Tech Briefs Magazine - November 2023 - 56

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TECHNOLOGY & SOCIETY
This monthly column explores the inter-relationships between technology and society. It features people and projects aiming to
deliver a positive impact on the world facing unprecedented social and environmental challenges.
3D-Printed Living Material for Cleaning Contaminated
Water
A new type of material offers a sustainable solution to remove pollutants from water.
D
ubbed an " engineered living material, "
a new type of material developed
at the University of California
San Diego could offer a sustainable
and eco-friendly solution to clean pollutants
from water.
" It is a 3D-printed gel-based structure
containing the bacteria that
have been programmed to produce
an output that transforms organic
pollutants into benign molecules; in
our case it is water decontamination, "
said Co-First Author and Debika Datta,
who is a nanoengineering postdoctoral
researcher at UCSD. " The
bacteria were also programmed 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 team's objective, Datta said, was to
investigate a category of materials known
as engineered living materials, wherein
an engineered micro-organism is incorporated
into a polymeric substance.
There has been minimal research into
the integration of cyanobacteria with
conventional materials.
To create the living material in
this study, the researchers used alginate,
a natural polymer derived from
seaweed, hydrated it to make a gel,
AT A GLANCE
INNOVATORS: Co-First Author Debika
Datta, UCSD nanoengineering postdoctoral
researcher, and team.
INNOVATION: Engineered living material
offers sustainable, eco-friendly solution to
rid water of pollutants.
IMPACT: Cleaner, more readily available
drinking water.
56
fold, " Datta said. " Initially, when we
discovered that the alginate material
could support cell growth, it was an
exciting moment for us. However,
our initial alginate hydrogels were
in a disk or circular shape, and we
observed uneven cell growth within
the matrix. The breakthrough came
when we realized the importance of
incorporating void spaces into the
matrix. "
According to her, this adjustment
was crucial because these micro-orThe
living material is 3D printed as a grid-like structure.
(Image: ucsd.edu)
and then mixed it with a type of water-dwelling,
photosynthetic bacteria
known as cyanobacteria.
" These photosynthetic micro-organisms
are relatively resource-efficient, as
they primarily require CO2
, water, and
abundant light, " Datta said. " Initially,
we were interested in the creation of
scaffolding materials that facilitate the
growth of cyanobacteria. We did try
a variety of different materials, and
among them the natural polymer alginate,
which has its source from the
seaweed, turned out to provide the
best support for growth and survival, "
she added.
The mixture was then 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.
" Certainly, one of the key challenges
we encountered was designing the scafwww.techbriefs.com
ganisms
rely on gaseous diffusion
for their growth. " So, we decided to
change the matrix shape to custom
designs we created in-house, such
as a honeycomb or a grid pattern, and
this modification yielded fantastic results.
It enabled us to achieve uniform
cell growth throughout the matrix. We
achieved this by utilizing additive manufacturing
3D printing technique, "
she added.
As a proof-of-concept experiment,
the team genetically engineered the cyanobacteria
in its material to continually
produce a decontaminating enzyme
called laccase. In this study, the researchers
demonstrated that their material
can be used to decontaminate the dyebased
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.
" We are also trying to use micro-organisms
for production of polymers, taking
a biosynthetic approach rather than
conventional chemical synthesis in the
lab, which could be a potential step toward
green chemistry, " Datta said.
This article was written by Andrew
Corselli, Digital Content Editor at SAE
Media Group. For more information,
visit mrsec.ucsd.edu.
Tech Briefs, November 2023

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Tech Briefs Magazine - November 2023

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