{"id":18919,"date":"2009-06-16T15:10:00","date_gmt":"2009-06-16T15:10:00","guid":{"rendered":"http:\/\/198.74.50.173\/2009\/06\/controllable-dna-binding-on.html"},"modified":"2017-04-07T05:29:07","modified_gmt":"2017-04-07T05:29:07","slug":"controllable-dna-binding-on","status":"publish","type":"post","link":"https:\/\/www.nextbigfuture.com\/2009\/06\/controllable-dna-binding-on.html","title":{"rendered":"Controllable DNA binding on Nanoparticles"},"content":{"rendered":"

\"\"id=\"BLOGGER_PHOTO_ID_5347944091547381170\"<\/a>
The novel DNA ‘sticky ends’ can form intra-particle loops and hairpins (e.g. schemes II & III), giving more control over the particles’ interactions than conventional sticky ends that can only form inter-particle bridges (scheme Ia).<\/i><\/p>\n

Researchers at New York Univ. have created a method to precisely bind nano- and micrometer-sized particles together into larger-scale structures with useful materials properties. <\/a> [H\/T CRNANO: Breakthrough! Particle Assembly Technique.<\/A><\/p>\n

Their work, which appears in the latest issue of the journal Nature Materials, overcomes the problem of uncontrollable sticking, which had been a barrier to the successful creation of stable microscopic and macroscopic structures with a sophisticated architecture.<\/p>\n

In order to obtain self-replication, the researchers coat micrometer-sized particles with short stretches of DNA, so-called “sticky ends”. Each sticky end consists of a particular sequence of DNA building blocks and sticky ends with complementary sequences form very specific bonds that are reversible. Below a certain temperature, the particles recognize each other and bind together, while they unbind again above that temperature. This enables a scheme in which the particles spontaneously organize into an exact copy on top of a template, which can then be released by elevating the temperature.<\/p>\n

Scientists have used DNA-mediated interactions before, but it has always been very difficult to bind only a subset of particles\u2014usually, either all particles or no particles are bound. This makes it challenging to make well-defined structures. Therefore, the NYU team, comprised of researchers in the Physics Department’s Center for Soft Matter Research and in the university’s Department of Chemistry, sought to find a method to better control the interactions and organization of the particles.<\/p>\n

\u201cWe can finely tune and even switch off the attractions between particles, rendering them inert unless they are heated or held together\u2014like a nano-contact glue,\u201d said Mirjam Leunissen, a post-doctoral fellow in the Center for Soft Matter Research and the study\u2019s lead author. <\/p>\n

To maneuver the particles, the team used optical traps, or tweezers. This tool, created by David Grier, chair of NYU\u2019s Department of Physics and one of the paper\u2019s authors, uses laser beams to move objects as small as a few nanometers, or one-billionth of a meter. <\/p>\n

The work has a range of possible applications. Notably, because the size of micrometer-scale particles\u2014approximately one-tenth the thickness of a strand of human hair\u2014is comparable to the wavelength of visible light, ordered arrays of these particles can be used for optical devices. These include sensors and photonic crystals that can switch light analogous to the way semi-conductors switch electrical currents. Moreover, the same organizational principles apply to smaller nanoparticles, which possess a wide range of electrical, optical, and magnetic properties that are useful for applications. <\/p><\/blockquote>\n