Technology developed for the manufacture of aeroplane parts is being hijacked to produce the next generation of biomedical materials. Sara Abdulla reports.
Every year 20,000 Americans die for want of an organ transplant. But synthetic alternatives to donated organs still leave a lot to be desired. Now, new technology spawned by a collaboration between physicians and materials scientists is paving the way for the next generation of tissue engineering.
"The problem with the stuff we use to make organ replacements at the moment is that it's nothing like real tissue," says Linda Griffith of the Massachusetts Institute of Technology, speaking at this week's 'Bench to Bedside and Back' conference at the Harvard Medical School: "it is made up of a tangled mess of fibres like the felt of a Christmas stocking."
To get round this, Griffith and colleagues are using a technique called 3D powder printing - perfected for the manufacture of military vehicles and missiles - to mimic the exquisite detail of the mass of blood vessels that make up organs such as the heart. 3D powder printing allows a structure of great complexity to be built up as a stack of wafer-thin layers, each of which supports the formation of the next.
These layers are made by a roller that pushes powdered polymer across a flat plate that is supported by a piston. Next, minuscule beads of glue are sprayed onto the powder layer in the places where the next layer needs to stick. The piston is notched down a tiny amount and the process is repeated. Finally the layered structure is removed from the plate, whereupon the unwanted powder falls away, leaving only the required object.
Originally this technique was developed for use with ceramic powders. Griffith and colleagues have modified the process so that it can be used with biodegradable polymers that will form a supporting structure upon which the body can lay down its own material. The resolution obtained with ceramics meant that the printing could produce channels of around 40 micrometres (thousandths of a millimetre) across with walls about 20 micrometres thick. So far, bio-polymer resolution is lagging behind slightly, so the team is working both on refining the process and on ways of persuading the body to carry out its own smaller scale organization on the basis of a larger-scale implant. Use in humans, however is still many years down the line.
Meanwhile, the existing technology has found an alternative use. Griffith and colleagues have received a five-million-dollar grant from the US defence department to look into using their 3D powder printed polymer as a bio-filter-and-alarm system with which agents of chemical warfare might be detected and their interactions with human tissue assessed
http://www.nature.com/news/1999/991014/full/news991014-5.html
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