From a runny nose and watery eyes triggered by pollen in the air to a life threatening shock set off by a bee sting, allergic reactions are often whole-body responses initiated by individual cells responding to their immediate environment on the molecular level.

Cell biologists have made recent progress in identifying the many molecules that combine to mediate a wide variety of cellular responses, but much less is known about how the receptors for the environmental stimuli on a cell's surface orchestrate the spatial assembly of the intracellular signaling pathways.

But that's changing with the advent of new materials engineered at the micro- and nanoscale, said Barbara Baird, professor of chemistry and chemical biology, at the annual meeting of the American Academy for the Advancement of Science (AAAS) in San Diego Feb. 21. And better understanding those intracellular structural rearrangements could have a wide variety of applications, from new ways of diagnosing and treating disease to better materials for medical implants, Baird said.

With collaborators in engineering and materials sciences and at the Cornell Nanobiotechnology Center, researchers in Baird's laboratory use wafers that are etched and/or chemically modified with micron-sized features (micropatterned arrays) to study how receptors bind to specifically engineered stimulus proteins, or ligands.

Baird's work focuses on mast cells, which play a central role in the allergic immune response. Using fluorescence microscopy, she can observe the process in which immunoglobulin E (IgE), tightly associated with receptors on the cell membrane, binds with ligands to trigger a cellular response with a spatially controlled mechanism. (Mast cells are about 10 microns in diameter; receptors are about 10 nanometers. A micron is one-millionth of a meter; a nanometer is one-billionth of a meter.)

"Now we can control the environment that the cell sees on the [same] length scale that it's seeing in its native environment," Baird said in an earlier interview.

The researchers are also using surfaces coated with polymers of different thicknesses, compositions and dimensions (relative to the diameter of the cell) to study how cells interact with various surfaces. That work could lead to materials engineered to elicit or inhibit certain cellular responses.

"You use [nanotechnology] to probe the system, and then you can take advantage of that knowledge to manipulate the system," Baird said. Understanding what makes cells adhere or not adhere to a surface could be key in developing materials for medical implants, for example; the same materials can be adapted to bind specific receptor proteins in biosensors to detect the presence of certain antibodies in the blood.

Interdisciplinary collaboration is crucial in nanobiotechnology, Baird noted. "You have to have this very close interaction between the engineers and the biologists in making the right tools that ask the right questions," she said.