April 17, 2006
Dip-Pen Lithography Creates Active Protein Nanoarrays
Arrays of proteins attached to solid surfaces have become important tools in drug discovery and cancer diagnostics, but in general, the immobilized proteins themselves are inactivated by the processes used to create these arrays. Now, however, researchers at Northwestern University have used dip-pen nanolithography to create arrays of antibodies that retain their ability to bind to their biological substrates.
Reporting its work in the journal Advanced Materials, a team of investigators led by Chad Mirkin, Ph.D., demonstrated that it could use a 26-pen array to create functional antibody spots ranging from 150 to 650 nanometers in diameter on a gold-coated substrate. To accomplish this first, the researchers used the pen array to lay down spots of molecules known as N-hydroxysuccinimide esters, which in turn bind strongly to a genetically engineered protein known as protein A/G. Protein A/G was designed to bind to a specific protein sequence found in many antibodies without adversely affecting the functional characteristics of the antibody.
Once protein A/G is firmly anchored to the array, the researchers then add the antibody, which binds to the linking protein and is then able to bind to its intended target. In the current work, Mirkin and his team prepared multiple arrays with several different antibodies. Each array displayed the same antibody attached to each of the 14,000 spots on the array. The researchers note, though, that dip-pen nanolithography could be used to deposit a different antibody at each spot on the array.
This work is detailed in a paper titled, “Biologically active protein nanoarrays generated using parallel dip-pen lithography.” Mirkin is the principle investigator of the NCI-funded Center for Cancer Nanotechnology Excellence at Northwestern University’s Robert H. Lurie Comprehensive Cancer Center. This paper was published online in advance of print publication. An abstract of this paper is available at the journal’s website.