Modular construction—on a molecular scale

June 13, 2016, US Department of Energy
A cage-like protein (gray) called ferritin was engineered to have metal hubs (blue) on its surface. Organic molecules (purple) can bridge these metal hubs, controllably creating a porous, crystalline material with potential applications ranging from catalysis to separations. Credit: F. Akif Tezcan, University of California, San Diego

Modular constructions from cages (proteins), hubs (metal ions), and struts (organic linkers) allows the rational design of porous scaffolds. The inherent chemical and structural diversity of these building blocks leads to a new class of versatile, self-assembled materials.

This is the first instance where synthesis of a crystalline framework in which proteins as well as and organic molecules are essential construction components. This new fabrication route to functional materials has potential applications such as hydrogen fuel storage and carbon capture.

Formation of a 3-dimensional (3D) porous, crystalline framework material—formed by spherical proteins that assemble via directed interactions between these proteins, metal ions, and organic linkers—has been realized for the first time. Proteins hold great potential as for due to their wide range of available chemical and structural motifs combined with exquisite capabilities for catalysis and electron transfer. However, successful design and synthesis of 3D protein crystals is rare. Considerably more success in synthesizing crystalline materials has been achieved using small organic and inorganic building blocks, particularly the versatile metal-organic frameworks (MOFs) for purification and catalytic applications.

Researchers at the University of California, San Diego engineered a spherical, cage-like (ferritin) to display eight on its surface in a symmetrical fashion. These surface zinc ions were analogous to small metal hubs in MOFs. Bifunctional organic linkers then bridged the zinc ions between two proteins, causing the nanoscale metal hubs to self-assemble into a predicted 3D crystalline lattice arrangement. The resulting crystals were highly porous, had very high solvent content, and allowed the proteins to perform their native enzymatic activity (transforming soluble iron ions into crystalline iron oxides). This new self-assembly strategy could lead to new materials for catalysis and separations.

Explore further: Don't call them stiff: Metal organic frameworks show unexpected flexibility

More information: Pamela A. Sontz et al. A Metal Organic Framework with Spherical Protein Nodes: Rational Chemical Design of 3D Protein Crystals, Journal of the American Chemical Society (2015). DOI: 10.1021/jacs.5b07463

Related Stories

Porous, layered material can serve as a graphene analog

May 19, 2015

An electrically conductive material, with layers resembling graphene (single sheet of graphite), was synthesized under mild conditions using a well-known molecule that allows good electronic coupling of nickel ions and organic ...

Recommended for you

Fish-inspired material changes color using nanocolumns

March 20, 2019

Inspired by the flashing colors of the neon tetra fish, researchers have developed a technique for changing the color of a material by manipulating the orientation of nanostructured columns in the material.


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.