Nanotechnology holds promise for security applications

How state-of the-art sensor technology could be used for detecting and combating chemical, biological agents

We have all become used to being scanned at the airport with imaging systems using terahertz radiation.  Researchers at the University of Pittsburgh have described a detector using this same radiation that can now detect individual molecules.  Rather than a body scanner, it is a molecule scanner that could eventually open the way to a variety of practical applications that might include chemical threat detection.

James McGrath at the University of Rochester has created microscopically thin silicone nanomembranes that can be used as separation tools for biological materials.  This advance could lead to credit card-sized medical devices (a “laboratory-on-a-chip”) that are inexpensive, easily portable and able to detect biological agents such as anthrax.  Due to their minuscule size they work with only about a quarter volt of electricity, meaning that the power requirements can be met by small, long-lasting batteries.

The microscope has also traditionally played a key role in medical diagnosis.  The ability to make specialized microscopes more portable would have distinct advantages for early disease detection and diagnosis.  The laboratory of Aydogan Ozcan at the University of California in Los Angeles has developed a fluorescent microscope that can be mounted on a smartphone and used to detect viruses and bacteria, eliminating the need for expensive and cumbersome lab equipment.  The ability to substitute small and portable devices for other sorts of laboratory-based equipment is increasing rapidly as well.  A research team in Israel has used a common green laser pointer to create a portable Raman spectrometer that has the capability of rapidly detecting small levels of toxic chemicals.

Other disease detection methods are similarly being enhanced.  Scientists at the University of Toronto’s Institute of Biomaterials and Biomedical Engineering have created a biosensor using DNA powder and gold nanoparticles that facilitates rapid detection of a variety of infectious diseases from a single drop of blood or saliva.  Multiple diseases can be tested from a single sample. The DNA powder is stable for years, meaning that testing materials can be stockpiled, prepositioned at multiple locations and available for use quickly.  Chemists at Johannes Gutenberg University in Germany have developed a nanosensor about the size of the head of a pin that can identify proteins in blood, saliva or other body fluid and differentiate between harmless and dangerous bacteria.  The technique used could also be appropriate for detecting illicit drugs or toxins in the environment or in food.

Complementary to detecting disease agents and toxins is the ability to determine which treatment agents will be effective.  To that end, Army scientists at the Edgewood Chemical Biological Center have built a “human-on-a-chip.”  This device contains a small patch of human tissue, created from stem cells, that will mimic an actual organ such as the heart, liver, lung or nervous system, to determine how the body reacts to chemical warfare agents and which treatment options are most effective.

A biologic or chemical attack resulting in large numbers of affected individuals would stress traditional methods of making medical assessments to the limit.  Blood glucose levels, for example, are usually monitored by using a lancing device on the side of a finger to obtain a drop of blood which is then absorbed by a test strip that is placed into a meter.  Although simple, effective and accurate for an individual who has diabetes, this method may not be practical in terms of time, expense and supply availability when dealing with measurements scaled up by several orders of magnitude.  However, Mitchell Lerner and his associates at the University of Pennsylvania have constructed a glucose sensor built upon carbon nanotubes coated with molecules that bind to glucose.  Devices built using this technology would do away with finger sticks since they are sensitive enough to detect glucose levels in saliva.  These nanotube-based sensors would also be much cheaper than the enzyme-based test strips currently available.