Credit: A Cannabinoid Fuel Cell Capable of Producing Current by Oxidizing Δ9-Tetrahydrocannabinol. Di Huang, Christina R. Forbes, Neil K. Garg, Evan R. Darzi. Org. Lett. 2022.
The decriminalization of cannabis has opened the door to public safety concerns, impaired driving chief among them. Unlike alcohol, cannabis can show up in tests days (or even months) after consumption—when altered brain chemistry is no longer a threat. But then how do you ensure fairness in cannabis detection? How do you keep people safe while not infringing on the rights of legal users? Evan Darzi and Neil Garg believe the answer to that question is electrochemistry.
A few years ago, Garg, a distinguished professor at UCLA, was giving a lecture about the fundamental chemistry of the alcohol breathalyzer. An audience member asked why a similar technology did not exist for marijuana—and the spark was lit.
Many conversations, experiments, tests, and innovations in the Garg Research Lab later, and ElectraTect was born. ElectraTect, Inc. was founded in 2020 based on a study published in Organic Letters by Darzi and Garg earlier that year related to the detection of THC. Late last year, the team published another study further detailing the development of the world’s first cannabis fuel cell sensor.
Editor-in-Chief Michelle Taylor recently spoke with ElectraTect co-founder Darzi to learn more about the team’s innovative technology.
Q: The key to your technology is electrochemical oxidation. What can you tell me about that process in THC?
A: The electrochemical oxidation that is core to our technology involves the transformation of the THC phenol to a quinone in a 4e-/4 H+ process. This is analogous to the ethanol to acetaldehyde oxidation at the core of modern alcohol fuel cell sensors. Our strategy was to look at THC oxidation from a fundamental organic chemistry perspective to adapt a chemical oxidation into one that could be done electrochemically. We like this approach because of the analogy to the development of alcohol fuel cell sensors. The fundamental science for alcohol sensors originated in the 1920’s as a colorimetric assay utilizing a chromium complex that turned blue when exposed to ethanol. Over the course of several decades, this oxidation of ethanol to acetic acid by way of acetaldehyde was transformed into the electrochemical fuel cell sensors we have today.
THC is much more complex than ethanol with 21 carbon and 30 protons and the literature surrounding this space was relatively limited. In dissecting the reactivity of THC, we quickly identified the phenol ring as a prime candidate for redox chemistry and possibly a colorimetric change similar to the original alcohol sensors described above. In combing through the literature for phenolic oxidations of cannabinoid we identified a nice cannabinoid oxidation of the phenol to a quinone from one of the stalwarts of cannabis chemistry, Professor Raphael Mechoulum. Inspired by these hypervalent iodide oxidations and the history of alcohol sensor development, we sought to discover an electrolytic system capable of the overall transformation of THC to the corresponding quinone (THCQ).
Q: Could you further explain how your cannabis fuel cell sensor works?
A: In order to develop a THC fuel cell sensor we needed to make another fundamental leap in the technology. Our initial disclosure of the electrolytic oxidation of THC to THCQ in an undivided cell and required that current be applied to promote the oxidative chemistry to occur. However, a fuel cell sensor fundamentally works in a complementary fashion where the oxidation is facilitated by a catalyst and the holes generated by the catalyst generate a measurable current proportional to the concentration of the fuel i.e. THC in a divided cell. We were able to identify a lead catalyst/electrode candidate through the development of a simplified H-Cell. Under these conditions, we were able to produce a current proportional to fuel concentration and were able to show that the oxidation of THC to THCQ was at least in part still operative.
Q: We've been talking about marijuana breathalyzers for more than a few years now. What makes your technology different/unique?
A: Our goal early on in this process was to develop a technology that was analogous to the gold standard for alcohol breath detection. However, developing fuel sensor technology for THC is an extraordinarily difficult undertaking given the chemical complexity of THC. So, rather than screen components of existing fuel cell sensors in a top-down fashion, we approached this problem from the bottom up looking at what fundamental reactivity was necessary at the molecular level to translate into a THC fuel cell sensor.
Q: How did your background in synthetic organic chemistry benefit the creation of your patented technology?
A: Our expertise in synthetic organic chemistry and my PhD experience in organic electronics guided our approach from day one. We started with digging into fundamental chemical oxidations of phenols and slowly built up to the THC fuel cells we have today through rigorous experimentation. Our ability to understand what happens to THC at a molecular level has been crucial to the technology development.
Q: Right now, you have two patents pending. What's next?
A: Now that we have the first cannabinoid fuel cells and associated intellectual property, we are ideally poised to enter the market. We have some R&D in the works, but look out for commercialization within the next two years or so.