Protein Tags Devised to Stop Counterfeit Drugs

Capsule with unique identifier tag, illuminated with a green filter for greater visibility (Jung Woo Leem, Purdue University)

17 Jan. 2020. A bio-engineering lab developed a tiny edible tag from natural proteins that uniquely identifies individual doses of medicines to prevent counterfeiting. Researchers from Purdue University in West Lafayette, Indiana describe their system in yesterday’s issue of the journal Nature Communications.

The team from the Natural and Biological Photonics Lab of bio-engineering professor Young Kim is seeking reliable and feasible techniques for protecting patients and health care systems overall from counterfeit drugs. The problem, say the authors, is worldwide and growing, with at times deadly consequences. The Guardian newspaper in July 2019 reported that some 250,000 children die each year from counterfeit drugs for treating malaria and pneumonia. And a pharma industry paper in 2018 says cheap pill-making machines, available on the Internet, are turning out synthetic fentanyl and counterfeit drugs at an alarming rate, with deaths from their products reported in at least 30 states in the U.S.

Kim and colleagues at Purdue, with associates at institutions in Korea, aim to apply the concept of a physically unclonable function, or PUF proposed to secure Internet-of-things connected devices, with authentication applied to each pill or capsule given to patients. These PUF identifiers would be fabricated on tiny tags that need to be safe for patients, and not disrupt the chemical mechanisms of medications, while still be feasible for implementation by drug manufacturers.

The researchers developed the physical tag as a tiny 7 millimeter square transparent strip of film made from fibroin, a natural protein in silk that dissolves in water. To produce identifiers for the tags, the team genetically engineered silkworms to produce fluorescent fibroin in blue, green, yellow, and red colors. These colored silk proteins are then dried and crushed into micro-scale particles, and arrayed on the silk protein film in patterns to form of unique bar code for each tablet or capsule. The team says the process can be scaled up for large-scale manufacturing, and does not use organic solvents or synthetic polymers, making it safe for patients.

The colored fluorescent silk proteins are distributed on the clear film background in a random manner, which makes it possible to translate those patterns into unique cryptographic keys for authentication. The researchers validated the random pattern of these cryptographic keys against a test suite at the U.S. National Institute of Standards and Technology. While the colored silk particles would not be visible to the naked eye, the patterns can be illuminated and read with LED light. The team envisions a smartphone app to read the color pattern on the tag, translate the pattern into data, and verify the authenticity of the drug from an online database.

“Our concept is to use a smartphone to shine an LED light on the tag and take a picture of it,” says postdoctoral researcher and first author Jung Woo Leem in a university statement. “The app then identifies if the medicine is genuine or fake.”

Kim and Leem are listed as authors on provisional patents filed for the technology by Purdue University. In addition, Kim recently founded the company CryptoMED LLC, to develop the mobile components of the system. In this video, the researchers tell more about and demonstrate the tags.

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