While the legalization of marijuana continues at a steady rate in the U.S., this does not mean that, on having taken the substance, someone is any safer to get behind the wheel of a motor vehicle.
The rise in marijuana use has led to the police services in the U.S. asking for more effective tools for assessing whether someone has been driving under the influence of the psychoactive drug.
A potential device has been developed by Stanford University scientists. This involves the use of magnetic nanotechnology. The technique is not dissimilar from medical devices used as a cancer screen. The new device measures a driver’s marijuana intoxication in the same way that a breathalyzer assesses alcohol levels.
The device measures levels of the main psychoactive agent THC (tetrahydrocannabinol) in saliva. The test is fast would save the need for a driver to be taken to a police station for lengthy blood or urine tests (where the time to result from testing laboratories can take several hours).
The device, created by a team led by Professor Shan Wang, uses magnetic biosensors to detect tiny THC molecules in saliva. In practical use, a suspect would have a sample of their saliva taken using a cotton swab. The swab would then be tested via a portable device and the results transmitted to a smartphone. THC alters the pattern of magnetism in nanoparticles, a movement which triggers antibodies. If the antibodies are attracted to THC molecules then a positive detection is made via a micro-sized immunoassay. Because some U.S. states have a THC limit of 0 or 5 nanograms per milliliter of blood, the device is required to be very sensitive.
At present the device is being tested out by a small number of police services in practical situations.
The research is published in the journal Analytical Chemistry. The paper is titled “Small Molecule Detection in Saliva Facilitates Portable Tests of Marijuana Abuse.”
