Non periodic patterning of super-hydrophobic surfaces for the manipulation of few molecules

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Tailored Ag nanoparticles/nanoporous superhydrophobic surfaces hybrid devices for the detection of single molecule

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Evaluation of stimulus-effect relations in left ventricular growth using a simple multiscale model

\u3cp\u3eCardiac growth is the natural capability of the heart to change size in response to changes in blood flow demand of the growing body. Cardiac diseases can trigger the same process leading to an abnormal type of growth. Prediction of cardiac growth would be clinically valuable, but so far published models on cardiac growth differ with respect to the stimulus-effect relation and constraints used for maximum growth. In this study, we use a zero-dimensional, multiscale model of the left ventricle to evaluate cardiac growth in response to three valve diseases, aortic and mitral regurgitation along with aortic stenosis. We investigate how different combinations of stress- and strain-based stimuli affect growth in terms of cavity volume and wall volume and hemodynamic performance. All of our simulations are able to reach a converged state without any growth constraint, with the most promising results obtained while considering at least one stress-based stimulus. With this study, we demonstrate how a simple model of left ventricular mechanics can be used to have a first evaluation on a designed growth law.\u3c/p\u3

Leaf-Inspired Authentically Complex Microvascular Networks for Deciphering Biological Transport Process

The vascular transport of molecules, cells, and nanoconstructs is a fundamental biophysical process impacting tissue regeneration, delivery of nutrients and therapeutic agents, and the response of the immune system to external pathogens. This process is often studied in single-channel microfluidic devices lacking the complex tridimensional organization of vascular networks. Here, soft lithography is employed to replicate the vein system of a Hedera elix leaf on a polydimethilsiloxane (PDMS) template. The replica is then sealed and connected to an external pumping system to realize an authentically complex microvascular network. This satisfies energy minimization criteria by Murray\u2019s law and comprises a network of channels ranging in size from capillaries ( 3c50 \u3bcm) to large arterioles and venules ( 3c400 \u3bcm). Micro-PIV (micro\u2013particle image velocimetry) analysis is employed to characterize flow conditions in terms of streamlines, fluid velocity, and flow rates. To demonstrate the ability to reproduce physiologically relevant transport processes, two different applications are demonstrated: vascular deposition of tumor cells and lysis of blood clots. To this end, conditions are identified to culture cells within the microvasculature and realize a confluent endothelial monolayer. Then, the vascular deposition of circulating breast (MDA-MB 231) cancer cells is documented throughout the network under physiologically relevant flow conditions. Firm cell adhesion mostly occurs in channels with low mean blood velocity. As a second application, blood clots are formed within the chip by mixing whole blood with a thrombin solution. After demonstrating the blood clot stability, tissue plasminogen activator (tPA) and tPA-carrying nanoconstructs (tPA-DPNs) are employed as thrombolytics. In agreement with previous data, clot dissolution is equally induced by tPA and tPA-DPNs. The proposed leaf-inspired chip can be efficiently used to study a variety of vascular transport processes in complex microvascular networks, where geometry and flow conditions can be modulated and monitored throughout the experimental campaign

Electroless deposition dynamics of silver nanoparticles clusters: A diffusion limited aggregation (DLA) approach

Silver nanoparticles (NPs) aggregates with an overall size in the nano meter range were fabricated employing non conventional electroless techniques. The structure of the aggregates was analyzed through direct SEM and AFM imaging; space-frequency based variables, including fractal dimension, were extracted in order to yield a quantitative measurement of the topography of the systems at study. These observations were explained within the framework of diffusion limited aggregation (DLA). DLA theory founds upon the paradigm that, in the limit of very fast chemical reactions, diffusion is the sole driving force that regulates the dynamics of aggregation of NPs. The mathematical model confirmed the experimental findings whereby the fractal dimension of the clusters is size dependent, that is, larger systems are more discontinuous than smaller. The model would also predict that, under certain conditions, a characteristic length exists beyond which the fractal dimension is constant. DLA theory is consistent and predictive in nature, and may be of valuable help in designing devices that utilize rough metal surfaces and the derived effects thereof, including SERS substrates

A simple all-solution approach to the synthesis of large ZnO nanorod networks

Soft-lithography of Zn-loaded hydrogels and a subsequent hydrothermal growth process yield self-assembling networks of bridging ZnO nanorods (NRs). They are grown on seeding micropillars of ZnO until they touch, forming junctions that provide a preferred electrical path for the operative current of functional devices (e.g. gas senors)