Micrographers for non-invasive surgery
Miniature surgical instruments with a diameter of about 0.1 mm, developed at Johns Hopkins University (USA), promise a revolution in many fields of medicine.
Micrographer (microgripper) works in the same way as industrial grapples or surgical instruments that are used, for example, in biopsy, although the developers – David H. Gracias and his laboratory staff – claim that they spied the shape of their invention from crabs. Unlike existing analogues, these micrographers do not injure tissues, do not require the use of mechanical traction or electric motors and can painlessly penetrate into any part of the body.
The six-beam sprocket consists of a polymer core and several layers of metals (the design scheme is shown in the figure at the end of the article). With the help of a magnetic field, one or more of these stars, controlling their position with the help of computer or magnetic resonance imaging, can be brought through the blood vessels to the most inaccessible areas of the body. When the temperature rises to 40 degrees, the plastic softens, allowing the metal paws to shrink and capture a microscopic area of tissue.
Researchers have not yet worked with living objects, but they have learned to masterfully control micrographers in thin, including convoluted, glass capillaries. For training, they used microscopic glass beads, choosing colored ones from a bunch and not touching transparent ones. After that, it was possible to proceed to experiments with living cells.
In pictures from the Hopkins University press release (left to right): imitation of a biopsy from a culture of living cells; a similar, but more complex task is to capture a sample of dense bovine bladder tissue; capture of living cells labeled with a fluorescent marker. In the text of the press release and in additional materials to the article by Timothy G. Leong et al. Tetherless thermobiochemically actuated microgrippers, published in PNAS, there are several videos on which all these tricks can be seen as live – take a look, you won't regret it. At the same time, the cells are not damaged: they remained viable even three days after manipulation.
In the future, micrographers can also be used to deliver cells (for example, "just" stem cells or genetically modified ones) and medicines to the right place. However, for this it is necessary to ensure that the petals of the micro-tool can not only close, but also open under the influence of substances harmless to the body. Now this can be done only with the help of chemicals that are not suitable for use in a living organism – in the figure from the article by Jatinder S. Randhawa et al. Pick-and-Place Using Chemically Actuated Microgrippers, published in the Journal of American Chemical Society, shows how micrographers close in acetic acid solution and slam shut under the action of hydrogen peroxide). To continue the work, the Grazias group received a one and a half million grant from the National Institutes of Health (NIH). In five years, the researchers hope to get a tool suitable for use not only in industry, but also in medicine. And the photolithography technology – the same one used in the manufacture of computer microchips – will allow the production of micrographers to be established without much difficulty.
Portal "Eternal youth" www.vechnayamolodost.ru
15.01.2009