Researchers at Cornell University’s department of applied and engineering physics have addressed the issue of microarray spot uniformity, shape, and resolution, by exploiting the principle of a childhood drawing aid—the stencil.
“Our parylene peel-array technology centers on a simple concept of a polymer stencil placed on top of the surface of the array,” explained Christine Tan, the technology’s developer. “The stencil acts as a physical constraint for spotted biomolecules, so you can deposit your molecules by whatever method you choose over the top, and then peel off the parylene layer to leave highly uniform spots. The technology can be used to generate any size, shape, or density of spot pattern.
“Some of our most recent work has even demonstrated the feasibility of generating nanometer-sized array features with nanoscale resolution comparable to existing printing technologies like dip-pen lithography. This could potentially allow the future production of nanoarrays using existing arrayjet printers or spotters, which are currently only capable of printing spots with diameters in the 10–100s of microns range.”
The flexibility of the system is inherent in its simplicity, Tan said. “The peel-arrays can be used either as stand-alone technology, to generate large uniform arrays of any biomolecule or even cells, or as a complement to any existing microarray-spotting method. The stencils act to cleanup print-spot morphology and can facilitate the printing of multiple species on a surface.
“When combined with standard DNA-printing instrumentation, for example, we have shown the reproducibility of DNA microarrays is significantly improved. By reducing the traditional DNA-drying artefacts of donut-shaped spots, we can make the standard deviations of DNA microarray experiments much smaller.”
Importantly, the peel-array technology can be used in wet or dry environments and has demonstrated major benefits in applications such as patterning lipid bilayers and proteins, where hydration is required to maintain bilayer and protein integrity, Tan added.
Additional studies with patterning fibronectin have confirmed that by using the parylene peel-arrays the protein retains its 3-D conformity and functionality for cell binding. “The parylene stencils allow users to pattern molecules and keep them hydrated. We have also used the stencils to generate uniform, large-area arrays of single tumor cells to investigate the role of cell-cell interaction in cancer, and to pattern lipid bilayers embedded with antigen for studying immune cell activation.”
Tan is looking for investors to start a business. “This is a useful technology with many potential applications in drug screening, cancer studies, biosensors, and basic science research,” she said. “We hope to make this simple and adaptable product available to everyone who uses microarrays.”