Artificial Cells

Nov 10, 2005

Do cells always have to be developed from organic carbon-containing compounds? When resourceful scientists stretch their imaginations, they quickly find an answer to this question. This is demonstrated by the work of Achim Müller of Bielefeld, Germany, and his co-workers, who have constructed an "artificial cell" from an inorganic macromolecule: a spherical polyoxymolybdate cluster.

Twenty round openings, each surrounded by an alternating series of nine molybdenum and nine oxygen atoms, form pores in the artificial cell membrane. Covalently bound in the interior are twofold negatively charged sulfate groups, which provide for a significant negative charge on the surface of the capsules. Water molecules are also found inside the sphere. Each pore is closed off by a “stopper” consisting of a urea molecule bound to the Mo9O9 ring by noncovalent interactions.

A typical example of biological signaling processes in living cells is a controlled ion flow through special channel proteins in the cell membrane. This can be controlled through the binding of a suitable ligand or by the electrochemical potential across the cell membrane, so ultimately by the difference in concentration of ions inside and outside the cell. Calcium ions (Ca2+) play an important role in many biological functions. For this reason, Müller et al. chose to use Ca2+ for their further experiments. They added Ca2+ ions to an aqueous solution of the molybdate capsules and examined the resulting crystals by X-ray crystal structure analysis, which revealed that not only did the calcium ions wander into capsules but that the urea stoppers were also back in place inside the Mo9O9 pores.

This behavior of the artificial cell mirrors events that unfold in a voltage-gated ion channel in a living cell. Initially, the pores are closed. When an excess of Ca2+ ions is added, their positive charges cancel out the negative charges on the surface of the sphere which changes the electrochemical gradient across the artificial cell membrane. The lids on the pores open, allowing Ca2+ ions to flow into the capsule. This possibly changes the charge distribution across the artificial cell membrane again such that the pores close up.

Source: Angewandte Chemie

Explore further: UC Santa Barbara receives $65M from Munger

add to favorites email to friend print save as pdf

Related Stories

Nanosafety research: The quest for the gold standard

Oct 29, 2014

Empa toxicologist Harald Krug has lambasted his colleagues in the journal Angewandte Chemie. He evaluated several thousand studies on the risks associated with nanoparticles and discovered no end of shortc ...

Surface properties command attention

Oct 17, 2014

Whether working on preventing corrosion for undersea oil fields and nuclear power plants, or for producing electricity from fuel cells or oxygen from electrolyzers for travel to Mars, associate professor ...

Environmental pollutants make worms susceptible to cold

Sep 19, 2014

Some pollutants are more harmful in a cold climate than in a hot, because they affect the temperature sensitivity of certain organisms. Now researchers from Danish universities have demonstrated how this ...

Synthetic molecule makes cancer self-destruct

Aug 11, 2014

Researchers from The University of Texas at Austin and five other institutions have created a molecule that can cause cancer cells to self-destruct by ferrying sodium and chloride ions into the cancer cells.

Researchers solve crystal structure of key biofilm protein

Jan 02, 2013

(Phys.org)—Researchers at the University of Cincinnati (UC) report that they have solved the crystal structure of a protein involved in holding bacterial cells together in a biofilm, a major development in their exploration ...

Recommended for you

UC Santa Barbara receives $65M from Munger

15 hours ago

A physics institute at the University of California, Santa Barbara, has received a $65 million donation—the largest single gift in the university's history.

Genes play a key part in the recipe for a happy country

20 hours ago

Why are the Danes naturally more cheerful than the Brits, and why are we in turn more upbeat than the French? Research presented as part of this year's ESRC Festival of Social Sciences shows us that the recipe behind a happy ...

The economics of age gaps and marriage

21 hours ago

Men and women who are married to spouses of similar ages are smarter, more successful and more attractive compared to couples with larger age gaps, according to a paper from CU Denver Economics Assistant Professor Hani Mansour ...

User comments : 0

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.