Counterfeiting is an ongoing problem across nearly every industry, including healthcare, where unlicensed third parties can produce counterfeit drugs and medical devices. These products are shipped in fake packaging, lacking the necessary ingredients that make them effective therapies and causing harm to patients. There currently exist many high-tech anti-counterfeiting measures, such as those used to print money, but as counterfeiters become more accustomed to these technologies, new methods are necessary to ensure only genuine products hit the market. Here are several of the newer forms of anti-counterfeit measures currently under development that may one day be used to safeguard medicinal products across the globe.

Multiband MgGeO₃-based luminescent nanophosphors¹

Published in May of this year, scientists at Western University in London, Ontario, devised one of the first “tunable” anti-counterfeit materials using the persistent luminescence compound MgGeO₃. This inorganic phosphor material becomes visible under UV light and remains visible for a specific length of time once the UV light is removed. The pattern of light fading can become highly complex as needed, with some shades of light fading and others remaining in a layered fashion for a more extended period. The specific co-dopants they added in their study were Yb³⁺, Eu3⁺, and Li⁺, with Yb³⁺ allowing them to generate signals in the infrared region of the light spectrum.

One of the intriguing aspects of this work is that while persistent luminescent materials were previously available at the micrometer size, their method incorporates nano-sized particles, termed MGO:Mn nanorods, making it much harder to counterfeit. Because of their small size, they could also be integrated into relatively small items.

Azobenzene-containing linear liquid crystal copolymer²

Instead of focusing on two different particle wavelengths, researchers from Fudan University in Shanghai decided to generate what they termed a “dual-mode” pattern using azobenzene-containing linear liquid crystal copolymers (ALCP). The dual-mode pattern represents two images superimposed on one another within a single material. This is a typically challenging process since placing the second image often distorts the first, making it unusable as an anti-counterfeiting measure. Here, they chose ALCP because of its ability to generate sharp images with polarized light and how easy it is to manipulate into distinct patterns.

The team began with a layer of ALCP, which was micropatterned with “FDU” (representing Fudan University), and then cured using a green light. They created a second “layer” of the structural image by stenciling another pattern over the film and exposing it to polarized light, which altered the pattern of the azobenzene molecules. Altogether, this created one pattern (the FDU) visible using ambient light alongside a second pattern that can only be revealed using polarized light. Since the method these scientists used does not physically alter the material’s molecular structure, the image can be later rewritten if needed.

Multilevel QR codes³

The Quick Response (QR) code  is one of the most widely used 2D barcodes throughout healthcare, research, and the industrial sector. They use four standard modes of encoding: numeric, alphanumeric, byte/binary, and kanji. Now, a group of scientists from Soochow University in Suzhou, China, have developed a multilevel version of the QR code composed of a digital polymer that incorporates the stimulus-responsive chromophores spiropyran, rhodamine B, and rhodamine 6G. The barcode works using an initial first level that requires identifying the hidden QR code, such that it becomes visible to the naked eye. Once discovered, a smartphone can be used to perform an initial scan of the QR code, representing the second layer of security. Finally, the encryption provided by the digital polymer can only be solved using tandem mass spectrometry.

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References:

1. Liu Y, et al. Multiband MgGeO3-Based Persistent Luminescent Nanophosphors for Dynamic and Multimodal Anti- ACS Applied Nano Materials. 2024;7(10).
2. Pan F, et al. Dual-Mode Patterns Enabled by Photofluidization of an Azobenzene-Containing Linear Liquid Crystal Copolymer. Langmuir. 2024;40(22).
3. Huang X, et al. Multilevel Anti-counterfeiting Barcode with Enhanced Information Encryption Based on Stimulus-Responsive Digital Polymers. ACS Applied Materials & Interfaces.