That synthesis might be undertaken by the direct manipulation of atoms was suggested by Richard Feynman in 1959, although term "nano-technology" (1) was not coined until 1974, by Norio Taniguchi. In 1986, K. Eric Drexler published his book Engines of creation: the coming era of nanotechnology, which contained the notion of a nanoscale "assembler" with the capacity to build copies of itself and other items, by atomic level manipulation. The groundbreaking invention, in 1981, of the scanning tunnelling microscope (STM) demonstrated that individual atoms could be visualised, and the technology was further developed to physically move adsorbed atoms and molecules around on a surface (2). Notable examples (2) demonstrated for publicity purposes are the sign-writing of "IBM" using 35 xenon atoms on a Ni(110) surface, and of "2000" using 47 CO molecules on a Cu(211) surface, by researchers in the eponymous organisation, to auger in the new millennium. Considerably larger molecules can also be moved using an STM tip, for example 1,4-diiodobenzene and biphenyl, which have been towed around on copper surfaces. The tunnelling electrons may also be used to initiate chemical reactions, the products of which can be subsequently manipulated over the surface, so providing proof of chemical change having occurred, e.g. the conversion of iodobenzene to biphenyl. As a definition, nanotechnology (nanotech) can be described as the manipulation of matter over an atomic, molecular, and supramolecular dimension. Molecular nanotechnology is the intention of manipulating atoms and molecules, so to create macroscale products. The prefix "nano" is derived from the Greek word meaning "dwarf". The US National Nanotechnology Initiative (3) defines nanotechnology as, "the manipulation of matter with at least one dimension in the range 1-100 nm", where quantum mechanical effects become increasingly important as the smaller end of the range is accessed. It is critical that the particular materials, and devices made from them, should possess properties that are different from the bulk (micrometric or larger) materials, as a consequence of their small size, which may include enhanced mechanical strength, chemical reactivity, electrical conductivity, magnetism and optical effects (e.g. Figure 1).
One nm is one billionth, or 10 (9), of a metre, which in relative size to a metre is about the same as that of a marble to the Earth (4). Placed in a different context, an average man's beard grows about 1 nm in the time it takes him to lift the razor to his face (4). The lower limit is set by the size of atoms, which are the fundamental building blocks of nanotechnology devices, while the upper limit is of a more arbitrary quality but is of the dimension at which the particular phenomena of the quantum realm begin to appear, which are essential to the nano-device. A device that is merely a miniaturised form of an equivalent macroscopic version does not ascribe to nanotechnology, lacking these particular phenomena, but is classified under the heading microtechnology'. In regard to the fabrication of nanodevices, we find the "bottom-up" approach, where materials and devices are constructed from molecular components which self-assemble via molecular recognition, while in the "top-down" approach, nano-objects are built from larger entities, not involving control at an atomic level (6).
[FIGURE 1 OMITTED]
The plural forms "nanotechnologies" and "nanoscale technologies" thus refer to the many and various aspects, devices and their applications that have in common this scale of the quantum realm. Indeed, there are multifarious potential applications of nanoscale materials, including industrial and military uses, as attested by the investment of $3.7 billion, by the US National Nanotechnology Initiative, $1.2 billion by the European Union and $ 750 million in Japan (1). It may be that nanotechnology can provide advances in medicine, electronics, biomaterials, energy production and, as is the subject of this article, in agriculture and more broadly in the food industry. …