Researchers are exploring several ways to imitate biology at the submicrometer level.

One approach tries to inorganically duplicate biological materials that have extraordinary properties, such as those of geckos, which can cling even to smooth surfaces when upside down because of capillary and van der Waals forces between the surface and densely packed 200-nm-wide keratin hairs on the soles of their feet.

A second major biomimetic approach uses natural or newly designed proteins to create nanostructures. Bacteria form a one-molecule-thick layer of crystalline proteins on their exteriors, called S-layers, which repeat on a 10-nm crystalline grid.

Other researchers are experimenting with using proteins’ ability to specifically bind with each other and with inorganic materials as a way to build new materials. One of the characteristics of biologically produced nonliving materials, such as abalone shell and spider silk, is a hierarchical structure. This structuring often imparts remarkable characteristics to a material, such as silk’s great strength.

However, scientists as yet cannot predict the shape of proteins or their binding properties just from the sequences of their constituent amino acids, because protein- folding simulations have not advanced that far.

An alternative approach selects proteins with the desired binding properties from a large number of randomly generated molecules. This can be done by the genetic engineering of bacteriophage viruses.

Researchers are using this at various laboratories to create a library of proteins that bind to specific elements and inorganic compounds. These could be used in the assembly of nanoparticles into specific nanoscale devices, such as quantum dots.

Other approaches use viruses or DNA as part of the structure itself.