UC San Diego researchers have developed
a "living material," made of a natural polymer combined with
genetically engineered bacteria, that could offer a sustainable and
eco-friendly solution to clean pollutants from water. Credit: David Baillot/UC
San Diego Jacobs School of Engineering
Researchers
at the University of California San Diego have developed a new type of material
that could offer a sustainable and eco-friendly solution to clean pollutants
from water.
Dubbed an "engineered living
material," it is a 3D-printed structure made of a seaweed-based polymer
combined with bacteria that have been genetically engineered to produce an
enzyme that transforms various organic pollutants into benign molecules. The
bacteria were also engineered to self-destruct in the presence of a molecule
called theophylline, which is often found in tea and chocolate. This offers a
way to eliminate them after they have done their job.
The researchers describe the new
decontaminating material in a paper published in Nature
Communications.
"What's innovative is the pairing
of a polymer material with a biological system to create a living material that
can function and respond to stimuli in ways that regular synthetic materials
cannot," said Jon Pokorski, a professor of nanoengineering at UC San Diego
who co-led the research.
The work was a collaboration among engineers, materials scientists and biologists at the UC San Diego Materials Research Science and Engineering Center (MRSEC). Co-principal investigators of the multidisciplinary team include molecular biology professors Susan Golden and James Golden and nanoengineering professor Shaochen Chen.
A "living material," made of a natural
polymer combined with genetically engineered bacteria, could offer a
sustainable and eco-friendly solution to clean pollutants from water. Credit:
UC San Diego Jacobs School of Engineering
"This collaboration allowed us
to apply our knowledge of the genetics and physiology of cyanobacteria to
create a living material," said Susan Golden, a faculty member in the
School of Biological Sciences. "Now we can think creatively about
engineering novel functions into cyanobacteria to make more useful
products."
To create the living material in
this study, the researchers used alginate, a natural polymer derived from
seaweed, hydrated it to make a gel and mixed it with a type of
water-dwelling, photosynthetic bacteria known as cyanobacteria.
The mixture was fed into a 3D
printer. After testing various 3D-printed geometries for their material, the
researchers found that a grid-like structure was optimal for keeping the
bacteria alive. The chosen shape has a high surface area to volume ratio, which places most of the
cyanobacteria near the material's surface to access nutrients, gases and light.
The increased surface area also
makes the material more effective at decontamination.
As a proof-of-concept experiment,
the researchers genetically engineered the cyanobacteria in their material to
continually produce a decontaminating enzyme called laccase. Studies have shown
that laccase can be used to neutralize a variety of organic pollutants
including bisphenol A (BPA), antibiotics, pharmaceutical drugs and dyes.
In this study, the researchers
demonstrated that their material can be used to decontaminate the dye-based
pollutant indigo carmine, which is a blue dye that is widely used in the
textile industry to color denim. In tests, the material decolorized a water
solution containing the dye.
The researchers also developed a
way to eliminate the cyanobacteria after the pollutants have been cleared. They
genetically engineered the bacteria to respond to a molecule called
theophylline. The molecule triggers the bacteria to produce a protein that
destroys their cells.
"The living material can act
on the pollutant of interest, then a small molecule can be added afterwards to
kill the bacteria," said Pokorski. "This way, we can alleviate any
concerns about having genetically modified bacteria lingering in the
environment."
A preferable solution, the
researchers note, is to have the bacteria destroy themselves without the addition of
chemicals. This will be one of the future directions of this research.
"Our goal is to make materials
that respond to stimuli that are already present in the environment," said
Pokorski.
"We're excited about the possibilities that this work can lead to, the exciting new materials we can create. This is the kind of research that can result when researchers with cross-disciplinary expertise in materials and biological sciences join forces. This is all made possible thanks to our interdisciplinary research group at the UC San Diego MRSEC."
by University of California - San
Diego
Source: 3D-printed 'living material' could clean up contaminated water (phys.org)
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