A team of scientists from the University of Pavia has developed a cutting-edge voltammetric sensor that can rapidly and selectively detect indazole-type synthetic cannabinoids (SCs) in complex matrices without the need for sample cleanup. This revolutionary technique, detailed in the latest issue of *Analytica Chimica Acta*, harnesses molecularly imprinted polymer (MIP) technology to target a specific class of SCs that pose significant challenges for detection due to their widespread illegal distribution and varied chemical structures.

Published on February 1, 2024, the research article titled “Molecularly Imprinted Polymer-based voltammetric sensor for amino acids/indazole derivatives synthetic cannabinoids detection” provides a comprehensive study outlining the preparation, optimization, and application of the MIP-based sensor. Daniele Merli and colleagues at the Department of Chemistry, University of Pavia, have showcased how this novel approach could shape the future of forensic sciences by enabling rapid on-site drug testing.

The Need for Rapid Detection of Synthetic Cannabinoids

The use of synthetic cannabinoids has risen globally, presenting a significant challenge for law enforcement and public health agencies. These designer drugs mimic the psychoactive effects of Δ9-tetrahydrocannabinol (THC), the active component in cannabis, but can be much more potent and unpredictable, leading to severe health implications. Their diverse chemical structures—centered around aromatic cores like indole, imidazole, and pyrrole—complicate detection methods, especially when dealing with complex samples. A reliable, quick, and specific detection method is crucial for immediate action and focused subsequent analysis.

Leveraging Molecularly Imprinted Polymers for Selective Detection

MIPs are synthetic polymers designed to recognize specific target molecules, making them perfect for applications in sensor technology. The researchers at the University of Pavia optimized a polyacrylate-based MIP to functionalize a platinum electrode, which served as the sensing element for the voltammetric sensor. The team employed a non-psychotropic compound structurally related to indazole-type SCs as the template to ensure safety during the MIP formulation. By applying a Design of Experiments approach, the MIP composition was fine-tuned for maximum performance.

Understanding the Sensor Design and Function

The primary technique used in this study, differential pulse voltammetry (DPV), involved electrochemical measurements in acetonitrile/lithium perchlorate 0.1 M medium. This approach enabled the quantification of selected SCs with a limit of detection (LOD) of around 0.01 mM and linearity up to 0.8 mM, demonstrating high sensitivity. The researchers performed a thorough characterisation of the electrochemical behavior of the SCs to ensure accurate and precise readings.

Performance and Reliability of the Voltammetric Sensor

The performance of the MIP-based sensor was tested by comparison with non-imprinted polymer (NIP) modified and bare electrodes, revealing enhanced selectivity and reproducibility. Importantly, recovery tests conducted on simulated pills and smoking mixtures yielded results in the 70-115 % range, validating the method’s reliability. The sensor demonstrated the ability to identify and quantify indazole-based SCs as a class in complex samples without previous sample cleanup, showcasing the elimination of interferences from cutting substances and natural cannabinoids.

The Impact on Forensic Science and Public Safety

The implications of this research are far-reaching for forensic science and public safety. On-site detection of SCs can facilitate faster responses by law enforcement and potentially mitigate the spread of these hazardous substances. Furthermore, the ability to differentiate between SCs and natural cannabinoids can streamline legal proceedings by providing clear evidence in drug-related cases.

Concerns and Future Directions

While this research has made significant strides in detecting SCs, the authors acknowledge that continued efforts are needed to expand the sensor’s capabilities to other classes of SCs. Additionally, long-term studies on the durability and reusability of the sensor in various environmental conditions would fortify its application in forensic contexts.

Conclusions

The development of the MIP-based voltametric sensor by the team at the University of Pavia marks a significant advancement in the detection of indazole-type synthetic cannabinoids. With its high sensitivity, selectivity, and rapid performance, this sensor is poised to become an instrumental tool in combating the illegal SC trade and enhancing public health measures.

DOI: 10.1016/j.aca.2023.342151

References

1. Merli, D., Lio, E., Protti, S., Coccia, R., Profumo, A., & Alberti, G. (2024). Molecularly Imprinted Polymer-based voltammetric sensor for amino acids/indazole derivatives synthetic cannabinoids detection. Analytica Chimica Acta, 1288, 342151. https://doi.org/10.1016/j.aca.2023.342151

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Keywords

1. Synthetic Cannabinoids Detection
2. Molecularly Imprinted Polymer Sensor
3. Voltammetric Sensor for Drugs
4. Indazole-based SCs Analysis
5. Electrochemical Drug Testing