Nanoneedle

Nanoneedles may be conical or tubular needles in the nanometre size range, made from silicon or boron-nitride with a central bore of sufficient size to allow the passage of large molecules, or solid needles useful in Raman spectroscopy, light emitting diodes (LED) and laser diodes.

In 2005 the Research Institute for Cell Engineering at Japan's National Institute of Advanced Industrial Science and Technology (AIST) and Tokyo University of Agriculture and Technology used nanoneedles controlled by an atomic force microscope (AFM) to penetrate the nucleus of living cells and insert molecules of nucleic acid, proteins or possibly to carry out cell surgery. The technique can accurately establish the position of the needle by monitoring the force exerted. Cells to be used for tracking, diagnosing, and treatment of illness may be removed from the body and replaced after being injected. The 100 nm diameter needles were cut from silicon AFM tips using focused ion beam etching.

The University of California, Berkeley in 2008 produced gallium arsenide (GaAs) nanoneedles which emit extremely bright light, though not yet lasers, when optically pumped. With a length of 3-4 micrometres, they taper to tips of 2-5 nm across. In addition to optoelectronic devices, the needles will be useful in atomic force microscopy (AFM), and can be easily grown in arrays. Such AFM arrays, besides producing near-atomic resolution images of surfaces, could lead to new forms of data storage by direct manipulation of atoms. The needles may also find a use in tip-enhanced Raman spectroscopy, a process in which molecular energy levels are measured by comparing the frequency of incident light with that of outgoing light. A sharp needle tip allows for a more precise examination of the sample, down perhaps to that of single molecules.

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