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: Youth migration is changing definitions of childhood

add to favorites email to friend print save as pdf

Related Stories

Microfluidics to accelerate cell membrane research

Jan 07, 2015

Life processes depend fundamentally on phenomena occurring on the membranes separating cells from their environment. Hitherto poorly understood, the mechanisms responsible for transport through the cell membrane ...

Patent issued for substance with medical benefits

Nov 04, 2014

A novel jelly-like substance developed by Kansas State University researchers was recently issued a U.S. patent. The substance may be used for biomedical applications, ranging from cell culture and drug delivery to repairing ...

Recommended for you

When aid brings conflict, not relief

1 hour ago

Although you might expect that providing aid to impoverished villages in the Philippines could only bring them relief, a University of Illinois study found that the villages that qualified for some forms of aid actually saw ...

New tattoos discovered on Oetzi mummy

4 hours ago

With the aid of a non-invasive photographic technique, researchers at the EURAC-Institute for Mummies and the Iceman have been able to show up all the tattoos on the man who was found preserved in a glacier, ...

Study identifies common elements of STEM schools

5 hours ago

Science, technology, engineering and mathematics schools vary in many ways, but they share eight major common elements. So finds a nationwide study of 23 STEM schools conducted by the University of Chicago's Outlier Research ...

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.