Scientists Create and Manipulate Nanoscale
"Water Wires"

Scientists at Brookhaven Lab’s National Synchrotron Light Source are studying how protons move in water at the nanoscale with an eye to implications in other areas of science. Hydrogen fuel cell technology may be one of the beneficiaries.
— By Laura Mgrdichian

Tiny strands of water or “water wires” may give scientists a new view of the properties of water. Brookhaven scientists have created the strands measuring less than one nanometer (a billionth of a meter) in width to look at very small quantities of water, such as that found inside cells, which behave differently than water at the macro-scale.

“Water in cells is distinct from bulk water as we know it,” explained physicist and principal investigator Tom Vogt (see inset at left). “For instance, it can take the form of long chains of single water molecules, which we call ‘water wires’ or ‘water polymers.’ But scientists know very little about water in this form.”

The orientation of the water wires (water molecules are shown as red balls) at room temperature and 200 degrees Celsius. When the wires are heated, they change direction. The yellow balls represent sodium ions.

They do know, however, that water wires are responsible for proton transport across cell membranes, which is one step in the fundamental process by which most organisms produce energy. Scientists understand how proton conduction occurs in bulk water, but not yet in water at the nanoscale. Studying water wires may shed light on the mechanism.

“In order to understand the biological role of water wires, we must relate their structure to the properties they display, such as their stability and how they transport protons,” Vogt said. “Confining very small amounts of water inside minerals and glasses is a good way to model and thus learn about water polymers.”

Vogt and his fellow researchers placed a sample of the mineral natrolite inside a diamond anvil cell, a device that applies very high pressure to a sample using the polished faces of two diamonds. In this case, the pressure was applied after the researchers first surrounded the natrolite sample with a water/alcohol solution. As the high pressure altered the natrolite structure, it also forced water molecules into its empty spaces — a process called pressure-induced hydration. Like tennis balls inserted into a canister, the water molecules nestled one-by-one within the structural framework, forming water wires.