Correlative Imaging of Motoneuronal Cell Elasticity by Pump and Probe Spectroscopy.

Because of their role of information transmitter between the spinal cord and the muscle fibers, motor neurons are subject to physical stimulation and mechanical property modifications. We report on motoneuron elasticity investigated by time-resolved pump and probe spectroscopy. A dual picosecond geometry simultaneously probing the acoustic impedance mismatch at the cell-titanium transducer interface and acoustic wave propagation inside the motoneuron is presented.

Surface-induced assembly of sophorolipids.

The surface self-assembly properties of acidic sophorolipids, a bolaform microbial glycolipids with pH-responsive properties in solution, were studied based on the chemical nature of the support and pH of the solution. Sophorolipids generally form micelles in water but formation of morphologies like platelets and twisted fibers depending on pH have also been reported. The surface self-assembly was achieved using dip-coating on three different substrates namely gold, silicon(111) and TiO anatase.

Substrate-induced PC12 cell differentiation without filopodial, lamellipodial activity or NGF stimulationa.

Nanoscale gradients in energy of adhesion are physical cues from the extracellular environment that can significantly affect cell functions and enhance the neuronal differentiation of PC12 cells. How such surface effects can trigger differentiation and initiate neurite outgrowth, remains to be elucidated. Here we used surface modification, atomic force microscopy and immunofluorescence to analyze PC12 cells.

Interplay between long- and short-range interactions drives neuritogenesis on stiff surfaces.

Substrate factors such as surface energy distribution can affect cell functions, such as neuronal differentiation of PC12 cells. However, the surface effects that trigger such cell responses need to be clarified and analyzed. Here we show that the total surface tension is not a critical parameter.

Neuronal adhesion and differentiation driven by nanoscale surface free-energy gradients.

Recent results indicate that, in addition to chemical, spatial and mechanical cues, substrate physical cues such as gradients in surface energy may also impact cell functions, such as neuronal differentiation of PC12 cells. However, it remains to be determined what surface effect is the most critical in triggering PC12 cell differentiation. Here we show that, beyond continuously probing the surface energy landscape of their environment, PC12 cells are highly sensitive to nanoscale chemical heterogeneities.

Influence of surface energy distribution on neuritogenesis.

PC12 cells are a useful model to study neuronal differentiation, as they can undergo terminal differentiation, typically when treated with nerve growth factor (NGF). In this study we investigated the influence of surface energy distribution on PC12 cell differentiation, by atomic force microscopy (AFM) and immunofluorescence. Glass surfaces were modified by chemisorption: an aminosilane, n-[3-(trimethoxysilyl)propyl]ethylendiamine (C(8)H(22)N(2)O(3)Si; EDA), was grafted by polycondensation.

Layering and prewetting in experimental systems: an assessment cross-referred to current theories.

The first aim of this review is to assess the experimental data available about surface phase transitions at the contact between fluid bulk phases and either their vapour in the case of liquids (free interfaces) or solid substrates in general and to test their "universal" behaviour out of any consideration about critical laws, which constitute a topic by themselves. As, here, the level under consideration is only the microscopic one, wetting transitions are excluded. Our second goal is to compare these experimental data to their description by models, which are far more numerous.

Analytical approach for the Lucas-Washburn equation.

Porous media can be characterized by studying the kinetics of liquid rise within the pore spaces. Although porous media generally have a complex structure, they can be modeled as a single, vertical capillary or as an assembly of such capillaries. The main difficulties lie in separately estimating the effective mean radius of the capillaries and the contact angle between the liquid and the pore.