"You smoked marijuana?"... Caught within 5 minutes

Institute for Basic Science Develops On-Site Immediate Diagnostic Testing Equipment

Outdoor Marijuana Farm's Cannabis Plantation
Photo by Getty Images Bank

[Asia Economy Reporter Kim Bong-su] The trend of marijuana legalization is growing mainly in the United States and Europe. However, driving within 3 to 4 hours after marijuana consumption can lead to situations similar to drunk driving, necessitating rapid diagnosis and response on-site. A domestic research team has developed a testing technology that can determine marijuana smoking status within 5 minutes.

The Institute for Basic Science (IBS) announced on the 2nd that a research team led by Research Fellow Lee Hak-ho of the Nano Medicine Research Center (Harvard Medical School professor) and Director Chun Jin-woo (Yonsei University professor), in collaboration with Professor Kim Min-gon’s team at Gwangju Institute of Science and Technology, developed a point-of-care (POC) technology that accurately detects marijuana use within 5 minutes. By using a radial membrane and optical equipment, they increased sensitivity compared to existing methods and significantly reduced the required time.

Internal Schematic of the EPOCH Saliva Preprocessing Kit
The preprocessing kit measures and separates approximately 20 uL of saliva from the saliva collection swab, then mixes it with gold nanoparticles (pre-bound with THC antibodies) that are prepared inside the kit. The entire preprocessing process using the kit is carried out sequentially by operating the two pumps (P1, P2) located at the top. The filter installed above the measuring reservoir serves to remove impurities contained in the saliva.

Marijuana testing mainly uses the lateral flow assay (LFA) or gas chromatography-mass spectrometry (GC-MS). LFA is simple and fast but has very low accuracy. On the other hand, GC-MS is highly accurate but takes several days for detection and is expensive.

To overcome these limitations, the research team developed the “express probe for on-site cannabis inhalation” (EPOCH), which combines radial flow analysis with a transmission-type optical sensor design. EPOCH detects small molecules in saliva within 3 minutes using radial flow. Additionally, they developed a transmission light detection algorithm that surpasses the limitations of conventional reflected light analysis, enabling ultra-sensitive detection of analytes. They also integrated these technologies into a compact measuring device using a smartphone, allowing convenient use anytime and anywhere.

EPOCH can detect the active substance in marijuana (Tetrahydrocannabinol; THC) within 5 minutes (from sample collection to result output). The detection limit is 0.17 ng/ml, meeting international standards for confirming marijuana smoking status (below 1 ng/ml). By combining flow analysis and transmission light detection models, it achieves both speed and accuracy.

Clinical trials verifying actual marijuana smoking status also demonstrated EPOCH’s excellence. Among 86 participants, 43 were in the marijuana use group (3 chewed, 40 smoked), and the other 43 were in the non-use control group (including 13 regular cigarette users). The results showed 100% accuracy. Despite differences in consumption methods, amounts, and saliva collection times (within 10 minutes), the system accurately determined use status without error. All non-use controls tested negative.

Research lead Lee Hak-ho said, “This achievement overcomes the limitations of existing marijuana detection methods (LFA or GC-MS), enabling ultra-sensitive rapid detection,” and added, “It is expected to be a very useful platform not only for marijuana but also for infectious diseases like COVID-19 and cancer diagnostics.”

The research results were published on the 20th of last month in the international journal Science Translational Medicine (IF 17.96).