Nanoprinter to Mass-Produce NanoDevices

The capability to generate these complicated devices would make DNA analysis as ordinary and economical as blood testing, thereby significantly speeding up efforts to understand the mechanisms of disease.

The demand for smaller devices of increasing complexity in areas from biomedicine to information technology has prompted several research efforts toward high-resolution, high-throughput nano-printing techniques. Researchers led by Prof. Francesco Stellacci, from the department of materials science and engineering at the Massachusetts Institute of Technology (MIT, Boston, MA, USA) have developed a printing method that is unrivaled in both information content per printing cycle and resolution. They achieved the latter using what Arum Amy Yu, an MIT graduate student and member of the research team, calls "nature's most efficient printing technique: the DNA/RNA information transfer.”

In the new printing technique, called supramolecular nano-stamping (SuNS), single strands of DNA basically self-assemble upon a surface to copy a nano-scale pattern made of their complementary DNA strands. The duplicates are identical to the master and can therefore be used as masters themselves. This increases print output exponentially while enabling the reproduction of very complicated nano-scale patterns.

One of these patterns is found on a DNA microarray, a glass chip or silicon printed with up to 500,000 tiny dots. Each dot is made up of multiple DNA molecules of known sequence, i.e., a snippet of an individual's genetic code. Researchers use DNA microarrays to find and analyze a person's DNA or messenger-RNA genetic code. Frequent, widespread use of these devices is complicated by the fact that producing them is a painstaking process that involves at least 400 printing steps and costs about U.S.$500 per microarray.

MIT's nano-printing technique requires only three steps and could reduce the cost of each microarray to under U.S.$50. "This would completely revolutionize diagnostics,” said Prof. Stellacci. With the ability to mass-produce these devices and thereby make DNA analysis routine, "we could know years in advance of cancer, hepatitis, or Alzheimer's.”

Another advantage would be large-scale diagnostics that could provide beneficial data about disease processes such as diabetes. "We don't know if it's genetic. The only way to find out is to test a lot of people,” said Prof. Stellacci. "The more we test with microarrays, the more we know about illnesses, and the more we can detect them.”

SuNS has applications beyond DNA microarrays. Materials both organic and inorganic (i.e., metal nanoparticles) can be made to assemble along a pattern comprised of DNA strands. This makes SuNS a versatile method that could be used to produce other complex nano-devices currently manufactured slowly and expensively: micro- and nano-fluidics channels, single-electron transistors, metallic wires, and optical biosensors.

A report on the technology was published in May 2005 in the online section of the journal Nano Letters.




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