Friday, October 8, 2010

This week in nanotechnology, October 8, 2010

The Royal Swedish Academy of Sciences has decided to award the Nobel Prize in Physics for 2010 to Andre Geim and Konstantin Novoselov, University of Manchester, "for groundbreaking experiments regarding the two-dimensional material graphene".

In recent years, studies have shown that for many types of cancer, combination drug therapy is more effective than single drugs. However, it is usually difficult to get the right amount of each drug to the tumor. Now researchers at MIT and Brigham and Women's Hospital have developed a nanoparticle that can deliver precise doses of two or more drugs to prostate cancer cells.

The enigmatic Möbius strip has long been an object of fascination, appearing in numerous works of art, most famously a woodcut by M.C. Escher, in which a tribe of ants traverses the form's single, never-ending surface. Scientists have now reproduced a nanoscale Möbius strip, joining up braid-like segments of DNA to create Möbius structures measuring just 50 nanometers across—roughly the width of a virus particle. Eventually, researchers hope to capitalize on the unique material properties of such nano-architectures, applying them to the development of biological and chemical sensing devices, nanolithography, drug delivery mechanisms pared down to the molecular scale and a new breed of nanoelectronics.
nanoscale DNA Möbius strip
This is the design for the DNA Möbius strip. Single-stranded viral DNA is used as scaffolding and 164 short segments of DNA are used as staple strands, to create the nanostructure. The Möbius form is composed of eleven double helices, assembled in parallel (left). Each double-helical length contains a twist of 180 degrees along its central axis, before it seamlessly reconnects with itself. The central helix, (seen in red) circles around the length of the strip once. The other helices circle twice, while also twisting around the core helix by 180 degrees before reconnecting to close the Möbius loop. (Center) A small segment of the strip with the details of the helices shown. Scaffold strands are seen in blue and staple strands are different colors. To create the Möbius, 20.5 units like this were used, with the precise folding pattern pre-programmed through the design of appropriate nucleotide base-pairing. (Right) Atomic Force Microscopy image.

Early detection is critical for improving cancer survival rates. Yet, one of the deadliest cancers in the United States, lung cancer, is notoriously difficult to detect in its early stages. Now, researchers have developed a method to detect lung cancer by merely shining diffuse light on cells swabbed from patients' cheeks. Nanoscale disturbances in cheek cells indicate the presence of lung cancer. Regular microscopy looking at chromatin, the genetic material inside a cell's nucleus, will not reveal significant dissimilarities between the cheek cells of a healthy person and those of a lung cancer patient. However, a new technique called partial wave spectroscopic microscopy (PWS) zeroes in on smaller-than-microscopic disturbances at the nano-level, which are harbingers of trouble.

Cornell researchers have developed a new method to create a patterned single-crystal thin film of semiconductor material that could lead to more efficient photovoltaic cells and batteries. The "holy grail" for such applications has been to create on a silicon base, or substrate, a film with a 3-D structure at the nanoscale, with the crystal lattice of the film aligned in the same direction (epitaxially) as in the substrate. Doing so is the culmination of years of research into using polymer chemistry to create nanoscale self-assembling structures.