Scientists |
Urban
beach closures due to coliform outbreaks have become disturbing signs
of summer, yet water-testing technology has never been fast enough to
keep up with changing conditions, nor accessible enough to check all
waters.
Now, researchers at McMaster University have developed a rapid testing method using a simple paper strip that can detect E. coli in recreational water within minutes. The new tool can close the gap between outbreak and detection, improving public safety.
Scientists
from the Sentinel Bioactive Paper Network have created and validated
the viability of the test strip, which can detect potentially harmful
concentrations of E. coli in water quickly and simply, with much greater accuracy than existing portable technology.
The work is described in a paper published online in the journal Analytical and Bioanalytical Chemistry.
“Coliforms
are always a big problem,” says the paper’s lead author John Brennan, a
McMaster chemistry professor who holds the Canada Research Chair in
Bioanalytical Chemistry. “The methods used to detect outbreaks are slow,
and tend not to be portable, as they often need a lab-based
amplification step prior to testing, causing a time lag between an
outbreak and a beach closure.”
The
Natural Sciences and Engineering Research Council of Canada funds
Sentinel, a strategic research network that spans the country and is
based at McMaster. Several dozen researchers are involved in its
initiatives.
Bioactive
paper is both old and new, Brennan explains. Since the late 1950s,
physicians have been using bioactive paper to test for glucose in urine.
In the last several years, the area has expanded quickly and research
has become very competitive as scientists work on new applications.
“It’s always a race,” Brennan says.
The
new strips are coated with chemicals that react to the bacteria, and
are printed using inkjet technology similar to that found in standard
desktop printers. Within 30 minutes of sampling, the paper changes
colour to indicate the presence of E. coli, with colours coded to represent different forms and concentrations of the bacteria.
In
the future, the test should make it possible for consumers to check
their water affordably and easily, without additional equipment,
scientific knowledge or long waits.
“One
of the problems right now is that there is no simple, fast and cheap
way to test recreational water, and certainly nothing out there in the
realm of rapid tests for drinking water,” Brennan says.
Field
testing of the prototype strips is planned or under way in Canada and
across the globe, in regions where untreated water poses particular
health hazards. The results of these studies will help to refine the
test strips and may lead to strips that are sensitive enough to tell
whether water is safe enough to drink, says Brennan.
The standards for safe drinking water are hundreds of times tighter than those for safe swimming
water. Typically, limits for safe swimming allow for a maximum of 100
to 500 cells in 100 mL of water, depending on jurisdiction. For water to
be considered safe for drinking, there cannot be even one cell in 100
mL, which is little less than half a cup of water.
The
next stage of pre-commercial development of the test strips is already
funded by NSERC through a Phase I Idea to Innovation grant.
Commercialization of a final product could take as little as two to
three years.
Multiplexed paper test strip for quantitative bacterial detection
Source: Springer
