Glowing spirals: Chemical scaffolds guide living cells into precisely defined three-dimensional patterns

March 7, 2011
Glowing spirals: Chemical scaffolds guide living cells into precisely defined three-dimensional patterns

(PhysOrg.com) -- To find our way, we use maps. Cells use "chemical maps" to find the way: they orient themselves by following concentration gradients of attractants or repellants. David H. Gracias and a team at Johns Hopkins University (Baltimore, USA) have now developed a clever new method to produce three-dimensional patterns of chemical concentration gradients in vitro -- with previously unattainable versatility and precision in both space and time.

As the scientists report in the journal Angewandte Chemie, they use tiny containers of different shapes and patterned with different arrangements of slits through which substances can diffuse. They were thus able to induce fluorescing cells to organize themselves into a glowing green spiral.

Concentration gradients not only can guide bacteria, , and amoebae; they are also very important in the early stages of because the development of seed leaves (cotyledon) is controlled through concentration gradients of . Three-dimensional chemical patterns play a role in many physiological and pathological processes, including the growth of blood vessels, regulation of blood pressure and , and . Our also follow concentration gradients to find the spot where they are needed.

In order to examine these processes more closely, scientists want to imitate such chemical gradients in vitro. Making a three-dimensional chemical pattern and maintaining it long enough is not so easy. Previous microfluidic methods only allowed for the generation of two-dimensional patterns of limited size. An alternative technique discussed here is the diffusion of chemicals through precisely formed porous containers in stationary media. Variation of the container geometry and pore pattern in the walls makes it possible to realize a wide variety of three-dimensional concentration patterns.

The special trick: Gracias and his co-workers “build” their containers from two-dimensional surfaces held together with tiny hinges. These were designed so that the containers fold up on their own when heated and then stay tightly closed on cooling. In this way, they are able to make containers ranging in size from 100 nm to a few millimeters for potential applications at the sub-cellular to tissue scale. Before being folded, established lithographic methods can be used to perforate each surface with a well-defined arrangement of slits or holes with nano-microscale precision.

With an offset arrangement of slits on four surfaces of a cube shaped container, the researchers were able to release an attractant to generate a concentration gradient in the form of a spiral winding around the container. Fluorescing bacteria followed this pattern and arranged themselves into a glowing spiral.

Explore further: Designer Gradients Speed Surface Science Experiments

More information: David Gracias, Direction of Cellular Self-Organization by the Generation of Three- Dimensional Chemical Patterns, Angewandte Chemie International Edition 2011, 50, No. 11, 2549–2553, dx.doi.org/10.1002/anie.201007107

Related Stories

Designer Gradients Speed Surface Science Experiments

June 8, 2006

Researchers from the National Institute of Standards and Technology have demonstrated an elegantly simple technique for synthesizing a wide variety of complex surfaces that vary in a controlled fashion across a test strip. ...

Container transport on a nano scale

September 6, 2006

Lock one or more molecules up within a cage of nanometer dimensions. Take this ‘nanocontainer’ to the desired spot and free the molecules. Or keep them locked up for a while and introduce other molecules into the container, ...

Close encounters with 3-D cell growth

December 16, 2008

(PhysOrg.com) -- MIT engineers have built a device that gives them an unprecedented view of three-dimensional cell growth and migration, including the formation of blood vessels and the spread of tumor cells.

Recommended for you

Brazilian wasp venom kills cancer cells by opening them up

September 1, 2015

The social wasp Polybia paulista protects itself against predators by producing venom known to contain a powerful cancer-fighting ingredient. A Biophysical Journal study published September 1 reveals exactly how the venom's ...

Naturally-occurring protein enables slower-melting ice cream

August 31, 2015

(Phys.org)—Scientists have developed a slower-melting ice cream—consider the advantages the next time a hot summer day turns your child's cone with its dream-like mound of orange, vanilla and lemon swirls with chocolate ...

Antibody-making bacteria promise drug development

August 31, 2015

Monoclonal antibodies, proteins that bind to and destroy foreign invaders in our bodies, routinely are used as therapeutic agents to fight a wide range of maladies including breast cancer, leukemia, asthma, arthritis, psoriasis, ...

0 comments

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.