Initially, the scientists believe their nano-printing method might be of benefit in making DNA microarrays. Currently manufacturing these devices requires at least 400 printing steps and costs around $500 per microarray. But supramolecular nanostamping would need only three steps and could reduce the cost of each microarray to less than $50. "This would completely revolutionize diagnostics," said Francesco Stellacci of MIT. "The more we test with microarrays, the more we know about illnesses and the more we can detect them."
To carry out the technique, the researchers created a gold master patterned with single-stranded DNA molecules. The molecules were modified with hexyl-thiol so that they bonded to the gold surface. Stellacci and colleagues immersed this master in a solution of complementary DNA (cDNA) strands that were also modified with hexyl-thiol attachment groups. The cDNA hybridized to the DNA strands on the master, with their attachment groups pointing away from the gold substrate. This created double-stranded DNA.
Next the team brought a second gold substrate into contact with the master. The upwards-facing thiol groups of the complementary DNA bonded to this secondary substrate. Heating the structure caused dehybridization of the DNA double strands and left the complementary DNA bonded to the secondary substrate in a replica of the master pattern.
According to the researchers, the technique transfers both spatial and chemical information at the same time. Crucially, it can also print different types of molecules at once, by using a master bonded to several types of DNA and a solution containing each of the relevant types of complementary DNA.
What's more, the researchers believe supramolecular nanostamping is the only printing method where the printed substrate can be reused as a master. This enables an exponential increase in the number of masters and potentially makes the technique suitable for mass production.
The researchers have demonstrated the technique using gold and glass substrates but reckon they could adapt it to many different substrates by using different chemical linkers. And the method could also make use of reversible molecular recognition reactions other than that of DNA, for example receptor-receptand and antibody-antigen binding.
The researchers reported their work in Nano Letters.