NUROTOXINS DETECTED IN INKJET-PRINTERS , INK & PAPER

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NUROTOXINS DETECTED IN INKJET-PRINTERS , INK & PAPER

 user 2009-07-14 at 11:53:36 am Views: 91
  • #22655

    http://www.examiner.com/x-16026-Napa-County-Science-News-Examiner~y2009m7d13-
    NUROTOXINS DETECTED IN INKJET-PRINTERS , INK & PAPER
    It’s
    almost like something out of a James Bond movie. Fearing an
    assassination attempt using paraoxon (a potent organophosphate
    neurotoxin) Bond takes out a laptop computer and portable inkjet
    printer. Replacing the printer cartridges with some containing
    specially designed ink, he then pulls up a special program on the
    laptop and prints a small “dipstick” pattern. Cutting out the dipstick,
    he then dips it in a glass of vodka that was delivered to his room. The
    dipstick turns sickly yellow, showing that the vodka is safe to drink.
    Had there been paraoxon present the dipstick would have either remained
    white or turned only slightly yellow.

    This may sound
    far-fetched, but researchers at McMaster University’s Department of
    Chemistry, under the direction of Dr. John Brennan have just developed
    such a dipstick. Although not quite as easy to produce as the James
    Bond scenario implies, the key components of the process are paper, an
    inkjet printer and specially prepared inks.
    Using an inkjet printer
    to produce bioactive paper, the more technically correct term for this
    technology, is not a new idea. In 2008 researchers in the Department of
    Applied Chemistry at Keio University in Japan developed bioactive paper
    using an inkjet printer. Their paper could simultaneously test for
    serum albumen, glucose and pH, commonly measured parameters in
    urinalysis. Of course, dipsticks for urinalysis are already used, but
    being able to produce them so readily with just paper and an inkjet
    printer could represent a cost reduction innovation. Other similar
    applications have been studied by other researchers.

    Dr.
    Brennan’s hope was to take the basic science behind these previous
    successes and use it to develop dipsticks for detection of more
    challenging chemicals for which expensive instrumentation is currently
    required. A simple paper dipstick approach could save money, produce
    results much more rapidly and could be used in the field. Currently the
    expensive instruments used to detect neurotoxins like paraoxon and
    aflatoxin B1 are not particularly portable, often requiring that field
    samples be returned to the lab for analysis. More rapid, in the field,
    results would be far superior.In a paper published in the July 1, 2009
    issue of Analytical Chemistry, the methods used by Dr. Brennan’s
    research team are outlined. It is a multi-step process in which first a
    layer of polyvinylamine (PVAm) is printed directly onto the paper. PVAm
    is used to bind negatively charged chemicals, and in the case of this
    assay it was used to keep the product of the color reaction bound to
    the paper. Secondly, a silica sol-gel layer was printed, followed by
    printing a layer of buffered acetylcholineesterase (AChE) solution. The
    AChE is a key component, as this enzyme is inhibited by neurotoxins. A
    final silica sol layer was printed to seal everything into a more
    durable matrix.To use the dipstick, it is first dipped in a sample that
    is being tested for a neurotoxin, such as Aflatoxin B1. After dipping,
    it is removed and is then dipped into a standard acetylcholine (ACh)
    solution. The assay is designed so that when AChE breaks down the ACh,
    a yellow color is produced. The darker the color of yellow, the more
    active the AChE is. If there was any neurotoxin in the solution being
    tested, it will inhibit the AChE, resulting in less breakdown of ACh
    and a less intense yellow color. Therefore, the higher the
    concentration of the neurotoxin, the less yellow the dipstick will turn.
     
    The
    elegance of this new procedure is that it works quickly (about 5
    minutes), it is very accurate at detecting even small quantities of the
    neurotoxin and the results can be analyzed visually by comparing the
    intensity of the yellow color against a standard series of yellow
    bands. For greater accuracy the dipstick can be scanned into a computer
    and analyzed. As long as PVAm is used as the base layer, the color
    remains for several days with minimal change in intensity. Lastly, when
    stored at 4°C, the dipsticks worked even after 60 days of storage
    (possibly longer) and the same degree of accuracy was obtained.Although
    this approach is not yet in commercial production, it seems like it
    should be fairly easy to produce and the cost should be relatively low.
    Having such dipsticks readily available would make field testing for
    neurotoxins very simple. This same approach could likely be used for a
    variety of other assays for other toxins. It might even be possible
    incorporate multiple tests into one dipstick. There are still some
    technical hurdles to overcome for these to reach the marketplace, but
    this represents a much needed advance in field testing potential.