter the conformation of collagen (triple‐helix), and slightly delay the kinetics of its self‐assembly. In the adsorbed state, by exploring the dewetting patterns of collagen layers from atomic force microscopy (AFM) images, a method is developed to extract parameters describing the characteristics of collagen networks. It is shown that collagen layer is strongly impacted by the presence of nanoparticles in the medium. These results are consistent with the analysis of the protein layers in the hydrated state, showing a rigidification, as observed by quartz crystal microbalance with dissipation monitoring (QCM‐D), and the formation of shorter and/or less extended fibrillar structures with a lower surface density, as probed by AFM force spectroscopy. The approach described here provides a reconciliation between disparate views of collagen layers' characterization in the dried and the hydrated states. It also offers new perspectives to assess the impact of nanoparticles on the organization of collagen during in vitro tests, particularly at the stage of cell adhesion. [ABSTRACT FROM AUTHOR]

In this work the mechanism of (3-aminopropyl)triethoxysilane (APTES) interaction with silicon surfaces is investigated at the molecular level. We studied the influence of experimental parameters such as time, temperature, and concentration on the quality of the APTES layer in terms of chemical properties, morphology, and stability in aqueous medium. This was achieved using a highly sensitive IR mode recently developed, grazing angle attenuated total reflection (GA-ATR). This technique provides structural information on the formed APTES layer. The topography of this layer was investigated by atomic force microscopy in aqueous medium. The hydrophilicity was also studied using contact angle measurement. Combining these techniques enables discussion of the mechanism of silane grafting. Considerable differences were observed depending on the reaction temperature, room temperature or 90 °C. The data suggest the presence of two adsorption sites with different affinities on the oxidized silicon layer. This also allows the optimal parameters to be established to obtain an ordered and stable silane layer. The adsorption of proteins on the APTES layer was achieved and monitored using in situ quartz crystal microbalance with dissipation monitoring and ex situ GA-ATR analyses.