DNA TRIGGERS SHAPE...
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DNA triggers shape-shifting in hydrogels, opening a new way to make 'soft
robots'
Summary:
Biochemical engineers have used sequences of DNA molecules
to induce shape-changing in water-based gels, demonstrating a new tactic to
produce "soft" robots and "smart" medical devices that do
not rely on cumbersome wires, batteries or tethers.
Biochemical engineers at the Johns
Hopkins University have used sequences of DNA molecules to induce
shape-changing in water-based gels, demonstrating a new tactic to produce
"soft" robots and "smart" medical devices that do not rely on
cumbersome wires, batteries or tethers.
The research advance, supervised by
three faculty members in the university's Whiting School of Engineering, is
detailed in the Sept. 15 issue of the journal Science.
The team members reported that their
process used specific DNA sequences called "hairpins" to cause a
centimeter-size hydrogel sample to swell to 100 times its original volume. The
reaction was then halted by a different DNA sequence, dubbed a "terminator
hairpin."
This approach could make it possible
to weave moving parts into soft materials. The researchers have suggested that
their process could someday play a role in creating smart materials,
metamorphic devices, complex programmed actuators and autonomous robots with
potential marine and medical applications.
To control how shape-shifting occurs
in different parts of the target hydrogel, the researchers took a cue from the
computer industry. They employed a photo-patterning technique similar to the
one used to make tiny but intricate microchips. Various biochemical patterns
embedded in different regions of the gel were designed to respond to specific
DNA instructions to cause bending, folding or other responses.
"DNA sequences can be thought
of as an analog to computer code," said David H. Gracias, a professor in
the university's Department of Chemical and Biomolecular Engineering, and one
of two senior authors of the Science article. "Just as computer software
can direct specific tasks, DNA sequences can cause a material to bend or expand
in a certain way at a specific site."
He added that this is not an unusual
occurrence in nature. "Shape changing is very important in biology,"
Gracias said. "Think about how a caterpillar turns into butterfly."
The study's other senior author,
Rebecca Schulman, is an assistant professor in the same department. Her
research group designs intelligent materials and devices using techniques from
DNA nanotechnology. "We've been fascinated by how living cells can use
chemical signals to decide how to grow or move and use chemical energy to power
themselves," she said. "We wanted to build machines that could act in
a similar way. Our fabrication technology makes it possible to design very
complicated devices in a range of sizes."
Thao (Vicky) Nguyen, a Johns Hopkins
expert in the mechanics of polymers and biomaterials, provided key
contributions to the research and was a co-author of the paper. "Using
computer simulations, we developed a design rule to transform the large
swelling of the hydrogel into the desired shape-change response," she
said. Nguyen is an associate professor and the Marlin U. Zimmerman Jr. Faculty
Scholar in the Department of Mechanical Engineering."
To confirm their ability to control
which hydrogel targets were activated, the team members used DNA
sequence-responsive flower-shaped hydrogels. In each "flower," two
sets of petals were fabricated, and each set was designed to respond only to
one of two different DNA sequences. When exposed to both sequences, all of the
petals folded in response. But when they were exposed to just one of the
sequences, only the petals matched to that sequence folded.
The team also fabricated hydrogel
crab-shaped devices in which the antennae, claws and legs each curled up in in
response to their matching DNA sequence. The crab devices remained in their
actuated state for at least 60 days. The crab shape was selected in honor of
the popular seafood served in the university's home state of Maryland.
The new technology detailed in the Science
paper is protected by a provisional patent obtained through the university's
Johns Hopkins Tech Ventures office.
DNA triggers shape-shifting in hydrogels, opening a new way to make 'soft robots'
Summary:
Biochemical engineers have used sequences of DNA molecules
to induce shape-changing in water-based gels, demonstrating a new tactic to
produce "soft" robots and "smart" medical devices that do
not rely on cumbersome wires, batteries or tethers.
Biochemical engineers at the Johns
Hopkins University have used sequences of DNA molecules to induce
shape-changing in water-based gels, demonstrating a new tactic to produce
"soft" robots and "smart" medical devices that do not rely on
cumbersome wires, batteries or tethers.
The research advance, supervised by
three faculty members in the university's Whiting School of Engineering, is
detailed in the Sept. 15 issue of the journal Science.
The team members reported that their
process used specific DNA sequences called "hairpins" to cause a
centimeter-size hydrogel sample to swell to 100 times its original volume. The
reaction was then halted by a different DNA sequence, dubbed a "terminator
hairpin."
This approach could make it possible
to weave moving parts into soft materials. The researchers have suggested that
their process could someday play a role in creating smart materials,
metamorphic devices, complex programmed actuators and autonomous robots with
potential marine and medical applications.
To control how shape-shifting occurs
in different parts of the target hydrogel, the researchers took a cue from the
computer industry. They employed a photo-patterning technique similar to the
one used to make tiny but intricate microchips. Various biochemical patterns
embedded in different regions of the gel were designed to respond to specific
DNA instructions to cause bending, folding or other responses.
"DNA sequences can be thought
of as an analog to computer code," said David H. Gracias, a professor in
the university's Department of Chemical and Biomolecular Engineering, and one
of two senior authors of the Science article. "Just as computer software
can direct specific tasks, DNA sequences can cause a material to bend or expand
in a certain way at a specific site."
He added that this is not an unusual
occurrence in nature. "Shape changing is very important in biology,"
Gracias said. "Think about how a caterpillar turns into butterfly."
The study's other senior author,
Rebecca Schulman, is an assistant professor in the same department. Her
research group designs intelligent materials and devices using techniques from
DNA nanotechnology. "We've been fascinated by how living cells can use
chemical signals to decide how to grow or move and use chemical energy to power
themselves," she said. "We wanted to build machines that could act in
a similar way. Our fabrication technology makes it possible to design very
complicated devices in a range of sizes."
Thao (Vicky) Nguyen, a Johns Hopkins
expert in the mechanics of polymers and biomaterials, provided key
contributions to the research and was a co-author of the paper. "Using
computer simulations, we developed a design rule to transform the large
swelling of the hydrogel into the desired shape-change response," she
said. Nguyen is an associate professor and the Marlin U. Zimmerman Jr. Faculty
Scholar in the Department of Mechanical Engineering."
To confirm their ability to control
which hydrogel targets were activated, the team members used DNA
sequence-responsive flower-shaped hydrogels. In each "flower," two
sets of petals were fabricated, and each set was designed to respond only to
one of two different DNA sequences. When exposed to both sequences, all of the
petals folded in response. But when they were exposed to just one of the
sequences, only the petals matched to that sequence folded.
The team also fabricated hydrogel
crab-shaped devices in which the antennae, claws and legs each curled up in in
response to their matching DNA sequence. The crab devices remained in their
actuated state for at least 60 days. The crab shape was selected in honor of
the popular seafood served in the university's home state of Maryland.
The new technology detailed in the Science
paper is protected by a provisional patent obtained through the university's
Johns Hopkins Tech Ventures office.
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