3-D nanoscale structure of the inside of a synthetic calcite crystal grown in an agarose gel. In this environment, the crystal grows around the polymeric fibers. Credit: Estroff/Muller labs

Materials scientists continue to try to understand how biological systems are able to create superior crystalline materials such as the calcite found in sea shells, sea urchin spines and even algae. One group of these biomineralization investigators is led by Lara Estroff, a Cornell University assistant professor of materials science and engineering. She and her colleagues are studying how lab-created calcite crystals grow in tandem with proteins and other large molecules. They reported their findings in the Nov. 27 issue of the journal Science.

“We knew the organics were in there, but what no one had been able to do up until now was actually see what that organic-inorganic interface looked like,” said Estroff, whose lab focuses on the synthesis and characterization of bio-inspired materials.

Estroff and graduate student Hanying Li grew samples of calcite in a hydrogel called agarose. Li and Estroff already had determined that this gel environment made the crystals grow very differently than in solution. This time, the researchers prepared their crystals with Focused Ion Beam technology to slice samples thin enough for an electron beam to pass through for imaging.

Scanning transmission electron microscopy methods developed by associate professor of applied and engineering physics David Muller and physics graduate student Huolin Xin revealed that the crystals trap large molecules by growing around them.

Estroff says their research provides more ideas on how to make and manipulate nature-inspired composite materials. They say the applications could range from electronics to photovoltaics to completely new classes of materials.