A CRISPR-based sensor detected methamphetamine in laboratory experiments and a wearable microfluidic format. The supplied paper does not establish diagnostic accuracy in people using methamphetamine, or validate sweat measurements as evidence of individual impairment.
Wang and colleagues combined drug-binding aptamers, magnetic beads and Cas12a. Binding of methamphetamine or cocaine released a DNA trigger, which activated cleavage of a fluorescent reporter. The assay detected the target small molecules indirectly through that engineered signal chain.
Experiments included tubes, a microfluidic patch and spiked sweat preparations. The methods explicitly described artificial sweat, while some later passages used human-sweat terminology. That inconsistent matrix description should not be converted into a claim of a validated clinical participant study.
The paper reported a calculated methamphetamine detection limit of 27.5 pg/mL for the optimized analytical assay. Visual observation on the patch was assessed separately using ultraviolet illumination and smartphone images.
The abstract and later patch descriptions used differing limits and units. Those statements do not support one unqualified field-detection cutoff. A calculated analytical limit, a visible-signal threshold and clinical sensitivity are different performance characteristics.
Selected substances, including glucose, dopamine and medicines, produced little signal under the tested conditions. That supports specificity against that panel, not against every related drug, metabolite or environmental contaminant.
Further validation would need well-characterized authentic specimens, appropriate reference methods and defined collection and interpretation procedures. The study established no sweat-to-blood conversion, timing-of-use rule or impairment relationship. Its contribution is a laboratory proof of concept for detecting methamphetamine and cocaine, with clear boundaries between analytical development and operational forensic use.
Read our analysis of why specimen results and impairment require separate interpretation.
Point-of-care testing of methamphetamine and cocaine utilizing wearable sensors. doi:10.1016/j.ab.2024.115526.