Technology has become not only increasingly more efficient, but also more compact. From cell phones to iPods to hand-held computers, everything has gotten smaller. Now researchers at McMaster University (Hamilton, Ontario, Canada), have found a way to minimize to bit-sized proportions a lab method used to detect contaminants in water. And it all fits inside a dissolvable pill.
“This is regular chemistry that we know
works, but now is in pill form,” said John Brennan, director of McMaster’s
Biointerfaces Institute, where the work took place, in a news release. “The
user can be anybody in a village anywhere who can take a pill out of a bottle
and drop it into water,” he said.
To the grocery
store we go
Carlos Filipe, a professor of chemical
engineering at the university who is part of the Sentinel Bioactive Paper
Network that works on paper-based sensors, said his research team developed the
lab test using enzymes and nucleic acids to detect water contaminants.
But according to the team’s research paper
that appeared in Angewandte Chemie, most bioassays use enzymes and
small-molecule substrates that are “liable to various degrees and require
special shipping and storage. The instability of these molecules can arise from
either thermal denaturation or chemical modification, such as oxidation or
hydrolysis.” Subsequently, the bioassays may have to be shipped on dry ice,
which is expensive, according to the research paper. They also may have to be
stored in freezers, but repeated freezing and thawing to room temperatures for
testing can compromise the bioassays and can lead to “less reliable test
results,” according to the researchers.
To counteract this problem, the team wanted
to develop a tablet or capsule that could hold the assay reagents. It would
allow for premeasured quantities of the reagents and additional preservatives
that could prolong their shelf life, according to the research paper. But the
challenge of creating such a capsule was finding a material that could
encapsulate the biomolecules in a form suitable for shipping; provide
protection for entrapped biomolecules against thermal denaturation and chemical
modification during shipping and storage; and be readily soluble in an aqueous
solution, allowing for the release of the encapsulated molecules while not
interfering with the assay itself, according to the paper.
One of his students stumbled upon Listerine®
Breath Strips at the grocery store, Filipe said. These strips are made of a
substance called pullulan, which according to the paper, is a natural
polysaccharide produced by fungus.
“It dissolves in water but resolidifies into
films upon drying,” according to the paper.
So, the team decided to use pullulan to
encapsulate the bioassay.
“The beauty is you don’t have to keep it
refrigerated,” Filipe said. He said the enzymes are usually
temperature-sensitive, but the research team managed to create a prototype that
could be left out of the refrigerator.
The pills they created also are economical,
Filipe said. “We can make the solvent pills for less than a dollar [each],” he
said. “That’s pretty cheap.”
Everything in a
The most recent pill the research team developed
can detect the presence of pesticides at concentrations of 1 part per trillion,
The capsule, when dissolved, shows the level
of pesticide contamination according to the color intensity, which can be
measured with the help of the cell phone, Filipe said. The user can take a
picture of the color and send it to a server or remote computer that can detect
the color intensity. He said the location where the sample was taken and the
results then can be populated on Google Maps as a type of crowd-sourced
The research team plans to conduct a field
test of the pesticide capsule. A fellow researcher in Koriya, India, will
complete testing by the end of the year, Filipe said.
In the meantime, Filipe said the team is
working on capsules that can be used to detect heavy metals and Escherichia
coli. He anticipates that they will be able to develop capsules that can
detect nutrients such as phosphorus and nitrogen.
“My vision is to one day have something
similar to a box of pills that people use for the days-of-the-week medications,
except each slot would contain a pill that detects some [water] contaminant,”
at USGS and NOAA study the effects of oyster aquaculture on nutrient removal
farming has long been a tradition in the Chesapeake Bay region, going as far
back as the 1600s, when early English settler William Strachey wrote that
“Oysters there be in whole banks and beds, and those of the best. I have seen
some 13 inches long,” according to the Oyster Company of Virginia (North, Va.).
Now, as well as bringing revenue to the region through aquaculture, the
practice of oyster farming could serve an additional purpose: It could help
remove excess nutrients from the bay.
All of the nitrogen currently polluting the
Potomac River estuary could be removed if 40% of its river bed were used for
shellfish cultivation, according to a joint study conducted by the U.S.
Geological Survey (USGS) and the National Oceanic and Atmospheric
Administration (NOAA). The results of the study were published in the journal Aquatic
The researchers discovered that a combination
of aquaculture and restored oyster reefs may provide even larger overall
ecosystem benefits because the oysters can clean an enormous volume of algae —
the prime culprit of poor water quality, according to a USGS news release.
oysters, seeing results
Suzanne Bricker, a physical scientist in
NOAA’s National Centers for Coastal Ocean Science and one of the authors of the
research paper, said the joint study of how oysters could help remove nutrients
from waterbodies began in the early 1990s when “NOAA conducted two studies into
the conditions, causes, and future outlook of nutrient-related water quality,
also called eutrophication, in U.S. estuaries.”
In the most recent study, the research team
evaluated nitrogen flows from the Potomac River headwaters and evaluated the
estuary’s eutrophication. The team wanted to determine how oyster aquaculture
“could be used to remove nutrients directly from the water, complementing
traditional land-based measures,” according to the news release. The team
discovered that the estuary could benefit from the growth of more oysters. In
fact, if only 15% to 20% of the estuary’s bottom was cultivated with oysters,
the shellfish crop could remove nearly half of the incoming nutrients,
according to the study. But Bricker said they were unable to determine if there
was a direct linear relationship between how many shellfish are planted and how
much eutrophication occurs in an estuary, “though we do know that systems that
have filter feeders have less chlorophyll and detritus in the water,” she said.
Bricker said these positive results in
estuaries aren’t just the result of oyster aquaculture; other shellfish also
could be used to remove nutrients.
“We’ve done modeling exercises with oysters,
mussels, clams — and all can be used for bioremediation,” Bricker said. “In
Chesapeake Bay, oysters get the most attention but clams would work well, too.”
Another benefit of using oysters as nutrient
filters is the boost to the local economy. Once matured, these oysters could be
sold for food.
“As long as there is no other reason that the
shellfish could not be eaten, then they can be sold for consumption,” Bricker
said. “Some of the reasons would be pathogens, contamination from mercury or
other pollutants, like toxins accumulated from red tide or harmful algal
Bricker said the fact that these oysters can
be sold is what makes nutrient management “so intriguing.”
“We in the U.S. import almost 90% of the
seafood we consume, and China is the largest exporter globally and they do not
follow the same health code rules that we do,” Bricker said. This gives the
chance for the U.S. to cultivate more seafood domestically, she said.
In the meantime, the USGS and NOAA research
team is finishing similar eutrophication projects in Long Island Sound near
Connecticut, Puget Sound in Washington State, and Great Bay Piscataqua
Estuaries in New Hampshire, and they are hoping to get additional funds to do
more exploration in other places, Bricker said.
“We have a proposal to do a comparative
analysis in North Carolina between two places, one that is more and one that is
less eutrophic,” Bricker said.
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