New Technique Used to Create DNA Nanostructures

Originally Published MDDI November 2002

R&D DIGEST

A technique capable of making minute patterns of DNA molecules on surfaces could provide the basis for developing faster, more-powerful devices for DNA sequencing, biological sensors, and disease diagnosis. Chemists at the University of California, Davis, and Wayne State University (Detroit) say they have developed such a technique. The method, called nanografting, can be used to make DNA patterns that are up to a thousand times smaller than those in commercially available microarrays, says UC Davis chemist Gang-yu Liu, who developed the method in collaboration with Christine Chow at Wayne State University and UC Davis graduate students Maozi Liu and Nabil Amro.

Says Liu, "We believe these are the smallest nanostructures of DNA yet made." DNA lines as small as 15 nm across by 150 nm long—equivalent to eight DNA molecules across—were created. The researcher adds the same method can be used to make structures as small as 2 by 4 nm.

The patterns are made by coating a gold film with long, closely-packed molecules called thiols. The thiols attach to the gold through a sulfur atom at one end, and stand upright. An atomic force microscopy probe is then used to remove a portion of the thiols. Short pieces of DNA, oligonucleotides, which have thiols attached at one end, are then added. The thiols bond the DNA head-first onto the exposed gold so that each DNA piece stands up above the thiol layer.

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