Portable Instrument for Assessing Zinc Deficiency in Children and the Elderly - PROJECT DESCRIPTION
OVERVIEW. We will build a portable instrument for diagnosing zinc deficiency by the use of a quick,
painless fingernail reading taken in the field. Sequellae of zinc deficiency are a leading cause of death
among toddlers throughout the world; UNICEF estimates 450,000 deaths per year. Zinc deficiency also
causes stunted development of the brains and the bodies of about 17-30% of all poor children in the US.
Forty percent (21,000,000) of US school children are so poor they are given
free lunch, and neither those free meals nor their habitual home meals contain
much of the foods (red meat, shellfish) in which zinc is abundant.
One of the main reasons that zinc deficiency goes untreated is that no
one can diagnose it. To be sure, the signs of chronic, severe zinc deficiency
can be recognized: stunted physical and mental development, open sores,
loss of hair, infection proneness, fragile nails, and so on. But there is no good
diagnostic test for early-stage, moderate (i.e., treatable) zinc deficiency. Serum
zinc, in particular, like serum glucose, follows intake up and down in the short
Figure 1. XRAY fluorescence term, over hours, but does not reflect zinc nutritional status.
image of zinc in a fingernail
clipping shows the uniformity We have solved the diagnostic problem. Abundant data indicate that
of the zinc across the lateral the zinc content of fingernails is a sensitive and reliable indicator of zinc
extent deficiency. Furthermore, though the zinc concentration of a nail will change
along the longitudinal (proximo-distal) dimension if one makes lasting and
substantial changes in zinc intake, the zinc concentration is relatively uniform in the lateral dimension (FIG
1) and from one finger to the next (FIG 2). Our proposed hand-held, field-portable, battery powered
instrument will give the diagnostic measurement of fingernail zinc in 30-60 seconds with no inconvenience
or discomfort to the subject. Using our diagnostic instrument, clinicians, aid workers, teachers, and others
can go from village to village (or school to school) assessing the zinc nutritional status of 100s of children
every day.
Our instrument uses a miniature laser to make a brief “spark” on the nail; the light emissions from
that spark reveal the percent of zinc in the nail. This method (laser-induced-breakdown-spectroscopy,
LIBS) is used in many applications, including the “Chem Cam” that is mounted on the NASA Curiosity
Rover on Mars. Besides the electricity for each measurement, there are no consumables.
SIGNIFICANCE. The W.H.O., Gates Foundation, UNICEF, and
the Copenhagen Consensus have all noted that zinc deficiency is 140 ppm
a leading cause of death and stunted mental and physical 134 ppm 125 ppm
development among toddlers, world wide. The Copenhagen
Consensus have even identified dietary zinc supplementation as a
leading cost-effective step to improve world health.
INNOVATION. The use of LIBS to detect and quantify elements in
solid media is not new, but the application of LIBS to nutritional (or
toxicological) screening of people's tissues in situ is new,
pioneered and patented (pending) by NeuroBioTex. While the
concept is straightforward, the biology, optics, physics, and
engineering are challenging. For example, incorporation of dietary
zinc occurs at the growth plate, which is under the skin, between
the cuticle and knuckle, so after a large and lasting increase in
zinc intake, it takes about 60-90 days before the nail with elevated
zinc emerges from under the cuticle. On the positive side,
Figure 2/ Stability of zinc across 4 fingers and thumb is
illustrated by King-Killilea atomic absorption laboratory
data. Thumb and 4th finger omitted because different
lengths and thus different growth eras.
however, by measuring zinc along the proximo-distal length of the exposed nail, one can scan another 3-4
months of a subject's past zinc intake history.
RESEARCH STRATEGY. We are partnering with some of the best laser and LIBS scientists and
engineers in the world. In fact, we are opening a small NeuroBioTex facility within the Buildings of Ocean
Optics, Inc. (OOi), which is adjacent to the U. C. Florida campus. This will insure that we can work closely
with our UCF and OOi collaborators. The leaders in zinc nutrition, Janet King, Ananda Prasad, and Harold
Sandstead will continue to guide the clinical, zinc deficiency diagnostic side of our research.
