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November
2005 Welcome
to your latest issue of BIOMEDICAL OPTICS UPDATE , the monthly report
for the clients of Optimum Technologies, Inc. Please feel free to
pass this issue along to interested colleagues. Written
by Andrea Pierce, Ph.D. In this issue: • NIR Oxygenation Sensor Protects Brain During Surgery • Glucose Sensing Via Eye’s Aqueous Humor • Antibody-Coated Optical Nanoprobe Interrogates Single Cells • Clot Catching Device Helps Stroke Victims • Optical Patent Application Of Note •
Optical
Expertise For The Life Sciences NIR Oxygenation Sensor Protects Brain During Surgery Measuring
systemic blood oxygenation during surgery doesn’t always correlate
to brain oxygenation, which can lead to brain damage. A new cerebral
oximeter allows anesthesiologists an accurate measure of brain tissue
status. The non-invasive device has sensors that attach to patient’s
forehead that emit NIR light that is transmitted through the skull
into the brain. By using known hemoglobin absorption parameters,
the device can directly measure cerebral tissue oxygenation. In
addition, when used in combination with traditional pulse oximetry,
the cerebral oximeter can give a calculated value of cerebral venous
oxygen saturation. According to inventor Dr. David MacLeod of Duke
University, the device gives an accurate estimation of cerebral
perfusion, important in protecting the brain from damage during
surgery. Trials are underway to monitor this parameter in patients
undergoing heart surgery. Glucose Sensing Via Eye’s Aqueous Humor A
UK company is developing an optical sensor to monitor a diabetic’s
glucose level without drawing a blood sample. Unlike other non-invasive
glucose sensors, this device does not shine a light through the
skin, but instead relies on the light from a 670 nm LED focused
into the eye. According to Dan Daly, director of UK-based company
Lein Applied Diagnostics, that is developing the device, there is
good correlation of aqueous humor glucose levels with that of the
blood, with a lag time of 5-10 minutes. Daly states that the company
has been awarded two patents on the technology, and it is safe,
requiring optical output in the microwatt range, with a measurement
time of one-tenth second. Antibody-Coated Optical Nanoprobe Interrogates Single Cells Oak
Ridge Researcher, Tuan Vo-Dinh, has developed a nanosensor with
an antibody-based bioprobe for monitoring chemically induced damage
to cells. To demonstrate proof of principle, a carcinogen, benzo
[a] pyrene, was introduced to a growing cell culture, and a second
biomarker, BPT (benzo [a] pyrene tetrol), was then added to the
cells. Cellular incorporation of the biomarker, indicative of cell
damage, was detected via an antibody-coated quartz optical fiber
nanoprobe pulled in a fiber puller to range of 10-100 nm. By coating
the fibers on the nanoprobe with silver to prevent light from escaping,
the antibody-coated tip of the probe functioned as the only light
emitter. Upon interrogation of the cell culture with the probe,
fluorescence of BPT molecules binding to antibodies on the fiber
tip indicates cell damage. Future applications of this device may
be for chemical and biological warfare sensing and defense. Clot Catching Device Helps Stroke Victims Researchers
at Lawrence Livermore National Laboratory (LLNL) offer an alternative
to traditional clot busting treatment that uses a corkscrew-shaped
polymer device. According to Ward Small of LLNL, the system has
a NIR diode laser coupled to a shape memory polymer micro-actuator
using an optical fiber. When laser radiation transmitted along the
fiber and is absorbed by a thin coating of platinum dye, the polymer
heats up and changes its conformation into a corkscrew shape. When
the device is immersed in water at physiological temperature, its
shape conformation changes from a straight rod into a long spiral
form with diameter of 3 mm. Initial tests inserting the device into
a model carotid artery with an artificial blood clot proved the
device’s ability to “catch” the clot and pull it back through the
occlusion. The research team is now in discussions with medical
device manufacturers to commercialize the technology. Optical Patent Application Of Note US
Patent application 20050209692 describes a two optic accommodative
intraocular lens (IOL) system invented by Xiaoxiao Zhang of Forth
Worth, TX. The first lens in the system is fixed in the anterior
chamber of an eye, and the second lens has a non-circular ring with
radial dimensions that are different in at least two meridians and
implanted in the posterior section of the eye within the capsular
bag. An application of this invention is in the treatment of cataracts
where surgical removal and replacement of the lens with an artificial
intraocular lens (IOL).
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