Development of a point-of-care test for the detection of MDMA in Latent Fingerprints using surface plasmon resonance and lateral flow technology Caroline Pollard 1 , Mark Hudson 2 , James M McDonnell 3 , Paul G Royall 4 , Kim Wolff 1 1 Department of Analytical, Forensic and Environmental Sciences, King’s College London 2 Intelligent Fingerprinting 3 Randall Centre for Cell and Molecular Biophysics, King’s College London 4 Institute of Pharmaceutical Science, King’s College London Introduction. Point-of-care tests (POCTs) are commonly used to detect drugs of abuse 1 . Currently, none exist to detect MDMA specifically in latent fingerprints as the drug is only detected as a cross-reactant thus decreasing the POCT’s sensitivity. Our study’s aim was to design a sensitive POCT for the detection of MDMA in LFPs by combining surface plasmon resonance (SPR) with lateral flow immunoassay (LFA) technology. Utilising POCT to analyse LFPs produces a fast non-invasive screening method which can be applied to a range of scenarios including admission for clubs/festivals and evidence of drug use for police officers. Methods. SPR tested the binding kinetics between the antibody and BSA-conjugate to understand their suitability for a LFA. Once confirmed, titrations of fluorescently labelled anti-MDMA (96 – 144 µg/mL) and BSA-MDMA (11 – 43 ng) concentrations were tested to establish the cut-off (threshold) by producing dose response curves. These were produced by spiking the LFA with MDMA. Cross-reactivity of other amphetamines, such as 3,4-para- Methoxy-N-methylamphetamine (PMMA) and Methylenedioxy-N-ethylamphetamine (MDEA), were also tested. Results. A high affinity binding pair (EC 50 ~ 0.2 nM) was identified confirming the anti-MDMA and BSA-MDMA as suitable for the LFA suggesting that binding was not only quickly but tight. MDMA dose response curve (0 – 400 pg/10 µL) on the LFA showed a sharp drop-in signal upon the addition of MDMA allowing a clear distinction between negative and positive outcomes. Optimum cartridge performance was calculated with a cut-off of 60 pg/10 µL (100% sensitivity, 0.95 specificity and 98% accuracy). PMMA displayed the biggest cross-reactivity (250%) followed by MDEA (183%). Conclusion . A LFA has been developed which detects the presence of MDMA at a reporting screening cut-off of 60 pg/ 10 µL. This assay screening cut-off level will be investigated for performance in future clinical trials. References 1. C. George and A. Pang, in Detection of Drug Miuse: Biomarkers, Analytical Avances and Interpretation , ed. K. Wolff, The Royal Society of Chemistry, UK, 2017, vol. 1, ch. 2, pp. 23-45.
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