Mode-synthesizing atomic force microscopy for volume characterization of mixed metal nanoparticles.

Atomic force microscopy (AFM) and other techniques derived from AFM have revolutionized the understanding of materials and biology at the nanoscale, but mostly provide surface properties. The observation of subsurface nanoscale features and properties remains a great challenge in nanometrology. The operating principle of the mode-synthesizing AFM (MSAFM) is based on the interaction of two ultrasonic waves, one launched by the AFM probe fp , a second launched by the sample fs , and their resulting nonlinear frequency mixing. Recent developments highlighted the need for quantitative correlation between the role of the frequency actuation of the probe fp and the sample fs . Here we present the great potential of MSAFM for advanced volume characterization of metallic nanoparticles presenting a multilayered structure composed of a nickel core surrounded by a gold envelope.

[CHARACTERIZATION OF THE DIFFERENCE IN THE MORPHOLOGY OF DETERGENT RESISTANT MEMBRANES DOMAINS ISOLATED FROM DIFFERENT CELL TYPES BY ATOMIC FORCE MICROSCOPY].

Planar raft and caveolae are specific membrane clusters with high concentration of cholesterol and lipids with saturated fatty acid. These clasters are resistant to detergents and are denoted as detergent resistant membranes domains (DRMs). Their morphology and size have been studied by atomic force microscopy. The size of planar rafts isolated by Librol from monocytes of healthy volunteers was 150.6 ± 68.6 nm--diameters and 5.7 ± 2.9 nm--height, the size of caveolae was 87.3 ± 46.1 nm--diameters and 9.4 ± 5.4 nm--height. Significant difference have been found morphology and size of DRMs isolated from monocytes of healthy volunteers and patients suffering from myocardial infarction as well as between DRMs isolated from endothelial cells. The study of time-dependent changes in the morphology of isolated planar rafts and caveolae has shown that they quickly aggregate during keeping. Therefore, to asses the actual size and morphology of the DRMS, they should be investigated immediately after isolation.

Homogeneous large-scale crystalline nanoparticle-covered substrate with high SERS performance.

This article details the surface-enhanced Raman scattering (SERS) performance of plasmonic substrates fabricated by a physical metal evaporation technique that uses no precursor or intermediate coating. We outline a cost-effective nanofabrication protocol that uses common laboratory equipment to produce homogeneously covered crystalline nanoparticle substrates. Our fabrication yields a homogeneous SERS response over the whole surface. The platform is tested with methylene blue diluted at various concentrations to estimate the sensitivity, homogeneity, and reproducibility of the process. The capacity of the substrates is also confirmed with spectroscopic investigations of human microsomal cytochrome b5.

From surface to intracellular non-invasive nanoscale study of living cells impairments.

Among the enduring challenges in nanoscience, subsurface characterization of living cells holds major stakes. Developments in nanometrology for soft matter thriving on the sensitivity and high resolution benefits of atomic force microscopy have enabled detection of subsurface structures at the nanoscale. However, measurements in liquid environments remain complex, in particular in the subsurface domain. Here we introduce liquid-mode synthesizing atomic force microscopy (l-MSAFM) to study both the inner structures and the chemically induced intracellular impairments of living cells. Specifically, we visualize the intracellular stress effects of glyphosate on living keratinocytes skin cells. This new approach, l-MSAFM, for nanoscale imaging of living cell in their physiological environment or in presence of a chemical stress agent could resolve the loss of inner structures induced by glyphosate, the main component of a well-known pesticide (RoundUp™). This firsthand ability to monitor the cell's inner response to external stimuli non-destructively and in liquid, has the potential to unveil critical nanoscale mechanisms of life science.

Imaging the local density of states of optical corrals.

This paper reports the experimental observation, at optical frequencies, of the electromagnetic local density of states established by nanostructures corresponding to the recently introduced concept of optical corral [G. Colas des Francs et al., Phys. Rev. Lett. 86, 4950 (2001)]. The images obtained by a scanning near-field optical microscope under specific operational conditions are found in agreement with the theoretical maps of the optical local density of states. A clear functionality of detection by the scanning near-field optical microscope is thereby identified since the theoretical maps are computed without including any specific tip model.