A new way to study the impact of spatial patterns of chemical and physical properties on living cells has been developed by scientists with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab). Differences of only a few nanometers can determine the fate of a cell — whether it lives or dies, remains normal or turns cancerous.

Berkeley Lab chemist Jay Groves led a study in which artificial membranes made up of a fluid bilayer of lipid molecules were embedded with fixed arrays of gold nanoparticles to control the spacing of proteins and other cellular molecules placed on the membranes. This gave the researchers an unprecedented opportunity to study how spatial patterns on membrane surfaces influence the behavior of cells.

The gold nanoparticle arrays were patterned through a self-assembly process that provides controllable spacing between particles in the array in the important range of 50 to 150 nanometers.

“The gold nanoparticles are similar to the size of a single protein molecule, which gets us to a scale we couldn’t really access before,” says Groves.

Blocking spread of cancer cells

Groves and his team successfully tested their hybrid membranes on a line of breast cancer cells known as MDA-MB-231 that is highly invasive. With their hybrid membranes, the team demonstrated that in the absence of cell adhesion molecules, the membrane remained essentially free of the cancer cells, but when both the nanoparticles and the lipid were functionalized with molecules that promote cell adhesion, the cancer cells were found all over the surface.

Spatial patterning of chemical and physical properties on artificial membranes of lipid bilayers is a time-tested way to study the behavior of cultured biological cells. Natural lipid bilayer membranes surround virtually all living cells as well as many of the structures inside the cell including the nucleus. These membranes provide a barrier that restrains the movement of proteins and other cellular molecules, penning them into their proper locations and preventing them from moving into areas where they do not belong.

Ref.: Theobald Lohmüller et al., Supported Membranes Embedded with Fixed Arrays of Gold Nanoparticles, Nano Letters, 2011 [DOI: 10.1021/nl202847t]