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Posted: Nov 02, 2009

Molecular machines: from electronics to biology

(Nanowerk Spotlight) In today's addition to our Application Note series we are looking at the future of electronics and the implications for research instrumentation. We are showing two examples of atomic force microscope (AFM) applications employed in this research.
Current CMOS (complementary metal–oxide–semiconductor) technology used for making integrated circuits is constantly being scaled down. These devices will reach their ultimate physical limits in 10 to 15 years. As chip structures – which currently already have reached nanoscale dimensions – continue to shrink below the 20 nanometer mark, ever more complex challenges arise and scaling appears not to be economically feasible any more. And below 10 nm, the fundamental physical limits of CMOS technology will be reached. Researchers are therefore exploring novel concepts for future nanoelectronic devices.
DNA-based electronics is a prime example of an entirely alternative approach (take a look at some of our previous Spotlights like "DNA nanotechnology in computers knocks down another roadblock"). Efficient attachment of DNA to metal surfaces or electrodes is essential for charge-transport measurements, scanning tunneling microscopy, and for fabricating devices and sensors (see our recent Spotlight "Carbon nanotube-DNA nanotechnology for improved fuel cell catalysts"). DNA nanotechnology will take advantage of the unprecedented recognition and assembling properties of DNA. Researchers are confident that DNA-based nanoelectronic devices will enable to reduce the size of the current silicon-based devices by approximately 1000 times.
AFM image of two silver nanoparticles linked by DNA
AFM image of two silver nanoparticles linked by DNA. (Image: Prof. Alexander Kotlyar, Tel Aviv University. The image was obtained by ETALON probes. The image was presented to the NT-MDT probes ProIMAGE Contest 2009).
The equipment
AFM image of two silver nanoparticles linked by DNA ETALON probes: High accuracy polysilicon AFM probes with high aspect ratio tip (curvature radius 10 nm) and high accuracy resonant frequency (typical dispersion ± 20%). These ETALON probes are the very tips needed for research in the nanoelectronics field.
GOLDEN probes: Conventional high resolution AFM silicon probes for contact mode are available with different coatings (Au, Al, PtIr, TiN, Au, diamond doped conductive etc) and tipless. Probes without any coating and for non-contact modes are available as well.
Organic and plastic electronics is an area projected to grow into a $30 billion industry by 2015. This branch of science includes the integration of electronics and biomaterials for the purpose of creating bimolecular machines, which could have a wide range of application in chemistry, physics, biology, medicine, materials science, nanoscience, engineering and device fabrication etc. One visionary field for these technologies is nanobionics, an area where the boundaries between electronics and biology become fuzzy.
AFM image of complex: single protein (trypsin) - single wall carbon nanotube deposited on mica On the left: AFM image of complex: single protein (trypsin) - single wall carbon nanotube deposited on mica. These biomolecules (radius of gyration ∼6 nm) adsorb spontaneously on the sidewalls of single-walled carbon nanotubes (SWCNT).
The atomically flat surface is required in order to observe SWCNT with diameter ∼1-1.7 nm. There is no binding of CNT on negatively charge surface of mica in absence of biomolecules.
The coupling of carbon nanotubes with biomolecules represents a prototype system for bio-nanomaterials conjugates, which preludes to the integration of electronic functionality into biomolecular recognition.
(Image: Dr. Eva Bystrenova, ISMN-CNR. Scan size: 80 x 250 nm. The image was obtained by probes NSG11. The image was presented to the NT-MDT probes ProIMAGE Contest 2009)
The equipment
Probe NanoLaboratory NTEGRA Aura Probe NanoLaboratory >NTEGRA Aura performs under controlled atmosphere environments – it is meant for carrying out SPM experiments in low vacuum and controlled environments providing high purity conditions. NTEGRA Aura-wide capabilities allow to produce and investigate the DNA derivatives with electrical properties, as well as to carry out researches in the sphere of molecular biology.
Source: NT-MDT

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