2001 - Volume 2 - Journal of Engineered Fibers and Fabrics

INJ DEPARTMENTS
TECHNOLOGY
WATCH
Tracing Water Pollution Sources
In the past, water polluters have benefitted
from the fact that water pollution can be
clearly identified, but the source of pollution
is much more difficult. That situation
may be changing somewhat, with the
advent of a DNA “fingerprinting” test to
trace the source of water pollution.
This test, which was developed at the
University of Missouri-Columbia, is based
on tracing the water pollution back to its
sources by using the DNA from bacteria.
The presence of fecal E. coli bacteria —
microbes that live in the intestines of their
host until they are excreted — commonly
is employed to establish if the pollution is
due to human or animal wastes. While
these organisms of themselves are nonpathogenic,
their presence in a water gives
a warning of the potential presence of other
disease-producing strains of E. coli, salmonella
or hepatitis virus that can also be
found in human and animal waste.
The method utilizes a technique known
as DNA pattern recognition, or ribotyping.
This novel approach takes advantage of the
fact that each host species harbors specific
types of E. coli in the intestinal tract that
have specific DNA patterns, or “fingerprints.”
The DNA results are then compared
to known DNA patterns from known
host species. This then gives an indication
of possible sources of the contamination.
At the present time, the method can be
used to clearly identify contamination
coming from eight common hosts:
humans, cows, pigs, horses, dogs, chickens,
turkeys and migratory geese. Further
work is being carried out to expand the
DNA database of hosts and to further
refine the technique to identifying characteristics
of pollution sources. Current
chemical analysis, of course, can provide
very precise information on the presence of
organic and inorganic pollutants; these
dates, coupled with water flow and movement
patterns, can generally pinpoint the
sources with convincing results.
Active Antibacterials
The use of antibacterial agents in a host
of consumer, medical and industrial products
has exploded in the past few years.
Seven times as many antibacterial products
were produced in 1998 than in 1992.
Antibacterial finish has become the standard
finish in some textile product categories.
Nonwoven products have participated
in this action is a significant way,
especially in nonwoven wipes.
The practice has become sufficiently
widespread that consideration has been
given to legislation to stiffen controls on
the use of such materials. Some warnings
have been put forth by the medical profession,
arising from the concern that such
materials can kill beneficial germs as well
as deleterious ones. Also, there is concern
that resistance to such agents can develop
and could lead to a range of super-germs.
Despite such concerns, the use of these
agents is proliferating.
Most such agents act by leaching from
the material to which they are originally
applied, and then contact the microorganisms
and kill them by such contact. These
are the “leaching” type agents.
Their effectiveness diminishes as the
leaching continues, of course, and the
leaching can lead to excessive skin contact
or even to the crossing of the skin barrier;
such behavior can lead to a variety of
problems.
Another class of antibacterial agents is
actually bound to the substrate by molecular
or other forces. Such “bound” materials
usually have hydrophilic or other
groups in the molecule which can penetrate
the microorganism, allowing quaternary
ammonium groups or other groups
to rupture the organism’s cell wall, leading
to expiration. This bound type of
material can kill when the organism
resides on the substrate; hence, it is more
limited in scope.
An interesting class of durable agents
was recently described with the added
feature of being capable of regeneration
of the active chemical moiety. In this
agent, one functional group is used to
attach the molecule permanently to cellulose
fiber via a molecular bond. The functional
group also contains a cyclic hydantoin
group, which can be easily chlorinated
to form the reactive cyclic chlorohydantoin
group. This latter group is an
effective disinfecting agent that is widely
used in swimming pools and other similar
applications. As the disinfecting
action continues, the chloro-group is converted
back into the unsubstituted hydantoin
group. This latter group can be easily
converted back into the active chlorohydantoin
form; such chlorination can be
done simply by treating the fabric with a
chlorine bleach. Hence, the regenerable
feature.
Very recently a special polymer has
been developed at Massachusetts
Institute of Technology that is claimed
to have special germicidal properties.
When the polymer is coated onto a hard
surface, the developers claim that it is
there permanently and can guard against
infections commonly spread by sneezes
and dirty hands. The materials is
described as hexyl-PVP (PVP-polyvinyl
pyridine).
The PVP portion has been known to be
active in solution, but attempts to immobilize
the material on a surface seemed to
render the polymers totally inactive. The
researchers found that the addition of the
alkyl chain (3-6 carbon atoms) eliminated
the inactivation. It is claimed that this
material in a coating form is able to kill up
to 99% of Staphylococcus, Pseudomonas,
and E. coli, all common disease-causing
organisms. The killing action is stated to
be via a powerful chemical-electrical
action. The researchers have hypothesized
that the addition of the polymer side chain
of the right length provides flexibility for
the coating material to penetrate the bacterial
cell wall envelope on contact and do
its job. These are the first engineered surfaces
that have been shown to kill airborne
microbes in the absence of any liquid
medium. This work suggests a new
possible approach to engineer a solid surface
to provide bacteria-killing action.
The major markets for most types of
10 INJ Summer 2001