Neutrons are non-destructive, highly penetrating probes, valuable for studying changes in membranes over time. Because they behave like tiny waves of energy, neutrons also make excellent rulers. Depending on temperature, the length of the neutron ruler can be tuned over a range spanning from roughly the size of a single atom to the size of a molecule composed of hundreds or thousands of atoms.
The CNBT team is now building a unique instrument with dual capabilities: diffractometry and reflectometry. It will detect neutrons that are reflected or otherwise scattered after striking membrane samples. Reflected or diffracted neutrons will provide information on the location, orientation, size and composition of membrane components. In addition, the team is upgrading another instrument useful for studying large molecules--a small-angle neutron spectrometer--that will be shared with researchers in other fields.
The instruments are scheduled to be completed in 2003. They will provide cell membrane scientists with access to powerful technologies well beyond the resources of individual researchers.
"This is an extremely hard problem," says NIST biophysicist Susan Krueger, a CNBT collaborator interested in enhancing neutron-based measurement capabilities. "We'll be testing lots of membrane systems and lots of different approaches to capturing the data we need."
The job facing cell-membrane researchers is akin to assembling an intricate and dynamic three-dimensional puzzle. Many pieces have complex contours that not only are unknown but also are subject to change.
"No single instrument or set of
techniques can supply all the missing
information," says NIST's Krueger. In
addition to neutron scattering, an
Contact: Mark Bello (NIST)
National Institute of Standards and Technology (NIST)