Multimodal sensing in rewritable, data matrix azobenzene-based devices

Here, we exploited the UV light and thermal triggered E <-> Z photoisomerization of an azobenzene compound to fabricate multimodal readable and rewritable data matrix based devices. We first demonstrated that the UV light sensing capabilities can be simultaneously monitored by the change in optical, spectroscopic, and electrical properties. Then we exploited this capability by integrating tetra(azobenzene)methane crystals in a micrometric TAG whose information can be modified and repristinated by local UV treatment and thermal annealing. The system was characterized by polarized optical microscopy, Raman spectroscopy, conductive atomic force microscopy and Kelvin Probe Force Microscopy

Study of Probes and Substrates for Low Temperature Atomic Force Microscopy and Biological Applications

The atomic force microscopy in ultrahigh vacuum and at low temperature demonstrated its excellent capability to reach atomic resolution. Nevertheless in the case of biological samples high resolution has been achieved only in very few cases. We demonstrated here the importance of the appropriate choice of probes and substrates in order to image DNA at low temperature with high resolution. We investigated properties of three types of cantilevers and they were studied by scanning electron microscopy as a function of temperature. A large bending of cantilevers, which were coated from both sides, was observed at low temperatures. Therefore uncoated cantilevers are strongly recommended for low temperature applications. Different methods for immobilization of DNA on the substrate are examined at low temperatures. First images of linear DNA on graphite at 82 K under ultrahigh vacuum conditions are presented

Study of Probes and Substrates for Low Temperature Atomic Force Microscopy and Biological Applications

The atomic force microscopy in ultrahigh vacuum and at low temperature demonstrated its excellent capability to reach atomic resolution. Nevertheless in the case of biological samples high resolution has been achieved only in very few cases. We demonstrated here the importance of the appropriate choice of probes and substrates in order to image DNA at low temperature with high resolution. We investigated properties of three types of cantilevers and they were studied by scanning electron microscopy as a function of temperature. A large bending of cantilevers, which were coated from both sides, was observed at low temperatures. Therefore uncoated cantilevers are strongly recommended for low temperature applications. Different methods for immobilization of DNA on the substrate are examined at low temperatures. First images of linear DNA on graphite at 82 K under ultrahigh vacuum conditions are presented

Measurement of DNA Morphological Parameters at Highly Entangled Regime on Surfaces

The morphology of circular DNA deposited from a solution on the mica surface is analyzed from the power spectrum density (PSD) of the atomic force microscopy (AFM) images. Sample morphology is modulated in a broad range of concentration C from isolated molecules to highly entangled networks. DNA exhibits a multiaffine behavior with two correlation length scales: the persistence length P which remains constant (approximate to 50 nm) within the C range and the intermolecular distance which exhibits a decay with increasing C. Applying a diffusion based model in which xi scales as xi approximate to D(-0.25)center dot C(-0.5), we extracted the DNA diffusion coefficient D approximate to 2 x 10(-7) cm(2)/S. This value is consistent with a high-molecular-weight plasmid DNA supercoiled in the solution

Patterning pentacene surfaces by local oxidation nanolithography

Sequential and parallel local oxidation nanolithographies have been applied to pattern pentacene samples by creating a variety of nanostructures. The sequential local oxidation process is performed with an atomic force microscope and requires the application of a sequence of voltage pulses of 36 V for 1 ms. The parallel local oxidation process is performed by using a conductive and patterned stamp. Then, a voltage pulse is applied between the stamp and the pentacene surface. Patterns formed by arrays of parallel lines covering 1 mm2 regions and with a periodicity of less than 1 mm have been generated in a few seconds. We also show that the patterns can be used as templates for the deposition of antibodies

A low-temperature ultrahigh vacuum atomic force microscope for biological applications

We present an atomic force microscope ~AFM for operation at low temperatures under ultrahigh vacuum conditions. It uses the laser beam deflection method to measure the bending of the cantilever. The four quadrant photodiode allows the detection of vertical and lateral forces. The AFM has been developed for studying biological samples. Images of deoxyribonucleic acid plasmids have been obtained in contact mode