Jun. 07, 2013

Self-Organized Gold Honeycomb Structure

The early growth stage and growth evolution to a unique gold (Au) honeycomb nano-network on Si(111)7×7 at room temperature have been studied by direct filled-state and empty-state imaging by scanning tunneling microscopy (STM). The gold honeycomb structure is made up of six triangular gold clusters around the corner hole interconnected to one another in the dimer rows of the Si(111)7×7 substrate. moreApr. 22, 2013

Infrared Images of Single Electrons

Scattering-type near-field optical microscopy (s-SNOM) is a powerful technique to image nano objects. It can be employed in a broad spectral range, namely the complete infrared region spanning from the terahertz range up to the visible range. In this article we describe a system which utilizes a free-electron laser as a spectrally narrow and widely tunable source of infrared radiation. This system was employed to study electrons confined in self-assembled InAs quantum dots. We spatially resolved single quantum dots upon resonant excitation of transitions between discrete energy levels of the confined electrons.
moreApr. 02, 2013

Molecularly Resolved Cellulose Nitrate

The development of nanostructured lacquers and propellants needs to master the cellulose nitrate processing on the nanoscale. The challenge is the deposition of single cellulose nitrate molecules to image them with molecular resolution. We report on the effect of solvent, shaking duration and deposition techniques, from which the spray technique succeeded, for the first time to our knowledge, to image by Atomic Force Microscopy, individual molecular cellulose nitrate polymeric chains.
moreFeb. 26, 2013

Fractal Dimension and Entropy of Biological Membrane

Complexity of cell membrane poses difficulties to quantify corresponding morphology changes during cell life. To quantify it, we present an evaluation of entropy and fractal dimension of macrophage membranes from Atomic Force Microscopy (AFM) images before and after treatment with microtubule destabilizing or stabilizing agents. We show that entropy and fractal dimension are sensitive to the weak micromorphology changes produced by small concentrations and incubation times of these treatments.
moreJan. 03, 2013

“Trolling”-Mode Atomic Force Microscopy

Imaging biological materials is one of the main branches of biomedical engineering. Particularly, imaging living cells at the single-cell level is highly important for fundamental understanding of cell behavior and its interaction with the extracellular matrix. The resolution of commonly used optical microscopy is limited by diffraction of light to ~200 nm. However, the major elements of the cell membrane such as transmembrane proteins, ion channels, cell adhesion proteins etc. are essentially nanostructures, which cannot be resolved with optical microscopy. moreDec. 17, 2012

Carbon Nanotubes as Ideal AFM Probes

Carbon nanotubes (CNT) have been demonstrated since 1996 as ideal probes for scanning probe methods because of their nano-size, their cylinder geometry and their mechanical properties. Their use hasn‘t spread out as expected, due to lack of control of their fabrication and of their interaction with surfaces. Sixteen years later, this knowledge is now acquired. Carbon nanotube probes can provide more than high resolution thanks to their high mechanical and chemical stability and surface sensitivity.
moreDec. 10, 2012

Towards Manipulation of Single Proteins

Here we use scanning probe microscopy (SPM) to image and manipulate individual pig gastric mucin protein molecules attached to a graphite surface. Experiments on the bare graphite surface with STM show that, upon drying of a droplet of mucin solution and subsequent washing with ultrapure water, mucin molecules are arranged in a linear fashion. We show that these molecules can be unraveled by a mechanical molecule/tip interaction one segment (45 nm) at a time without fragmenting the molecule. moreDec. 06, 2012

Supported Phospholipid Bilayers

Solid supported phospholipid bilayers (SPB) formed by fusion of small unilamellar vesicles on glass, quartz and mica surfaces constitute an attractive model for studying lipid membrane properties and functions. Therefore, it is crucial to understand the mechanisms of SPB formation under different experimental ­conditions. In situ atomic force microscopy imaging can reveal the details of this process. Introduction more