Synthetic cannabinoids, a class of new psychoactive substances, bind to cannabinoid receptors CB1 and CB2 much more strongly than tetrahydrocannabinol (THC) and cannabidiol (CBD), raising public health concerns due to their toxicity and addiction risk.

Current detection methods mainly use advanced techniques like high-performance liquid chromatography-mass spectrometry (HPLC-MS), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR), which are accurate but time-consuming and require complex equipment.

In contrast, visual detection methods such as colorimetry and fluorescence are quicker and easier to interpret, making them better for on-site use. However, there is still a need for visual detection techniques specifically targeting MDMB-CA series synthetic cannabinoids.

To address this challenge, researchers from the Xinjiang Technical Institute of Physics and Chemistry of the Chinese Academy of Sciences have developed an innovative zinc(II)-enhanced excimer fluorescence probe. Utilizing a conjugation modulation and metal-bridging strategy, the probe achieves highly specific recognition of MDMB-CA series synthetic cannabinoids through multiple non-covalent interactions.

Theoretical analysis revealed that the ratiometric fluorescence emission results from a transition from excimer emission to fluorescence resonance energy transfer (FRET)-based emission, elucidating the optical response mechanism.

The work is published in the journal Angewandte Chemie International Edition.

Experimental results demonstrate that the probe can specifically detect multiple MDMB-CA series synthetic cannabinoids within five seconds, with no interference from 14 potentially confounding substances. The team further developed a portable detection chip integrating extraction and enrichment functions, enabling accurate detection of synthetic cannabinoids in complex matrices such as e-cigarette oil and tobacco leaves. Additionally, the probe is capable of detecting synthetic cannabinoids and their metabolites in urine samples.

This study introduces a novel excimer fluorescence probe based on conjugation modulation and metal-bridging strategies, offering a new approach for the detection and identification of synthetic cannabinoids. Beyond advancing the field of synthetic cannabinoid detection, this research also contributes to the broader development of sensing probes and provides new insights for accurately detecting structurally diverse and weakly reactive chemical substances.