Nano particle self assembly 'photographed'

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Researchers claim to have imaged the self assembly of nanoparticles, opening the possibility of a blueprint for building designer molecular machines atom by atom.

The researchers at the University of Glasgow, along with colleagues at the University of Bielefeld, Germany, have devised an experiment which enabled them to observe molecules being constructed around what appeared to be a transient template cluster. The experiment involved the construction a flow reactor system for the assembly of the nano particles under dynamic 'flowing' conditions. This new experimental approach allows self assembly to be examined in a new way at the nano level, giving rise to what the researchers describe as 'unprecedented mechanistic information' unmasking the complexities of molecular self assembly. During the experiment, the researchers observed the self assembly of molybdenum oxide wheel molecules around an intermediate structure in the centre of the wheel which they found to be the 'template' or scaffold used to construct the larger molecule. Following completion of the molybdenum oxide wheel molecule, which is 3.6 nanometres in diameter, the template was ejected, freeing it to repeat the process. The researchers were able to 'photograph' this process and the template using X-ray crystallography. Prof Leroy Cronin, (pictured) gardiner chair of chemistry, Department of Chemistry, who devised and led the study, said: "This advance is very important since in the construction of molecular nano objects we must rely on 'self assembly' where the nano scale objects builds itself – a process which is almost impossible to understand or control using current step wise chemical synthesis approaches. Therefore, understanding the assembly process is vital if we are to create a new range of functional nano objects." This discovery, says Prof Cronin, could lead the way for the designed assembly of a range of precisely defined nano particles with a host of applications in electronics. Prof Cronin added that it could, "allow the design of intelligent or smart nano sensors and nano functional machines, not to mention the fundamental implications regarding the assembly of complex chemical systems, the most spectacular example of which are living cells." Although it is currently possible to synthesise many substances and materials in chemistry through the interactions of different compounds, at the nanoscale the task becomes almost impossible because it becomes harder to control. Cronin explained: "This result is massively interesting, not only do we get to 'image' self assembly for the first time using this type of flow system, this discovery will allow us to devise new types of blueprint that could allow the assembly of a whole new class of designer nano particles opening a whole new world of discoveries and applications."